iShares Large Cap Core Active ETF [Member] iShares 10 20 Year Treasury Bond ETF [Member] iShares MSCI U S A Quality Factor ETF [Member] BlackRock Total Return Fund Class K [Member] iShares Core MSCI Emerging Markets ETF [Member] iShares S And P 500 Growth ETF [Member] iShares U S Equity Factor Rotation Active ETF [Member] iShares S And P 500 Value ETF [Member] iShares Core S And P 500 ETF [Member] International Tilts Master Portfolio [Member] Equity Funds Securities [Member] C000050687 [Member] Class R C000166010 [Member] Class K C000050686 [Member] Investor C C000050685 [Member] Investor A C000050684 [Member] Institutional Short-Term Investments [Member] Fixed Income Funds [Member] C000050742 [Member] C000050743 [Member] C000050744 [Member] C000166011 [Member] C000050745 [Member] BlackRock Strategic Income Opportunities Portfolio Class K [Member] iShares U S Treasury Bond ETF [Member] iShares Securitized Income Active ETF [Member] iShares Flexible Income Active ETF [Member] iShares Systematic Bond ETF [Member] iShares Core International Aggregate Bond ETF [Member] C000050788 [Member] C000166012 [Member] C000050787 [Member] C000050786 [Member] C000050785 [Member] C000050829 [Member] C000050830 [Member] C000050831 [Member] C000166013 [Member] C000050832 [Member] Investment Type [Axis] Net Assets Investment Company Portfolio Turnover No Trading Symbol Flag