v3.25.4
Investment Strategy
Oct. 31, 2025
Morgan Stanley Institutional Liquidity Funds - Institutional Class Portfolios | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its
portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Class Portfolios | MSILF Government Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest substantially all of its assets in U.S. Treasury obligations and certain U.S. government securities, the interest from which is generally exempt from state income taxation, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. The  U.S. government securities that the Fund may purchase include those issued or guaranteed either by the U.S. Treasury or certain agencies, authorities or instrumentalities of the U.S. Government. The Fund may also invest in repurchase agreements with the Federal Reserve Bank of New York. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. government securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Plus Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the  U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Plus Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Plus Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Select Class Portfolios | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a
good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Select Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the  U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Select Class Portfolios | MSILF Government Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest substantially all of its assets in U.S. Treasury obligations and certain U.S. government securities, the interest from which is generally exempt from state income taxation, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. The  U.S. government securities that the Fund may purchase include those issued or guaranteed either by the U.S. Treasury or certain agencies, authorities or instrumentalities of the U.S. Government. The Fund may also invest in repurchase agreements with the Federal Reserve Bank of New York. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. government securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Select Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Institutional Select Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Investor Class Portfolios | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a
good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Investor Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Investor Class Portfolios | MSILF Government Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest substantially all of its assets in U.S. Treasury obligations and certain U.S. government securities, the interest from which is generally exempt from state income taxation, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. The  U.S. government securities that the Fund may purchase include those issued or guaranteed either by the U.S. Treasury or certain agencies, authorities or instrumentalities of the U.S. Government. The Fund may also invest in repurchase agreements with the Federal Reserve Bank of New York. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. government securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Investor Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Investor Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Administrative Class Portfolios | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a
good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Administrative Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the  U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Administrative Class Portfolios | MSILF Government Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest substantially all of its assets in U.S. Treasury obligations and certain U.S. government securities, the interest from which is generally exempt from state income taxation, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. The  U.S. government securities that the Fund may purchase include those issued or guaranteed either by the U.S. Treasury or certain agencies, authorities or instrumentalities of the U.S. Government. The Fund may also invest in repurchase agreements with the Federal Reserve Bank of New York. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. government securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Administrative Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Administrative Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Advisory Class Portfolios | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a
good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Advisory Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Advisory Class Portfolios | MSILF Government Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest substantially all of its assets in U.S. Treasury obligations and certain U.S. government securities, the interest from which is generally exempt from state income taxation, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. The  U.S. government securities that the Fund may purchase include those issued or guaranteed either by the U.S. Treasury or certain agencies, authorities or instrumentalities of the U.S. Government. The Fund may also invest in repurchase agreements with the Federal Reserve Bank of New York. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. government securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Advisory Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Advisory Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Participant Class Portfolios | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a
good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Participant Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the  U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Participant Class Portfolios | MSILF Government Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest substantially all of its assets in U.S. Treasury obligations and certain U.S. government securities, the interest from which is generally exempt from state income taxation, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. The  U.S. government securities that the Fund may purchase include those issued or guaranteed either by the U.S. Treasury or certain agencies, authorities or instrumentalities of the U.S. Government. The Fund may also invest in repurchase agreements with the Federal Reserve Bank of New York. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. government securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Participant Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Participant Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Cash Management Class Portfolios | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a
good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Cash Management Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Cash Management Class Portfolios | MSILF Government Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest substantially all of its assets in U.S. Treasury obligations and certain U.S. government securities, the interest from which is generally exempt from state income taxation, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. The  U.S. government securities that the Fund may purchase include those issued or guaranteed either by the U.S. Treasury or certain agencies, authorities or instrumentalities of the U.S. Government. The Fund may also invest in repurchase agreements with the Federal Reserve Bank of New York. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. government securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Cash Management Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Cash Management Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Select Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Select Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Select Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain  U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in  U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - CastleOak Share Class | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its
portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - CastleOak Share Class | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Impact Class Portfolios | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its
portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Impact Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the  U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Impact Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Impact Partner Class Portfolios | MSILF Prime Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund invests in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial corporations and U.S. non-financial corporations. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. The Fund is permitted to hold a portion of its assets in cash.
The Fund may also invest in U.S. dollar-denominated foreign securities and money market instruments.
The Fund operates as an “institutional money market fund,” which is neither a “government money market fund” nor “retail money market fund” as such terms are defined in or interpreted under Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”). As such, the Fund is required to price and transact in its shares at a net asset value per share (“NAV”) reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV), rounded to a minimum of the fourth decimal place. Like other money market funds of its type, the Fund is subject to the possible imposition of a discretionary liquidity fee if the Adviser, as the delegate of the Board of Trustees, determines that such fee is in the best interests of the Fund.
In addition, under Rule 2a-7, as an institutional prime money market fund, the Fund is required to impose a mandatory liquidity fee if the Fund experiences total daily net redemptions exceeding 5% of the Fund’s net assets (or such smaller amount of net redemptions as the Board of Trustees determines) based on flow information available within a reasonable period after the computation of the Fund’s net asset value on that day. The amount of a mandatory liquidity fee to be imposed will be based on a good faith estimate, supported by data, of the costs the Fund would incur if the Fund sold a pro rata amount of each security in its
portfolio to satisfy the amount of the net redemptions. If the Fund’s liquidity costs cannot be estimated in good faith and supported by data, a 1% default mandatory liquidity fee will be imposed. If the amount of the mandatory liquidity fee would be de minimis (i.e., less than 0.01% of the value of the shares redeemed), the Fund is not required to impose a mandatory liquidity fee. The Board of Trustees has delegated to the Adviser the responsibility for making mandatory liquidity fee determinations.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Impact Partner Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Impact Partner Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Advisor Class Portfolios | MSILF Government Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in obligations issued or guaranteed by the  U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Advisor Class Portfolios | MSILF Treasury Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.
Morgan Stanley Institutional Liquidity Funds - Advisor Class Portfolios | MSILF Treasury Securities Portfolio  
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Fund has adopted a policy to invest exclusively in U.S. Treasury obligations, which are backed by the full faith and credit of the United States, and, accordingly, qualifies as a “government money market fund” under federal regulations. The Fund is permitted to hold a portion of its assets in cash.
A “government money market fund” is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A “government money market fund” is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a “liquidity fee” on redemptions. In selecting investments, the Adviser seeks to maintain the Fund’s share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment. As a “government money market fund,” the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended (“Rule 2a-7” under the “1940 Act”) to seek to maintain a stable net asset value per share of $1.00.
In addition, the Fund has adopted a policy that provides, under normal circumstances, at least 80% of the Fund’s assets will be invested in U.S. Treasury obligations, which are backed by the full faith and credit of the United States. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days’ notice in writing of any changes.
The Fund’s investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.