S000004306 [Member] Investment Strategy - iShares S&P 100 ETF	Mar. 31, 2026
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	The Fund seeks to track the investment results of the S&P 100® (the “Underlying Index”), which measures the performance of the large-capitalization sector of the U.S. equity market. It is a subset of the S&P 500® (the “Parent Index”) and consists of blue chip stocks from a diverse range of industries in the Parent Index with exchange listed options. As of March 31, 2026, the Underlying Index represented approximately 64% of the market capitalization of U.S. equities. As of March 31, 2026, stocks must have a market capitalization of at least $22 billion for initial inclusion in the Parent Index; this threshold and constituents' market capitalization may fluctuate depending on the overall level of the equity markets. As of March 31, 2026, a significant portion of the Underlying Index was represented by securities of companies in the consumer goods and services and technology industries or sectors. The components of the Underlying Index are likely to change over time. The Fund seeks to track the investment results of the Underlying Index before fees and expenses of the Fund. BFA uses a representative sampling indexing strategy to manage the Fund. “Representative sampling” is an indexing strategy that involves investing in a representative sample of securities or other instruments intended to collectively have an investment profile similar to that of an applicable underlying index. The instruments selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of an applicable underlying index. The Fund may or may not hold all of the components of the Underlying Index. The Fund may use derivatives to gain or reduce exposure to the components of the Underlying Index or exposure to one or more market risk factors associated with such components. Subject to the limits described herein, the Fund may purchase and hold cash and cash equivalents, including shares of money market funds advised by BFA or its affiliates, and may also purchase and hold instruments not included in the Underlying Index when BFA believes that such instruments will help the Fund track the performance of the Underlying Index over time, including in light of expected liquidity or trading costs, anticipated additions to or deletions from the Underlying Index, or other reasons as determined by BFA. In accordance with Rule 35d-1 under the Investment Company Act of 1940, as amended (the “1940 Act”), under normal circumstances, the Fund will not invest less than 80% of the value of its net assets, plus the amount of any borrowings for investment purposes, in components of its Underlying Index. Investments in derivatives and other investments will be counted toward the Fund’s 80% investment policy to the extent that they provide exposure to the components of its Underlying Index or exposure to one or more market risk factors associated with such components. The Fund’s 80% investment policy may be changed by the Trust’s Board of Trustees (the “Board”) upon 60 days’ notice to shareholders. The Fund may lend securities representing up to one-third of the value of the Fund's total assets (including the value of any collateral received). The Underlying Index is a product of S&P Dow Jones Indices LLC (the “Index Provider” or “SPDJI”), which is independent of the Fund and BFA. The Index Provider determines the composition and relative weightings of the components of the Underlying Index and publishes information regarding the market value of the Underlying Index. Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. For purposes of this limitation, securities of the U.S. government (including its agencies and instrumentalities) and repurchase agreements collateralized by U.S. government securities are not considered to be issued by members of any industry. Diversification Policy. The Fund intends to be diversified in approximately the same proportion as the Underlying Index is diversified and to invest all or substantially all of its assets in components of the Underlying Index in approximately the same proportion as each component’s weighting in the Underlying Index. This diversification policy may limit the Fund’s ability to use representative sampling. The Fund may become “non-diversified,” as defined in the 1940 Act, solely as a result of a change in relative market capitalization or index weighting of one or more components of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non-diversified” due solely to a change in the relative market capitalization or index weighting of one or more components of the Underlying Index. The Fund discloses its portfolio holdings and weightings at www.iShares.com.
Strategy Portfolio Concentration [Text]	Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. For purposes of this limitation, securities of the U.S. government (including its agencies and instrumentalities) and repurchase agreements collateralized by U.S. government securities are not considered to be issued by members of any industry.

The Fund seeks to track the investment results of the S&P 100® (the “Underlying Index”), which measures the performance of the large-capitalization sector of the U.S. equity market. It is a subset of the S&P 500® (the “Parent Index”) and consists of blue chip stocks from a diverse range of industries in the Parent Index with exchange listed options. As of March 31, 2026, the Underlying Index represented approximately 64% of the market capitalization of U.S. equities. As of March 31, 2026, stocks must have a market capitalization of at least $22 billion for initial inclusion in the Parent Index; this threshold and constituents' market capitalization may fluctuate depending on the overall level of the equity markets.

As of March 31, 2026, a significant portion of the Underlying Index was represented by securities of companies in the consumer goods and services and technology industries or sectors. The components of the Underlying Index are likely to change over time.

The Fund seeks to track the investment results of the Underlying Index before fees and expenses of the Fund. BFA uses a representative sampling indexing strategy to manage the Fund. “Representative sampling” is an indexing strategy that involves investing in a representative sample of securities or other instruments intended to collectively have an investment profile similar to that of an applicable underlying index. The instruments selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of an applicable underlying index. The Fund may or may not hold all of the components of the Underlying Index. The Fund may use derivatives to gain or reduce

exposure to the components of the Underlying Index or exposure to one or more market risk factors associated with such components. Subject to the limits described herein, the Fund may purchase and hold cash and cash equivalents, including shares of money market funds advised by BFA or its affiliates, and may also purchase and hold instruments not included in the Underlying Index when BFA believes that such instruments will help the Fund track the performance of the Underlying Index over time, including in light of expected liquidity or trading costs, anticipated additions to or deletions from the Underlying Index, or other reasons as determined by BFA.

In accordance with Rule 35d-1 under the Investment Company Act of 1940, as amended (the “1940 Act”), under normal circumstances, the Fund will not invest less than 80% of the value of its net assets, plus the amount of any borrowings for investment purposes, in components of its Underlying Index. Investments in derivatives and other investments will be counted toward the Fund’s 80% investment policy to the extent that they provide exposure to the components of its Underlying Index or exposure to one or more market risk factors associated with such components. The Fund’s 80% investment policy may be changed by the Trust’s Board of Trustees (the “Board”) upon 60 days’ notice to shareholders.

The Underlying Index is a product of S&P Dow Jones Indices LLC (the “Index Provider” or “SPDJI”), which is independent of the Fund and BFA. The Index Provider determines the composition and relative weightings of the components of the Underlying Index and publishes information regarding the market value of the Underlying Index.

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. For purposes of this limitation, securities of the U.S. government (including its agencies and instrumentalities) and repurchase agreements collateralized by U.S. government securities are not considered to be issued by members of any industry.

Diversification Policy. The Fund intends to be diversified in approximately the same proportion as the Underlying Index is diversified and to invest all or substantially all of its assets in components of the Underlying Index in approximately the same proportion as each component’s weighting in the Underlying Index. This diversification policy may limit the Fund’s ability to use representative sampling. The Fund may become “non-diversified,” as defined in the 1940 Act, solely as a result of a change in relative market capitalization or index weighting of one or more components of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non-diversified” due solely to a change in the relative market capitalization or index weighting of one or more components of the Underlying Index. The Fund discloses its portfolio holdings and weightings at www.iShares.com.