v3.26.1
Shareholder Report, Holdings (Details)
Mar. 31, 2026
C000050687 [Member] | iShares Large Cap Core Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [1]
C000050687 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [1]
C000050687 [Member] | iShares MSCI U S A Quality Factor ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [1]
C000050687 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [1]
C000050687 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [1]
C000050687 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.70% [1]
C000050687 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [1]
C000050687 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.30% [1]
C000050687 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [1]
C000050687 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.20% [1]
C000050687 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 82.40%
C000050687 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000050687 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00%
C000166010 [Member] | iShares Large Cap Core Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [2]
C000166010 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [2]
C000166010 [Member] | iShares MSCI U S A Quality Factor ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [2]
C000166010 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [2]
C000166010 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [2]
C000166010 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.70% [2]
C000166010 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [2]
C000166010 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.30% [2]
C000166010 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [2]
C000166010 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.20% [2]
C000166010 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 82.40%
C000166010 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000166010 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00%
C000050686 [Member] | iShares Large Cap Core Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [3]
C000050686 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [3]
C000050686 [Member] | iShares MSCI U S A Quality Factor ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [3]
C000050686 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [3]
C000050686 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [3]
C000050686 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.70% [3]
C000050686 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [3]
C000050686 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.30% [3]
C000050686 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [3]
C000050686 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.20% [3]
C000050686 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 82.40%
C000050686 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000050686 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00%
C000050685 [Member] | iShares Large Cap Core Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [4]
C000050685 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [4]
C000050685 [Member] | iShares MSCI U S A Quality Factor ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [4]
C000050685 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [4]
C000050685 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [4]
C000050685 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.70% [4]
C000050685 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [4]
C000050685 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.30% [4]
C000050685 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [4]
C000050685 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.20% [4]
C000050685 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 82.40%
C000050685 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000050685 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00%
C000050684 [Member] | iShares Large Cap Core Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [5]
C000050684 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [5]
C000050684 [Member] | iShares MSCI U S A Quality Factor ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [5]
C000050684 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [5]
C000050684 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [5]
C000050684 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.70% [5]
C000050684 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [5]
C000050684 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.30% [5]
C000050684 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [5]
C000050684 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.20% [5]
C000050684 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 82.40%
C000050684 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000050684 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00%
C000050742 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [6]
C000050742 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [6]
C000050742 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.80% [6]
C000050742 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [6]
C000050742 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.80% [6]
C000050742 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.90% [6]
C000050742 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [6]
C000050742 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.10% [6]
C000050742 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [6]
C000050742 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [6]
C000050742 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 42.50%
C000050742 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000050742 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.60%
C000050743 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [7]
C000050743 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [7]
C000050743 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.80% [7]
C000050743 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [7]
C000050743 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.80% [7]
C000050743 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.90% [7]
C000050743 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [7]
C000050743 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.10% [7]
C000050743 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [7]
C000050743 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [7]
C000050743 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 42.50%
C000050743 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000050743 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.60%
C000050744 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [8]
C000050744 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [8]
C000050744 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.80% [8]
C000050744 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [8]
C000050744 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.80% [8]
C000050744 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.90% [8]
C000050744 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [8]
C000050744 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.10% [8]
C000050744 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [8]
C000050744 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [8]
C000050744 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 42.50%
C000050744 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000050744 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.60%
C000166011 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [9]
C000166011 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [9]
C000166011 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.80% [9]
C000166011 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [9]
C000166011 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.80% [9]
C000166011 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.90% [9]
C000166011 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [9]
C000166011 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.10% [9]
C000166011 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [9]
C000166011 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [9]
C000166011 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 42.50%
C000166011 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000166011 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.60%
C000050745 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [10]
C000050745 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [10]
C000050745 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.80% [10]
C000050745 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [10]
C000050745 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.80% [10]
C000050745 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.90% [10]
C000050745 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.10% [10]
C000050745 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.10% [10]
C000050745 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [10]
C000050745 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [10]
C000050745 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 42.50%
C000050745 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000050745 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.60%
C000050788 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.00% [11]
C000050788 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.10% [11]
C000050788 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [11]
C000050788 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.80% [11]
C000050788 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [11]
C000050788 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.10% [11]
C000050788 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [11]
C000050788 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [11]
C000050788 [Member] | iShares Systematic Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [11]
C000050788 [Member] | iShares Core International Aggregate Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.00% [11]
C000050788 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40%
C000050788 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000050788 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 77.50%
C000166012 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.00% [12]
C000166012 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.10% [12]
C000166012 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [12]
C000166012 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.80% [12]
C000166012 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [12]
C000166012 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.10% [12]
C000166012 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [12]
C000166012 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [12]
C000166012 [Member] | iShares Systematic Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [12]
C000166012 [Member] | iShares Core International Aggregate Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.00% [12]
C000166012 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40%
C000166012 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000166012 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 77.50%
C000050787 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.00% [13]
C000050787 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.10% [13]
C000050787 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [13]
C000050787 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.80% [13]
C000050787 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [13]
C000050787 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.10% [13]
C000050787 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [13]
C000050787 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [13]
C000050787 [Member] | iShares Systematic Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [13]
C000050787 [Member] | iShares Core International Aggregate Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.00% [13]
C000050787 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40%
C000050787 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000050787 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 77.50%
C000050786 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.00% [14]
C000050786 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.10% [14]
C000050786 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [14]
C000050786 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.80% [14]
C000050786 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [14]
C000050786 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.10% [14]
C000050786 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [14]
C000050786 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [14]
C000050786 [Member] | iShares Systematic Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [14]
C000050786 [Member] | iShares Core International Aggregate Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.00% [14]
C000050786 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40%
C000050786 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000050786 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 77.50%
C000050785 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.00% [15]
C000050785 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.10% [15]
C000050785 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [15]
C000050785 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.80% [15]
C000050785 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [15]
C000050785 [Member] | iShares U S Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.10% [15]
C000050785 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [15]
C000050785 [Member] | iShares Flexible Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [15]
C000050785 [Member] | iShares Systematic Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [15]
C000050785 [Member] | iShares Core International Aggregate Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.00% [15]
C000050785 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40%
C000050785 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000050785 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 77.50%
C000050829 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [16]
C000050829 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.10% [16]
C000050829 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [16]
C000050829 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70% [16]
C000050829 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [16]
C000050829 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.30% [16]
C000050829 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.90% [16]
C000050829 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [16]
C000050829 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [16]
C000050829 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [16]
C000050829 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.90%
C000050829 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000050829 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000050830 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [17]
C000050830 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.10% [17]
C000050830 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [17]
C000050830 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70% [17]
C000050830 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [17]
C000050830 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.30% [17]
C000050830 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.90% [17]
C000050830 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [17]
C000050830 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [17]
C000050830 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [17]
C000050830 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.90%
C000050830 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000050830 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000050831 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [18]
C000050831 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.10% [18]
C000050831 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [18]
C000050831 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70% [18]
C000050831 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [18]
C000050831 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.30% [18]
C000050831 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.90% [18]
C000050831 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [18]
C000050831 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [18]
C000050831 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [18]
C000050831 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.90%
C000050831 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000050831 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000166013 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [19]
C000166013 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.10% [19]
C000166013 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [19]
C000166013 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70% [19]
C000166013 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [19]
C000166013 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.30% [19]
C000166013 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.90% [19]
C000166013 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [19]
C000166013 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [19]
C000166013 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [19]
C000166013 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.90%
C000166013 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000166013 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000050832 [Member] | iShares 10 20 Year Treasury Bond ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [20]
C000050832 [Member] | BlackRock Total Return Fund Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.10% [20]
C000050832 [Member] | iShares Core MSCI Emerging Markets ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [20]
C000050832 [Member] | iShares S And P 500 Growth ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70% [20]
C000050832 [Member] | iShares U S Equity Factor Rotation Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [20]
C000050832 [Member] | iShares S And P 500 Value ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.30% [20]
C000050832 [Member] | iShares Core S And P 500 ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.90% [20]
C000050832 [Member] | International Tilts Master Portfolio [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.10% [20]
C000050832 [Member] | BlackRock Strategic Income Opportunities Portfolio Class K [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.10% [20]
C000050832 [Member] | iShares Securitized Income Active ETF [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.10% [20]
C000050832 [Member] | Equity Funds Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.90%
C000050832 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000050832 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
[1] Excludes short-term securities.
[2] Excludes short-term securities.
[3]
Excludes short-term securities.
[4]
Excludes short-term securities.
[5]
Excludes short-term securities.
[6] Excludes short-term securities.
[7] Excludes short-term securities.
[8]
Excludes short-term securities.
[9]
Excludes short-term securities.
[10]
Excludes short-term securities.
[11] Excludes short-term securities.
[12] Excludes short-term securities.
[13] Excludes short-term securities.
[14] Excludes short-term securities.
[15] Excludes short-term securities.
[16]
Excludes short-term securities.
[17] Excludes short-term securities.
[18] Excludes short-term securities.
[19]
Excludes short-term securities.
[20]
Excludes short-term securities.