Class K [Member] Performance Management - Class K - BlackRock LifePath Dynamic Retirement Fund	Dec. 31, 2025
Prospectus [Line Items]
Bar Chart and Performance Table [Heading]	Performance Information
Performance Narrative [Text Block]	The information shows you how LifePath Dynamic Retirement Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart shows the returns for Class K Shares of the Fund for each of the last ten calendar years, except as described below. The average annual total returns table compares the performance of the Fund to that of the Bloomberg U.S. Aggregate Bond Index, the Russell 1000^® Index and the LifePath Dynamic Retirement Fund Custom Benchmark, a customized weighted index comprised of the Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, ICE^® U.S. Treasury 0-5 Year Inflation Linked Bond Index, FTSE Nareit All Equity REIT Index, S&P Global Infrastructure IndexTM (Net), MSCI ACWI ex USA IMI Index (Net), Russell 1000^® Index and Russell 2000^® Index, which are representative of the asset classes in which the Fund invests according to their weightings as of the most recent quarter-end. The weightings of the indices in the LifePath Dynamic Retirement Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy. The returns of the LifePath Dynamic Retirement Fund Custom Benchmark shown in the average annual total returns table are not recalculated or restated when they are adjusted to reflect the Fund’s asset allocation strategy but rather reflect the LifePath Dynamic Retirement Fund Custom Benchmark’s actual allocation over time, which may be different from the current allocation. The Russell 1000^® Index and the LifePath Dynamic Retirement Fund Custom Benchmark are relevant to the Fund because they have characteristics similar to the Fund’s investment strategy. Effective November 1, 2024, the LifePath Dynamic Retirement Fund Custom Benchmark against which the Fund measures its performance was changed to add ICE^® U.S. Treasury 0-5 Year Inflation Linked Bond Index, FTSE Nareit All Equity REIT Index and S&P Global Infrastructure IndexTM (Net) and to gradually remove Bloomberg U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L) and FTSE EPRA Nareit Developed Index. Effective July 29, 2022, the LifePath Dynamic Retirement Fund Custom Benchmark against which the Fund measures its performance was changed to remove Bloomberg U.S. Aggregate Bond Index and to add Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Intermediate Government Bond Index and Bloomberg U.S. Securitized: MBS, ABS and CMBS Index. Effective March 31, 2018, the investment adviser determined not to allocate any of the Fund’s assets to underlying funds that invest primarily in commodities. Performance for the periods shown prior to March 31, 2018 is based on the prior target asset allocation. Effective November 7, 2016, the Fund changed its investment strategy to (i) incorporate a Global Tactical Asset Allocation into its glidepath, (ii) increase the flexibility of its equity allocations and (iii) diversify its fixed-income strategies. Performance for the periods shown prior to November 7, 2016 is based on the prior investment strategy. To the extent that dividends and distributions have been paid by the Fund, the performance information of the Fund in the chart and table assumes reinvestment of the dividends and distributions. The table includes all applicable fees. How the Fund performed in the past (before and after taxes) is not necessarily an indication of how it will perform in the future. If BFA, BAL and their affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s performance, including its current net asset value, can be obtained by visiting http://www.blackrock.com or can be obtained by phone at (800) 882-0052.
Performance Past Does Not Indicate Future [Text]	How the Fund performed in the past (before and after taxes) is not necessarily an indication of how it will perform in the future.
Performance Information Illustrates Variability of Returns [Text]	The information shows you how LifePath Dynamic Retirement Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Additional Market Index [Text]	The average annual total returns table compares the performance of the Fund to that of the Bloomberg U.S. Aggregate Bond Index, the Russell 1000® Index and the LifePath Dynamic Retirement Fund Custom Benchmark, a customized weighted index comprised of the Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, FTSE Nareit All Equity REIT Index, S&P Global Infrastructure IndexTM (Net), MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index and Russell 2000® Index, which are representative of the asset classes in which the Fund invests according to their weightings as of the most recent quarter-end.The Russell 1000® Index and the LifePath Dynamic Retirement Fund Custom Benchmark are relevant to the Fund because they have characteristics similar to the Fund’s investment strategy.
Bar Chart [Heading]	Class K Shares ANNUAL TOTAL RETURNS LifePath Dynamic Retirement Fund As of 12/31
Bar Chart Closing [Text Block]	During the ten-year period shown in the bar chart, the highest return for a quarter was 11.68% (quarter ended June 30, 2020) and the lowest return for a quarter was –10.13% (quarter ended March 31, 2020).
Performance Table Heading	For the periods ended 12/31/25Average Annual Total Returns
Performance Table Narrative	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table Market Index Changed	Effective November 1, 2024, the LifePath Dynamic RetirementFund Custom Benchmark against which the Fund measures its performance was changed to add ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, FTSE Nareit All Equity REIT Index and S&P Global Infrastructure IndexTM (Net) and to gradually remove Bloomberg U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L) and FTSE EPRA Nareit Developed Index.
Performance Table Uses Highest Federal Rate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Availability Website Address [Text]	http://www.blackrock.com
Performance Availability Phone [Text]	(800) 882-0052
Class K
Prospectus [Line Items]
Highest Quarterly Return, Label [Optional Text]	highest return
Highest Quarterly Return	11.68%
Highest Quarterly Return, Date	Jun. 30, 2020
Lowest Quarterly Return, Label [Optional Text]	lowest return
Lowest Quarterly Return	(10.13%)
Lowest Quarterly Return, Date	Mar. 31, 2020

Class K [Member] Performance Management - Class K - BlackRock LifePath Dynamic Retirement Fund

Dec. 31, 2025

Bar Chart and Performance Table [Heading]

Performance Information

The information shows you how LifePath Dynamic Retirement Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart shows the returns for Class K Shares of the Fund for each of the last ten calendar years, except as described below. The average annual total returns table compares the performance of the Fund to that of the Bloomberg U.S. Aggregate Bond Index, the Russell 1000^® Index and the LifePath Dynamic Retirement Fund Custom Benchmark, a customized weighted index comprised of the Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, ICE^® U.S. Treasury 0-5 Year Inflation Linked Bond Index, FTSE Nareit All Equity REIT Index, S&P Global Infrastructure IndexTM (Net), MSCI ACWI ex USA IMI Index (Net), Russell 1000^® Index and Russell 2000^® Index, which are representative of the asset classes in which the Fund invests according to their weightings as of the most recent quarter-end. The weightings of the indices in the LifePath Dynamic Retirement Fund Custom Benchmark are adjusted periodically to reflect the investment adviser’s evaluation and adjustment of the Fund’s asset allocation strategy. The returns of the LifePath Dynamic Retirement Fund Custom Benchmark shown in the average annual total returns table are not recalculated or restated when they are adjusted to reflect the Fund’s asset allocation strategy but rather reflect the LifePath Dynamic Retirement Fund Custom Benchmark’s actual allocation over time, which may be different from the current allocation. The Russell 1000^® Index and the LifePath Dynamic Retirement Fund Custom Benchmark are relevant to the Fund because they have characteristics similar to the Fund’s investment strategy. Effective November 1, 2024, the LifePath Dynamic Retirement

Fund Custom Benchmark against which the Fund measures its performance was changed to add ICE^® U.S. Treasury 0-5 Year Inflation Linked Bond Index, FTSE Nareit All Equity REIT Index and S&P Global Infrastructure IndexTM (Net) and to gradually remove Bloomberg U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L) and FTSE EPRA Nareit Developed Index. Effective July 29, 2022, the LifePath Dynamic Retirement Fund Custom Benchmark against which the Fund measures its performance was changed to remove Bloomberg U.S. Aggregate Bond Index and to add Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Intermediate Government Bond Index and Bloomberg U.S. Securitized: MBS, ABS and CMBS Index. Effective March 31, 2018, the investment adviser determined not to allocate any of the Fund’s assets to underlying funds that invest primarily in commodities. Performance for the periods shown prior to March 31, 2018 is based on the prior target asset allocation. Effective November 7, 2016, the Fund changed its investment strategy to (i) incorporate a Global Tactical Asset Allocation into its glidepath, (ii) increase the flexibility of its equity allocations and (iii) diversify its fixed-income strategies. Performance for the periods shown prior to November 7, 2016 is based on the prior investment strategy. To the extent that dividends and distributions have been paid by the Fund, the performance information of the Fund in the chart and table assumes reinvestment of the dividends and distributions. The table includes all applicable fees. How the Fund performed in the past (before and after taxes) is not necessarily an indication of how it will perform in the future. If BFA, BAL and their affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s performance, including its current net asset value, can be obtained by visiting http://www.blackrock.com or can be obtained by phone at (800) 882-0052.

Performance Past Does Not Indicate Future [Text]

How the Fund performed in the past (before and after taxes) is not necessarily an indication of how it will perform in the future.

Performance Information Illustrates Variability of Returns [Text]

The information shows you how LifePath Dynamic Retirement Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Additional Market Index [Text]

The average annual total returns table compares the performance of the Fund to that of the Bloomberg U.S. Aggregate Bond Index, the Russell 1000® Index and the LifePath Dynamic Retirement Fund Custom Benchmark, a customized weighted index comprised of the Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, FTSE Nareit All Equity REIT Index, S&P Global Infrastructure IndexTM (Net), MSCI ACWI ex USA IMI Index (Net), Russell 1000® Index and Russell 2000® Index, which are representative of the asset classes in which the Fund invests according to their weightings as of the most recent quarter-end.The Russell 1000® Index and the LifePath Dynamic Retirement Fund Custom Benchmark are relevant to the Fund because they have characteristics similar to the Fund’s investment strategy.

Bar Chart [Heading]

Class K Shares ANNUAL TOTAL RETURNS LifePath Dynamic Retirement Fund As of 12/31

Bar Chart Closing [Text Block]

During the ten-year period shown in the bar chart, the highest return for a quarter was 11.68% (quarter ended June 30, 2020) and the lowest return for a quarter was –10.13% (quarter ended March 31, 2020).

Performance Table Heading

For the periods ended 12/31/25Average Annual Total Returns

Performance Table Narrative

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Market Index Changed

Effective November 1, 2024, the LifePath Dynamic RetirementFund Custom Benchmark against which the Fund measures its performance was changed to add ICE® U.S. Treasury 0-5 Year Inflation Linked Bond Index, FTSE Nareit All Equity REIT Index and S&P Global Infrastructure IndexTM (Net) and to gradually remove Bloomberg U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L) and FTSE EPRA Nareit Developed Index.

Performance Table Uses Highest Federal Rate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Availability Website Address [Text]

http://www.blackrock.com

Performance Availability Phone [Text]

(800) 882-0052

Class K

Prospectus [Line Items]

Highest Quarterly Return, Label [Optional Text]

highest return

Highest Quarterly Return

11.68%

Highest Quarterly Return, Date

Jun. 30, 2020

Lowest Quarterly Return, Label [Optional Text]

lowest return

Lowest Quarterly Return

(10.13%)

Lowest Quarterly Return, Date

Mar. 31, 2020