Shareholder Report |
12 Months Ended | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Jun. 30, 2026
USD ($)
Holding
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| Shareholder Report [Line Items] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Document Type | N-CSR | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Amendment Flag | false | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Registrant Name | BlackRock Large Cap Focus Value Fund, Inc. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Entity Central Index Key | 0000216557 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Entity Investment Company Type | N-1A | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Document Period End Date | Jun. 30, 2026 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| C000006076 [Member] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Shareholder Report [Line Items] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fund Name | BlackRock Large Cap Focus Value Fund, Inc. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Class Name | Investor C Shares | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Trading Symbol | MCBAX | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock Large Cap Focus Value Fund, Inc. (the “Fund”) for the period of July 1, 2025 to June 30, 2026. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period.
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| 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)
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| Expenses Paid, Amount | $ 183 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Expense Ratio, Percent | 1.63% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Factors Affecting Performance [Text Block] | How did the Fund perform last year?
What contributed to performance? The largest positive contributor to the Fund’s performance was the allocation to the information technology sector, highlighted by holdings within the technology hardware, storage & peripherals industry. Positioning in both the consumer discretionary and materials sectors also contributed notably, particularly in the automobiles and containers & packaging subsectors, respectively. What detracted from performance? The largest detractor from performance was the allocation to the financials sector, where exposure to the financial services industry weighed most heavily on results. While there were no other detractors at the sector level during the period, exposure to the professional services and software industries also detracted from total return. 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. |
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| 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: July 1, 2016 through June 30, 2026 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance.
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| Average Annual Return [Table Text Block] | Average annual total returns
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| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Change Date | Oct. 28, 2025 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Performance Information Location [Text Block] | Visit blackrock.com for more recent performance information. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net Assets | $ 1,997,153,597 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Holdings Count | Holding | 52 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Advisory Fees Paid, Amount | $ 7,973,483 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Investment Company Portfolio Turnover | 91.00% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Additional Fund Statistics [Text Block] | Key Fund statistics
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| Holdings [Text Block] | What did the Fund invest in? (as of June 30, 2026) Sector allocation
Ten largest holdings
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| Largest Holdings [Text Block] | Ten largest holdings
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| Material Fund Change [Text Block] | Material fund changes This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762. The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Strategies [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Risks Change [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Summary of Change Legend [Text Block] | This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
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| Updated Prospectus Phone Number | (800) 441-7762 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Prospectus Web Address | blackrock.com/fundreports | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| C000006074 [Member] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Shareholder Report [Line Items] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fund Name | BlackRock Large Cap Focus Value Fund, Inc. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Class Name | Investor A Shares | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Trading Symbol | MDBAX | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock Large Cap Focus Value Fund, Inc. (the “Fund”) for the period of July 1, 2025 to June 30, 2026. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period.
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| 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)
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| Expenses Paid, Amount | $ 90 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Expense Ratio, Percent | 0.80% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Factors Affecting Performance [Text Block] | How did the Fund perform last year?
What contributed to performance? The largest positive contributor to the Fund’s performance was the allocation to the information technology sector, highlighted by holdings within the technology hardware, storage & peripherals industry. Positioning in both the consumer discretionary and materials sectors also contributed notably, particularly in the automobiles and containers & packaging subsectors, respectively. What detracted from performance? The largest detractor from performance was the allocation to the financials sector, where exposure to the financial services industry weighed most heavily on results. While there were no other detractors at the sector level during the period, exposure to the professional services and software industries also detracted from total return. 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. |
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| 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: July 1, 2016 through June 30, 2026 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance.
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| Average Annual Return [Table Text Block] | Average annual total returns
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| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Change Date | Oct. 28, 2025 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Performance Information Location [Text Block] | Visit blackrock.com for more recent performance information. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net Assets | $ 1,997,153,597 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Holdings Count | Holding | 52 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Advisory Fees Paid, Amount | $ 7,973,483 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Investment Company Portfolio Turnover | 91.00% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Additional Fund Statistics [Text Block] | Key Fund statistics
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| Holdings [Text Block] | What did the Fund invest in? (as of June 30, 2026) Sector allocation
Ten largest holdings
|
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| Largest Holdings [Text Block] | Ten largest holdings
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| Material Fund Change [Text Block] | Material fund changes This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762. The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Strategies [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Risks Change [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Summary of Change Legend [Text Block] | This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
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| Updated Prospectus Phone Number | (800) 441-7762 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Prospectus Web Address | blackrock.com/fundreports | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| C000006077 [Member] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Shareholder Report [Line Items] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fund Name | BlackRock Large Cap Focus Value Fund, Inc. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Class Name | Institutional Shares | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Trading Symbol | MABAX | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock Large Cap Focus Value Fund, Inc. (the “Fund”) for the period of July 1, 2025 to June 30, 2026. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period.
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| 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)
|
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| Expenses Paid, Amount | $ 62 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Expense Ratio, Percent | 0.55% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Factors Affecting Performance [Text Block] | How did the Fund perform last year?
What contributed to performance? The largest positive contributor to the Fund’s performance was the allocation to the information technology sector, highlighted by holdings within the technology hardware, storage & peripherals industry. Positioning in both the consumer discretionary and materials sectors also contributed notably, particularly in the automobiles and containers & packaging subsectors, respectively. What detracted from performance? The largest detractor from performance was the allocation to the financials sector, where exposure to the financial services industry weighed most heavily on results. While there were no other detractors at the sector level during the period, exposure to the professional services and software industries also detracted from total return. 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. |
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| 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: July 1, 2016 through June 30, 2026 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance.
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| Average Annual Return [Table Text Block] | Average annual total returns
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| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Change Date | Oct. 28, 2025 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Performance Information Location [Text Block] | Visit blackrock.com for more recent performance information. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net Assets | $ 1,997,153,597 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Holdings Count | Holding | 52 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Advisory Fees Paid, Amount | $ 7,973,483 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Investment Company Portfolio Turnover | 91.00% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Additional Fund Statistics [Text Block] | Key Fund statistics
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| Holdings [Text Block] | What did the Fund invest in? (as of June 30, 2026) Sector allocation
Ten largest holdings
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| Largest Holdings [Text Block] | Ten largest holdings
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| Material Fund Change [Text Block] | Material fund changes This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762. The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Strategies [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Risks Change [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Summary of Change Legend [Text Block] | This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
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| Updated Prospectus Phone Number | (800) 441-7762 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Prospectus Web Address | blackrock.com/fundreports | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| C000007847 [Member] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Shareholder Report [Line Items] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fund Name | BlackRock Large Cap Focus Value Fund, Inc. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Class Name | Class R Shares | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Trading Symbol | MRBVX | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock Large Cap Focus Value Fund, Inc. (the “Fund”) for the period of July 1, 2025 to June 30, 2026. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period.
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| 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)
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| Expenses Paid, Amount | $ 131 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Expense Ratio, Percent | 1.17% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Factors Affecting Performance [Text Block] | How did the Fund perform last year?
What contributed to performance? The largest positive contributor to the Fund’s performance was the allocation to the information technology sector, highlighted by holdings within the technology hardware, storage & peripherals industry. Positioning in both the consumer discretionary and materials sectors also contributed notably, particularly in the automobiles and containers & packaging subsectors, respectively. What detracted from performance? The largest detractor from performance was the allocation to the financials sector, where exposure to the financial services industry weighed most heavily on results. While there were no other detractors at the sector level during the period, exposure to the professional services and software industries also detracted from total return. 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. |
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| 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: July 1, 2016 through June 30, 2026 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance.
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| Average Annual Return [Table Text Block] | Average annual total returns
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| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Change Date | Oct. 28, 2025 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Performance Information Location [Text Block] | Visit blackrock.com for more recent performance information. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net Assets | $ 1,997,153,597 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Holdings Count | Holding | 52 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Advisory Fees Paid, Amount | $ 7,973,483 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Investment Company Portfolio Turnover | 91.00% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Additional Fund Statistics [Text Block] | Key Fund statistics
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| Holdings [Text Block] | What did the Fund invest in? (as of June 30, 2026) Sector allocation
Ten largest holdings
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| Largest Holdings [Text Block] | Ten largest holdings
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| Material Fund Change [Text Block] | Material fund changes This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762. The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Strategies [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Risks Change [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Summary of Change Legend [Text Block] | This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
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| Updated Prospectus Phone Number | (800) 441-7762 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Prospectus Web Address | blackrock.com/fundreports | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| C000152172 [Member] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Shareholder Report [Line Items] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fund Name | BlackRock Large Cap Focus Value Fund, Inc. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Class Name | Class K Shares | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Trading Symbol | MBVKX | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock Large Cap Focus Value Fund, Inc. (the “Fund”) for the period of July 1, 2025 to June 30, 2026. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period.
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| 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)
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| Expenses Paid, Amount | $ 53 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Expense Ratio, Percent | 0.47% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Factors Affecting Performance [Text Block] | How did the Fund perform last year?
What contributed to performance? The largest positive contributor to the Fund’s performance was the allocation to the information technology sector, highlighted by holdings within the technology hardware, storage & peripherals industry. Positioning in both the consumer discretionary and materials sectors also contributed notably, particularly in the automobiles and containers & packaging subsectors, respectively. What detracted from performance? The largest detractor from performance was the allocation to the financials sector, where exposure to the financial services industry weighed most heavily on results. While there were no other detractors at the sector level during the period, exposure to the professional services and software industries also detracted from total return. 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. |
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| 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: July 1, 2016 through June 30, 2026 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance.
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| Average Annual Return [Table Text Block] | Average annual total returns
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| 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material Change Date | Oct. 28, 2025 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Performance Information Location [Text Block] | Visit blackrock.com for more recent performance information. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net Assets | $ 1,997,153,597 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Holdings Count | Holding | 52 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Advisory Fees Paid, Amount | $ 7,973,483 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Investment Company Portfolio Turnover | 91.00% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Additional Fund Statistics [Text Block] | Key Fund statistics
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| Holdings [Text Block] | What did the Fund invest in? (as of June 30, 2026) Sector allocation
Ten largest holdings
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| Largest Holdings [Text Block] | Ten largest holdings
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| Material Fund Change [Text Block] | Material fund changes This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762. The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Strategies [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Material Fund Change Risks Change [Text Block] | The Fund's Board previously approved certain changes to the Fund’s investment strategy and investment process. Under normal circumstances, the Fund seeks to invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in large cap value equity securities and derivatives that provide investment exposure to such securities or to one or more market risk factors associated with such securities. These changes were effective on October 28, 2025.
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| Summary of Change Legend [Text Block] | This is a summary of certain changes to the Fund since June 30, 2025. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after June 30, 2026 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
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| Updated Prospectus Phone Number | (800) 441-7762 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated Prospectus Web Address | blackrock.com/fundreports |