C000220929 [Member] Class K C000220931 [Member] Investor A C000220930 [Member] Institutional C000220934 [Member] C000220932 [Member] C000220933 [Member] iShares MSCI Emerging Markets Small Cap ETF [Member] iShares MSCI Canada ETF [Member] iShares MSCI EAFE Small Cap ETF [Member] iShares Developed Real Estate Index Fund Class K [Member] iShares ESG Aware MSCI USA Small Cap ETF [Member] iShares ESG Aware MSCI EM ETF [Member] iShares TIPS Bond ETF [Member] iShares ESG Aware MSCI EAFE ETF [Member] iShares ESG Aware MSCI USA ETF [Member] iShares ESG Aware U S Aggregate Bond ETF [Member] C000220940 [Member] C000220939 [Member] C000220938 [Member] C000220941 [Member] C000220942 [Member] C000220943 [Member] Equity Funds Securities [Member] Fixed Income Funds [Member] Money Market Funds [Member] Liabilities in Excess of Other Assets [Member] C000220945 [Member] C000220946 [Member] C000220944 [Member] C000220948 [Member] C000220947 [Member] C000220949 [Member] C000220952 [Member] C000220950 [Member] C000220951 [Member] C000220955 [Member] C000220953 [Member] C000220954 [Member] C000220957 [Member] C000220958 [Member] C000220956 [Member] Standard & Poor's, AAA Rating [Member] Standard & Poor's, AA Rating [Member] Standard & Poor's, A Rating [Member] Standard & Poor's, BBB Rating [Member] Standard & Poor's, BB Rating [Member] Standard & Poor's, B Rating [Member] Standard & Poor's, CCC Rating [Member] Standard & Poor's, CC Rating [Member] Standard & Poor's, C Rating [Member] Standard & Poor's, D Rating [Member] Corporate Bond Securities [Member] Municipal Bonds [Member] Common Stock [Member] Asset-Backed Securities [Member] Other Investments [Member] C000244506 [Member] C000244507 [Member] U S Government Sponsored Agency Securities [Member] U S Treasury Obligations [Member] Non Agency Mortgage Backed Securities [Member] Foreign Agency Obligations [Member] Capital Trusts [Member] Investment Companies [Member] N R [Member] C000251819 [Member] C000251818 [Member] C000251817 [Member] Investment Type [Axis] Net Assets Investment Company Portfolio Turnover No Trading Symbol Flag