v3.26.1
Shareholder Report
 6 Months Ended
Apr. 30, 2026
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name BlackRock Funds
Entity Central Index Key 0000844779
Entity Investment Company Type N-1A
Document Period End Date Apr. 30, 2026
C000234047 [Member]  
Shareholder Report [Line Items]  
Fund Name iShares U.S. Long Credit Bond Index Fund
Class Name iShares U.S. Long Credit Bond Index Fund
Trading Symbol BLCBX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about iShares U.S. Long Credit Bond Index Fund (the “Fund”) for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-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 six months ?
(based on a hypothetical $10,000 investment)
Fund name Costs of a $10,000
investment		 Costs paid as a percentage of a
$10,000 investment
iShares U.S. Long Credit Bond Index Fund $0(a) 0.00%(b)(c)
​(a)
Rounds to less than $1.
​(b)
Annualized.
​(c)
Rounds to less than 0.01%.
Expenses Paid, Amount $ 0 [1]
Expense Ratio, Percent 0.00% [2],[3]
Net Assets $ 2,389,993,455
Holdings Count | Holding 3,323
Investment Company Portfolio Turnover 9.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $2,389,993,455
Number of Portfolio Holdings 3,323
Portfolio Turnover Rate 9%
Holdings [Text Block]
What did the Fund invest in?
(as of April 30, 2026)
Portfolio composition
Investment Type Percent of Total
Investments(a)
Corporate Bonds 90.4 %
Foreign Agency Obligations 5.7 %
Municipal Bonds 3.9 %
​(a)
Excludes short-term securities.
C000234048 [Member]  
Shareholder Report [Line Items]  
Fund Name iShares U.S. Intermediate Credit Bond Index Fund
Class Name iShares U.S. Intermediate Credit Bond Index Fund
Trading Symbol BICBX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about iShares U.S. Intermediate Credit Bond Index Fund (the “Fund”) for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-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 six months ?
(based on a hypothetical $10,000 investment)
Fund name Costs of a $10,000
investment		 Costs paid as a percentage of a
$10,000 investment
iShares U.S. Intermediate Credit Bond Index Fund $0(a) 0.00%(b)(c)
​(a)
Rounds to less than $1.
​(b)
Annualized.
​(c)
Rounds to less than 0.01%.
Expenses Paid, Amount $ 0 [4]
Expense Ratio, Percent 0.00% [5],[6]
Net Assets $ 3,687,958,485
Holdings Count | Holding 5,805
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $3,687,958,485
Number of Portfolio Holdings 5,805
Portfolio Turnover Rate 11%
Holdings [Text Block]
What did the Fund invest in?
(as of April 30, 2026)
Portfolio composition
Investment Type Percent of Total
Investments(a)
Corporate Bonds 88.7 %
Foreign Agency Obligations 10.8 %
Municipal Bonds 0.5 %
​(a)
Excludes short-term securities.
C000234049 [Member]  
Shareholder Report [Line Items]  
Fund Name iShares U.S. Long Government Bond Index Fund
Class Name iShares U.S. Long Government Bond Index Fund
Trading Symbol BLGBX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about iShares U.S. Long Government Bond Index Fund (the “Fund”) for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-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 six months ?
(based on a hypothetical $10,000 investment)
Fund name Costs of a $10,000
investment		 Costs paid as a percentage of a
$10,000 investment
iShares U.S. Long Government Bond Index Fund $0(a) 0.00%(b)(c)
​(a)
Rounds to less than $1.
​(b)
Annualized.
​(c)
Rounds to less than 0.01%.
Expenses Paid, Amount $ 0 [7]
Expense Ratio, Percent 0.00% [8],[9]
Net Assets $ 3,037,670,819
Holdings Count | Holding 104
Investment Company Portfolio Turnover 7.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $3,037,670,819
Number of Portfolio Holdings 104
Portfolio Turnover Rate 7%
Holdings [Text Block]
What did the Fund invest in?
(as of April 30, 2026)
Portfolio composition
Investment Type Percent of Total
Investments(a)
U.S. Treasury Obligations 99.2 %
U.S. Government Sponsored Agency Securities 0.8 %
​(a)
Excludes short-term securities.
C000234050 [Member]  
Shareholder Report [Line Items]  
Fund Name iShares U.S. Intermediate Government Bond Index Fund
Class Name iShares U.S. Intermediate Government Bond Index Fund
Trading Symbol BIGBX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about iShares U.S. Intermediate Government Bond Index Fund (the “Fund”) for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-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 six months ?
(based on a hypothetical $10,000 investment)
Fund name Costs of a $10,000
investment		 Costs paid as a percentage of a
$10,000 investment
iShares U.S. Intermediate Government Bond Index Fund $0(a) 0.00%(b)(c)
​(a)
Rounds to less than $1.
​(b)
Annualized.
​(c)
Rounds to less than 0.01%.
Expenses Paid, Amount $ 0 [10]
Expense Ratio, Percent 0.00% [11],[12]
Net Assets $ 7,697,357,911
Holdings Count | Holding 217
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $7,697,357,911
Number of Portfolio Holdings 217
Portfolio Turnover Rate 16%
Holdings [Text Block]
What did the Fund invest in?
(as of April 30, 2026)
Portfolio composition
Investment Type Percent of Total
Investments(a)
U.S. Treasury Obligations 98.6 %
U.S. Government Sponsored Agency Securities 1.4 %
​(a)
Excludes short-term securities.
C000234051 [Member]  
Shareholder Report [Line Items]  
Fund Name iShares U.S. Securitized Bond Index Fund
Class Name iShares U.S. Securitized Bond Index Fund
Trading Symbol BISBX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about iShares U.S. Securitized Bond Index Fund (the “Fund”) for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-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 six months ?
(based on a hypothetical $10,000 investment)
Fund name Costs of a $10,000
investment		 Costs paid as a percentage of a
$10,000 investment
iShares U.S. Securitized Bond Index Fund $0(a) 0.00%(b)(c)
​(a)
Rounds to less than $1.
​(b)
Annualized.
​(c)
Rounds to less than 0.01%.
Expenses Paid, Amount $ 0 [13]
Expense Ratio, Percent 0.00% [14],[15]
Net Assets $ 5,799,521,298
Holdings Count | Holding 1,990
Investment Company Portfolio Turnover 110.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $5,799,521,298
Number of Portfolio Holdings 1,990
Portfolio Turnover Rate 110%
Holdings [Text Block]
What did the Fund invest in?
(as of April 30, 2026)
Portfolio composition
Investment Type Percent of Total
Investments(a)
U.S. Government Sponsored Agency Securities 96.0 %
Non-Agency Mortgage-Backed Securities 2.5 %
Asset-Backed Securities 1.4 %
Corporate Bonds 0.1 %
​(a)
Excludes short-term securities.
C000253864 [Member]  
Shareholder Report [Line Items]  
Fund Name iShares Enhanced Roll Yield Index Fund
Class Name iShares Enhanced Roll Yield Index Fund
Trading Symbol BERYX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about iShares Enhanced Roll Yield Index Fund (the “Fund”) for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-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 six months ?
(based on a hypothetical $10,000 investment)
Fund name Costs of a $10,000
investment		 Costs paid as a percentage of a
$10,000 investment
iShares Enhanced Roll Yield Index Fund $0(a) 0.00%(b)(c)
​(a)
Rounds to less than $1.
​(b)
Annualized.
​(c)
Rounds to less than 0.01%.
Expenses Paid, Amount $ 0 [16]
Expense Ratio, Percent 0.00% [17],[18]
Net Assets $ 455,024,218
Holdings Count | Holding 161
Investment Company Portfolio Turnover 0.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $455,024,218
Number of Portfolio Holdings 161
Portfolio Turnover Rate 0%
Holdings [Text Block]
What did the Fund invest in?
(as of April 30, 2026)
Portfolio composition
Asset Type Percent of
Net Assets
U.S. Treasury Obligations 59.8 %
Certificates of Deposit 20.3 %
Futures contracts, net cumulative appreciation 12.6 %
Money Market Funds 9.3 %
Commercial Paper 3.2 %
Liabilities in Excess of Other Assets (5.2 )
Ten largest holdings
Security Percent of
Net Assets
BlackRock Cash Funds: Treasury, SL Agency Shares 9.3 %
U.S. Treasury Bills, 4.32%, 07/14/26 5.4 %
U.S. Treasury Bills, 4.40%, 06/02/26 3.9 %
U.S. Treasury Bills, 4.00%, 08/14/26 3.3 %
U.S. Treasury Bills, 3.79%, 08/24/26 3.3 %
U.S. Treasury Bills, 4.03%, 02/19/27 3.3 %
U.S. Treasury Bills, 3.98%, 08/10/26 3.3 %
U.S. Treasury Bills, 4.05%, 11/13/26 3.3 %
U.S. Treasury Bills, 3.75%, 02/05/27 3.2 %
U.S. Treasury Bills, 3.90%, 09/14/26 3.2 %
Largest Holdings [Text Block]
Ten largest holdings
Security Percent of
Net Assets
BlackRock Cash Funds: Treasury, SL Agency Shares 9.3 %
U.S. Treasury Bills, 4.32%, 07/14/26 5.4 %
U.S. Treasury Bills, 4.40%, 06/02/26 3.9 %
U.S. Treasury Bills, 4.00%, 08/14/26 3.3 %
U.S. Treasury Bills, 3.79%, 08/24/26 3.3 %
U.S. Treasury Bills, 4.03%, 02/19/27 3.3 %
U.S. Treasury Bills, 3.98%, 08/10/26 3.3 %
U.S. Treasury Bills, 4.05%, 11/13/26 3.3 %
U.S. Treasury Bills, 3.75%, 02/05/27 3.2 %
U.S. Treasury Bills, 3.90%, 09/14/26 3.2 %
[1]
Rounds to less than $1.
[2]
Annualized.
[3]
Rounds to less than 0.01%.
[4]
Rounds to less than $1.
[5] Annualized.
[6] Rounds to less than 0.01%.
[7] Rounds to less than $1.
[8] Annualized.
[9] Rounds to less than 0.01%.
[10]
Rounds to less than $1.
[11]
Annualized.
[12]
Rounds to less than 0.01%.
[13]
Rounds to less than $1.
[14]
Annualized.
[15]
Rounds to less than 0.01%.
[16] Rounds to less than $1.
[17] Annualized.
[18] Rounds to less than 0.01%.