Investment Strategy	Dec. 31, 2025
Investor A, Institutional \| iShares Russell 2000 Small-Cap Index Fund
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	Russell 2000 Small-Cap Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the Russell 2000. The Fund will be substantially invested in securities in the Russell 2000, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the Russell 2000. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index. The Fund may invest in a statistically selected sample of stocks included in the Russell 2000 and in derivative instruments linked to the Russell 2000. The Fund may not invest in all of the common stocks in the Russell 2000, or in the same weightings as in the Russell 2000. The Fund chooses investments so that the market capitalizations, industry weightings and other fundamental characteristics of the stocks and derivative instruments chosen are similar to the Russell 2000 as a whole. As of March 31, 2026, the companies in the Russell 2000 have a market capitalization ranging from $3.29 million to $39.25 billion. The Fund is a “feeder” fund that invests all of its assets in the Series, a series of the Master LLC, which has the same investment objective and strategies as the Fund. All investments are made at the Series level. This structure is sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the investment results of the Series. For simplicity, this prospectus uses the name of the Fund or the term “Fund” (as applicable) to include the Series.
Investor A, Institutional \| iShares MSCI EAFE International Index Fund
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	MSCI EAFE International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the MSCI EAFE Index. The Fund will be substantially invested in securities in the MSCI EAFE Index, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the MSCI EAFE Index. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index. MSCI EAFE International Index Fund invests in a statistically selected sample of equity securities included in the MSCI EAFE Index and in derivative instruments linked to the MSCI EAFE Index. Equity securities include common stock, preferred stock and securities or other instruments whose price is linked to the value of common stock. The Fund will, under normal circumstances, invest in all of the countries represented in the MSCI EAFE Index. The Fund may not, however, invest in all of the companies within a country represented in the MSCI EAFE Index, or in the same weightings as in the MSCI EAFE Index.
Class K \| iShares Russell 2000 Small-Cap Index Fund
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	Russell 2000 Small-Cap Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the Russell 2000. The Fund will be substantially invested in securities in the Russell 2000, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the Russell 2000. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index. The Fund may invest in a statistically selected sample of stocks included in the Russell 2000 and in derivative instruments linked to the Russell 2000. The Fund may not invest in all of the common stocks in the Russell 2000, or in the same weightings as in the Russell 2000. The Fund chooses investments so that the market capitalizations, industry weightings and other fundamental characteristics of the stocks and derivative instruments chosen are similar to the Russell 2000 as a whole. As of March 31, 2026, the companies in the Russell 2000 have a market capitalization ranging from $3.29 million to $39.25 billion. The Fund is a “feeder” fund that invests all of its assets in the Series, a series of the Master LLC, which has the same investment objective and strategies as the Fund. All investments are made at the Series level. This structure is sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the investment results of the Series. For simplicity, this prospectus uses the name of the Fund or the term “Fund” (as applicable) to include the Series.
Class K \| iShares MSCI EAFE International Index Fund
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	MSCI EAFE International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the MSCI EAFE Index. The Fund will be substantially invested in securities in the MSCI EAFE Index, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the MSCI EAFE Index. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index. MSCI EAFE International Index Fund invests in a statistically selected sample of equity securities included in the MSCI EAFE Index and in derivative instruments linked to the MSCI EAFE Index. Equity securities include common stock, preferred stock and securities or other instruments whose price is linked to the value of common stock. The Fund will, under normal circumstances, invest in all of the countries represented in the MSCI EAFE Index. The Fund may not, however, invest in all of the companies within a country represented in the MSCI EAFE Index, or in the same weightings as in the MSCI EAFE Index.
Investor P \| iShares Russell 2000 Small-Cap Index Fund
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	Russell 2000 Small-Cap Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the Russell 2000. The Fund will be substantially invested in securities in the Russell 2000, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the Russell 2000. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index. The Fund may invest in a statistically selected sample of stocks included in the Russell 2000 and in derivative instruments linked to the Russell 2000. The Fund may not invest in all of the common stocks in the Russell 2000, or in the same weightings as in the Russell 2000. The Fund chooses investments so that the market capitalizations, industry weightings and other fundamental characteristics of the stocks and derivative instruments chosen are similar to the Russell 2000 as a whole. As of March 31, 2026, the companies in the Russell 2000 have a market capitalization ranging from $3.29 million to $39.25 billion. The Fund is a “feeder” fund that invests all of its assets in the Series, a series of the Master LLC, which has the same investment objective and strategies as the Fund. All investments are made at the Series level. This structure is sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the investment results of the Series. For simplicity, this prospectus uses the name of the Fund or the term “Fund” (as applicable) to include the Series.
Investor P \| iShares MSCI EAFE International Index Fund
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	MSCI EAFE International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the MSCI EAFE Index. The Fund will be substantially invested in securities in the MSCI EAFE Index, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the MSCI EAFE Index. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index. MSCI EAFE International Index Fund invests in a statistically selected sample of equity securities included in the MSCI EAFE Index and in derivative instruments linked to the MSCI EAFE Index. Equity securities include common stock, preferred stock and securities or other instruments whose price is linked to the value of common stock. The Fund will, under normal circumstances, invest in all of the countries represented in the MSCI EAFE Index. The Fund may not, however, invest in all of the companies within a country represented in the MSCI EAFE Index, or in the same weightings as in the MSCI EAFE Index.
Class G \| iShares MSCI EAFE International Index Fund
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	MSCI EAFE International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the MSCI EAFE Index. The Fund will be substantially invested in securities in the MSCI EAFE Index, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the MSCI EAFE Index. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index. MSCI EAFE International Index Fund invests in a statistically selected sample of equity securities included in the MSCI EAFE Index and in derivative instruments linked to the MSCI EAFE Index. Equity securities include common stock, preferred stock and securities or other instruments whose price is linked to the value of common stock. The Fund will, under normal circumstances, invest in all of the countries represented in the MSCI EAFE Index. The Fund may not, however, invest in all of the companies within a country represented in the MSCI EAFE Index, or in the same weightings as in the MSCI EAFE Index.

Russell 2000 Small-Cap Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the Russell 2000. The Fund will be substantially invested in securities in the Russell 2000, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the Russell 2000. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index.

The Fund may invest in a statistically selected sample of stocks included in the Russell 2000 and in derivative instruments linked to the Russell 2000. The Fund may not invest in all of the common stocks in the Russell 2000, or in the same weightings as in the Russell 2000. The Fund chooses investments so that the market capitalizations, industry weightings and other fundamental characteristics of the stocks and derivative instruments chosen are similar to the Russell 2000 as a whole. As of March 31, 2026, the companies in the Russell 2000 have a market capitalization ranging from $3.29 million to $39.25 billion.

The Fund is a “feeder” fund that invests all of its assets in the Series, a series of the Master LLC, which has the same investment objective and strategies as the Fund. All investments are made at the Series level. This structure is sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the investment results of the Series. For simplicity, this prospectus uses the name of the Fund or the term “Fund” (as applicable) to include the Series.

Prospectus [Line Items]

Strategy Narrative [Text Block]

MSCI EAFE International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the MSCI EAFE Index. The Fund will be substantially invested in securities in the MSCI EAFE Index, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the MSCI EAFE Index. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index.

MSCI EAFE International Index Fund invests in a statistically selected sample of equity securities included in the MSCI EAFE Index and in derivative instruments linked to the MSCI EAFE Index. Equity securities include common stock, preferred stock and securities or other instruments whose price is linked to the value of common stock. The Fund will, under normal circumstances, invest in all of the countries represented in the MSCI EAFE Index. The Fund may not, however, invest in all of the companies within a country represented in the MSCI EAFE Index, or in the same weightings as in the MSCI EAFE Index.

Prospectus [Line Items]

Strategy Narrative [Text Block]

Russell 2000 Small-Cap Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the Russell 2000. The Fund will be substantially invested in securities in the Russell 2000, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the Russell 2000. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index.

The Fund may invest in a statistically selected sample of stocks included in the Russell 2000 and in derivative instruments linked to the Russell 2000. The Fund may not invest in all of the common stocks in the Russell 2000, or in the same weightings as in the Russell 2000. The Fund chooses investments so that the market capitalizations, industry weightings and other fundamental characteristics of the stocks and derivative instruments chosen are similar to the Russell 2000 as a whole. As of March 31, 2026, the companies in the Russell 2000 have a market capitalization ranging from $3.29 million to $39.25 billion.

The Fund is a “feeder” fund that invests all of its assets in the Series, a series of the Master LLC, which has the same investment objective and strategies as the Fund. All investments are made at the Series level. This structure is sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the investment results of the Series. For simplicity, this prospectus uses the name of the Fund or the term “Fund” (as applicable) to include the Series.

Prospectus [Line Items]

Strategy Narrative [Text Block]

MSCI EAFE International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the MSCI EAFE Index. The Fund will be substantially invested in securities in the MSCI EAFE Index, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the MSCI EAFE Index. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index.

MSCI EAFE International Index Fund invests in a statistically selected sample of equity securities included in the MSCI EAFE Index and in derivative instruments linked to the MSCI EAFE Index. Equity securities include common stock, preferred stock and securities or other instruments whose price is linked to the value of common stock. The Fund will, under normal circumstances, invest in all of the countries represented in the MSCI EAFE Index. The Fund may not, however, invest in all of the companies within a country represented in the MSCI EAFE Index, or in the same weightings as in the MSCI EAFE Index.

Prospectus [Line Items]

Strategy Narrative [Text Block]

Russell 2000 Small-Cap Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the Russell 2000. The Fund will be substantially invested in securities in the Russell 2000, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the Russell 2000. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index.

The Fund may invest in a statistically selected sample of stocks included in the Russell 2000 and in derivative instruments linked to the Russell 2000. The Fund may not invest in all of the common stocks in the Russell 2000, or in the same weightings as in the Russell 2000. The Fund chooses investments so that the market capitalizations, industry weightings and other fundamental characteristics of the stocks and derivative instruments chosen are similar to the Russell 2000 as a whole. As of March 31, 2026, the companies in the Russell 2000 have a market capitalization ranging from $3.29 million to $39.25 billion.

The Fund is a “feeder” fund that invests all of its assets in the Series, a series of the Master LLC, which has the same investment objective and strategies as the Fund. All investments are made at the Series level. This structure is sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the investment results of the Series. For simplicity, this prospectus uses the name of the Fund or the term “Fund” (as applicable) to include the Series.

Prospectus [Line Items]

Strategy Narrative [Text Block]

MSCI EAFE International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the MSCI EAFE Index. The Fund will be substantially invested in securities in the MSCI EAFE Index, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the MSCI EAFE Index. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index.

MSCI EAFE International Index Fund invests in a statistically selected sample of equity securities included in the MSCI EAFE Index and in derivative instruments linked to the MSCI EAFE Index. Equity securities include common stock, preferred stock and securities or other instruments whose price is linked to the value of common stock. The Fund will, under normal circumstances, invest in all of the countries represented in the MSCI EAFE Index. The Fund may not, however, invest in all of the companies within a country represented in the MSCI EAFE Index, or in the same weightings as in the MSCI EAFE Index.

Prospectus [Line Items]

Strategy Narrative [Text Block]

MSCI EAFE International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the MSCI EAFE Index. The Fund will be substantially invested in securities in the MSCI EAFE Index, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the MSCI EAFE Index. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index.

MSCI EAFE International Index Fund invests in a statistically selected sample of equity securities included in the MSCI EAFE Index and in derivative instruments linked to the MSCI EAFE Index. Equity securities include common stock, preferred stock and securities or other instruments whose price is linked to the value of common stock. The Fund will, under normal circumstances, invest in all of the countries represented in the MSCI EAFE Index. The Fund may not, however, invest in all of the companies within a country represented in the MSCI EAFE Index, or in the same weightings as in the MSCI EAFE Index.