Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Nov. 01, 2012
Dreyfus BASIC California Municipal Money Market Fund (Prospectus Summary) | Dreyfus BASIC California Municipal Money Market Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Summary
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The fund seeks to provide a high level of current income exempt from federal and California state income taxes to the extent 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.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (charged if your account balance is less than $50,000)	[1]
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 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	As a money market fund, the fund is subject to the maturity, quality, liquidity and diversification requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended, which are designed to help money market funds maintain a stable share price of $1.00. To pursue its goal, the fund normally invests substantially all of its net assets in short-term, high quality municipal obligations that provide income exempt from federal and California state 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 California state income taxes, income from some of the fund's holdings may be subject to the federal alternative minimum tax. In addition, the fund may invest temporarily 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 California municipal obligations are not available for investment.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	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. Although the fund invests only in high quality debt securities, any of the fund's holdings could have its credit rating downgraded or could default. 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 California'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 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	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 [Text]	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 [Text Block]	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 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 [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 (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 [Text Block]	rr_BarChartNarrativeTextBlock	The bar chart shows changes in the performance of the fund's shares from year to year.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter                  Q3, 2007: 0.83%               Worst Quarter                 Q3, 2011: 0.00%               The fund's year-to-date total return as of 9/30/12 was 0.00%.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	For the fund's current yield, call toll free 1-800-DREYFUS (inside the U.S. only).
Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns as of 12/31/11
Dreyfus BASIC California Municipal Money Market Fund (Prospectus Summary) | Dreyfus BASIC California Municipal Money Market Fund | Dreyfus BASIC California Municipal Money Market Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Exchange fee	rr_ExchangeFee	5.00
Account closeout fee	rr_ShareholderFeeOther	5.00
Wire and Dreyfus TeleTransfer redemption fee	ck0000717341_ShareholderFeeOther2	5.00
Checkwriting charge	ck0000717341_ShareholderFeeOther3	2.00
Management fees	rr_ManagementFeesOverAssets	0.45%
Other expenses	rr_OtherExpensesOverAssets	0.01%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.46%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual fund operating expenses (after fee waiver and/or expense reimbursement)	rr_NetExpensesOverAssets	0.45%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	1996-05-08
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	46
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	144
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	252
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	567
Annual Return 2002	rr_AnnualReturn2002	1.00%
Annual Return 2003	rr_AnnualReturn2003	0.60%
Annual Return 2004	rr_AnnualReturn2004	0.75%
Annual Return 2005	rr_AnnualReturn2005	1.95%
Annual Return 2006	rr_AnnualReturn2006	2.99%
Annual Return 2007	rr_AnnualReturn2007	3.26%
Annual Return 2008	rr_AnnualReturn2008	1.95%
Annual Return 2009	rr_AnnualReturn2009	0.21%
Annual Return 2010	rr_AnnualReturn2010	0.01%
Annual Return 2011	rr_AnnualReturn2011	0.00%
Year to Date Return, Label	rr_YearToDateReturnLabel	The fund's year-to-date total return
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2012
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.00%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2007
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	0.83%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	0.00%
1 Year	rr_AverageAnnualReturnYear01	none
5 Years	rr_AverageAnnualReturnYear05	1.07%
10 Years	rr_AverageAnnualReturnYear10	1.26%

[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).