Label	Element	Value
Investor Shares Prospectus \| DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT FUND
Risk/Return:	rr_RiskReturnAbstract
Supplement to Prospectus [Text Block]	rr_SupplementToProspectusTextBlock	November 18, 2020 DREYFUS TAX EXEMPT CASH MANAGEMENT FUNDS - Dreyfus AMT-Free Tax Exempt Cash Management Investor Shares Supplement to Summary Prospectus, Prospectus and Statement of Additional Information IMPORTANT NOTICE REGARDING CHANGE IN INVESTMENT POLICY Effective on or about February 1, 2021 (the "Effective Date"), the current investment policy that the fund be managed so that income paid by the fund not be subject to the federal alternative minimum tax will be discontinued. The fund will continue to normally invest substantially all of its net assets in short-term, high quality municipal obligations that provide income exempt from federal income tax. ***** In addition, as of the Effective Date, the fund's name will be changed to "Dreyfus Tax Exempt Cash Management". ***** Also, effective on the Effective Date, Investor shares of the fund will be converted to Institutional shares. Institutional shares of the fund have a lower total annual expense ratio and a better performance record than Investor shares of the fund. Investors may obtain a free copy of the Prospectus for Institutional shares of the fund by calling 1-800-346-3621.
Risk/Return [Heading]	rr_RiskReturnHeading	DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT FUND

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Investor Shares Prospectus | DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT FUND

Risk/Return:

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Supplement to Prospectus [Text Block]

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November 18, 2020

DREYFUS TAX EXEMPT CASH MANAGEMENT FUNDS

- Dreyfus AMT-Free Tax Exempt Cash Management

Investor Shares

Supplement to Summary Prospectus, Prospectus and
Statement of Additional Information

IMPORTANT NOTICE REGARDING CHANGE IN INVESTMENT POLICY

Effective on or about February 1, 2021 (the "Effective Date"), the current investment policy that the fund be managed so that income paid by the fund not be subject to the federal alternative minimum tax will be discontinued. The fund will continue to normally invest substantially all of its net assets in short-term, high quality municipal obligations that provide income exempt from federal income tax.

*******

In addition, as of the Effective Date, the fund's name will be changed to "Dreyfus Tax Exempt Cash Management".

*******

Also, effective on the Effective Date, Investor shares of the fund will be converted to Institutional shares. Institutional shares of the fund have a lower total annual expense ratio and a better performance record than Investor shares of the fund. Investors may obtain a free copy of the Prospectus for Institutional shares of the fund by calling 1-800-346-3621.

Risk/Return [Heading]

rr_RiskReturnHeading

DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT FUND