Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jun. 01, 2011
DREYFUS CASH MANAGEMENT PLUS INC (Sixth Prospectus Summary) | DREYFUS CASH MANAGEMENT PLUS INC
Risk/Return:	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Fund Summary
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	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	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	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	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 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:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategy
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	As a money market fund, the fund is subject to maturity, quality, liquidity and diversification requirements designed to help it maintain a stable share price of $1.00. 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; 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. Normally, the fund invests at least 25% of its net assets in domestic or dollar-denominated foreign bank obligations.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. Although the fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the fund. The fund's yield will fluctuate as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. Additionally, while the fund has maintained a constant share price since inception, and will continue to try to do so, neither The Dreyfus Corporation nor its affiliates are required to make a capital infusion, enter into a capital support agreement or take other actions to prevent the fund's share price from falling below $1.00. The following are the principal risks that could reduce the fund's income level and/or share price: o 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 a money market fund's share price to drop below a dollar. o Credit risk. Failure of an issuer to make timely interest or principal payments, or a decline or perception of a decline in the credit quality of a security, can cause the security's price to fall, potentially lowering the fund's share price. The credit quality of the securities held by the fund can change rapidly in certain market environments, and the default of a single holding could have the potential to cause significant deterioration of the fund's net asset value. o 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 at or near their perceived value. In such a market, the value of such securities may fall dramatically, potentially lowering the fund's share price, even during periods of declining interest rates. Also, during such periods, redemptions by a few large investors in the fund may have a significant adverse effect on the fund's net asset value and remaining fund shareholders. o Banking industry risk. The risks generally associated with concentrating investments in the banking industry, such as interest rate risk, credit risk, and regulatory developments relating to the banking industry. o Foreign investment risk. The risks generally associated with dollar-denominated foreign investments, such as economic and political developments, seizure or nationalization of deposits, imposition of taxes or other restrictions on payment of principal and interest. o 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. o 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. o Repurchase agreement counterparty risk. The risk that a counterparty in a repurchase agreement could fail to honor the terms of its agreement.
Risk, Money Market Fund	rr_RiskMoneyMarketFund	Although the fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the fund 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	rr_PerformanceNarrativeTextBlock	The following bar chart and table provide some indication of the risks of investing in the fund. The table shows the average annual total returns of the fund's Select shares over time. The fund's past performance (before and after taxes) is no guarantee of future results. More recent performance information may be available at www.dreyfus.com.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following bar chart and table provide some indication of the risks of investing in the fund.
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.dreyfus.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	The fund's past performance (before and after taxes) is no guarantee of future results.
Bar Chart, Heading	rr_BarChartHeading	Year-by-Year Total Returns as of 12/31 each year (%)
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	The bar chart shows changes in the performance of the fund's Select shares from year to year.
Bar Chart, Closing	rr_BarChartClosingTextBlock	Best Quarter Q1, 2008: 0.78% Worst Quarter Q4, 2010: 0.00% The year-to-date total return of the fund's Select shares as of 3/31/11 was 0.00%.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	For the current yield for Select shares call toll-free 1-800-346-3621. Individuals or entities for whom institutions may purchase or redeem shares should call the institution directly.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns as of 12/31/10
DREYFUS CASH MANAGEMENT PLUS INC (Sixth Prospectus Summary) | DREYFUS CASH MANAGEMENT PLUS INC | Select Shares
Risk/Return:	rr_RiskReturnAbstract
Year to Date Return, Label	rr_YearToDateReturnLabel	The year-to-date total return of the fund's Select shares
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2011
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.00%
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, 2010
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	0.00%
DREYFUS CASH MANAGEMENT PLUS INC | Select Shares
Risk/Return:	rr_RiskReturnAbstract
Management fees	rr_ManagementFeesOverAssets	0.20%
Distribution and/or Service (Rule 12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.80%
Other expenses	rr_OtherExpensesOverAssets	0.01%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.01%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	103
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	322
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	558
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,236
Annual Return 2008	rr_AnnualReturn2008	2.12%
Annual Return 2009	rr_AnnualReturn2009	0.06%
Annual Return 2010	rr_AnnualReturn2010	0.00%
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	none
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	1.24%
Average Annual Returns, Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 29, 2007