485BPOS

File No. 2-89359

811-03964

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933[X]

Pre-Effective Amendment No.[__]

Post-Effective Amendment No. 60[X]

and/or

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940[X]

Amendment No. 60[X]

(Check appropriate box or boxes.)

Dreyfus Government Cash Management Funds

(Exact Name of Registrant as Specified in Charter)

c/o The Dreyfus Corporation

200 Park Avenue, New York, New York 10166

(Address of Principal Executive Offices) (Zip Code)

Registrant's Telephone Number, including Area Code: (212) 922-6400

Bennett A. MacDougall, Esq.

200 Park Avenue

New York, New York 10166

(Name and Address of Agent for Service)

It is proposed that this filing will become effective (check appropriate box)

X__ immediately upon filing pursuant to paragraph (b)

_____on (date) pursuant to paragraph (b)

_____ (days) days after filing pursuant to paragraph (a)(1)

_____on (date) pursuant to paragraph (a)(1)

_____ (days) days after filing pursuant to paragraph (a)(2)

_____on (date) pursuant to paragraph (a)(2) of Rule 485

If appropriate, check the following box:

_____this post-effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for effectiveness of this Amendment to the Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Amendment to the Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of New York, and State of New York on the 14th day of June 2018.

Dreyfus Government Cash Management Funds

BY:	/s/ Bradley J. Skapyak*
	Bradley J. Skapyak, PRESIDENT

Pursuant to the requirements of the Securities Act of 1933, this Amendment to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

Signatures	Title	Date
/s/ Bradley J. Skapyak*	President (Principal Executive Officer)	06/14/2018
Bradley J. Skapyak
/s/ James Windels*	Treasurer (Principal Financial Officer and Accounting Officer)	06/14/2018
James Windels
/s/ Joseph S. DiMartino*	Chairman of the Board	06/14/2018
Joseph S. DiMartino
/s/ Francine J. Bovich*	Board Member	06/14/2018
Francine J. Bovich
/s/ J. Charles Cardona*	Board Member	06/14/2018
J. Charles Cardona
/s/ Gordon J. Davis*	Board Member	06/14/2018
Gordon J. Davis
/s/ Isabel P. Dunst*	Board Member	06/14/2018
Isabel P. Dunst
/s/ Robin A. Melvin*	Board Member	06/14/2018
Robin A. Melvin
/s/ Nathan Leventhal*	Board Member	06/14/2018
Nathan Leventhal
/s/ Roslyn M. Watson*	Board Member	06/14/2018

Roslyn M. Watson
/s/ Benaree Pratt Wiley*	Board Member	06/14/2018
Benaree Pratt Wiley

*BY:	/s/ James Bitetto
	James Bitetto Attorney-in-Fact

INDEX OF EXHIBITS

Exhibits

EX-101.INS – Instance Document.

EX-101.SCH – Taxonomy.

EX-101.CAL – Calculation Linkbase.

EX-101.DEF – Definition Linkbase.

EX-101.LAB – Labels Linkbase.

EX-101.PRE – Presentation Linkbase.

XML

Document and Entity Information	Total
Prospectus:
Document Type	485BPOS
Document Period End Date	Jan. 31, 2018
Registrant Name	DREYFUS GOVERNMENT CASH MANAGEMENT Funds
Central Index Key	0000740766
Amendment Flag	false
Document Creation Date	May 29, 2018
Document Effective Date	Jun. 01, 2018
Prospectus Date	Jun. 01, 2018
Administrative Shares Prospectus | Dreyfus Cash Management | administrative shares
Prospectus:
Trading Symbol	DACXX
Administrative Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Administrative Shares
Prospectus:
Trading Symbol	DAGXX
Administrative Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Administrative Shares
Prospectus:
Trading Symbol	DAPXX
Administrative Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Administrative Shares
Prospectus:
Trading Symbol	DTAXX
Administrative Shares Prospectus | Dreyfus Treasury Securities Cash Management | Administrative Shares
Prospectus:
Trading Symbol	DARXX
Institutional Shares Prospectus | Dreyfus Cash Management | Institutional Shares
Prospectus:
Trading Symbol	DICXX
Institutional Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash mangement - Institutional Shares
Prospectus:
Trading Symbol	DGCXX
Institutional Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Institutional Shares
Prospectus:
Trading Symbol	DIPXX
Institutional Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Institutional Shares
Prospectus:
Trading Symbol	DTRXX
Institutional Shares Prospectus | Dreyfus Treasury Securities Cash Management | Institutional Shares
Prospectus:
Trading Symbol	DIRXX
Institutional Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-Free TAX EXEMPT CASH MANAGEMENT - Institutional Shares
Prospectus:
Trading Symbol	DEIXX
Institutional Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Institutional Shares
Prospectus:
Trading Symbol	DIMXX
Institutional Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Institutional Shares
Prospectus:
Trading Symbol	DIYXX
Investor Shares Prospectus | Dreyfus Cash Management | Investor Shares
Prospectus:
Trading Symbol	DVCXX
Investor Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Investor Shares
Prospectus:
Trading Symbol	DGVXX
Investor Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Investor Shares
Prospectus:
Trading Symbol	DVPXX
Investor Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Investor Shares
Prospectus:
Trading Symbol	DTVXX
Investor Shares Prospectus | Dreyfus Treasury Securities Cash Management | Investor Shares
Prospectus:
Trading Symbol	DVRXX
Investor Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT - Investor Shares
Prospectus:
Trading Symbol	DEVXX
Investor Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Investor Shares
Prospectus:
Trading Symbol	DVMXX
Investor Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Investor Shares
Prospectus:
Trading Symbol	DVYXX
Participant Shares Prospectus | Dreyfus Government Cash Management | Dreyfus Government Cash Management - Participant Shares
Prospectus:
Trading Symbol	DPGXX
Participant Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Participant Shares
Prospectus:
Trading Symbol	DGPXX
Participant Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Participant Shares
Prospectus:
Trading Symbol	DTPXX
Participant Shares Prospectus | Dreyfus Treasury Securities Cash Management | Participant Shares
Prospectus:
Trading Symbol	DPRXX

XML

Administrative Shares Prospectus | Dreyfus Cash Management

Fund Summary - Dreyfus Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Administrative Shares Prospectus Dreyfus Cash Management administrative shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.10%
Other expenses	0.05%
Total annual fund operating expenses	0.35%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Cash Management | administrative shares | USD ($)	36	113	197	443

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Cash Management | administrative shares | USD ($)	36	113	197	443

Principal Investment Strategy

To pursue its goal, the fund normally invests in a diversified portfolio of high quality, short-term, dollar-denominated debt securities, including: securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities; certificates of deposit, time deposits, bankers' acceptances and other short-term securities issued by domestic or foreign banks or thrifts or their subsidiaries or branches; repurchase agreements, including tri-party repurchase agreements; asset-backed securities; municipal securities; domestic and dollar-denominated foreign commercial paper and other short-term corporate obligations, including those with floating or variable rates of interest; and dollar-denominated obligations issued or guaranteed by one or more foreign governments or any of their political subdivisions or agencies.

The fund's investments are concentrated in the banking industry, because the fund normally invests at least 25% of its net assets in domestic or dollar-denominated foreign bank obligations.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the net asset value (NAV) of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Principal Risks

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Banking industry risk. The risks generally associated with concentrating investments in the banking industry include interest rate risk, credit risk, and regulatory developments relating to the banking industry.

·Foreign investment risk. The risks generally associated with dollar-denominated foreign investments include economic and political developments, seizure or nationalization of deposits, imposition of taxes or other restrictions on payment of principal and interest.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement and/or, for a tri-party repurchase agreement, the third party bank providing payment administration, collateral custody and management services for the transaction, could fail to honor the terms of the agreement.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.96%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.35%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Administrative Shares Prospectus | Dreyfus Cash Management | administrative shares	0.96%	0.24%	0.45%

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Administrative Shares Prospectus | Dreyfus Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

To pursue its goal, the fund normally invests in a diversified portfolio of high quality, short-term, dollar-denominated debt securities, including: securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities; certificates of deposit, time deposits, bankers' acceptances and other short-term securities issued by domestic or foreign banks or thrifts or their subsidiaries or branches; repurchase agreements, including tri-party repurchase agreements; asset-backed securities; municipal securities; domestic and dollar-denominated foreign commercial paper and other short-term corporate obligations, including those with floating or variable rates of interest; and dollar-denominated obligations issued or guaranteed by one or more foreign governments or any of their political subdivisions or agencies.

The fund's investments are concentrated in the banking industry, because the fund normally invests at least 25% of its net assets in domestic or dollar-denominated foreign bank obligations.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the net asset value (NAV) of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Banking industry risk. The risks generally associated with concentrating investments in the banking industry include interest rate risk, credit risk, and regulatory developments relating to the banking industry.

·Foreign investment risk. The risks generally associated with dollar-denominated foreign investments include economic and political developments, seizure or nationalization of deposits, imposition of taxes or other restrictions on payment of principal and interest.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement and/or, for a tri-party repurchase agreement, the third party bank providing payment administration, collateral custody and management services for the transaction, could fail to honor the terms of the agreement.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.96%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.35%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.35%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.96%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Administrative Shares Prospectus | Dreyfus Cash Management | administrative shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.05%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.35%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

113

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

197

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

443

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

36

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

113

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

197

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 443

Annual Return 2008

rr_AnnualReturn2008

2.83%

Annual Return 2009

rr_AnnualReturn2009

0.43%

Annual Return 2010

rr_AnnualReturn2010

0.05%

Annual Return 2011

rr_AnnualReturn2011

0.01%

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.24%

Annual Return 2017

rr_AnnualReturn2017

0.96%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.96%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.24%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.45%

XML

Administrative Shares Prospectus | Dreyfus Government Cash Management

Fund Summary - Dreyfus Government Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Administrative Shares Prospectus Dreyfus Government Cash Management dreyfus government cash management - Administrative Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.10%
Other expenses	0.01%
Total annual fund operating expenses	0.31%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Administrative Shares | USD ($)	32	100	174	393

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Administrative Shares | USD ($)	32	100	174	393

Principal Investment Strategy

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest), repurchase agreements collateralized solely by government securities and/or cash, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities and repurchase agreements collateralized solely by government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash and/or repurchase agreements collateralized by cash). The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.85%

Worst Quarter
Q4, 2011: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.29%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Administrative Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Administrative Shares	0.69%	0.17%	0.32%

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Administrative Shares Prospectus | Dreyfus Government Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Government Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest), repurchase agreements collateralized solely by government securities and/or cash, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities and repurchase agreements collateralized solely by government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash and/or repurchase agreements collateralized by cash). The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.85%

Worst Quarter
Q4, 2011: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.29%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.29%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.85%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Administrative Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Administrative Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.31%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 32

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

100

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

174

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

393

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

32

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

100

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

174

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 393

Annual Return 2008

rr_AnnualReturn2008

2.19%

Annual Return 2009

rr_AnnualReturn2009

0.15%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

0.01%

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.14%

Annual Return 2017

rr_AnnualReturn2017

0.69%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.69%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.17%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.32%

XML

Administrative Shares Prospectus | Dreyfus Government Securities Cash Management

Fund Summary - Dreyfus Government Securities Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Administrative Shares Prospectus Dreyfus Government Securities Cash Management Dreyfus Government Securities Cash Management - Administrative Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.10%
Other expenses	0.02%
Total annual fund operating expenses	0.32%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Administrative Shares | USD ($)	33	103	180	406

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Administrative Shares | USD ($)	33	103	180	406

Principal Investment Strategy

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in government securities.

The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government. While the fund is permitted to invest in the full range of government securities, the fund currently is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.81%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.29%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Administrative Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Administrative Shares	0.63%	0.14%	0.29%

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Administrative Shares Prospectus | Dreyfus Government Securities Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Government Securities Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in government securities.

The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government. While the fund is permitted to invest in the full range of government securities, the fund currently is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.81%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.29%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.29%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.81%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Administrative Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Administrative Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.32%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 33

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

103

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

180

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

406

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

33

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

103

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

180

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 406

Annual Return 2008

rr_AnnualReturn2008

2.12%

Annual Return 2009

rr_AnnualReturn2009

0.07%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.08%

Annual Return 2017

rr_AnnualReturn2017

0.63%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.63%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.14%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.29%

XML

Administrative Shares Prospectus | Dreyfus Treasury & Agency Cash Management

Fund Summary - Dreyfus Treasury & Agency Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Administrative Shares Prospectus Dreyfus Treasury & Agency Cash Management Administrative Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.10%
Other expenses	0.01%
Total annual fund operating expenses	0.31%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Administrative Shares | USD ($)	32	100	174	393

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Administrative Shares | USD ($)	32	100	174	393

Principal Investment Strategy

The fund pursues its investment objective by investing only in U.S. Treasury securities, repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities and repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash or repurchase agreements collateralized by cash), and typically invests exclusively in such securities.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.62%

Worst Quarter
Q3, 2010: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.29%

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Administrative Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Administrative Shares	0.65%	0.16%	0.23%

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Administrative Shares Prospectus | Dreyfus Treasury & Agency Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Treasury & Agency Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in U.S. Treasury securities, repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities and repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash or repurchase agreements collateralized by cash), and typically invests exclusively in such securities.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.62%

Worst Quarter
Q3, 2010: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.29%

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.29%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.62%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Administrative Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Administrative Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.31%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 32

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

100

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

174

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

393

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

32

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

100

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

174

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 393

Annual Return 2008

rr_AnnualReturn2008

1.44%

Annual Return 2009

rr_AnnualReturn2009

0.03%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

0.01%

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

0.01%

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.10%

Annual Return 2017

rr_AnnualReturn2017

0.65%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.65%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.16%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.23%

XML

Administrative Shares Prospectus | Dreyfus Treasury Securities Cash Management

Fund Summary - Dreyfus Treasury Securities Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Administrative Shares Prospectus Dreyfus Treasury Securities Cash Management Administrative Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.10%
Other expenses	0.01%
Total annual fund operating expenses	0.31%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Treasury Securities Cash Management | Administrative Shares | USD ($)	32	100	174	393

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Administrative Shares Prospectus | Dreyfus Treasury Securities Cash Management | Administrative Shares | USD ($)	32	100	174	393

Principal Investment Strategy

The fund pursues its investment objective by investing only in U.S. Treasury securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in U.S. Treasury securities.

The fund is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.61%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.29%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Administrative Shares Prospectus | Dreyfus Treasury Securities Cash Management | Administrative Shares	0.61%	0.14%	0.21%

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Administrative Shares Prospectus | Dreyfus Treasury Securities Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Treasury Securities Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in U.S. Treasury securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in U.S. Treasury securities.

The fund is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Administrative shares from year to year. The table shows the average annual total returns of the fund's Administrative shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.61%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Administrative shares as of March 31, 2018 was 0.29%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.29%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.61%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Administrative shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Administrative Shares Prospectus | Dreyfus Treasury Securities Cash Management | Administrative Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.31%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 32

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

100

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

174

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

393

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

32

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

100

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

174

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 393

Annual Return 2008

rr_AnnualReturn2008

1.39%

Annual Return 2009

rr_AnnualReturn2009

none

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.07%

Annual Return 2017

rr_AnnualReturn2017

0.61%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.61%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.14%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.21%

XML

Institutional Shares Prospectus | Dreyfus Cash Management

Fund Summary - Dreyfus Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Institutional Shares Prospectus Dreyfus Cash Management Institutional Shares
Management fees	0.20%
Other expenses (including shareholder services fees)	0.05%
Total annual fund operating expenses	0.25%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Cash Management | Institutional Shares | USD ($)	26	80	141	318

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Cash Management | Institutional Shares | USD ($)	26	80	141	318

Principal Investment Strategy

To pursue its goal, the fund normally invests in a diversified portfolio of high quality, short-term, dollar-denominated debt securities, including: securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities; certificates of deposit, time deposits, bankers' acceptances and other short-term securities issued by domestic or foreign banks or thrifts or their subsidiaries or branches; repurchase agreements, including tri-party repurchase agreements; asset-backed securities; municipal securities; domestic and dollar-denominated foreign commercial paper and other short-term corporate obligations, including those with floating or variable rates of interest; and dollar-denominated obligations issued or guaranteed by one or more foreign governments or any of their political subdivisions or agencies.

The fund's investments are concentrated in the banking industry, because the fund normally invests at least 25% of its net assets in domestic or dollar-denominated foreign bank obligations.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the net asset value (NAV) of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Principal Risks

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Banking industry risk. The risks generally associated with concentrating investments in the banking industry include interest rate risk, credit risk, and regulatory developments relating to the banking industry.

·Foreign investment risk. The risks generally associated with dollar-denominated foreign investments include economic and political developments, seizure or nationalization of deposits, imposition of taxes or other restrictions on payment of principal and interest.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement and/or, for a tri-party repurchase agreement, the third party bank providing payment administration, collateral custody and management services for the transaction, could fail to honor the terms of the agreement.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.98%

Worst Quarter
Q1, 2015: 0.01%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.37%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Institutional Shares Prospectus | Dreyfus Cash Management | Institutional Shares	1.05%	0.30%	0.52%

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Institutional Shares Prospectus | Dreyfus Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

To pursue its goal, the fund normally invests in a diversified portfolio of high quality, short-term, dollar-denominated debt securities, including: securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities; certificates of deposit, time deposits, bankers' acceptances and other short-term securities issued by domestic or foreign banks or thrifts or their subsidiaries or branches; repurchase agreements, including tri-party repurchase agreements; asset-backed securities; municipal securities; domestic and dollar-denominated foreign commercial paper and other short-term corporate obligations, including those with floating or variable rates of interest; and dollar-denominated obligations issued or guaranteed by one or more foreign governments or any of their political subdivisions or agencies.

The fund's investments are concentrated in the banking industry, because the fund normally invests at least 25% of its net assets in domestic or dollar-denominated foreign bank obligations.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the net asset value (NAV) of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Banking industry risk. The risks generally associated with concentrating investments in the banking industry include interest rate risk, credit risk, and regulatory developments relating to the banking industry.

·Foreign investment risk. The risks generally associated with dollar-denominated foreign investments include economic and political developments, seizure or nationalization of deposits, imposition of taxes or other restrictions on payment of principal and interest.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement and/or, for a tri-party repurchase agreement, the third party bank providing payment administration, collateral custody and management services for the transaction, could fail to honor the terms of the agreement.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.98%

Worst Quarter
Q1, 2015: 0.01%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.37%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.37%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.98%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

0.01%

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Institutional Shares Prospectus | Dreyfus Cash Management | Institutional Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.05%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

80

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

141

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

318

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

26

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

80

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

141

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 318

Annual Return 2008

rr_AnnualReturn2008

2.93%

Annual Return 2009

rr_AnnualReturn2009

0.52%

Annual Return 2010

rr_AnnualReturn2010

0.14%

Annual Return 2011

rr_AnnualReturn2011

0.08%

Annual Return 2012

rr_AnnualReturn2012

0.09%

Annual Return 2013

rr_AnnualReturn2013

0.04%

Annual Return 2014

rr_AnnualReturn2014

0.03%

Annual Return 2015

rr_AnnualReturn2015

0.05%

Annual Return 2016

rr_AnnualReturn2016

0.34%

Annual Return 2017

rr_AnnualReturn2017

1.05%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.05%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.30%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.52%

XML

Institutional Shares Prospectus | Dreyfus Government Cash Management

Fund Summary - Dreyfus Government Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Institutional Shares Prospectus Dreyfus Government Cash Management dreyfus government cash mangement - Institutional Shares
Management fees	0.20%
Other expenses (including shareholder services fees)	0.01%
Total annual fund operating expenses	0.21%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash mangement - Institutional Shares | USD ($)	22	68	118	268

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash mangement - Institutional Shares | USD ($)	22	68	118	268

Principal Investment Strategy

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest), repurchase agreements collateralized solely by government securities and/or cash, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities and repurchase agreements collateralized solely by government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash and/or repurchase agreements collateralized by cash). The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.87%

Worst Quarter
Q4, 2011: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.32%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Institutional Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash mangement - Institutional Shares	0.79%	0.21%	0.36%

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Institutional Shares Prospectus | Dreyfus Government Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Government Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest), repurchase agreements collateralized solely by government securities and/or cash, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities and repurchase agreements collateralized solely by government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash and/or repurchase agreements collateralized by cash). The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.87%

Worst Quarter
Q4, 2011: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.32%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.32%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.87%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Institutional Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash mangement - Institutional Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.21%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 22

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

68

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

118

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

268

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

22

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

68

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

118

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 268

Annual Return 2008

rr_AnnualReturn2008

2.29%

Annual Return 2009

rr_AnnualReturn2009

0.23%

Annual Return 2010

rr_AnnualReturn2010

0.04%

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

0.01%

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.02%

Annual Return 2016

rr_AnnualReturn2016

0.24%

Annual Return 2017

rr_AnnualReturn2017

0.79%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.79%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.21%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.36%

XML

Institutional Shares Prospectus | Dreyfus Government Securities Cash Management

Fund Summary - Dreyfus Government Securities Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Institutional Shares Prospectus Dreyfus Government Securities Cash Management Dreyfus Government Securities Cash Management - Institutional Shares
Management fees	0.20%
Other expenses (including shareholder services fees)	0.02%
Total annual fund operating expenses	0.22%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Institutional Shares | USD ($)	23	71	124	280

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Institutional Shares | USD ($)	23	71	124	280

Principal Investment Strategy

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in government securities.

The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government. While the fund is permitted to invest in the full range of government securities, the fund currently is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.84%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.31%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Institutional Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Institutional Shares	0.73%	0.19%	0.33%

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Institutional Shares Prospectus | Dreyfus Government Securities Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Government Securities Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in government securities.

The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government. While the fund is permitted to invest in the full range of government securities, the fund currently is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.84%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.31%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.31%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.84%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Institutional Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Institutional Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.22%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 23

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

71

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

124

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

280

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

23

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

71

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

124

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 280

Annual Return 2008

rr_AnnualReturn2008

2.22%

Annual Return 2009

rr_AnnualReturn2009

0.15%

Annual Return 2010

rr_AnnualReturn2010

0.01%

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.20%

Annual Return 2017

rr_AnnualReturn2017

0.73%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.73%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.19%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.33%

XML

Institutional Shares Prospectus | Dreyfus Treasury & Agency Cash Management

Fund Summary - Dreyfus Treasury & Agency Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Institutional Shares Prospectus Dreyfus Treasury & Agency Cash Management Institutional Shares
Management fees	0.20%
Other expenses (including shareholder services fees)	0.01%
Total annual fund operating expenses	0.21%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Institutional Shares | USD ($)	22	68	118	268

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Institutional Shares | USD ($)	22	68	118	268

Principal Investment Strategy

The fund pursues its investment objective by investing only in U.S. Treasury securities, repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities and repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash or repurchase agreements collateralized by cash), and typically invests exclusively in such securities.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.65%

Worst Quarter
Q1, 2010: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.31%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Institutional Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Institutional Shares	0.75%	0.20%	0.26%

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Institutional Shares Prospectus | Dreyfus Treasury & Agency Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Treasury & Agency Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in U.S. Treasury securities, repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities and repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash or repurchase agreements collateralized by cash), and typically invests exclusively in such securities.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.65%

Worst Quarter
Q1, 2010: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.31%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.31%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.65%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Institutional Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Institutional Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.21%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 22

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

68

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

118

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

268

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

22

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

68

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

118

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 268

Annual Return 2008

rr_AnnualReturn2008

1.54%

Annual Return 2009

rr_AnnualReturn2009

0.09%

Annual Return 2010

rr_AnnualReturn2010

0.01%

Annual Return 2011

rr_AnnualReturn2011

0.01%

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

0.01%

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.02%

Annual Return 2016

rr_AnnualReturn2016

0.20%

Annual Return 2017

rr_AnnualReturn2017

0.75%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.75%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.20%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.26%

XML

Institutional Shares Prospectus | Dreyfus Treasury Securities Cash Management

Fund Summary - Dreyfus Treasury Securities Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Institutional Shares Prospectus Dreyfus Treasury Securities Cash Management Institutional Shares
Management fees	0.20%
Other expenses (including shareholder services fees)	0.01%
Total annual fund operating expenses	0.21%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Treasury Securities Cash Management | Institutional Shares | USD ($)	22	68	118	268

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus Treasury Securities Cash Management | Institutional Shares | USD ($)	22	68	118	268

Principal Investment Strategy

The fund pursues its investment objective by investing only in U.S. Treasury securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in U.S. Treasury securities.

The fund is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.63%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.31%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Institutional Shares Prospectus | Dreyfus Treasury Securities Cash Management | Institutional Shares	0.72%	0.18%	0.24%

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Institutional Shares Prospectus | Dreyfus Treasury Securities Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Treasury Securities Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in U.S. Treasury securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in U.S. Treasury securities.

The fund is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.63%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.31%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.31%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.63%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Institutional Shares Prospectus | Dreyfus Treasury Securities Cash Management | Institutional Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.21%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 22

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

68

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

118

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

268

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

22

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

68

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

118

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 268

Annual Return 2008

rr_AnnualReturn2008

1.49%

Annual Return 2009

rr_AnnualReturn2009

0.03%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.17%

Annual Return 2017

rr_AnnualReturn2017

0.72%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.72%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.18%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.24%

XML

Institutional Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund

Fund Summary - Dreyfus AMT-Free Tax Exempt Cash Management Fund

Investment Objective

The fund seeks as high a level of current income exempt from federal income tax as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Institutional Shares Prospectus Dreyfus AMT-Free Tax Exempt Cash Management Fund DREYFUS AMT-Free TAX EXEMPT CASH MANAGEMENT - Institutional Shares
Management fees	0.20%
Other expenses (including shareholder services fees)	0.06%
Total annual fund operating expenses	0.26%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-Free TAX EXEMPT CASH MANAGEMENT - Institutional Shares | USD ($)	27	84	146	331

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-Free TAX EXEMPT CASH MANAGEMENT - Institutional Shares | USD ($)	27	84	146	331

Principal Investment Strategy

To pursue its goal, the fund normally invests substantially all of its assets in short-term, high quality municipal obligations that provide income exempt from federal income taxes. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. In addition, the fund may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes that acceptable municipal obligations are unavailable for investment.

While the fund is permitted to invest up to 20% of its assets in municipal obligations that provide income that may be subject to the federal alternative minimum tax, the fund currently is managed so that income paid by the fund will not be subject to the federal alternative minimum tax.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the NAV of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Principal Risks

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.71%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.24%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Institutional Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-Free TAX EXEMPT CASH MANAGEMENT - Institutional Shares	0.59%	0.17%	0.37%

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Institutional Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus AMT-Free Tax Exempt Cash Management Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income exempt from federal income tax as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

To pursue its goal, the fund normally invests substantially all of its assets in short-term, high quality municipal obligations that provide income exempt from federal income taxes. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. In addition, the fund may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes that acceptable municipal obligations are unavailable for investment.

While the fund is permitted to invest up to 20% of its assets in municipal obligations that provide income that may be subject to the federal alternative minimum tax, the fund currently is managed so that income paid by the fund will not be subject to the federal alternative minimum tax.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the NAV of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.71%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.24%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.24%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.71%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Institutional Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-Free TAX EXEMPT CASH MANAGEMENT - Institutional Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.06%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.26%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 27

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

84

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

146

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

331

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

27

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

84

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

146

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 331

Annual Return 2008

rr_AnnualReturn2008

2.30%

Annual Return 2009

rr_AnnualReturn2009

0.44%

Annual Return 2010

rr_AnnualReturn2010

0.10%

Annual Return 2011

rr_AnnualReturn2011

0.03%

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.23%

Annual Return 2017

rr_AnnualReturn2017

0.59%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.59%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.17%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.37%

XML

Institutional Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus

Fund Summary - Dreyfus Amt-Free Municipal Cash Management Plus

Investment Objective

The fund seeks as high a level of current income exempt from federal income tax as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Institutional Shares Prospectus Dreyfus AMT-Free Municipal Cash Management Plus Institutional Shares
Management fees	0.20%
Other expenses (including shareholder services fees)	0.24%
Total annual fund operating expenses	0.44%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Institutional Shares | USD ($)	45	141	246	555

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Institutional Shares | USD ($)	45	141	246	555

Principal Investment Strategy

To pursue its goal, the fund normally invests at least 80% of its net assets in short-term, high quality municipal obligations that provide income exempt from both federal income taxes and the federal alternative minimum tax. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. In addition, the fund may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes that acceptable municipal obligations are unavailable for investment.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could impair the fund's ability to maintain a stable net asset value.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or the fund's ability to maintain a stable net asset value.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.71%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.25%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Institutional Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Institutional Shares	0.61%	0.23%	0.42%

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Institutional Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Amt-Free Municipal Cash Management Plus

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income exempt from federal income tax as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

To pursue its goal, the fund normally invests at least 80% of its net assets in short-term, high quality municipal obligations that provide income exempt from both federal income taxes and the federal alternative minimum tax. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. In addition, the fund may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes that acceptable municipal obligations are unavailable for investment.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could impair the fund's ability to maintain a stable net asset value.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or the fund's ability to maintain a stable net asset value.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.71%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.25%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.25%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.71%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Institutional Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Institutional Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.24%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.44%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 45

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

141

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

246

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

555

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

45

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

141

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

246

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 555

Annual Return 2008

rr_AnnualReturn2008

2.34%

Annual Return 2009

rr_AnnualReturn2009

0.57%

Annual Return 2010

rr_AnnualReturn2010

0.12%

Annual Return 2011

rr_AnnualReturn2011

0.04%

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.55%

Annual Return 2017

rr_AnnualReturn2017

0.61%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.61%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.23%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.42%

XML

Institutional Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management

Fund Summary - Dreyfus AMT-Free New York Municipal Cash Management

Investment Objective

The fund seeks as high a level of current income exempt from federal, New York state and New York city personal income taxes as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Institutional Shares Prospectus Dreyfus AMT-Free New York Municipal Cash Management Institutional Shares
Management fees	0.20%
Other expenses (including shareholder services fees)	0.14%
Total annual fund operating expenses	0.34%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Institutional Shares | USD ($)	35	109	191	431

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Institutional Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Institutional Shares | USD ($)	35	109	191	431

Principal Investment Strategy

To pursue its goal, the fund normally invests at least 80% of its net assets in short-term, high quality municipal obligations that provide income exempt from federal, New York state and New York city income taxes and the federal alternative minimum tax. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. The fund also may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes acceptable New York municipal obligations are unavailable for investment. In addition, a portion of the fund's assets may be invested in short-term, high quality municipal obligations that do not pay income that are exempt from New York state income taxes.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could impair the fund's ability to maintain a stable net asset value.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or the fund's ability to maintain a stable net asset value.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

·State-specific risk. The fund is subject to the risk that New York's economy, and the revenues underlying its municipal obligations, may decline. Investing primarily in the municipal obligations of a single state makes the fund more sensitive to risks specific to that state and may entail more risk than investing in the municipal obligations of multiple states as a result of potentially less diversification.

·Non-diversification risk. The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.65%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.22%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Institutional Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Institutional Shares	0.55%	0.15%	0.36%

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Institutional Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus AMT-Free New York Municipal Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income exempt from federal, New York state and New York city personal income taxes as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

To pursue its goal, the fund normally invests at least 80% of its net assets in short-term, high quality municipal obligations that provide income exempt from federal, New York state and New York city income taxes and the federal alternative minimum tax. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. The fund also may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes acceptable New York municipal obligations are unavailable for investment. In addition, a portion of the fund's assets may be invested in short-term, high quality municipal obligations that do not pay income that are exempt from New York state income taxes.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could impair the fund's ability to maintain a stable net asset value.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or the fund's ability to maintain a stable net asset value.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

·State-specific risk. The fund is subject to the risk that New York's economy, and the revenues underlying its municipal obligations, may decline. Investing primarily in the municipal obligations of a single state makes the fund more sensitive to risks specific to that state and may entail more risk than investing in the municipal obligations of multiple states as a result of potentially less diversification.

·Non-diversification risk. The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Institutional shares from year to year. The table shows the average annual total returns of the fund's Institutional shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.65%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Institutional shares as of March 31, 2018 was 0.22%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.22%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.65%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Institutional shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Institutional Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Institutional Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.14%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.34%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 35

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

109

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

191

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

431

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

35

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

109

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

191

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 431

Annual Return 2008

rr_AnnualReturn2008

2.18%

Annual Return 2009

rr_AnnualReturn2009

0.51%

Annual Return 2010

rr_AnnualReturn2010

0.12%

Annual Return 2011

rr_AnnualReturn2011

0.04%

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.18%

Annual Return 2017

rr_AnnualReturn2017

0.55%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.55%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.15%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.36%

XML

Investor Shares Prospectus | Dreyfus Cash Management

Fund Summary - Dreyfus Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Shares Prospectus Dreyfus Cash Management Investor Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.25%
Other expenses	0.05%
Total annual fund operating expenses	0.50%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Cash Management | Investor Shares | USD ($)	51	160	280	628

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Cash Management | Investor Shares | USD ($)	51	160	280	628

Principal Investment Strategy

To pursue its goal, the fund normally invests in a diversified portfolio of high quality, short-term, dollar-denominated debt securities, including: securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities; certificates of deposit, time deposits, bankers' acceptances and other short-term securities issued by domestic or foreign banks or thrifts or their subsidiaries or branches; repurchase agreements, including tri-party repurchase agreements; asset-backed securities; municipal securities; domestic and dollar-denominated foreign commercial paper and other short-term corporate obligations, including those with floating or variable rates of interest; and dollar-denominated obligations issued or guaranteed by one or more foreign governments or any of their political subdivisions or agencies.

The fund's investments are concentrated in the banking industry, because the fund normally invests at least 25% of its net assets in domestic or dollar-denominated foreign bank obligations.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the net asset value (NAV) of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Principal Risks

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Banking industry risk. The risks generally associated with concentrating investments in the banking industry include interest rate risk, credit risk, and regulatory developments relating to the banking industry.

·Foreign investment risk. The risks generally associated with dollar-denominated foreign investments include economic and political developments, seizure or nationalization of deposits, imposition of taxes or other restrictions on payment of principal and interest.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement and/or, for a tri-party repurchase agreement, the third party bank providing payment administration, collateral custody and management services for the transaction, could fail to honor the terms of the agreement.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.92%
Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.31%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Investor Shares Prospectus | Dreyfus Cash Management | Investor Shares	0.80%	0.18%	0.39%

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Investor Shares Prospectus | Dreyfus Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

To pursue its goal, the fund normally invests in a diversified portfolio of high quality, short-term, dollar-denominated debt securities, including: securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities; certificates of deposit, time deposits, bankers' acceptances and other short-term securities issued by domestic or foreign banks or thrifts or their subsidiaries or branches; repurchase agreements, including tri-party repurchase agreements; asset-backed securities; municipal securities; domestic and dollar-denominated foreign commercial paper and other short-term corporate obligations, including those with floating or variable rates of interest; and dollar-denominated obligations issued or guaranteed by one or more foreign governments or any of their political subdivisions or agencies.

The fund's investments are concentrated in the banking industry, because the fund normally invests at least 25% of its net assets in domestic or dollar-denominated foreign bank obligations.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the net asset value (NAV) of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Banking industry risk. The risks generally associated with concentrating investments in the banking industry include interest rate risk, credit risk, and regulatory developments relating to the banking industry.

·Foreign investment risk. The risks generally associated with dollar-denominated foreign investments include economic and political developments, seizure or nationalization of deposits, imposition of taxes or other restrictions on payment of principal and interest.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement and/or, for a tri-party repurchase agreement, the third party bank providing payment administration, collateral custody and management services for the transaction, could fail to honor the terms of the agreement.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.92%
Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.31%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.31%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.92%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Investor Shares Prospectus | Dreyfus Cash Management | Investor Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.05%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.50%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 51

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

160

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

280

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

628

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

51

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

160

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

280

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 628

Annual Return 2008

rr_AnnualReturn2008

2.67%

Annual Return 2009

rr_AnnualReturn2009

0.31%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.10%

Annual Return 2017

rr_AnnualReturn2017

0.80%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.80%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.18%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.39%

XML

Investor Shares Prospectus | Dreyfus Government Cash Management

Fund Summary - Dreyfus Government Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Shares Prospectus Dreyfus Government Cash Management dreyfus government cash management - Investor Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.25%
Other expenses	0.01%
Total annual fund operating expenses	0.46%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Investor Shares | USD ($)	47	148	258	579

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Investor Shares | USD ($)	47	148	258	579

Principal Investment Strategy

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest), repurchase agreements collateralized solely by government securities and/or cash, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities and repurchase agreements collateralized solely by government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash and/or repurchase agreements collateralized by cash). The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.81%

Worst Quarter
Q4, 2011: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.25%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Investor Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Investor Shares	0.54%	0.12%	0.27%

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Investor Shares Prospectus | Dreyfus Government Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Government Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest), repurchase agreements collateralized solely by government securities and/or cash, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities and repurchase agreements collateralized solely by government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash and/or repurchase agreements collateralized by cash). The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.81%

Worst Quarter
Q4, 2011: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.25%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.25%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.81%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Investor Shares Prospectus | Dreyfus Government Cash Management | dreyfus government cash management - Investor Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.46%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 47

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

148

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

258

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

579

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

47

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

148

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

258

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 579

Annual Return 2008

rr_AnnualReturn2008

2.04%

Annual Return 2009

rr_AnnualReturn2009

0.07%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

0.01%

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.03%

Annual Return 2017

rr_AnnualReturn2017

0.54%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.54%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.12%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.27%

XML

Investor Shares Prospectus | Dreyfus Government Securities Cash Management

Fund Summary - Dreyfus Government Securities Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Shares Prospectus Dreyfus Government Securities Cash Management Dreyfus Government Securities Cash Management - Investor Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.25%
Other expenses	0.02%
Total annual fund operating expenses	0.47%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Investor Shares | USD ($)	48	151	263	591

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Investor Shares | USD ($)	48	151	263	591

Principal Investment Strategy

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in government securities.

The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government. While the fund is permitted to invest in the full range of government securities, the fund currently is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.78%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.25%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Investor Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Investor Shares	0.47%	0.10%	0.25%

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Investor Shares Prospectus | Dreyfus Government Securities Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Government Securities Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in government securities.

The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government. While the fund is permitted to invest in the full range of government securities, the fund currently is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.78%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.25%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.25%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.78%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Investor Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Investor Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.47%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 48

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

151

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

263

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

591

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

48

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

151

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

263

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 591

Annual Return 2008

rr_AnnualReturn2008

1.96%

Annual Return 2009

rr_AnnualReturn2009

0.02%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.01%

Annual Return 2017

rr_AnnualReturn2017

0.47%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.47%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.10%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.25%

XML

Investor Shares Prospectus | Dreyfus Treasury & Agency Cash Management

Fund Summary - Dreyfus Treasury & Agency Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Shares Prospectus Dreyfus Treasury & Agency Cash Management Investor Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.25%
Other expenses	0.01%
Total annual fund operating expenses	0.46%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Investor Shares | USD ($)	47	148	258	579

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Investor Shares | USD ($)	47	148	258	579

Principal Investment Strategy

The fund pursues its investment objective by investing only in U.S. Treasury securities, repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities and repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash or repurchase agreements collateralized by cash), and typically invests exclusively in such securities.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.58%

Worst Quarter
Q3, 2010: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.25%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Investor Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Investor Shares	0.50%	0.11%	0.19%

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Investor Shares Prospectus | Dreyfus Treasury & Agency Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Treasury & Agency Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in U.S. Treasury securities, repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities and repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash or repurchase agreements collateralized by cash), and typically invests exclusively in such securities.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.58%

Worst Quarter
Q3, 2010: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.25%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.25%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.58%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Investor Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Investor Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.46%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 47

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

148

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

258

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

579

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

47

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

148

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

258

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 579

Annual Return 2008

rr_AnnualReturn2008

1.30%

Annual Return 2009

rr_AnnualReturn2009

none

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

0.01%

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

0.01%

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.02%

Annual Return 2017

rr_AnnualReturn2017

0.50%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.50%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.11%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.19%

XML

Investor Shares Prospectus | Dreyfus Treasury Securities Cash Management

Fund Summary - Dreyfus Treasury Securities Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Shares Prospectus Dreyfus Treasury Securities Cash Management Investor Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.25%
Other expenses	0.01%
Total annual fund operating expenses	0.46%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Treasury Securities Cash Management | Investor Shares | USD ($)	47	148	258	579

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus Treasury Securities Cash Management | Investor Shares | USD ($)	47	148	258	579

Principal Investment Strategy

The fund pursues its investment objective by investing only in U.S. Treasury securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in U.S. Treasury securities.

The fund is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.57%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.25%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Investor Shares Prospectus | Dreyfus Treasury Securities Cash Management | Investor Shares	0.47%	0.10%	0.17%

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Investor Shares Prospectus | Dreyfus Treasury Securities Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Treasury Securities Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in U.S. Treasury securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in U.S. Treasury securities.

The fund is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.57%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.25%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.25%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.57%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Investor Shares Prospectus | Dreyfus Treasury Securities Cash Management | Investor Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.46%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 47

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

148

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

258

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

579

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

47

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

148

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

258

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 579

Annual Return 2008

rr_AnnualReturn2008

1.24%

Annual Return 2009

rr_AnnualReturn2009

none

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.01%

Annual Return 2017

rr_AnnualReturn2017

0.47%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.47%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.10%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.17%

XML

Investor Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund

Fund Summary - Dreyfus AMT-Free Tax Exempt Cash Management Fund

Investment Objective

The fund seeks as high a level of current income exempt from federal income tax as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Shares Prospectus Dreyfus AMT-Free Tax Exempt Cash Management Fund DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT - Investor Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.25%
Other expenses	0.05%
Total annual fund operating expenses	0.50%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT - Investor Shares | USD ($)	51	160	280	628

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT - Investor Shares | USD ($)	51	160	280	628

Principal Investment Strategy

To pursue its goal, the fund normally invests substantially all of its assets in short-term, high quality municipal obligations that provide income exempt from federal income taxes. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. In addition, the fund may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes that acceptable municipal obligations are unavailable for investment.

While the fund is permitted to invest up to 20% of its assets in municipal obligations that provide income that may be subject to the federal alternative minimum tax, the fund currently is managed so that income paid by the fund will not be subject to the federal alternative minimum tax.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the NAV of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Principal Risks

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.64%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.18%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Investor Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT - Investor Shares	0.36%	0.09%	0.27%

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Investor Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus AMT-Free Tax Exempt Cash Management Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income exempt from federal income tax as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

To pursue its goal, the fund normally invests substantially all of its assets in short-term, high quality municipal obligations that provide income exempt from federal income taxes. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. In addition, the fund may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes that acceptable municipal obligations are unavailable for investment.

While the fund is permitted to invest up to 20% of its assets in municipal obligations that provide income that may be subject to the federal alternative minimum tax, the fund currently is managed so that income paid by the fund will not be subject to the federal alternative minimum tax.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, although the NAV of the fund's shares will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit.  It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.  You could lose money by investing in the fund.  Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.  The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates.  The fund may impose a fee upon the sale of shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors.  Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time.  The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could cause the fund's share price to decline. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could lead to a decline in the fund's share price.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially leading to a decline in the fund's share price, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could have the potential to cause significant deterioration of the fund's NAV.

·Floating NAV risk. The fund does not maintain a stable NAV per share. The NAV of the fund's shares will be calculated to four decimal places and will "float," meaning the NAV will fluctuate with changes in the values of the fund's portfolio securities. You could lose money by investing in the fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or value of the fund's investments in municipal securities.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Because the share price of the fund will fluctuate, when you sell your shares they may be worth more or less than what you originally paid for them.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.64%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.18%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.18%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.64%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Investor Shares Prospectus | Dreyfus AMT-Free Tax Exempt Cash Management Fund | DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT - Investor Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.05%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.50%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 51

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

160

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

280

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

628

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

51

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

160

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

280

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 628

Annual Return 2008

rr_AnnualReturn2008

2.04%

Annual Return 2009

rr_AnnualReturn2009

0.24%

Annual Return 2010

rr_AnnualReturn2010

0.01%

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.07%

Annual Return 2017

rr_AnnualReturn2017

0.36%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.36%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.09%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.27%

XML

Investor Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus

Fund Summary - Dreyfus AMT-Free Municipal Cash Management Plus

Investment Objective

The fund seeks as high a level of current income exempt from federal income tax as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Shares Prospectus Dreyfus AMT-Free Municipal Cash Management Plus Investor Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.25%
Other expenses	0.14%
Total annual fund operating expenses	0.59%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Investor Shares | USD ($)	60	189	329	738

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Investor Shares | USD ($)	60	189	329	738

Principal Investment Strategy

To pursue its goal, the fund normally invests at least 80% of its net assets in short-term, high quality municipal obligations that provide income exempt from both federal income taxes and the federal alternative minimum tax. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. In addition, the fund may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes that acceptable municipal obligations are unavailable for investment.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could impair the fund's ability to maintain a stable net asset value.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or the fund's ability to maintain a stable net asset value.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.64%

Worst Quarter
Q3, 2015 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.19%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Investor Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Investor Shares	0.38%	0.18%	0.33%

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Investor Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus AMT-Free Municipal Cash Management Plus

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income exempt from federal income tax as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

To pursue its goal, the fund normally invests at least 80% of its net assets in short-term, high quality municipal obligations that provide income exempt from both federal income taxes and the federal alternative minimum tax. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. In addition, the fund may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes that acceptable municipal obligations are unavailable for investment.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could impair the fund's ability to maintain a stable net asset value.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or the fund's ability to maintain a stable net asset value.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.64%

Worst Quarter
Q3, 2015 0.00%

The year-to-date total return of the fund's Investor shares as of March 31, 2018 was 0.19%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.19%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.64%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Investor Shares Prospectus | Dreyfus AMT-Free Municipal Cash Management Plus | Investor Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.14%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.59%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 60

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

189

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

329

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

738

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

60

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

189

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

329

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 738

Annual Return 2008

rr_AnnualReturn2008

2.08%

Annual Return 2009

rr_AnnualReturn2009

0.34%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.50%

Annual Return 2017

rr_AnnualReturn2017

0.38%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.38%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.18%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.33%

XML

Investor Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management

Fund Summary - Dreyfus AMT-Free New York Municipal Cash Management

Investment Objective

The fund seeks as high a level of current income exempt from federal, New York state and New York city personal income taxes as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Shares Prospectus Dreyfus AMT-Free New York Municipal Cash Management Investor Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.25%
Other expenses	0.14%
Total annual fund operating expenses	0.59%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Investor Shares | USD ($)	60	189	329	738

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Investor Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Investor Shares | USD ($)	60	189	329	738

Principal Investment Strategy

To pursue its goal, the fund normally invests at least 80% of its net assets in short-term, high quality municipal obligations that provide income exempt from federal, New York state and New York city income taxes and the federal alternative minimum tax. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. The fund also may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes acceptable New York municipal obligations are unavailable for investment. In addition, a portion of the fund's assets may be invested in short-term , high quality municipal obligations that do not pay income that are exempt from New York state income taxes.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could impair the fund's ability to maintain a stable net asset value.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or the fund's ability to maintain a stable net asset value.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

·State-specific risk. The fund is subject to the risk that New York's economy, and the revenues underlying its municipal obligations, may decline. Investing primarily in the municipal obligations of a single state makes the fund more sensitive to risks specific to that state and may entail more risk than investing in the municipal obligations of multiple states as a result of potentially less diversification.

·Non-diversification risk. The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.59%

Worst Quarter
Q3, 2015: 0.00%

The year to date total return of the fund's Investor shares as of March 31, 2018 was 0.17%

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Investor Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Investor Shares	0.31%	0.07%	0.26%

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Investor Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus AMT-Free New York Municipal Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income exempt from federal, New York state and New York city personal income taxes as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

To pursue its goal, the fund normally invests at least 80% of its net assets in short-term, high quality municipal obligations that provide income exempt from federal, New York state and New York city income taxes and the federal alternative minimum tax. The fund also may invest in high quality, short-term structured notes, which are derivative instruments whose value is tied to underlying municipal obligations. The fund also may invest temporarily in high quality, taxable money market instruments, including when the portfolio manager believes acceptable New York municipal obligations are unavailable for investment. In addition, a portion of the fund's assets may be invested in short-term , high quality municipal obligations that do not pay income that are exempt from New York state income taxes.

The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of market conditions or other factors. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·Credit risk. Failure of an issuer of a security to make timely interest or principal payments when due, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall. Although the fund invests only in high quality debt securities, the credit quality of the securities held by the fund can change rapidly in certain market environments, and the default or a significant price decline of a single holding could impair the fund's ability to maintain a stable net asset value.

·Municipal securities risk. Municipal securities may be fully or partially backed or enhanced by the taxing authority of a local government, by the current or anticipated revenues from a specific project or specific assets, or by the credit of, or liquidity enhancement provided by, a private issuer. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or the fund's ability to maintain a stable net asset value.

·Structured notes risk. Structured notes, a type of derivative instrument, can be volatile, and the possibility of default by the financial institution or counterparty may be greater for these instruments than for other types of money market instruments. Structured notes typically are purchased in privately negotiated transactions from financial institutions and, thus, an active trading market for such instruments may not exist.

·Tax risk. To be tax-exempt, municipal obligations generally must meet certain regulatory requirements. If any such municipal obligation fails to meet these regulatory requirements, the interest received by the fund from its investment in such obligations and distributed to fund shareholders will be taxable.

·State-specific risk. The fund is subject to the risk that New York's economy, and the revenues underlying its municipal obligations, may decline. Investing primarily in the municipal obligations of a single state makes the fund more sensitive to risks specific to that state and may entail more risk than investing in the municipal obligations of multiple states as a result of potentially less diversification.

·Non-diversification risk. The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.

·Liquidity fee and/or redemption gate risk. The fund may impose a fee upon the sale of your shares (a "liquidity fee") or may temporarily suspend your ability to sell shares (a redemption "gate") if the fund's liquidity falls below required minimums because of unusual market conditions, an unusually high volume of redemption requests, redemptions by a few large investors, or other reasons. If a liquidity fee is imposed by the fund, it would reduce the amount you will receive upon the redemption of your shares. A "gate" will suspend your ability to redeem your shares while the gate is imposed and may prevent the fund from being able to pay redemption proceeds within the allowable time period stated in this prospectus.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Investor shares from year to year. The table shows the average annual total returns of the fund's Investor shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.59%

Worst Quarter
Q3, 2015: 0.00%

The year to date total return of the fund's Investor shares as of March 31, 2018 was 0.17%

Year to Date Return, Label

rr_YearToDateReturnLabel

year to date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.17%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.59%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Investor shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Investor Shares Prospectus | Dreyfus AMT-Free New York Municipal Cash Management | Investor Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.14%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.59%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 60

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

189

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

329

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

738

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

60

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

189

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

329

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 738

Annual Return 2008

rr_AnnualReturn2008

1.93%

Annual Return 2009

rr_AnnualReturn2009

0.28%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.05%

Annual Return 2017

rr_AnnualReturn2017

0.31%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.31%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.07%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.26%

XML

Participant Shares Prospectus | Dreyfus Government Cash Management

Fund Summary - Dreyfus Government Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Participant Shares Prospectus Dreyfus Government Cash Management Dreyfus Government Cash Management - Participant Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.40%
Other expenses	0.01%
Total annual fund operating expenses	0.61%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Participant Shares Prospectus | Dreyfus Government Cash Management | Dreyfus Government Cash Management - Participant Shares | USD ($)	62	195	340	762

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Participant Shares Prospectus | Dreyfus Government Cash Management | Dreyfus Government Cash Management - Participant Shares | USD ($)	62	195	340	762

Principal Investment Strategy

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest), repurchase agreements collateralized solely by government securities and/or cash, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities and repurchase agreements collateralized solely by government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash and/or repurchase agreements collateralized by cash). The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Participant shares from year to year. The table shows the average annual total returns of the fund's Participant shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.78%

Worst Quarter
Q4, 2011: 0.00%

The year-to-date total return of the fund's Participant shares as of March 31, 2018 was 0.21%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Participant Shares Prospectus | Dreyfus Government Cash Management | Dreyfus Government Cash Management - Participant Shares	0.39%	0.09%	0.24%

For the current yield for Participant shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Participant Shares Prospectus | Dreyfus Government Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Government Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest), repurchase agreements collateralized solely by government securities and/or cash, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities and repurchase agreements collateralized solely by government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash and/or repurchase agreements collateralized by cash). The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Participant shares from year to year. The table shows the average annual total returns of the fund's Participant shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.78%

Worst Quarter
Q4, 2011: 0.00%

The year-to-date total return of the fund's Participant shares as of March 31, 2018 was 0.21%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.21%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.78%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Participant shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Participant Shares Prospectus | Dreyfus Government Cash Management | Dreyfus Government Cash Management - Participant Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.40%

Other expenses

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.61%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 62

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

195

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

340

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

762

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

62

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

195

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

340

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 762

Annual Return 2008

rr_AnnualReturn2008

1.88%

Annual Return 2009

rr_AnnualReturn2009

0.04%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

0.01%

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.01%

Annual Return 2017

rr_AnnualReturn2017

0.39%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.39%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.09%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.24%

XML

Participant Shares Prospectus | Dreyfus Government Securities Cash Management

Fund Summary - Dreyfus Government Securities Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Participant Shares Prospectus Dreyfus Government Securities Cash Management Dreyfus Government Securities Cash Management - Participant Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.40%
Other expenses	0.02%
Total annual fund operating expenses	0.62%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Participant Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Participant Shares | USD ($)	63	199	346	774

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Participant Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Participant Shares | USD ($)	63	199	346	774

Principal Investment Strategy

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in government securities.

The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government. While the fund is permitted to invest in the full range of government securities, the fund currently is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Participant shares from year to year. The table shows the average annual total returns of the fund's Participant shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.74%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Participant shares as of March 31, 2018 was 0.21%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Participant Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Participant Shares	0.33%	0.07%	0.22%

For the current yield for Participant shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Participant Shares Prospectus | Dreyfus Government Securities Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Government Securities Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in government securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in government securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in government securities.

The securities in which the fund invests include those backed by the full faith and credit of the U.S. government, which include U.S. Treasury securities as well as securities issued by certain agencies of the U.S. government, and those that are neither insured nor guaranteed by the U.S. government. While the fund is permitted to invest in the full range of government securities, the fund currently is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Government securities risk. Not all obligations of the U.S. government, its agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some obligations are backed only by the credit of the issuing agency or instrumentality, and in some cases there may be some risk of default by the issuer. Any guarantee by the U.S. government or its agencies or instrumentalities of a security held by the fund does not apply to the market value of such security or to shares of the fund itself. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Participant shares from year to year. The table shows the average annual total returns of the fund's Participant shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.74%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Participant shares as of March 31, 2018 was 0.21%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.21%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.74%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Participant shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Participant Shares Prospectus | Dreyfus Government Securities Cash Management | Dreyfus Government Securities Cash Management - Participant Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.40%

Other expenses

rr_OtherExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.62%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 63

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

199

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

346

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

774

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

63

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

199

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

346

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 774

Annual Return 2008

rr_AnnualReturn2008

1.81%

Annual Return 2009

rr_AnnualReturn2009

0.01%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.01%

Annual Return 2017

rr_AnnualReturn2017

0.33%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.33%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.07%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.22%

XML

Participant Shares Prospectus | Dreyfus Treasury & Agency Cash Management

Fund Summary - Dreyfus Treasury & Agency Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Participant Shares Prospectus Dreyfus Treasury & Agency Cash Management Participant Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.40%
Other expenses	0.01%
Total annual fund operating expenses	0.61%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Participant Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Participant Shares | USD ($)	62	195	340	762

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Participant Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Participant Shares | USD ($)	62	195	340	762

Principal Investment Strategy

The fund pursues its investment objective by investing only in U.S. Treasury securities, repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities and repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash or repurchase agreements collateralized by cash), and typically invests exclusively in such securities.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Participant shares from year to year. The table shows the average annual total returns of the fund's Participant shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.55%

Worst Quarter
Q3, 2010: 0.00%

The year-to-date total return of the fund's Participant shares as of March 31, 2018 was 0.21%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Participant Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Participant Shares	0.35%	0.08%	0.16%

For the current yield for Participant shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Participant Shares Prospectus | Dreyfus Treasury & Agency Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Treasury & Agency Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in U.S. Treasury securities, repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government, and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities and repurchase agreements collateralized solely by U.S. Treasury securities or securities issued by U.S. government agencies that are backed by the full faith and credit of the U.S. government (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash or repurchase agreements collateralized by cash), and typically invests exclusively in such securities.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

·Repurchase agreement counterparty risk. The fund is subject to the risk that a counterparty in a repurchase agreement could fail to honor the terms of the agreement.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Participant shares from year to year. The table shows the average annual total returns of the fund's Participant shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.55%

Worst Quarter
Q3, 2010: 0.00%

The year-to-date total return of the fund's Participant shares as of March 31, 2018 was 0.21%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.21%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.55%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Participant shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Participant Shares Prospectus | Dreyfus Treasury & Agency Cash Management | Participant Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.40%

Other expenses

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.61%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 62

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

195

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

340

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

762

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

62

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

195

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

340

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 762

Annual Return 2008

rr_AnnualReturn2008

1.19%

Annual Return 2009

rr_AnnualReturn2009

none

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

0.01%

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

0.01%

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.01%

Annual Return 2017

rr_AnnualReturn2017

0.35%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.35%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.08%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.16%

XML

Participant Shares Prospectus | Dreyfus Treasury Securities Cash Management

Fund Summary - Dreyfus Treasury Securities Cash Management

Investment Objective

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Participant Shares Prospectus Dreyfus Treasury Securities Cash Management Participant Shares
Management fees	0.20%
Distribution and/or service (12b-1) fees	0.40%
Other expenses	0.01%
Total annual fund operating expenses	0.61%

Example

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Participant Shares Prospectus | Dreyfus Treasury Securities Cash Management | Participant Shares | USD ($)	62	195	340	762

Expense Example No Redemption	1 Year	3 Years	5 Years	10 Years
Participant Shares Prospectus | Dreyfus Treasury Securities Cash Management | Participant Shares | USD ($)	62	195	340	762

Principal Investment Strategy

The fund pursues its investment objective by investing only in U.S. Treasury securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in U.S. Treasury securities.

The fund is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Principal Risks

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Participant shares from year to year. The table shows the average annual total returns of the fund's Participant shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%)

Best Quarter
Q1, 2008: 0.53%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Participant shares as of March 31, 2018 was 0.21%.

Average Annual Total Returns as of 12/31/17

Average Annual Returns	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Participant Shares Prospectus | Dreyfus Treasury Securities Cash Management | Participant Shares	0.32%	0.07%	0.14%

For the current yield for Participant shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

XML

Label

Element

Value

Participant Shares Prospectus | Dreyfus Treasury Securities Cash Management

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary - Dreyfus Treasury Securities Cash Management

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund pursues its investment objective by investing only in U.S. Treasury securities (i.e., securities issued or guaranteed as to principal and interest by the U.S. government, including those with floating or variable rates of interest) and cash. The fund is a money market fund subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, and seeks to maintain a stable share price of $1.00.

The fund is a "government money market fund," as that term is defined in Rule 2a-7, and as such is required to invest at least 99.5% of its total assets in securities issued or guaranteed as to principal and interest by the U.S. government or its agencies or instrumentalities, repurchase agreements collateralized solely by cash and/or government securities, and cash. The fund normally invests at least 80% of its net assets in U.S. Treasury securities (i.e., under normal circumstances, the fund will not invest more than 20% of its net assets in cash), and typically invests exclusively in U.S. Treasury securities.

The fund is managed so that income paid by the fund will be exempt from state and local taxes. Because rules regarding the state and local taxation of dividend income can differ from state to state, investors are urged to consult their tax advisers about the taxation of the fund's dividend income in their state and locality.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund's yield will fluctuate as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in securities with different interest rates. The fund currently is not permitted to impose a fee upon the sale of shares (a "liquidity fee") or temporarily suspend redemptions (a redemption "gate") under distressed conditions as some other types of money market funds are, and the fund's board has no intention to impose a liquidity fee or redemption gate. Neither The Dreyfus Corporation nor its affiliates have a legal obligation to provide financial support to the fund, and you should not expect that The Dreyfus Corporation or its affiliates will provide financial support to the fund at any time. The following are the principal risks that could reduce the fund's income level and/or share price:

·Interest rate risk. This risk refers to the decline in the prices of fixed-income securities that may accompany a rise in the overall level of interest rates. A sharp and unexpected rise in interest rates could impair the fund's ability to maintain a stable net asset value. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of fund assets and could impair the fund's ability to maintain a stable net asset value.

·Liquidity risk. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities in a timely manner at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially impairing the fund's ability to maintain a stable net asset value, even during periods of declining interest rates.

·U.S. Treasury securities risk. A security backed by the U.S. Treasury or the full faith and credit of the United States is guaranteed only as to the timely payment of interest and principal when held to maturity, but the market prices for such securities are not guaranteed and will fluctuate.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the performance of the fund's Participant shares from year to year. The table shows the average annual total returns of the fund's Participant shares over time. The fund's past performance is not necessarily an indication of how the fund will perform in the future. More recent performance information may be available at www.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q1, 2008: 0.53%

Worst Quarter
Q3, 2015: 0.00%

The year-to-date total return of the fund's Participant shares as of March 31, 2018 was 0.21%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Mar. 31, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.21%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.53%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

For the current yield for Participant shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of 12/31/17

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

1-800-346-3621

Participant Shares Prospectus | Dreyfus Treasury Securities Cash Management | Participant Shares

Risk/Return:

rr_RiskReturnAbstract

Management fees

rr_ManagementFeesOverAssets

0.20%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.40%

Other expenses

rr_OtherExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.61%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 62

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

195

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

340

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

762

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

62

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

195

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

340

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 762

Annual Return 2008

rr_AnnualReturn2008

1.10%

Annual Return 2009

rr_AnnualReturn2009

none

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

0.01%

Annual Return 2017

rr_AnnualReturn2017

0.32%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.32%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.07%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.14%

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	Jun. 01, 2018