v3.25.4
Shareholder Report
12 Months Ended
Dec. 31, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSR
Amendment Flag false
Registrant Name BlackRock Funds III
Entity Central Index Key 0000893818
Entity Investment Company Type N-1A
Document Period End Date Dec. 31, 2025
C000101136 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index Retirement Fund
Class Name Class K Shares
Trading Symbol LIRKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index Retirement Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $7(a) 0.07%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 7 [1]
Expense Ratio, Percent 0.07% [1]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 12.48%.
  • For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index returned 7.30% and the Russell 1000® Index returned 17.37%. The LifePath Index Retirement Fund Custom Benchmark returned 12.55%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Class K Shares 12.48 % 4.02 % 6.00 %
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
Russell 1000® Index 17.37 13.59 14.59
LifePath Index Retirement Fund Custom Benchmark 12.55 4.11 6.08
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index Retirement Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index Retirement Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 13,180,541,904
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 3,435,086
Investment Company Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $13,180,541,904
Number of Portfolio Holdings 13
Net Investment Advisory Fees $3,435,086
Portfolio Turnover Rate 17%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Fixed-Income Funds 59.9 %
Equity Funds 40.1 %
Money Market Funds %(a)
Other Assets Less Liabilities
(a)
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 22.6 %
iShares U.S. Intermediate Government Bond Index Fund 21.2 %
iShares U.S. Securitized Bond Index Fund 13.1 %
iShares Core MSCI Total International Stock ETF 12.7 %
iShares 0-5 Year TIPS Bond ETF 9.7 %
iShares U.S. Long Government Bond Index Fund 7.1 %
iShares U.S. Intermediate Credit Bond Index Fund 6.5 %
iShares U.S. Long Credit Bond Index Fund 2.3 %
iShares Enhanced Roll Yield Index Fund 2.2 %
iShares Global Infrastructure ETF 1.5 %
(a)
Rounds to less than 0.1%.
(b)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 22.6 %
iShares U.S. Intermediate Government Bond Index Fund 21.2 %
iShares U.S. Securitized Bond Index Fund 13.1 %
iShares Core MSCI Total International Stock ETF 12.7 %
iShares 0-5 Year TIPS Bond ETF 9.7 %
iShares U.S. Long Government Bond Index Fund 7.1 %
iShares U.S. Intermediate Credit Bond Index Fund 6.5 %
iShares U.S. Long Credit Bond Index Fund 2.3 %
iShares Enhanced Roll Yield Index Fund 2.2 %
iShares Global Infrastructure ETF 1.5 %
(b)Excludes short-term securities.
C000201968 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index Retirement Fund
Class Name Investor P Shares
Trading Symbol LIRPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index Retirement Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $39(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 39 [2]
Expense Ratio, Percent 0.37% [2]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 12.17%.
  • For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index returned 7.30% and the Russell 1000® Index returned 17.37%. The LifePath Index Retirement Fund Custom Benchmark returned 12.55%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor P Shares 12.17 % 3.72 % 5.70 %
Investor P Shares (with sales charge) 6.28 2.60 5.13
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
Russell 1000® Index 17.37 13.59 14.59
LifePath Index Retirement Fund Custom Benchmark 12.55 4.11 6.08
Performance Inception Date Aug. 06, 2018
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index Retirement Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index Retirement Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 13,180,541,904
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 3,435,086
Investment Company Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $13,180,541,904
Number of Portfolio Holdings 13
Net Investment Advisory Fees $3,435,086
Portfolio Turnover Rate 17%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Fixed-Income Funds 59.9 %
Equity Funds 40.1 %
Money Market Funds %(a)
Other Assets Less Liabilities
(a)
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 22.6 %
iShares U.S. Intermediate Government Bond Index Fund 21.2 %
iShares U.S. Securitized Bond Index Fund 13.1 %
iShares Core MSCI Total International Stock ETF 12.7 %
iShares 0-5 Year TIPS Bond ETF 9.7 %
iShares U.S. Long Government Bond Index Fund 7.1 %
iShares U.S. Intermediate Credit Bond Index Fund 6.5 %
iShares U.S. Long Credit Bond Index Fund 2.3 %
iShares Enhanced Roll Yield Index Fund 2.2 %
iShares Global Infrastructure ETF 1.5 %
(a)
Rounds to less than 0.1%.
(b)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 22.6 %
iShares U.S. Intermediate Government Bond Index Fund 21.2 %
iShares U.S. Securitized Bond Index Fund 13.1 %
iShares Core MSCI Total International Stock ETF 12.7 %
iShares 0-5 Year TIPS Bond ETF 9.7 %
iShares U.S. Long Government Bond Index Fund 7.1 %
iShares U.S. Intermediate Credit Bond Index Fund 6.5 %
iShares U.S. Long Credit Bond Index Fund 2.3 %
iShares Enhanced Roll Yield Index Fund 2.2 %
iShares Global Infrastructure ETF 1.5 %
(b)Excludes short-term securities.
C000101134 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index Retirement Fund
Class Name Investor A Shares
Trading Symbol LIRAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index Retirement Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $39(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 39 [3]
Expense Ratio, Percent 0.37% [3]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 12.10%.
  • For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index returned 7.30% and the Russell 1000® Index returned 17.37%. The LifePath Index Retirement Fund Custom Benchmark returned 12.55%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor A Shares 12.10 % 3.71 % 5.69 %
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
Russell 1000® Index 17.37 13.59 14.59
LifePath Index Retirement Fund Custom Benchmark 12.55 4.11 6.08
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index Retirement Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index Retirement Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 13,180,541,904
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 3,435,086
Investment Company Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $13,180,541,904
Number of Portfolio Holdings 13
Net Investment Advisory Fees $3,435,086
Portfolio Turnover Rate 17%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Fixed-Income Funds 59.9 %
Equity Funds 40.1 %
Money Market Funds %(a)
Other Assets Less Liabilities
(a)
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 22.6 %
iShares U.S. Intermediate Government Bond Index Fund 21.2 %
iShares U.S. Securitized Bond Index Fund 13.1 %
iShares Core MSCI Total International Stock ETF 12.7 %
iShares 0-5 Year TIPS Bond ETF 9.7 %
iShares U.S. Long Government Bond Index Fund 7.1 %
iShares U.S. Intermediate Credit Bond Index Fund 6.5 %
iShares U.S. Long Credit Bond Index Fund 2.3 %
iShares Enhanced Roll Yield Index Fund 2.2 %
iShares Global Infrastructure ETF 1.5 %
(a)
Rounds to less than 0.1%.
(b)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 22.6 %
iShares U.S. Intermediate Government Bond Index Fund 21.2 %
iShares U.S. Securitized Bond Index Fund 13.1 %
iShares Core MSCI Total International Stock ETF 12.7 %
iShares 0-5 Year TIPS Bond ETF 9.7 %
iShares U.S. Long Government Bond Index Fund 7.1 %
iShares U.S. Intermediate Credit Bond Index Fund 6.5 %
iShares U.S. Long Credit Bond Index Fund 2.3 %
iShares Enhanced Roll Yield Index Fund 2.2 %
iShares Global Infrastructure ETF 1.5 %
(b)Excludes short-term securities.
C000101135 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index Retirement Fund
Class Name Institutional Shares
Trading Symbol LIRIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index Retirement Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $13(a) 0.12%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 13 [4]
Expense Ratio, Percent 0.12% [4]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 12.41%.
  • For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index returned 7.30% and the Russell 1000® Index returned 17.37%. The LifePath Index Retirement Fund Custom Benchmark returned 12.55%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Institutional Shares 12.41 % 3.97 % 5.96 %
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
Russell 1000® Index 17.37 13.59 14.59
LifePath Index Retirement Fund Custom Benchmark 12.55 4.11 6.08
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index Retirement Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index Retirement Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 13,180,541,904
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 3,435,086
Investment Company Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $13,180,541,904
Number of Portfolio Holdings 13
Net Investment Advisory Fees $3,435,086
Portfolio Turnover Rate 17%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Fixed-Income Funds 59.9 %
Equity Funds 40.1 %
Money Market Funds %(a)
Other Assets Less Liabilities
(a)
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 22.6 %
iShares U.S. Intermediate Government Bond Index Fund 21.2 %
iShares U.S. Securitized Bond Index Fund 13.1 %
iShares Core MSCI Total International Stock ETF 12.7 %
iShares 0-5 Year TIPS Bond ETF 9.7 %
iShares U.S. Long Government Bond Index Fund 7.1 %
iShares U.S. Intermediate Credit Bond Index Fund 6.5 %
iShares U.S. Long Credit Bond Index Fund 2.3 %
iShares Enhanced Roll Yield Index Fund 2.2 %
iShares Global Infrastructure ETF 1.5 %
(a)
Rounds to less than 0.1%.
(b)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 22.6 %
iShares U.S. Intermediate Government Bond Index Fund 21.2 %
iShares U.S. Securitized Bond Index Fund 13.1 %
iShares Core MSCI Total International Stock ETF 12.7 %
iShares 0-5 Year TIPS Bond ETF 9.7 %
iShares U.S. Long Government Bond Index Fund 7.1 %
iShares U.S. Intermediate Credit Bond Index Fund 6.5 %
iShares U.S. Long Credit Bond Index Fund 2.3 %
iShares Enhanced Roll Yield Index Fund 2.2 %
iShares Global Infrastructure ETF 1.5 %
(b)Excludes short-term securities.
C000101144 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2030 Fund
Class Name Institutional Shares
Trading Symbol LINIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2030 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $13(a) 0.12%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 13 [5]
Expense Ratio, Percent 0.12% [5]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 14.12%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2030 Fund Custom Benchmark returned 14.29%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Institutional Shares 14.12 % 5.83 % 7.89 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2030 Fund Custom Benchmark 14.29 5.95 7.99
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2030 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2030 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 13,533,216,634
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 2,640,827
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $13,533,216,634
Number of Portfolio Holdings 13
Net Investment Advisory Fees $2,640,827
Portfolio Turnover Rate 21%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 51.0 %
Fixed-Income Funds 49.0 %
Money Market Funds 0.1 %
Liabilities in Excess of Other Assets (0.1 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 28.6 %
iShares Core MSCI Total International Stock ETF 17.4 %
iShares U.S. Intermediate Government Bond Index Fund 14.3 %
iShares U.S. Securitized Bond Index Fund 10.7 %
iShares 0-5 Year TIPS Bond ETF 7.9 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 6.0 %
iShares U.S. Long Credit Bond Index Fund 2.5 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.8 %
iShares Global Infrastructure ETF 1.6 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 28.6 %
iShares Core MSCI Total International Stock ETF 17.4 %
iShares U.S. Intermediate Government Bond Index Fund 14.3 %
iShares U.S. Securitized Bond Index Fund 10.7 %
iShares 0-5 Year TIPS Bond ETF 7.9 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 6.0 %
iShares U.S. Long Credit Bond Index Fund 2.5 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.8 %
iShares Global Infrastructure ETF 1.6 %
(a)
Excludes short-term securities.
C000101143 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2030 Fund
Class Name Investor A Shares
Trading Symbol LINAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2030 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $40(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 40 [6]
Expense Ratio, Percent 0.37% [6]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 13.91%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2030 Fund Custom Benchmark returned 14.29%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor A Shares 13.91 % 5.58 % 7.64 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2030 Fund Custom Benchmark 14.29 5.95 7.99
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2030 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2030 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 13,533,216,634
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 2,640,827
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $13,533,216,634
Number of Portfolio Holdings 13
Net Investment Advisory Fees $2,640,827
Portfolio Turnover Rate 21%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 51.0 %
Fixed-Income Funds 49.0 %
Money Market Funds 0.1 %
Liabilities in Excess of Other Assets (0.1 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 28.6 %
iShares Core MSCI Total International Stock ETF 17.4 %
iShares U.S. Intermediate Government Bond Index Fund 14.3 %
iShares U.S. Securitized Bond Index Fund 10.7 %
iShares 0-5 Year TIPS Bond ETF 7.9 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 6.0 %
iShares U.S. Long Credit Bond Index Fund 2.5 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.8 %
iShares Global Infrastructure ETF 1.6 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 28.6 %
iShares Core MSCI Total International Stock ETF 17.4 %
iShares U.S. Intermediate Government Bond Index Fund 14.3 %
iShares U.S. Securitized Bond Index Fund 10.7 %
iShares 0-5 Year TIPS Bond ETF 7.9 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 6.0 %
iShares U.S. Long Credit Bond Index Fund 2.5 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.8 %
iShares Global Infrastructure ETF 1.6 %
(a)
Excludes short-term securities.
C000201971 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2030 Fund
Class Name Investor P Shares
Trading Symbol LIDPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2030 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $40(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 40 [7]
Expense Ratio, Percent 0.37% [7]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 13.86%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2030 Fund Custom Benchmark returned 14.29%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor P Shares 13.86 % 5.57 % 7.63 %
Investor P Shares (with sales charge) 7.88 4.44 7.05
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2030 Fund Custom Benchmark 14.29 5.95 7.99
Performance Inception Date Aug. 06, 2018
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2030 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2030 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 13,533,216,634
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 2,640,827
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $13,533,216,634
Number of Portfolio Holdings 13
Net Investment Advisory Fees $2,640,827
Portfolio Turnover Rate 21%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 51.0 %
Fixed-Income Funds 49.0 %
Money Market Funds 0.1 %
Liabilities in Excess of Other Assets (0.1 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 28.6 %
iShares Core MSCI Total International Stock ETF 17.4 %
iShares U.S. Intermediate Government Bond Index Fund 14.3 %
iShares U.S. Securitized Bond Index Fund 10.7 %
iShares 0-5 Year TIPS Bond ETF 7.9 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 6.0 %
iShares U.S. Long Credit Bond Index Fund 2.5 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.8 %
iShares Global Infrastructure ETF 1.6 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 28.6 %
iShares Core MSCI Total International Stock ETF 17.4 %
iShares U.S. Intermediate Government Bond Index Fund 14.3 %
iShares U.S. Securitized Bond Index Fund 10.7 %
iShares 0-5 Year TIPS Bond ETF 7.9 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 6.0 %
iShares U.S. Long Credit Bond Index Fund 2.5 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.8 %
iShares Global Infrastructure ETF 1.6 %
(a)
Excludes short-term securities.
C000101145 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2030 Fund
Class Name Class K Shares
Trading Symbol LINKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2030 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $8(a) 0.07%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 8 [8]
Expense Ratio, Percent 0.07% [8]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 14.19%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2030 Fund Custom Benchmark returned 14.29%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Class K Shares 14.19 % 5.89 % 7.95 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2030 Fund Custom Benchmark 14.29 5.95 7.99
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2030 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2030 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 13,533,216,634
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 2,640,827
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $13,533,216,634
Number of Portfolio Holdings 13
Net Investment Advisory Fees $2,640,827
Portfolio Turnover Rate 21%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 51.0 %
Fixed-Income Funds 49.0 %
Money Market Funds 0.1 %
Liabilities in Excess of Other Assets (0.1 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 28.6 %
iShares Core MSCI Total International Stock ETF 17.4 %
iShares U.S. Intermediate Government Bond Index Fund 14.3 %
iShares U.S. Securitized Bond Index Fund 10.7 %
iShares 0-5 Year TIPS Bond ETF 7.9 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 6.0 %
iShares U.S. Long Credit Bond Index Fund 2.5 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.8 %
iShares Global Infrastructure ETF 1.6 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 28.6 %
iShares Core MSCI Total International Stock ETF 17.4 %
iShares U.S. Intermediate Government Bond Index Fund 14.3 %
iShares U.S. Securitized Bond Index Fund 10.7 %
iShares 0-5 Year TIPS Bond ETF 7.9 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 6.0 %
iShares U.S. Long Credit Bond Index Fund 2.5 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.8 %
iShares Global Infrastructure ETF 1.6 %
(a)
Excludes short-term securities.
C000101148 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2035 Fund
Class Name Class K Shares
Trading Symbol LIJKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2035 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $8(a) 0.07%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 8 [9]
Expense Ratio, Percent 0.07% [9]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 16.09%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2035 Fund Custom Benchmark returned 16.08%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Class K Shares 16.09 % 7.23 % 9.01 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2035 Fund Custom Benchmark 16.08 7.26 9.03
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2035 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2035 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 11,620,250,893
Holdings Count | Holding 12
Advisory Fees Paid, Amount $ 1,707,902
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $11,620,250,893
Number of Portfolio Holdings 12
Net Investment Advisory Fees $1,707,902
Portfolio Turnover Rate 19%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 62.9 %
Fixed-Income Funds 37.1 %
Liabilities in Excess of Other Assets (— )(a)
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 35.1 %
iShares Core MSCI Total International Stock ETF 22.4 %
iShares U.S. Intermediate Government Bond Index Fund 12.0 %
iShares U.S. Securitized Bond Index Fund 9.5 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 4.5 %
iShares U.S. Long Credit Bond Index Fund 2.9 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.6 %
iShares Global Infrastructure ETF 1.8 %
Master Small Cap Index Series 1.0 %
(a)
Rounds to greater than (0.1)%.
(b)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 35.1 %
iShares Core MSCI Total International Stock ETF 22.4 %
iShares U.S. Intermediate Government Bond Index Fund 12.0 %
iShares U.S. Securitized Bond Index Fund 9.5 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 4.5 %
iShares U.S. Long Credit Bond Index Fund 2.9 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.6 %
iShares Global Infrastructure ETF 1.8 %
Master Small Cap Index Series 1.0 %
(b)Excludes short-term securities.
C000201972 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2035 Fund
Class Name Investor P Shares
Trading Symbol LIJPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2035 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $40(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 40 [10]
Expense Ratio, Percent 0.37% [10]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 15.69%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2035 Fund Custom Benchmark returned 16.08%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor P Shares 15.69 % 6.91 % 8.68 %
Investor P Shares (with sales charge) 9.62 5.76 8.10
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2035 Fund Custom Benchmark 16.08 7.26 9.03
Performance Inception Date Aug. 06, 2018
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2035 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2035 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 11,620,250,893
Holdings Count | Holding 12
Advisory Fees Paid, Amount $ 1,707,902
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $11,620,250,893
Number of Portfolio Holdings 12
Net Investment Advisory Fees $1,707,902
Portfolio Turnover Rate 19%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 62.9 %
Fixed-Income Funds 37.1 %
Liabilities in Excess of Other Assets (— )(a)
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 35.1 %
iShares Core MSCI Total International Stock ETF 22.4 %
iShares U.S. Intermediate Government Bond Index Fund 12.0 %
iShares U.S. Securitized Bond Index Fund 9.5 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 4.5 %
iShares U.S. Long Credit Bond Index Fund 2.9 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.6 %
iShares Global Infrastructure ETF 1.8 %
Master Small Cap Index Series 1.0 %
(a)
Rounds to greater than (0.1)%.
(b)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 35.1 %
iShares Core MSCI Total International Stock ETF 22.4 %
iShares U.S. Intermediate Government Bond Index Fund 12.0 %
iShares U.S. Securitized Bond Index Fund 9.5 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 4.5 %
iShares U.S. Long Credit Bond Index Fund 2.9 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.6 %
iShares Global Infrastructure ETF 1.8 %
Master Small Cap Index Series 1.0 %
(b)Excludes short-term securities.
C000101146 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2035 Fund
Class Name Investor A Shares
Trading Symbol LIJAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2035 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $40(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 40 [11]
Expense Ratio, Percent 0.37% [11]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 15.70%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2035 Fund Custom Benchmark returned 16.08%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor A Shares 15.70 % 6.91 % 8.68 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2035 Fund Custom Benchmark 16.08 7.26 9.03
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2035 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2035 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 11,620,250,893
Holdings Count | Holding 12
Advisory Fees Paid, Amount $ 1,707,902
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $11,620,250,893
Number of Portfolio Holdings 12
Net Investment Advisory Fees $1,707,902
Portfolio Turnover Rate 19%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 62.9 %
Fixed-Income Funds 37.1 %
Liabilities in Excess of Other Assets (— )(a)
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 35.1 %
iShares Core MSCI Total International Stock ETF 22.4 %
iShares U.S. Intermediate Government Bond Index Fund 12.0 %
iShares U.S. Securitized Bond Index Fund 9.5 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 4.5 %
iShares U.S. Long Credit Bond Index Fund 2.9 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.6 %
iShares Global Infrastructure ETF 1.8 %
Master Small Cap Index Series 1.0 %
(a)
Rounds to greater than (0.1)%.
(b)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 35.1 %
iShares Core MSCI Total International Stock ETF 22.4 %
iShares U.S. Intermediate Government Bond Index Fund 12.0 %
iShares U.S. Securitized Bond Index Fund 9.5 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 4.5 %
iShares U.S. Long Credit Bond Index Fund 2.9 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.6 %
iShares Global Infrastructure ETF 1.8 %
Master Small Cap Index Series 1.0 %
(b)Excludes short-term securities.
C000101147 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2035 Fund
Class Name Institutional Shares
Trading Symbol LIJIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2035 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $13(a) 0.12%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 13 [12]
Expense Ratio, Percent 0.12% [12]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 16.02%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2035 Fund Custom Benchmark returned 16.08%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Institutional Shares 16.02 % 7.19 % 8.95 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2035 Fund Custom Benchmark 16.08 7.26 9.03
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2035 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2035 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 11,620,250,893
Holdings Count | Holding 12
Advisory Fees Paid, Amount $ 1,707,902
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $11,620,250,893
Number of Portfolio Holdings 12
Net Investment Advisory Fees $1,707,902
Portfolio Turnover Rate 19%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 62.9 %
Fixed-Income Funds 37.1 %
Liabilities in Excess of Other Assets (— )(a)
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 35.1 %
iShares Core MSCI Total International Stock ETF 22.4 %
iShares U.S. Intermediate Government Bond Index Fund 12.0 %
iShares U.S. Securitized Bond Index Fund 9.5 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 4.5 %
iShares U.S. Long Credit Bond Index Fund 2.9 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.6 %
iShares Global Infrastructure ETF 1.8 %
Master Small Cap Index Series 1.0 %
(a)
Rounds to greater than (0.1)%.
(b)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(b) Percent of
Net Assets
Large Cap Index Master Portfolio 35.1 %
iShares Core MSCI Total International Stock ETF 22.4 %
iShares U.S. Intermediate Government Bond Index Fund 12.0 %
iShares U.S. Securitized Bond Index Fund 9.5 %
iShares U.S. Intermediate Credit Bond Index Fund 7.6 %
iShares U.S. Long Government Bond Index Fund 4.5 %
iShares U.S. Long Credit Bond Index Fund 2.9 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.6 %
iShares Global Infrastructure ETF 1.8 %
Master Small Cap Index Series 1.0 %
(b)Excludes short-term securities.
C000101150 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2040 Fund
Class Name Institutional Shares
Trading Symbol LIKIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2040 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $12(a) 0.11%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 12 [13]
Expense Ratio, Percent 0.11% [13]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 17.60%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2040 Fund Custom Benchmark returned 17.68%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Institutional Shares 17.60 % 8.42 % 9.89 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2040 Fund Custom Benchmark 17.68 8.48 9.96
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2040 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, Bloomberg Enhanced Roll Yield Total Return Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2040 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 14,627,170,300
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 1,401,698
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $14,627,170,300
Number of Portfolio Holdings 13
Net Investment Advisory Fees $1,401,698
Portfolio Turnover Rate 16%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 74.6 %
Fixed-Income Funds 25.4 %
Money Market Funds 0.2 %
Liabilities in Excess of Other Assets (0.2 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 40.8 %
iShares Core MSCI Total International Stock ETF 26.8 %
iShares U.S. Intermediate Government Bond Index Fund 7.4 %
iShares U.S. Securitized Bond Index Fund 6.6 %
iShares U.S. Intermediate Credit Bond Index Fund 4.5 %
iShares U.S. Long Government Bond Index Fund 3.4 %
iShares FTSE NAREIT All Equity REITs Index Fund 3.3 %
iShares U.S. Long Credit Bond Index Fund 3.2 %
iShares Global Infrastructure ETF 2.0 %
Master Small Cap Index Series 1.7 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 40.8 %
iShares Core MSCI Total International Stock ETF 26.8 %
iShares U.S. Intermediate Government Bond Index Fund 7.4 %
iShares U.S. Securitized Bond Index Fund 6.6 %
iShares U.S. Intermediate Credit Bond Index Fund 4.5 %
iShares U.S. Long Government Bond Index Fund 3.4 %
iShares FTSE NAREIT All Equity REITs Index Fund 3.3 %
iShares U.S. Long Credit Bond Index Fund 3.2 %
iShares Global Infrastructure ETF 2.0 %
Master Small Cap Index Series 1.7 %
(a)
Excludes short-term securities.
C000101149 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2040 Fund
Class Name Investor A Shares
Trading Symbol LIKAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2040 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $39(a) 0.36%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 39 [14]
Expense Ratio, Percent 0.36% [14]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 17.27%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2040 Fund Custom Benchmark returned 17.68%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor A Shares 17.27 % 8.14 % 9.62 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2040 Fund Custom Benchmark 17.68 8.48 9.96
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2040 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, Bloomberg Enhanced Roll Yield Total Return Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2040 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 14,627,170,300
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 1,401,698
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $14,627,170,300
Number of Portfolio Holdings 13
Net Investment Advisory Fees $1,401,698
Portfolio Turnover Rate 16%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 74.6 %
Fixed-Income Funds 25.4 %
Money Market Funds 0.2 %
Liabilities in Excess of Other Assets (0.2 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 40.8 %
iShares Core MSCI Total International Stock ETF 26.8 %
iShares U.S. Intermediate Government Bond Index Fund 7.4 %
iShares U.S. Securitized Bond Index Fund 6.6 %
iShares U.S. Intermediate Credit Bond Index Fund 4.5 %
iShares U.S. Long Government Bond Index Fund 3.4 %
iShares FTSE NAREIT All Equity REITs Index Fund 3.3 %
iShares U.S. Long Credit Bond Index Fund 3.2 %
iShares Global Infrastructure ETF 2.0 %
Master Small Cap Index Series 1.7 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 40.8 %
iShares Core MSCI Total International Stock ETF 26.8 %
iShares U.S. Intermediate Government Bond Index Fund 7.4 %
iShares U.S. Securitized Bond Index Fund 6.6 %
iShares U.S. Intermediate Credit Bond Index Fund 4.5 %
iShares U.S. Long Government Bond Index Fund 3.4 %
iShares FTSE NAREIT All Equity REITs Index Fund 3.3 %
iShares U.S. Long Credit Bond Index Fund 3.2 %
iShares Global Infrastructure ETF 2.0 %
Master Small Cap Index Series 1.7 %
(a)
Excludes short-term securities.
C000201973 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2040 Fund
Class Name Investor P Shares
Trading Symbol LIKPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2040 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $39(a) 0.36%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 39 [15]
Expense Ratio, Percent 0.36% [15]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 17.33%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2040 Fund Custom Benchmark returned 17.68%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor P Shares 17.33 % 8.16 % 9.62 %
Investor P Shares (with sales charge) 11.17 7.00 9.03
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2040 Fund Custom Benchmark 17.68 8.48 9.96
Performance Inception Date Aug. 06, 2018
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2040 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, Bloomberg Enhanced Roll Yield Total Return Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2040 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 14,627,170,300
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 1,401,698
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $14,627,170,300
Number of Portfolio Holdings 13
Net Investment Advisory Fees $1,401,698
Portfolio Turnover Rate 16%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 74.6 %
Fixed-Income Funds 25.4 %
Money Market Funds 0.2 %
Liabilities in Excess of Other Assets (0.2 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 40.8 %
iShares Core MSCI Total International Stock ETF 26.8 %
iShares U.S. Intermediate Government Bond Index Fund 7.4 %
iShares U.S. Securitized Bond Index Fund 6.6 %
iShares U.S. Intermediate Credit Bond Index Fund 4.5 %
iShares U.S. Long Government Bond Index Fund 3.4 %
iShares FTSE NAREIT All Equity REITs Index Fund 3.3 %
iShares U.S. Long Credit Bond Index Fund 3.2 %
iShares Global Infrastructure ETF 2.0 %
Master Small Cap Index Series 1.7 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 40.8 %
iShares Core MSCI Total International Stock ETF 26.8 %
iShares U.S. Intermediate Government Bond Index Fund 7.4 %
iShares U.S. Securitized Bond Index Fund 6.6 %
iShares U.S. Intermediate Credit Bond Index Fund 4.5 %
iShares U.S. Long Government Bond Index Fund 3.4 %
iShares FTSE NAREIT All Equity REITs Index Fund 3.3 %
iShares U.S. Long Credit Bond Index Fund 3.2 %
iShares Global Infrastructure ETF 2.0 %
Master Small Cap Index Series 1.7 %
(a)
Excludes short-term securities.
C000101151 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2040 Fund
Class Name Class K Shares
Trading Symbol LIKKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2040 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $7(a) 0.06%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 7 [16]
Expense Ratio, Percent 0.06% [16]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 17.66%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2040 Fund Custom Benchmark returned 17.68%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Class K Shares 17.66 % 8.48 % 9.95 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2040 Fund Custom Benchmark 17.68 8.48 9.96
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2040 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, Bloomberg Enhanced Roll Yield Total Return Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2040 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 14,627,170,300
Holdings Count | Holding 13
Advisory Fees Paid, Amount $ 1,401,698
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $14,627,170,300
Number of Portfolio Holdings 13
Net Investment Advisory Fees $1,401,698
Portfolio Turnover Rate 16%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 74.6 %
Fixed-Income Funds 25.4 %
Money Market Funds 0.2 %
Liabilities in Excess of Other Assets (0.2 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 40.8 %
iShares Core MSCI Total International Stock ETF 26.8 %
iShares U.S. Intermediate Government Bond Index Fund 7.4 %
iShares U.S. Securitized Bond Index Fund 6.6 %
iShares U.S. Intermediate Credit Bond Index Fund 4.5 %
iShares U.S. Long Government Bond Index Fund 3.4 %
iShares FTSE NAREIT All Equity REITs Index Fund 3.3 %
iShares U.S. Long Credit Bond Index Fund 3.2 %
iShares Global Infrastructure ETF 2.0 %
Master Small Cap Index Series 1.7 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 40.8 %
iShares Core MSCI Total International Stock ETF 26.8 %
iShares U.S. Intermediate Government Bond Index Fund 7.4 %
iShares U.S. Securitized Bond Index Fund 6.6 %
iShares U.S. Intermediate Credit Bond Index Fund 4.5 %
iShares U.S. Long Government Bond Index Fund 3.4 %
iShares FTSE NAREIT All Equity REITs Index Fund 3.3 %
iShares U.S. Long Credit Bond Index Fund 3.2 %
iShares Global Infrastructure ETF 2.0 %
Master Small Cap Index Series 1.7 %
(a)
Excludes short-term securities.
C000101154 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2045 Fund
Class Name Class K Shares
Trading Symbol LIHKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2045 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $8(a) 0.07%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 8 [17]
Expense Ratio, Percent 0.07% [17]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 19.10%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2045 Fund Custom Benchmark returned 19.15%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Class K Shares 19.10 % 9.61 % 10.75 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2045 Fund Custom Benchmark 19.15 9.58 10.74
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2045 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure Index® (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2045 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 10,670,393,292
Holdings Count | Holding 12
Advisory Fees Paid, Amount $ 1,118,928
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $10,670,393,292
Number of Portfolio Holdings 12
Net Investment Advisory Fees $1,118,928
Portfolio Turnover Rate 16%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 85.1 %
Fixed-Income Funds 14.9 %
Money Market Funds %(a)
Liabilities in Excess of Other Assets ( )(b)
Ten largest holdings
Security(c) Percent of
Net Assets
Large Cap Index Master Portfolio 46.2 %
iShares Core MSCI Total International Stock ETF 31.7 %
iShares FTSE NAREIT All Equity REITs Index Fund 4.1 %
iShares U.S. Securitized Bond Index Fund 3.9 %
iShares U.S. Intermediate Government Bond Index Fund 3.6 %
iShares U.S. Long Credit Bond Index Fund 3.3 %
Master Small Cap Index Series 2.5 %
iShares U.S. Intermediate Credit Bond Index Fund 2.2 %
iShares U.S. Long Government Bond Index Fund 1.8 %
iShares Global Infrastructure ETF 0.7 %
(a)
Rounds to less than 0.1%.
(b)
Rounds to greater than (0.1)%.
(c)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(c) Percent of
Net Assets
Large Cap Index Master Portfolio 46.2 %
iShares Core MSCI Total International Stock ETF 31.7 %
iShares FTSE NAREIT All Equity REITs Index Fund 4.1 %
iShares U.S. Securitized Bond Index Fund 3.9 %
iShares U.S. Intermediate Government Bond Index Fund 3.6 %
iShares U.S. Long Credit Bond Index Fund 3.3 %
Master Small Cap Index Series 2.5 %
iShares U.S. Intermediate Credit Bond Index Fund 2.2 %
iShares U.S. Long Government Bond Index Fund 1.8 %
iShares Global Infrastructure ETF 0.7 %
(c)Excludes short-term securities.
C000201974 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2045 Fund
Class Name Investor P Shares
Trading Symbol LIHPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2045 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $40(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 40 [18]
Expense Ratio, Percent 0.37% [18]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 18.74%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2045 Fund Custom Benchmark returned 19.15%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor P Shares 18.74 % 9.27 % 10.42 %
Investor P Shares (with sales charge) 12.51 8.10 9.83
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2045 Fund Custom Benchmark 19.15 9.58 10.74
Performance Inception Date Aug. 06, 2018
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2045 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure Index® (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2045 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 10,670,393,292
Holdings Count | Holding 12
Advisory Fees Paid, Amount $ 1,118,928
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $10,670,393,292
Number of Portfolio Holdings 12
Net Investment Advisory Fees $1,118,928
Portfolio Turnover Rate 16%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 85.1 %
Fixed-Income Funds 14.9 %
Money Market Funds %(a)
Liabilities in Excess of Other Assets ( )(b)
Ten largest holdings
Security(c) Percent of
Net Assets
Large Cap Index Master Portfolio 46.2 %
iShares Core MSCI Total International Stock ETF 31.7 %
iShares FTSE NAREIT All Equity REITs Index Fund 4.1 %
iShares U.S. Securitized Bond Index Fund 3.9 %
iShares U.S. Intermediate Government Bond Index Fund 3.6 %
iShares U.S. Long Credit Bond Index Fund 3.3 %
Master Small Cap Index Series 2.5 %
iShares U.S. Intermediate Credit Bond Index Fund 2.2 %
iShares U.S. Long Government Bond Index Fund 1.8 %
iShares Global Infrastructure ETF 0.7 %
(a)
Rounds to less than 0.1%.
(b)
Rounds to greater than (0.1)%.
(c)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(c) Percent of
Net Assets
Large Cap Index Master Portfolio 46.2 %
iShares Core MSCI Total International Stock ETF 31.7 %
iShares FTSE NAREIT All Equity REITs Index Fund 4.1 %
iShares U.S. Securitized Bond Index Fund 3.9 %
iShares U.S. Intermediate Government Bond Index Fund 3.6 %
iShares U.S. Long Credit Bond Index Fund 3.3 %
Master Small Cap Index Series 2.5 %
iShares U.S. Intermediate Credit Bond Index Fund 2.2 %
iShares U.S. Long Government Bond Index Fund 1.8 %
iShares Global Infrastructure ETF 0.7 %
(c)Excludes short-term securities.
C000101152 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2045 Fund
Class Name Investor A Shares
Trading Symbol LIHAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2045 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $40(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 40 [19]
Expense Ratio, Percent 0.37% [19]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 18.76%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2045 Fund Custom Benchmark returned 19.15%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor A Shares 18.76 % 9.27 % 10.42 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2045 Fund Custom Benchmark 19.15 9.58 10.74
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2045 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure Index® (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2045 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 10,670,393,292
Holdings Count | Holding 12
Advisory Fees Paid, Amount $ 1,118,928
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $10,670,393,292
Number of Portfolio Holdings 12
Net Investment Advisory Fees $1,118,928
Portfolio Turnover Rate 16%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 85.1 %
Fixed-Income Funds 14.9 %
Money Market Funds %(a)
Liabilities in Excess of Other Assets (— )(b)
Ten largest holdings
Security(c) Percent of
Net Assets
Large Cap Index Master Portfolio 46.2 %
iShares Core MSCI Total International Stock ETF 31.7 %
iShares FTSE NAREIT All Equity REITs Index Fund 4.1 %
iShares U.S. Securitized Bond Index Fund 3.9 %
iShares U.S. Intermediate Government Bond Index Fund 3.6 %
iShares U.S. Long Credit Bond Index Fund 3.3 %
Master Small Cap Index Series 2.5 %
iShares U.S. Intermediate Credit Bond Index Fund 2.2 %
iShares U.S. Long Government Bond Index Fund 1.8 %
iShares Global Infrastructure ETF 0.7 %
(a)
Rounds to less than 0.1%.
(b)
Rounds to greater than (0.1)%.
(c)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(c) Percent of
Net Assets
Large Cap Index Master Portfolio 46.2 %
iShares Core MSCI Total International Stock ETF 31.7 %
iShares FTSE NAREIT All Equity REITs Index Fund 4.1 %
iShares U.S. Securitized Bond Index Fund 3.9 %
iShares U.S. Intermediate Government Bond Index Fund 3.6 %
iShares U.S. Long Credit Bond Index Fund 3.3 %
Master Small Cap Index Series 2.5 %
iShares U.S. Intermediate Credit Bond Index Fund 2.2 %
iShares U.S. Long Government Bond Index Fund 1.8 %
iShares Global Infrastructure ETF 0.7 %
(c)Excludes short-term securities.
C000101153 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2045 Fund
Class Name Institutional Shares
Trading Symbol LIHIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2045 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $13(a) 0.12%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 13 [20]
Expense Ratio, Percent 0.12% [20]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 19.02%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2045 Fund Custom Benchmark returned 19.15%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Institutional Shares 19.02 % 9.54 % 10.69 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2045 Fund Custom Benchmark 19.15 9.58 10.74
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2045 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure Index® (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2045 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 10,670,393,292
Holdings Count | Holding 12
Advisory Fees Paid, Amount $ 1,118,928
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $10,670,393,292
Number of Portfolio Holdings 12
Net Investment Advisory Fees $1,118,928
Portfolio Turnover Rate 16%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 85.1 %
Fixed-Income Funds 14.9 %
Money Market Funds %(a)
Liabilities in Excess of Other Assets (— )(b)
Ten largest holdings
Security(c) Percent of
Net Assets
Large Cap Index Master Portfolio 46.2 %
iShares Core MSCI Total International Stock ETF 31.7 %
iShares FTSE NAREIT All Equity REITs Index Fund 4.1 %
iShares U.S. Securitized Bond Index Fund 3.9 %
iShares U.S. Intermediate Government Bond Index Fund 3.6 %
iShares U.S. Long Credit Bond Index Fund 3.3 %
Master Small Cap Index Series 2.5 %
iShares U.S. Intermediate Credit Bond Index Fund 2.2 %
iShares U.S. Long Government Bond Index Fund 1.8 %
iShares Global Infrastructure ETF 0.7 %
(a)
Rounds to less than 0.1%.
(b)
Rounds to greater than (0.1)%.
(c)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(c) Percent of
Net Assets
Large Cap Index Master Portfolio 46.2 %
iShares Core MSCI Total International Stock ETF 31.7 %
iShares FTSE NAREIT All Equity REITs Index Fund 4.1 %
iShares U.S. Securitized Bond Index Fund 3.9 %
iShares U.S. Intermediate Government Bond Index Fund 3.6 %
iShares U.S. Long Credit Bond Index Fund 3.3 %
Master Small Cap Index Series 2.5 %
iShares U.S. Intermediate Credit Bond Index Fund 2.2 %
iShares U.S. Long Government Bond Index Fund 1.8 %
iShares Global Infrastructure ETF 0.7 %
(c)Excludes short-term securities.
C000101156 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2050 Fund
Class Name Institutional Shares
Trading Symbol LIPIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2050 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $13(a) 0.12%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 13 [21]
Expense Ratio, Percent 0.12% [21]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 20.71%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2050 Fund Custom Benchmark returned 20.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Institutional Shares 20.71 % 10.40 % 11.21 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2050 Fund Custom Benchmark 20.74 10.41 11.25
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2050 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure Index® (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2050 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 11,328,527,605
Holdings Count | Holding 9
Advisory Fees Paid, Amount $ 884,465
Investment Company Portfolio Turnover 13.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $11,328,527,605
Number of Portfolio Holdings 9
Net Investment Advisory Fees $884,465
Portfolio Turnover Rate 13%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 93.8 %
Fixed-Income Funds 6.3 %
Liabilities in Excess of Other Assets (0.1 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 51.9 %
iShares Core MSCI Total International Stock ETF 36.0 %
iShares U.S. Long Credit Bond Index Fund 3.8 %
Master Small Cap Index Series 3.2 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.7 %
iShares U.S. Securitized Bond Index Fund 1.7 %
iShares U.S. Long Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Credit Bond Index Fund 0.2 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 51.9 %
iShares Core MSCI Total International Stock ETF 36.0 %
iShares U.S. Long Credit Bond Index Fund 3.8 %
Master Small Cap Index Series 3.2 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.7 %
iShares U.S. Securitized Bond Index Fund 1.7 %
iShares U.S. Long Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Credit Bond Index Fund 0.2 %
(a)
Excludes short-term securities.
C000101155 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2050 Fund
Class Name Investor A Shares
Trading Symbol LIPAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2050 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $41(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 41 [22]
Expense Ratio, Percent 0.37% [22]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 20.38%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2050 Fund Custom Benchmark returned 20.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor A Shares 20.38 % 10.12 % 10.94 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2050 Fund Custom Benchmark 20.74 10.41 11.25
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2050 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure Index® (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2050 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 11,328,527,605
Holdings Count | Holding 9
Advisory Fees Paid, Amount $ 884,465
Investment Company Portfolio Turnover 13.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $11,328,527,605
Number of Portfolio Holdings 9
Net Investment Advisory Fees $884,465
Portfolio Turnover Rate 13%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 93.8 %
Fixed-Income Funds 6.3 %
Liabilities in Excess of Other Assets (0.1 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 51.9 %
iShares Core MSCI Total International Stock ETF 36.0 %
iShares U.S. Long Credit Bond Index Fund 3.8 %
Master Small Cap Index Series 3.2 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.7 %
iShares U.S. Securitized Bond Index Fund 1.7 %
iShares U.S. Long Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Credit Bond Index Fund 0.2 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 51.9 %
iShares Core MSCI Total International Stock ETF 36.0 %
iShares U.S. Long Credit Bond Index Fund 3.8 %
Master Small Cap Index Series 3.2 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.7 %
iShares U.S. Securitized Bond Index Fund 1.7 %
iShares U.S. Long Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Credit Bond Index Fund 0.2 %
(a)
Excludes short-term securities.
C000201975 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2050 Fund
Class Name Investor P Shares
Trading Symbol LIPPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2050 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $41(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 41 [23]
Expense Ratio, Percent 0.37% [23]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 20.43%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2050 Fund Custom Benchmark returned 20.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor P Shares 20.43 % 10.12 % 10.94 %
Investor P Shares (with sales charge) 14.11 8.94 10.34
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2050 Fund Custom Benchmark 20.74 10.41 11.25
Performance Inception Date Aug. 06, 2018
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2050 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure Index® (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2050 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 11,328,527,605
Holdings Count | Holding 9
Advisory Fees Paid, Amount $ 884,465
Investment Company Portfolio Turnover 13.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $11,328,527,605
Number of Portfolio Holdings 9
Net Investment Advisory Fees $884,465
Portfolio Turnover Rate 13%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 93.8 %
Fixed-Income Funds 6.3 %
Liabilities in Excess of Other Assets (0.1 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 51.9 %
iShares Core MSCI Total International Stock ETF 36.0 %
iShares U.S. Long Credit Bond Index Fund 3.8 %
Master Small Cap Index Series 3.2 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.7 %
iShares U.S. Securitized Bond Index Fund 1.7 %
iShares U.S. Long Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Credit Bond Index Fund 0.2 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 51.9 %
iShares Core MSCI Total International Stock ETF 36.0 %
iShares U.S. Long Credit Bond Index Fund 3.8 %
Master Small Cap Index Series 3.2 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.7 %
iShares U.S. Securitized Bond Index Fund 1.7 %
iShares U.S. Long Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Credit Bond Index Fund 0.2 %
(a)
Excludes short-term securities.
C000101157 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2050 Fund
Class Name Class K Shares
Trading Symbol LIPKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2050 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $8(a) 0.07%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 8 [24]
Expense Ratio, Percent 0.07% [24]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 20.72%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2050 Fund Custom Benchmark returned 20.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Class K Shares 20.72 % 10.44 % 11.27 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2050 Fund Custom Benchmark 20.74 10.41 11.25
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2050 Fund Custom Benchmark”) comprised of the Bloomberg Enhanced Roll Yield Total Return Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure Index® (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2050 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 11,328,527,605
Holdings Count | Holding 9
Advisory Fees Paid, Amount $ 884,465
Investment Company Portfolio Turnover 13.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $11,328,527,605
Number of Portfolio Holdings 9
Net Investment Advisory Fees $884,465
Portfolio Turnover Rate 13%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 93.8 %
Fixed-Income Funds 6.3 %
Liabilities in Excess of Other Assets (0.1 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 51.9 %
iShares Core MSCI Total International Stock ETF 36.0 %
iShares U.S. Long Credit Bond Index Fund 3.8 %
Master Small Cap Index Series 3.2 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.7 %
iShares U.S. Securitized Bond Index Fund 1.7 %
iShares U.S. Long Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Credit Bond Index Fund 0.2 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 51.9 %
iShares Core MSCI Total International Stock ETF 36.0 %
iShares U.S. Long Credit Bond Index Fund 3.8 %
Master Small Cap Index Series 3.2 %
iShares FTSE NAREIT All Equity REITs Index Fund 2.7 %
iShares U.S. Securitized Bond Index Fund 1.7 %
iShares U.S. Long Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Government Bond Index Fund 0.3 %
iShares U.S. Intermediate Credit Bond Index Fund 0.2 %
(a)
Excludes short-term securities.
C000101160 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2055 Fund
Class Name Class K Shares
Trading Symbol LIVKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2055 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $8(a) 0.07%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 8 [25]
Expense Ratio, Percent 0.07% [25]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 21.59%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2055 Fund Custom Benchmark returned 21.59%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Class K Shares 21.59 % 10.79 % 11.45 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2055 Fund Custom Benchmark 21.59 10.76 11.44
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2055 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2055 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 7,814,406,475
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 445,938
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $7,814,406,475
Number of Portfolio Holdings 6
Net Investment Advisory Fees $445,938
Portfolio Turnover Rate 12%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 98.5 %
Fixed-Income Funds 1.9 %
Money Market Funds 0.1 %
Liabilities in Excess of Other Assets (0.5 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.1 %
iShares Core MSCI Total International Stock ETF 38.5 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.8 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.3 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.1 %
iShares Core MSCI Total International Stock ETF 38.5 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.8 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.3 %
(a)
Excludes short-term securities.
C000201976 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2055 Fund
Class Name Investor P Shares
Trading Symbol LIVPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2055 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $41(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 41 [26]
Expense Ratio, Percent 0.37% [26]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 21.27%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2055 Fund Custom Benchmark returned 21.59%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor P Shares 21.27 % 10.47 % 11.12 %
Investor P Shares (with sales charge) 14.91 9.28 10.52
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2055 Fund Custom Benchmark 21.59 10.76 11.44
Performance Inception Date Aug. 06, 2018
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2055 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2055 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 7,814,406,475
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 445,938
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $7,814,406,475
Number of Portfolio Holdings 6
Net Investment Advisory Fees $445,938
Portfolio Turnover Rate 12%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 98.5 %
Fixed-Income Funds 1.9 %
Money Market Funds 0.1 %
Liabilities in Excess of Other Assets (0.5 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.1 %
iShares Core MSCI Total International Stock ETF 38.5 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.8 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.3 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.1 %
iShares Core MSCI Total International Stock ETF 38.5 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.8 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.3 %
(a)
Excludes short-term securities.
C000101158 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2055 Fund
Class Name Investor A Shares
Trading Symbol LIVAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2055 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $41(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 41 [27]
Expense Ratio, Percent 0.37% [27]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 21.25%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2055 Fund Custom Benchmark returned 21.59%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Investor A Shares 21.25 % 10.46 % 11.12 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2055 Fund Custom Benchmark 21.59 10.76 11.44
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2055 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2055 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 7,814,406,475
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 445,938
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $7,814,406,475
Number of Portfolio Holdings 6
Net Investment Advisory Fees $445,938
Portfolio Turnover Rate 12%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 98.5 %
Fixed-Income Funds 1.9 %
Money Market Funds 0.1 %
Liabilities in Excess of Other Assets (0.5 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.1 %
iShares Core MSCI Total International Stock ETF 38.5 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.8 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.3 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.1 %
iShares Core MSCI Total International Stock ETF 38.5 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.8 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.3 %
(a)
Excludes short-term securities.
C000101159 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2055 Fund
Class Name Institutional Shares
Trading Symbol LIVIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2055 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $13(a) 0.12%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 13 [28]
Expense Ratio, Percent 0.12% [28]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 21.58%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2055 Fund Custom Benchmark returned 21.59%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years 10 Years
Institutional Shares 21.58 % 10.74 % 11.40 %
Russell 1000® Index 17.37 13.59 14.59
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 2.01
LifePath Index 2055 Fund Custom Benchmark 21.59 10.76 11.44
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2055 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2055 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 7,814,406,475
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 445,938
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $7,814,406,475
Number of Portfolio Holdings 6
Net Investment Advisory Fees $445,938
Portfolio Turnover Rate 12%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 98.5 %
Fixed-Income Funds 1.9 %
Money Market Funds 0.1 %
Liabilities in Excess of Other Assets (0.5 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.1 %
iShares Core MSCI Total International Stock ETF 38.5 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.8 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.3 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.1 %
iShares Core MSCI Total International Stock ETF 38.5 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.8 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.3 %
(a)
Excludes short-term securities.
C000166218 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2060 Fund
Class Name Institutional Shares
Trading Symbol LIZIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2060 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $13(a) 0.12%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 13 [29]
Expense Ratio, Percent 0.12% [29]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 21.66%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2060 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: February 29, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years Since Fund
Inception
Institutional Shares 21.66 % 10.76 % 12.34 %
Russell 1000® Index 17.37 13.59 15.50
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 1.83
LifePath Index 2060 Fund Custom Benchmark 21.74 10.80 12.36
Performance Inception Date Feb. 29, 2016
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2060 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2060 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 4,914,728,563
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 255,700
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $4,914,728,563
Number of Portfolio Holdings 6
Net Investment Advisory Fees $255,700
Portfolio Turnover Rate 10%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 99.2 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.2 %
Liabilities in Excess of Other Assets (0.4 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.8 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.8 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
C000166217 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2060 Fund
Class Name Investor A Shares
Trading Symbol LIZAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2060 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $41(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 41 [30]
Expense Ratio, Percent 0.37% [30]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 21.37%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2060 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: February 29, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years Since Fund
Inception
Investor A Shares 21.37 % 10.49 % 12.05 %
Russell 1000® Index 17.37 13.59 15.50
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 1.83
LifePath Index 2060 Fund Custom Benchmark 21.74 10.80 12.36
Performance Inception Date Feb. 29, 2016
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2060 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2060 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 4,914,728,563
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 255,700
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $4,914,728,563
Number of Portfolio Holdings 6
Net Investment Advisory Fees $255,700
Portfolio Turnover Rate 10%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 99.2 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.2 %
Liabilities in Excess of Other Assets (0.4 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.8 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.8 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
C000201977 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2060 Fund
Class Name Investor P Shares
Trading Symbol LIZPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2060 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $41(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 41 [31]
Expense Ratio, Percent 0.37% [31]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 21.35%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2060 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: February 29, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years Since Fund
Inception
Investor P Shares 21.35 % 10.49 % 12.06 %
Investor P Shares (with sales charge) 14.98 9.31 11.46
Russell 1000® Index 17.37 13.59 15.50
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 1.83
LifePath Index 2060 Fund Custom Benchmark 21.74 10.80 12.36
Performance Inception Date Feb. 29, 2016
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2060 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2060 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 4,914,728,563
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 255,700
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $4,914,728,563
Number of Portfolio Holdings 6
Net Investment Advisory Fees $255,700
Portfolio Turnover Rate 10%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 99.2 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.2 %
Liabilities in Excess of Other Assets (0.4 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.8 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.8 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)Excludes short-term securities.
C000166219 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2060 Fund
Class Name Class K Shares
Trading Symbol LIZKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2060 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $8(a) 0.07%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 8 [32]
Expense Ratio, Percent 0.07% [32]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 21.71%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2060 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: February 29, 2016 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years Since Fund
Inception
Class K Shares 21.71 % 10.81 % 12.39 %
Russell 1000® Index 17.37 13.59 15.50
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 1.83
LifePath Index 2060 Fund Custom Benchmark 21.74 10.80 12.36
Performance Inception Date Feb. 29, 2016
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2060 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2060 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 4,914,728,563
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 255,700
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $4,914,728,563
Number of Portfolio Holdings 6
Net Investment Advisory Fees $255,700
Portfolio Turnover Rate 10%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 99.2 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.2 %
Liabilities in Excess of Other Assets (0.4 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.8 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.8 %
Master Small Cap Index Series 3.6 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
C000213835 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2065 Fund
Class Name Class K Shares
Trading Symbol LIWKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2065 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $8(a) 0.07%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 8 [33]
Expense Ratio, Percent 0.07% [33]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 21.72%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2065 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: October 30, 2019 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years Since Fund
Inception
Class K Shares 21.72 % 10.83 % 12.26 %
Russell 1000® Index 17.37 13.59 15.52
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 0.95
LifePath Index 2065 Fund Custom Benchmark 21.74 10.79 12.19
Performance Inception Date Oct. 30, 2019
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2065 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2065 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 1,539,162,472
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 73,414
Investment Company Portfolio Turnover 9.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $1,539,162,472
Number of Portfolio Holdings 6
Net Investment Advisory Fees $73,414
Portfolio Turnover Rate 9%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 99.0 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.3 %
Liabilities in Excess of Other Assets (0.3 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.6 %
Master Small Cap Index Series 3.6 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.6 %
Master Small Cap Index Series 3.6 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
(a)
Excludes short-term securities.
C000213838 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2065 Fund
Class Name Investor P Shares
Trading Symbol LIWPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2065 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $41(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 41 [34]
Expense Ratio, Percent 0.37% [34]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 21.33%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2065 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: October 30, 2019 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years Since Fund
Inception
Investor P Shares 21.33 % 10.50 % 11.92 %
Investor P Shares (with sales charge) 14.96 9.32 10.96
Russell 1000® Index 17.37 13.59 15.52
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 0.95
LifePath Index 2065 Fund Custom Benchmark 21.74 10.79 12.19
Performance Inception Date Oct. 30, 2019
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2065 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2065 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 1,539,162,472
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 73,414
Investment Company Portfolio Turnover 9.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $1,539,162,472
Number of Portfolio Holdings 6
Net Investment Advisory Fees $73,414
Portfolio Turnover Rate 9%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 99.0 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.3 %
Liabilities in Excess of Other Assets (0.3 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.6 %
Master Small Cap Index Series 3.6 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.6 %
Master Small Cap Index Series 3.6 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
(a)
Excludes short-term securities.
C000213836 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2065 Fund
Class Name Investor A Shares
Trading Symbol LIWAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2065 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $41(a) 0.37%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 41 [35]
Expense Ratio, Percent 0.37% [35]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 21.36%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2065 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: October 30, 2019 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years Since Fund
Inception
Investor A Shares 21.36 % 10.50 % 11.93 %
Russell 1000® Index 17.37 13.59 15.52
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 0.95
LifePath Index 2065 Fund Custom Benchmark 21.74 10.79 12.19
Performance Inception Date Oct. 30, 2019
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2065 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2065 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 1,539,162,472
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 73,414
Investment Company Portfolio Turnover 9.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $1,539,162,472
Number of Portfolio Holdings 6
Net Investment Advisory Fees $73,414
Portfolio Turnover Rate 9%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 99.0 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.3 %
Liabilities in Excess of Other Assets (0.3 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.6 %
Master Small Cap Index Series 3.6 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.6 %
Master Small Cap Index Series 3.6 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
(a)
Excludes short-term securities.
C000213837 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2065 Fund
Class Name Institutional Shares
Trading Symbol LIWIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2065 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $13(a) 0.12%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 13 [36]
Expense Ratio, Percent 0.12% [36]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 21.68%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2065 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: October 30, 2019 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year 5 Years Since Fund
Inception
Institutional Shares 21.68 % 10.77 % 12.20 %
Russell 1000® Index 17.37 13.59 15.52
Bloomberg U.S. Aggregate Bond Index 7.30 (0.36 ) 0.95
LifePath Index 2065 Fund Custom Benchmark 21.74 10.79 12.19
Performance Inception Date Oct. 30, 2019
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2065 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2065 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 1,539,162,472
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 73,414
Investment Company Portfolio Turnover 9.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $1,539,162,472
Number of Portfolio Holdings 6
Net Investment Advisory Fees $73,414
Portfolio Turnover Rate 9%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 99.0 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.3 %
Liabilities in Excess of Other Assets (0.3 )
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.6 %
Master Small Cap Index Series 3.6 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 55.8 %
iShares Core MSCI Total International Stock ETF 38.6 %
Master Small Cap Index Series 3.6 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
(a)
Excludes short-term securities.
C000251822 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2070 Fund
Class Name Institutional Shares
Trading Symbol LIYIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2070 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Institutional Shares $18(a) 0.16%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 18 [37]
Expense Ratio, Percent 0.16% [37]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 22.43%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2070 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: September 24, 2024 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year Since Fund
Inception
Institutional Shares 22.43 % 21.48 %
Russell 1000® Index 17.37 16.36
Bloomberg U.S. Aggregate Bond Index 7.30 2.89
LifePath Index 2070 Fund Custom Benchmark 21.74 16.39
Performance Inception Date Sep. 24, 2024
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2070 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net),, Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2070 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 55,487,782
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 1,089
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $55,487,782
Number of Portfolio Holdings 6
Net Investment Advisory Fees $1,089
Portfolio Turnover Rate 11%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 97.8 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.4 %
Other Assets Less Liabilities 0.8
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 56.0 %
iShares Core MSCI Total International Stock ETF 37.1 %
Master Small Cap Index Series 3.7 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 56.0 %
iShares Core MSCI Total International Stock ETF 37.1 %
Master Small Cap Index Series 3.7 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
C000251821 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2070 Fund
Class Name Investor A Shares
Trading Symbol LIYAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2070 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor A Shares $44(a) 0.40%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 44 [38]
Expense Ratio, Percent 0.40% [38]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 22.04%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2070 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: September 24, 2024 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year Since Fund
Inception
Investor A Shares 22.04 % 21.02 %
Russell 1000® Index 17.37 16.36
Bloomberg U.S. Aggregate Bond Index 7.30 2.89
LifePath Index 2070 Fund Custom Benchmark 21.74 16.39
Performance Inception Date Sep. 24, 2024
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2070 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net),, Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2070 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 55,487,782
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 1,089
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $55,487,782
Number of Portfolio Holdings 6
Net Investment Advisory Fees $1,089
Portfolio Turnover Rate 11%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 97.8 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.4 %
Other Assets Less Liabilities 0.8
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 56.0 %
iShares Core MSCI Total International Stock ETF 37.1 %
Master Small Cap Index Series 3.7 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 56.0 %
iShares Core MSCI Total International Stock ETF 37.1 %
Master Small Cap Index Series 3.7 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
C000251823 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2070 Fund
Class Name Investor P Shares
Trading Symbol LIYPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2070 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Investor P Shares $43(a) 0.39%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 43 [39]
Expense Ratio, Percent 0.39% [39]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 22.07%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2070 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: September 24, 2024 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year Since Fund
Inception
Investor P Shares 22.07 % 21.05 %
Investor P Shares (with sales charge) 15.71 14.74
Russell 1000® Index 17.37 16.36
Bloomberg U.S. Aggregate Bond Index 7.30 2.89
LifePath Index 2070 Fund Custom Benchmark 21.74 16.39
Performance Inception Date Sep. 24, 2024
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2070 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net),, Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2070 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 55,487,782
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 1,089
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $55,487,782
Number of Portfolio Holdings 6
Net Investment Advisory Fees $1,089
Portfolio Turnover Rate 11%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 97.8 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.4 %
Other Assets Less Liabilities 0.8
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 56.0 %
iShares Core MSCI Total International Stock ETF 37.1 %
Master Small Cap Index Series 3.7 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 56.0 %
iShares Core MSCI Total International Stock ETF 37.1 %
Master Small Cap Index Series 3.7 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
C000251820 [Member]  
Shareholder Report [Line Items]  
Fund Name BlackRock LifePath® Index 2070 Fund
Class Name Class K Shares
Trading Symbol LIYKX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about BlackRock LifePath® Index 2070 Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
Additional Information Phone Number (800) 441‑7762
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
Class name Costs of a $10,000
investment
Costs paid as a percentage of a
$10,000 investment
Class K Shares $7(a) 0.06%(a)
(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
Expenses Paid, Amount $ 7 [40]
Expense Ratio, Percent 0.06% [40]
Factors Affecting Performance [Text Block]
How did the Fund perform last year ?
  • For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 22.48%.
  • For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37% and the Bloomberg U.S. Aggregate Bond Index returned 7.30%. The LifePath Index 2070 Fund Custom Benchmark returned 21.74%.
What contributed to performance?
International equities were the top contributor to absolute performance in the funds furthest from retirement, followed by U.S. large-cap equities, U.S. small cap equities, U.S. long-term corporate bonds, and U.S. real estate investment trusts ("REITs").
Large-cap U.S. equities were the top contributor in the funds at and near retirement, followed by international equities, U.S. intermediate-term government bonds, U.S. securitized bonds, U.S. 0- to 5-year Treasury Inflation Protected Securities, U.S. intermediate-term corporate bonds, U.S. long government bonds, commodities, global infrastructure stocks, U.S. long-term corporate bonds, U.S. small-cap stocks, and U.S. REITs.
What detracted from performance?
At a time of positive returns across the broader global financial markets, none of the funds’ holdings detracted from absolute performance.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Line Graph [Table Text Block]
Fund performance
Cumulative performance: September 24, 2024 through December 31, 2025
Initial investment of $10,000
Fund Performance - Growth of 10K
 See “Average annual total returns” for additional information on fund performance.
Average Annual Return [Table Text Block]
Average annual total returns
1 Year Since Fund
Inception
Class K Shares 22.48 % 21.55 %
Russell 1000® Index 17.37 16.36
Bloomberg U.S. Aggregate Bond Index 7.30 2.89
LifePath Index 2070 Fund Custom Benchmark 21.74 16.39
Performance Inception Date Sep. 24, 2024
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Prior Market Index Comparison [Text Block]
The Fund compares its performance to that of a customized weighted index (the “LifePath Index 2070 Fund Custom Benchmark”) comprised of the Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, FTSE Nareit All Equity REIT Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, Bloomberg Enhanced Roll Yield Total Return Index, MSCI ACWI ex USA IMI Index (Net),, Russell 1000® Index, Russell 2000® Index and S&P Global Infrastructure IndexTM (Net), which are representative of the asset classes in which the Fund invests. The weightings of the indices in the LifePath Index 2070 Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 55,487,782
Holdings Count | Holding 6
Advisory Fees Paid, Amount $ 1,089
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $55,487,782
Number of Portfolio Holdings 6
Net Investment Advisory Fees $1,089
Portfolio Turnover Rate 11%
Holdings [Text Block]
What did the Fund invest in?
(as of December 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 97.8 %
Fixed-Income Funds 1.0 %
Money Market Funds 0.4 %
Other Assets Less Liabilities 0.8
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 56.0 %
iShares Core MSCI Total International Stock ETF 37.1 %
Master Small Cap Index Series 3.7 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
Largest Holdings [Text Block]
Ten largest holdings
Security(a) Percent of
Net Assets
Large Cap Index Master Portfolio 56.0 %
iShares Core MSCI Total International Stock ETF 37.1 %
Master Small Cap Index Series 3.7 %
iShares U.S. Long Credit Bond Index Fund 1.0 %
iShares FTSE NAREIT All Equity REITs Index Fund 1.0 %
(a)
Excludes short-term securities.
[1] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[2] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[3] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[4] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[5] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[6] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[7] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[8] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[9] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[10] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[11] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[12] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[13] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[14] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[15] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[16] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[17] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[18] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[19] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[20] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[21] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[22] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[23] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[24] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[25] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[26] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[27] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[28] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[29] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[30] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[31] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[32] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[33] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[34] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[35] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[36] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[37] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[38] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[39] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[40] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.