v3.26.1
Shareholder Report, Holdings (Details)
Apr. 30, 2026
Hennessy Cornerstone Growth Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.00%
Hennessy Cornerstone Growth Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Hennessy Cornerstone Growth Fund - Investor Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 20.10%
Hennessy Cornerstone Growth Fund - Investor Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Hennessy Cornerstone Growth Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 27.70%
Hennessy Cornerstone Growth Fund - Investor Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 10.70%
Hennessy Cornerstone Growth Fund - Investor Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 10.70%
Hennessy Cornerstone Growth Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Hennessy Cornerstone Growth Fund - Investor Class | Real Estate [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Hennessy Cornerstone Growth Fund - Investor Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Hennessy Cornerstone Growth Fund - Investor Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Hennessy Cornerstone Growth Fund - Institutional Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.00%
Hennessy Cornerstone Growth Fund - Institutional Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Hennessy Cornerstone Growth Fund - Institutional Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 20.10%
Hennessy Cornerstone Growth Fund - Institutional Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Hennessy Cornerstone Growth Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 27.70%
Hennessy Cornerstone Growth Fund - Institutional Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 10.70%
Hennessy Cornerstone Growth Fund - Institutional Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 10.70%
Hennessy Cornerstone Growth Fund - Institutional Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Hennessy Cornerstone Growth Fund - Institutional Class | Real Estate [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Hennessy Cornerstone Growth Fund - Institutional Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Hennessy Cornerstone Growth Fund - Institutional Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Hennessy Focus Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 21.70%
Hennessy Focus Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 16.70%
Hennessy Focus Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 23.90%
Hennessy Focus Fund - Investor Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Hennessy Focus Fund - Investor Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.80%
Hennessy Focus Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.70%
Hennessy Focus Fund - Investor Class | Real Estate [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.60%
Hennessy Focus Fund - Investor Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Hennessy Focus Fund - Institutional Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 21.70%
Hennessy Focus Fund - Institutional Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 16.70%
Hennessy Focus Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 23.90%
Hennessy Focus Fund - Institutional Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Hennessy Focus Fund - Institutional Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.80%
Hennessy Focus Fund - Institutional Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.70%
Hennessy Focus Fund - Institutional Class | Real Estate [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.60%
Hennessy Focus Fund - Institutional Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Hennessy Cornerstone Mid Cap 30 Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Hennessy Cornerstone Mid Cap 30 Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 19.30%
Hennessy Cornerstone Mid Cap 30 Fund - Investor Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.50%
Hennessy Cornerstone Mid Cap 30 Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.70%
Hennessy Cornerstone Mid Cap 30 Fund - Investor Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 34.10%
Hennessy Cornerstone Mid Cap 30 Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.90%
Hennessy Cornerstone Mid Cap 30 Fund - Investor Class | Real Estate [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.40%
Hennessy Cornerstone Mid Cap 30 Fund - Investor Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Hennessy Cornerstone Mid Cap 30 Fund - Investor Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Hennessy Cornerstone Mid Cap 30 Fund - Institutional Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Hennessy Cornerstone Mid Cap 30 Fund - Institutional Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 19.30%
Hennessy Cornerstone Mid Cap 30 Fund - Institutional Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.50%
Hennessy Cornerstone Mid Cap 30 Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.70%
Hennessy Cornerstone Mid Cap 30 Fund - Institutional Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 34.10%
Hennessy Cornerstone Mid Cap 30 Fund - Institutional Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.90%
Hennessy Cornerstone Mid Cap 30 Fund - Institutional Class | Real Estate [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.40%
Hennessy Cornerstone Mid Cap 30 Fund - Institutional Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Hennessy Cornerstone Mid Cap 30 Fund - Institutional Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Hennessy Cornerstone Large Growth Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Hennessy Cornerstone Large Growth Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.50%
Hennessy Cornerstone Large Growth Fund - Investor Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 15.70%
Hennessy Cornerstone Large Growth Fund - Investor Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.10%
Hennessy Cornerstone Large Growth Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.60%
Hennessy Cornerstone Large Growth Fund - Investor Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 15.90%
Hennessy Cornerstone Large Growth Fund - Investor Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.80%
Hennessy Cornerstone Large Growth Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.40%
Hennessy Cornerstone Large Growth Fund - Investor Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Hennessy Cornerstone Large Growth Fund - Investor Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.50%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 15.70%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.10%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.60%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 15.90%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.80%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.40%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Hennessy Cornerstone Large Growth Fund - Institutional Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Hennessy Cornerstone Value Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Hennessy Cornerstone Value Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.40%
Hennessy Cornerstone Value Fund - Investor Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.10%
Hennessy Cornerstone Value Fund - Investor Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 24.00%
Hennessy Cornerstone Value Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 15.40%
Hennessy Cornerstone Value Fund - Investor Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 19.90%
Hennessy Cornerstone Value Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 8.40%
Hennessy Cornerstone Value Fund - Investor Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Hennessy Cornerstone Value Fund - Institutional Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Hennessy Cornerstone Value Fund - Institutional Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.40%
Hennessy Cornerstone Value Fund - Institutional Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.10%
Hennessy Cornerstone Value Fund - Institutional Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 24.00%
Hennessy Cornerstone Value Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 15.40%
Hennessy Cornerstone Value Fund - Institutional Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 19.90%
Hennessy Cornerstone Value Fund - Institutional Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 8.40%
Hennessy Cornerstone Value Fund - Institutional Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Hennessy Total Return Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Hennessy Total Return Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.30%
Hennessy Total Return Fund - Investor Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.20%
Hennessy Total Return Fund - Investor Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Hennessy Total Return Fund - Investor Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 25.30%
Hennessy Total Return Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Hennessy Total Return Fund - Investor Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 30.90%
Hennessy Equity and Income Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 8.00%
Hennessy Equity and Income Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.30%
Hennessy Equity and Income Fund - Investor Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.20%
Hennessy Equity and Income Fund - Investor Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Hennessy Equity and Income Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 22.50%
Hennessy Equity and Income Fund - Investor Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Hennessy Equity and Income Fund - Investor Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.60%
Hennessy Equity and Income Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.00%
Hennessy Equity and Income Fund - Investor Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Hennessy Equity and Income Fund - Investor Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Hennessy Equity and Income Fund - Investor Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Hennessy Equity and Income Fund - Investor Class | Collateralized Mortgage-Backed Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Hennessy Equity and Income Fund - Investor Class | U.S. Treasury Notes [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.60%
Hennessy Equity and Income Fund - Institutional Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 8.00%
Hennessy Equity and Income Fund - Institutional Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.30%
Hennessy Equity and Income Fund - Institutional Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.20%
Hennessy Equity and Income Fund - Institutional Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Hennessy Equity and Income Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 22.50%
Hennessy Equity and Income Fund - Institutional Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Hennessy Equity and Income Fund - Institutional Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.60%
Hennessy Equity and Income Fund - Institutional Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.00%
Hennessy Equity and Income Fund - Institutional Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Hennessy Equity and Income Fund - Institutional Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Hennessy Equity and Income Fund - Institutional Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Hennessy Equity and Income Fund - Institutional Class | Collateralized Mortgage-Backed Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Hennessy Equity and Income Fund - Institutional Class | U.S. Treasury Notes [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.60%
Hennessy Balanced Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.90%
Hennessy Balanced Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.00%
Hennessy Balanced Fund - Investor Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 8.70%
Hennessy Balanced Fund - Investor Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Hennessy Balanced Fund - Investor Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 20.90%
Hennessy Balanced Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.30%
Hennessy Balanced Fund - Investor Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 49.20%
Hennessy Energy Transition Fund - Investor Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Hennessy Energy Transition Fund - Investor Class | Short-Term Investments and Other Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.20%
Hennessy Energy Transition Fund - Investor Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
Hennessy Energy Transition Fund - Investor Class | Downstream Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 8.40%
Hennessy Energy Transition Fund - Investor Class | Exploration and Production Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 32.80%
Hennessy Energy Transition Fund - Investor Class | Integrated Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
Hennessy Energy Transition Fund - Investor Class | Midstream Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.20%
Hennessy Energy Transition Fund - Investor Class | Oil Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 24.50%
Hennessy Energy Transition Fund - Institutional Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Hennessy Energy Transition Fund - Institutional Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
Hennessy Energy Transition Fund - Institutional Class | Downstream [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 8.40%
Hennessy Energy Transition Fund - Institutional Class | Exploration and Production [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 32.80%
Hennessy Energy Transition Fund - Institutional Class | Integrated [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
Hennessy Energy Transition Fund - Institutional Class | Midstream [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.20%
Hennessy Energy Transition Fund - Institutional Class | Oil Services [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 24.50%
Hennessy Energy Transition Fund - Institutional Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.20%
Hennessy Midstream Fund - Investor Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value (1.30%)
Hennessy Midstream Fund - Investor Class | Crude Oil and Refined Products [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 23.20%
Hennessy Midstream Fund - Investor Class | Geathering and Processing [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 19.00%
Hennessy Midstream Fund - Investor Class | Natural Gas/NGL Transportation [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 59.10%
Hennessy Midstream Fund - Institutional Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value (1.30%)
Hennessy Midstream Fund - Institutional Class | Crude Oil and Refined Products [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 23.20%
Hennessy Midstream Fund - Institutional Class | Geathering and Processing [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 19.00%
Hennessy Midstream Fund - Institutional Class | Natural Gas/NGL Transportation [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 59.10%
Hennessy Gas Utility Fund - Investor Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 38.70%
Hennessy Gas Utility Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Hennessy Gas Utility Fund - Investor Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 56.10%
Hennessy Gas Utility Fund - Investor Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Hennessy Gas Utility Fund - Institutional Class | Energy Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 38.70%
Hennessy Gas Utility Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Hennessy Gas Utility Fund - Institutional Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 56.10%
Hennessy Gas Utility Fund - Institutional Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Hennessy Japan Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.10%
Hennessy Japan Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.80%
Hennessy Japan Fund - Investor Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Hennessy Japan Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 34.50%
Hennessy Japan Fund - Investor Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Hennessy Japan Fund - Investor Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 18.00%
Hennessy Japan Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.60%
Hennessy Japan Fund - Investor Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.30%
Hennessy Japan Fund - Investor Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Hennessy Japan Fund - Investor Class | Real Estate Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Hennessy Japan Fund - Institutional Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.10%
Hennessy Japan Fund - Institutional Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 11.80%
Hennessy Japan Fund - Institutional Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Hennessy Japan Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 34.50%
Hennessy Japan Fund - Institutional Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Hennessy Japan Fund - Institutional Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 18.00%
Hennessy Japan Fund - Institutional Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.60%
Hennessy Japan Fund - Institutional Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.30%
Hennessy Japan Fund - Institutional Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Hennessy Japan Fund - Institutional Class | Real Estate Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Hennessy Japan Small Cap Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
Hennessy Japan Small Cap Fund - Investor Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 18.90%
Hennessy Japan Small Cap Fund - Investor Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Hennessy Japan Small Cap Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 9.90%
Hennessy Japan Small Cap Fund - Investor Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Hennessy Japan Small Cap Fund - Investor Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 31.40%
Hennessy Japan Small Cap Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.10%
Hennessy Japan Small Cap Fund - Investor Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Hennessy Japan Small Cap Fund - Investor Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Hennessy Japan Small Cap Fund - Investor Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Hennessy Japan Small Cap Fund - Investor Class | Real Estate Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.40%
Hennessy Japan Small Cap Fund - Institutional Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
Hennessy Japan Small Cap Fund - Institutional Class | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 18.90%
Hennessy Japan Small Cap Fund - Institutional Class | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Hennessy Japan Small Cap Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 9.90%
Hennessy Japan Small Cap Fund - Institutional Class | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Hennessy Japan Small Cap Fund - Institutional Class | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 31.40%
Hennessy Japan Small Cap Fund - Institutional Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.10%
Hennessy Japan Small Cap Fund - Institutional Class | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Hennessy Japan Small Cap Fund - Institutional Class | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Hennessy Japan Small Cap Fund - Institutional Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Hennessy Japan Small Cap Fund - Institutional Class | Real Estate Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.40%
Hennessy Large Cap Financial Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 98.10%
Hennessy Large Cap Financial Fund - Investor Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Hennessy Large Cap Financial Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 98.10%
Hennessy Large Cap Financial Fund - Institutional Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Hennessy Small Cap Financial Fund - Investor Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.10%
Hennessy Small Cap Financial Fund - Investor Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Hennessy Small Cap Financial Fund - Institutional Class | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.10%
Hennessy Small Cap Financial Fund - Institutional Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Hennessy Technology Fund - Investor Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.30%
Hennessy Technology Fund - Investor Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 85.10%
Hennessy Technology Fund - Investor Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Hennessy Technology Fund - Institutional Class | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.30%
Hennessy Technology Fund - Institutional Class | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 85.10%
Hennessy Technology Fund - Institutional Class | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Hennessy Sustainable ETF | Communications Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.80%
Hennessy Sustainable ETF | Consumer Discretionary Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.10%
Hennessy Sustainable ETF | Consumer Staples Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 8.50%
Hennessy Sustainable ETF | Financial Services Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.30%
Hennessy Sustainable ETF | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.70%
Hennessy Sustainable ETF | Industrial Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.80%
Hennessy Sustainable ETF | Information Technology Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 19.80%
Hennessy Sustainable ETF | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Hennessy Sustainable ETF | Materials Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
Hennessy Sustainable ETF | Short-Term Investments and Other [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Hennessy Sustainable ETF | Real Estate Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%