Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Oct. 26, 2012
Hennessy Technology Fund (Second Prospectus Summary) | Hennessy Technology Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	HENNESSY TECHNOLOGY FUND
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Hennessy Technology Fund seeks long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fund 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 Institutional Class shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
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)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities, or "turns over" its portfolio. A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the predecessor to the Fund, the FBR Technology Fund, a series of The FBR Funds (the "Predecessor Technology Fund"), had a portfolio turnover rate of 141% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	141.00%
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	"Other Expenses" have been adjusted as necessary from amounts incurred during the Predecessor Technology Fund's (as defined below) most recent fiscal year to reflect current fees and expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in Institutional Class shares of the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in Institutional Class shares of 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 you reinvest all dividends and distributions, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on the assumptions, your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategy
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund invests at least 80% of its net assets plus the amount of any borrowings for investment purposes in securities of companies that are principally engaged in the research, design, development, manufacturing or distributing products or services in the technology industry. The Fund's policy of investing at least 80% of its net assets in companies principally engaged in technology may only be changed upon 60 days notice to shareholders. The Fund will primarily invest in equity securities (which include common stocks, preferred stocks, warrants and other securities convertible into common stocks, including convertible bonds and convertible preferred stock) of companies listed on a U.S. securities exchange or NASDAQ that are expected to experience earnings growth as a result of technology. Potential investments would include, but not be limited to, the following industries: computer software and hardware, semiconductors, scientific instrumentation, telecommunications, pharmaceuticals, chemicals, synthetic materials, defense and commercial electronics, data storage and retrieval, biotechnology, and healthcare and medical supplies. While the Fund's investments will primarily be in domestic U.S. securities, the Fund's investments may include foreign securities, including indirect investments such as ADRs or other types of depositary receipts, which are U.S. dollar-denominated receipts representing shares of foreign-based corporations. The Fund may invest up to 20% of its net assets in companies outside of the technology industry. The Portfolio Managers invest in the stocks of companies of any size without regard to market capitalization. The Portfolio Managers make investment decisions for the Fund on the basis of fundamental security analysis. Once an issuer is identified as an attractive candidate for the Fund's portfolio, the Portfolio Managers assess the relative value and growth potential of the security on the basis of various factors, which may include price to book ratio, price to earnings ratio, earnings yield and cash flow, among others. The Fund may invest, to a limited degree, in securities issued in initial public offerings ("IPOs"). Many of the common stocks purchased by the Fund will not pay dividends; instead, stocks will be bought for the potential that their prices will increase and provide capital appreciation for the Fund.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	Under normal market conditions, the Fund invests at least 80% of its net assets plus the amount of any borrowings for investment purposes in securities of companies that are principally engaged in the research, design, development, manufacturing or distributing products or services in the technology industry.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with any security, there are market and investment risks associated with an investment in the Fund. The value of an investment will fluctuate over time and it is possible to lose money. The principal risks of investing in the Fund include the following: Market Risk: The market value of a security may move up or down, and these fluctuations may cause a security to be worth more or less than the price originally paid for it. Market risk may affect a single company, industry, sector of the economy or the market as a whole. Equity Investments: Because the Fund invests in equity securities, fluctuations in the stock market in general, as well as in the value of particular equity securities held by the Fund, can affect the Fund's performance. The value of equity securities will fluctuate due to many factors, including the past and predicted earnings of the issuer, the quality of the issuer's management, general market conditions, forecasts for the issuer's industry and the value of the issuer's assets. Temporary Defensive Positions: The Fund may, from time to time, take temporary defensive positions in response to adverse market, economic, political or other conditions. To the extent the assets of the Fund are invested in temporary defensive positions, the Fund may not achieve its investment objective. For temporary defensive purposes, the Fund may invest in cash and/or short-term obligations. Mid-Cap and Small-Cap Investments: The Fund invests in small and medium sized companies, which may have more limited liquidity and greater price volatility than larger, more established companies. Small companies may have limited product lines, markets or financial resources and their management may be dependent on a limited number of key individuals. Industry Concentration: The Fund concentrates its investments within the technology industry. Because of its narrow industry focus, the performance of the Fund is tied closely to and is affected by developments in the technology industry and its related businesses. The value of the Fund's shares may fluctuate more than shares of a fund investing in other industries or in a broader range of industries. IPO Investments: IPO shares are subject to market risk and liquidity risk. The market value of IPO shares will fluctuate considerably due to facts such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited public information about the issuer. The purchase of IPO shares may involve high transaction costs. When a fund's asset base is small, a significant portion of the fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the fund. Foreign Securities Risk: The Fund invests in ADRs, which are foreign securities traded on U.S. exchanges. There are specific risks associated with investing in the securities of foreign companies not typically associated with investing in domestic companies. Risks include fluctuations in the exchange rates of foreign currencies that may affect the U.S. Dollar value of a security, and the possibility of substantial price volatility as a result of political and economic instability in the foreign country. Non-Diversification: The Fund is non-diversified, meaning it is likely to invest in fewer stocks than a diversified fund. The Fund may be more volatile because each stock in which it invests will have greater impact on the Fund's performance. High Portfolio Turnover Risks: The Fund's investment strategies may result in high portfolio turnover rates. This may increase the Fund's brokerage commission costs, which would reduce performance. Rapid portfolio turnover also exposes shareholders to a higher current realization of short-term gains which could cause you to pay higher taxes.
Risk Lose Money [Text]	rr_RiskLoseMoney	The value of an investment will fluctuate over time and it is possible to lose money.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is non-diversified, meaning it is likely to invest in fewer stocks than a diversified fund. The Fund may be more volatile because each stock in which it invests will have greater impact on the Fund's performance.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The Fund is a successor to the Predecessor Technology Fund pursuant to a reorganization that took place after the close of business on October 26, 2012. The performance information provided for the periods on or prior to October 26, 2012 is historical information for the Predecessor Technology Fund. Both the chart and the table below represent the performance of the Institutional Class shares of the Predecessor Technology Fund after March 12, 2010 (inception of the share class) and Investor Class for periods prior to that date. The returns for the Institutional Class shares will differ from the returns for the Investor Class shares because of differences in expenses of each share class. The Predecessor Technology Fund was managed by FBR Fund Advisers, Inc. and had the same investment objective and substantially similar investment strategy as the Fund. The following performance information provides some indication of the risks of investing in the Fund by showing changes in its performance from year to year and how the Fund's average annual returns compare with those of the S&P 500 Index, a broad measure of market performance, and the secondary benchmark of the NASDAQ Composite Index. For additional information on these indexes, please see "Index Descriptions" in the Prospectus. The Fund's past performance (before and after taxes) is not necessarily an indication of future performance. Performance may be higher or lower in the future. Updated performance information is available on the Fund's website (http://www.hennessyfunds.com).
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following performance information provides some indication of the risks of investing in the Fund by showing changes in its performance from year to year and how the Fund's average annual returns compare with those of the S&P 500 Index, a broad measure of market performance, and the secondary benchmark of the NASDAQ Composite Index.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	the secondary benchmark of the NASDAQ Composite Index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.hennessyfunds.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund's past performance (before and after taxes) is not necessarily an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	CALENDAR YEAR TOTAL RETURNS
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	For the period shown in the bar chart, the Fund's highest quarterly return was 26.38% for the quarter ended June 30, 2003 and the lowest quarterly return was -22.74% for the quarter ended December 31, 2008. The year-to-date return of the Predecessor Technology Fund's Institutional Class through September 30, 2012 is 10.49%.
Index No Deduction for Fees, Expenses, Taxes [Text]	rr_IndexNoDeductionForFeesExpensesTaxes	reflects no deduction for fees, expenses or taxes
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	The after-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on an investor's tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	The Fund's return after taxes on distributions and sales of Fund shares may be higher than its return before taxes and after taxes on distributions because it may include a tax benefit resulting from the capital losses that would have resulted.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	The after-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The Fund's return after taxes on distributions and sales of Fund shares may be higher than its return before taxes and after taxes on distributions because it may include a tax benefit resulting from the capital losses that would have resulted.
Caption	rr_AverageAnnualReturnCaption	AVERAGE ANNUAL TOTAL RETURNS (for the periods ended December 31, 2011)
Hennessy Technology Fund (Second Prospectus Summary) | Hennessy Technology Fund | S&P 500 Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500 Index (reflects no deduction for fees, expenses or taxes)
1 Year	rr_AverageAnnualReturnYear01	2.11%
5 Years	rr_AverageAnnualReturnYear05	(0.25%)
Since Inception	rr_AverageAnnualReturnSinceInception	3.17%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2002
Hennessy Technology Fund (Second Prospectus Summary) | Hennessy Technology Fund | NASDAQ Composite Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	NASDAQ Composite Index (reflects no deduction for fees, expenses or taxes)
1 Year	rr_AverageAnnualReturnYear01	(1.80%)
5 Years	rr_AverageAnnualReturnYear05	1.52%
Since Inception	rr_AverageAnnualReturnSinceInception	3.17%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2002
Hennessy Technology Fund (Second Prospectus Summary) | Hennessy Technology Fund | Institutional Class
Risk Return [Abstract]	rr_RiskReturnAbstract
Sales charge (load)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fee	rr_RedemptionFeeOverRedemption	none
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	1.63%	[1]
Acquired Fund Fees and Expenses (AFFE)	rr_AcquiredFundFeesAndExpensesOverAssets	0.03%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.56%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.83%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.73%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2015-02-28
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	176
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	718
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,286
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	2,833
Annual Return 2003	rr_AnnualReturn2003	52.86%
Annual Return 2004	rr_AnnualReturn2004	6.75%
Annual Return 2005	rr_AnnualReturn2005	11.80%
Annual Return 2006	rr_AnnualReturn2006	9.25%
Annual Return 2007	rr_AnnualReturn2007	9.36%
Annual Return 2008	rr_AnnualReturn2008	(42.89%)
Annual Return 2009	rr_AnnualReturn2009	54.93%
Annual Return 2010	rr_AnnualReturn2010	12.93%
Annual Return 2011	rr_AnnualReturn2011	(10.67%)
Year to Date Return, Label	rr_YearToDateReturnLabel	year-to-date return
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2012
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	10.49%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest quarterly return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	26.38%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest quarterly return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.74%)
Label	rr_AverageAnnualReturnLabel	Returns before taxes
1 Year	rr_AverageAnnualReturnYear01	(10.67%)
5 Years	rr_AverageAnnualReturnYear05	(0.48%)
Since Inception	rr_AverageAnnualReturnSinceInception	3.91%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2002
Hennessy Technology Fund (Second Prospectus Summary) | Hennessy Technology Fund | Institutional Class | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Returns after taxes on distributions
1 Year	rr_AverageAnnualReturnYear01	(10.67%)
5 Years	rr_AverageAnnualReturnYear05	(1.04%)
Since Inception	rr_AverageAnnualReturnSinceInception	(0.85%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2002
Hennessy Technology Fund (Second Prospectus Summary) | Hennessy Technology Fund | Institutional Class | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Returns after taxes on distributions and sale of fund shares
1 Year	rr_AverageAnnualReturnYear01	(6.93%)
5 Years	rr_AverageAnnualReturnYear05	(0.65%)
Since Inception	rr_AverageAnnualReturnSinceInception	(0.72%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2002

[1] "Other Expenses" have been adjusted as necessary from amounts incurred during the Predecessor Technology Fund's (as defined below) most recent fiscal year to reflect current fees and expenses.

[2] The Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement above differ from the amounts shown in the Fund's Financial Highlights for its most recent fiscal year, which reflects only the operating expenses of the Fund and do not include AFFE (i.e., fees and expenses of other funds in which the Fund has invested).

[3] Hennessy Advisors, Inc. (the "Manager") has agreed in writing to waive a portion of its investment advisory fees and assume certain expenses to the extent annual fund operating expenses exceed 1.70% of the Fund's average daily net assets (excluding interest, taxes, brokerage commissions, dividend expenses, acquired fund fees and expenses, extraordinary legal expenses, or any other extraordinary expenses). The Manager has agreed to maintain this expense limitation through February 28, 2015. The Manager may recoup any waived amount from the Fund pursuant to this agreement, if such reimbursement does not cause the Fund to exceed existing expense limitations and the reimbursement is made within three years after the year in which the expense was incurred. The agreement may only be terminated by the Fund's Board, and the Board has no current intention of terminating the agreement.