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Risk/Return:rr_RiskReturnAbstract 
ProspectusDaterr_ProspectusDateOct. 31, 2011
Dreyfus BASIC New York Municipal Money Market Fund (Prospectus Summary) | Dreyfus BASIC New York Municipal Money Market Fund
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return, Headingrr_RiskReturnHeadingFund Summary
Investment Objective, Headingrr_ObjectiveHeadingInvestment Objective
investment Objective, Primaryrr_ObjectivePrimaryTextBlock
The fund seeks to provide a high level of current income exempt from federal,
New York state and New York city income taxes to the extent consistent with the
preservation of capital and the maintenance of liquidity.
Expense, Headingrr_ExpenseHeadingFees and Expenses
Expense, Narrativerr_ExpenseNarrativeTextBlock
This table describes the fees and expenses that you may pay if you buy and hold
shares of the fund.
Shareholder Fees, Captionrr_ShareholderFeesCaptionShareholder Fees (charged if your account balance is less than $50,000)[1]
Operating Expenses, Captionrr_OperatingExpensesCaptionAnnual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Expense Example, Headingrr_ExpenseExampleHeadingExample
Expense Example, Narrativerr_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, Headingrr_StrategyHeadingPrincipal Investment Strategy
Investment Strategy, Narrativerr_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 substantially all of its
assets in short-term, high quality municipal obligations that provide income
exempt from federal and New York state and New York city 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.

Although the fund seeks to provide income exempt from federal and New York state
and New York city income taxes, interest from some of the fund's holdings may be
subject to the federal alternative minimum tax. In addition, the fund
temporarily may invest in high quality, taxable money market instruments and/or
municipal obligations that pay income exempt only from federal income tax,
including when the portfolio manager believes acceptable New York municipal
obligations are not available for investment.
Risk, Headingrr_RiskHeadingPrincipal Risks
Risk, Narrativerr_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 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.

o 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.

o 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 a single state makes the fund more sensitive to risks specific to
  the state and may magnify other risks.

o 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.
Risk, Nondiversified Statusrr_RiskNondiversifiedStatusThe 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 Fundrr_RiskMoneyMarketFundAlthough 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 Institutionrr_RiskNotInsuredDepositoryInstitutionAn 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, Headingrr_BarChartAndPerformanceTableHeadingPerformance
Performance, Narrativerr_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 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 Returnsrr_PerformanceInformationIllustratesVariabilityOfReturnsThe following bar chart and table provide some indication of the risks of investing in the fund.
Performance, Availability Website Addressrr_PerformanceAvailabilityWebSiteAddresswww.dreyfus.com
Performance, Past Does Not Indicate Futurerr_PerformancePastDoesNotIndicateFutureThe fund's past performance (before and after taxes) is no guarantee of future results.
Bar Chart, Headingrr_BarChartHeadingYear-by-Year Total Returns as of 12/31 each year (%)
Bar Chart, Narrativerr_BarChartNarrativeTextBlock
The bar chart shows changes in the performance of the fund's shares from
year to year.
Bar Chart, Closingrr_BarChartClosingTextBlock
Best Quarter
Q3, 2007: 0.83%
Worst Quarter
Q1, 2010: 0.00%
The fund's year-to-date total return as of 9/30/11 was 0.00%.
Performance Table, Closingrr_PerformanceTableClosingTextBlock
For the fund's current yield, call toll free 1-800-DREYFUS.
Average Annual Returns, Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns as of 12/31/10
Dreyfus BASIC New York Municipal Money Market Fund (Prospectus Summary) | Dreyfus BASIC New York Municipal Money Market Fund | Dreyfus BASIC New York Municipal Money Market Fund
 
Risk/Return:rr_RiskReturnAbstract 
Year to Date Return, Labelrr_YearToDateReturnLabelThe fund's year-to-date total return
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn0.00%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2007
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn0.83%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateMar. 31, 2010
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn0.00%
Dreyfus BASIC New York Municipal Money Market Fund | Dreyfus BASIC New York Municipal Money Market Fund
 
Risk/Return:rr_RiskReturnAbstract 
Exchange feerr_ExchangeFee 5.00
Account closeout feerr_ShareholderFeeOther5.00
Wire and Dreyfus TeleTransfer redemption feeck0000717341_ShareholderFeeOther25.00
Checkwriting chargeck0000717341_ShareholderFeeOther32.00
Management feesrr_ManagementFeesOverAssets0.45%
Other expensesrr_OtherExpensesOverAssets0.01%
Total annual fund operating expensesrr_ExpensesOverAssets0.46%
Fee waiver and/or expense reimbursementrr_FeeWaiverOrReimbursementOverAssets(0.01%)[2]
Total annual fund operating expenses (after fee waiver and/or expense reimbursement)rr_NetExpensesOverAssets0.45%
Expense Example, With Redemption, 1 Yearrr_ExpenseExampleYear0146
Expense Example, With Redemption, 3 Yearsrr_ExpenseExampleYear03144
Expense Example, With Redemption, 5 Yearsrr_ExpenseExampleYear05252
Expense Example, With Redemption, 10 Yearsrr_ExpenseExampleYear10 567
Annual Return 2001rr_AnnualReturn20012.24%
Annual Return 2002rr_AnnualReturn20021.03%
Annual Return 2003rr_AnnualReturn20030.62%
Annual Return 2004rr_AnnualReturn20040.74%
Annual Return 2005rr_AnnualReturn20051.95%
Annual Return 2006rr_AnnualReturn20063.04%
Annual Return 2007rr_AnnualReturn20073.27%
Annual Return 2008rr_AnnualReturn20082.05%
Annual Return 2009rr_AnnualReturn20090.40%
Annual Return 2010rr_AnnualReturn20100.00%
Average Annual Returns, 1 Yearrr_AverageAnnualReturnYear01 none
Average Annual Returns, 5 Yearsrr_AverageAnnualReturnYear051.75%
Average Annual Returns, 10 Yearsrr_AverageAnnualReturnYear101.53%
[1]Shareholder transaction fees are not charged if you have been a fund shareholder since May 8, 1996.
[2]The Dreyfus Corporation has agreed to pay all of the fund's expenses, except management fees and certain other expenses, including the fees and expenses of the non-interested board members and their counsel. The Dreyfus Corporation has agreed to reduce its fees in an amount equal to the fund's allocable portion of the fees and expenses of the non-interested board members and their counsel (in the amount of 0.01% for the past fiscal year).