| Form N-CSR Cover | 6 Months Ended |
| Jun. 30, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | Gabelli Utilities Fund |
| Entity Central Index Key | 0001087966 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jun. 30, 2024 |
| Shareholder Report | 6 Months Ended |
| Jun. 30, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | Gabelli Utilities Fund |
| Entity Central Index Key | 0001087966 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jun. 30, 2024 |
| C000002899 | |
| Shareholder Report [Line Items] | |
| Fund Name | The Gabelli Utilities Fund |
| Class Name | Class AAA |
| Trading Symbol | GABUX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about The Gabelli Utilities Fund (the Fund) for the period of January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at www.gabelli.com |
| Additional Information Phone Number | 800-GABELLI (800-422-3554) |
| Additional Information Website | www.gabelli.com</span>" id="sjs-B19"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| Expenses [Text Block] | What were the Fund costs for the last six months? (based on a hypothetical $10,000 investment) Class Name Costs of a $10k Investment Costs Paid as a % of a $10k Investment The Gabelli Utilities Fund - Class AAA $71 1.40% |
| Expenses Paid, Amount | $ 71 |
| Expense Ratio, Percent | 1.40% |
| Factors Affecting Performance [Text Block] | How did the Fund perform? During the six months ended June 30, 2024, the Gabelli Utilities Fund underperformed its broad-based benchmark, the S&P 500 and its comparative benchmarks, the S&P 500 Utilities Index and the Lipper Utility Fund Average. The potential for accelerated electric demand growth driven by technological innovation (artificial intelligence, data centers), electrification and manufacturing onshoring led to a momentum shift into power stocks. Shares of non-regulated power plant owners and developers surged on the AI-data center theme. Our Fund holds lower weights in the more volatile power names as well as a more diversified holdings list across the utility universe. |
| Performance Past Does Not Indicate Future [Text] | Past performance does not guarantee future results. |
| Line Graph [Table Text Block] | The Gabelli Utilities Fund - Class AAA S&P 500 Index S&P 500 Utilities Index Lipper Utility Fund Average 6/14 10,000 10,000 10,000 10,000 6/15 9,411 10,742 9,710 9,480 6/16 10,807 11,171 12,766 10,882 6/17 11,277 13,170 13,081 11,219 6/18 11,569 15,063 13,527 11,888 6/19 12,979 16,632 16,101 13,667 6/20 11,633 17,881 15,762 12,834 6/21 14,127 25,175 18,247 15,150 6/22 14,551 22,501 20,857 16,484 6/23 14,017 26,910 20,089 16,422 6/24 14,201 33,519 21,660 17,901 |
| Average Annual Return [Table Text Block] | Fund 6 months 1 Year 5 Year 10 Year The Gabelli Utilities Fund - Class AAA 4.59% 1.30% 1.84% 3.57% S&P 500 Index 15.29% 24.56% 15.05% 12.86% S&P 500 Utilities Index 9.44% 7.82% 6.11% 8.04% Lipper Utility Fund Average 8.50% 9.01% 5.55% 6.00% |
| No Deduction of Taxes [Text Block] | The table and graph presented above do not reflect the deduction of taxes a shareholder would pay on fund distributions or the redemption of fund shares. |
| Performance Table Market Index Changed [Text Block] | |
| Updated Performance Information Location [Text Block] | Updated Location: Visit www.confluence.com/funds for more recent performance information. |
| AssetsNet | $ 1,452,187,602 |
| Holdings Count | Holding | 220 |
| Advisory Fees Paid, Amount | $ 7,382,681 |
| InvestmentCompanyPortfolioTurnover | 0% |
| Additional Fund Statistics [Text Block] | Fund Statistics Total Net Assets $1,452,187,602 Number of Portfolio Holdings 220 Portfolio Turnover Rate 0% Management Fees $7,382,681 |
| Holdings [Text Block] | Industry Allocation (% of net assets) Industry Weighting . Energy and Utilities 86.6% Communications 8.3% Other 4.8% U.S. Government Obligations 0.1% Other Assets and Liabilities (Net) 0.2% |
| Largest Holdings [Text Block] | Top 10 Holdings (% of net assets) Top 10 NextEra Energy Inc. 8.9% National Fuel Gas Co. 5.8% Southwest Gas Holdings Inc. 3.7% The AES Corp. 3.6% American Electric Power Co. Inc. 3.6% Evergy Inc. 3.3% WEC Energy Group Inc. 2.8% ONEOK Inc. 2.7% Eversource Energy 2.6% Otter Tail Corp. 2.5% |
| Material Fund Change [Text Block] | |
| Updated Prospectus Phone Number | 800-GABELLI (800-422-3554) |
| Updated Prospectus Email Address | info@gabelli.com</span>" id="sjs-B39"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">info@gabelli.com</span> |
| Updated Prospectus Web Address | www.gabelli.com</span>" id="sjs-B40"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| C000239633 | |
| Shareholder Report [Line Items] | |
| Fund Name | The Gabelli Utilities Fund |
| Class Name | Class C |
| Trading Symbol | GUXPX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about The Gabelli Utilities Fund (the Fund) for the period of January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at www.gabelli.com |
| Additional Information Phone Number | 800-GABELLI (800-422-3554) |
| Additional Information Website | www.gabelli.com</span>" id="sjs-B50"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| Expenses [Text Block] | What were the Fund costs for the last six months? (based on a hypothetical $10,000 investment) Class Name Costs of a $10k Investment Costs Paid as a % of a $10k Investment The Gabelli Utilities Fund - Class C $64 1.28% |
| Expenses Paid, Amount | $ 64 |
| Expense Ratio, Percent | 1.28% |
| Factors Affecting Performance [Text Block] | How did the Fund perform? During the six months ended June 30, 2024, the Gabelli Utilities Fund underperformed its broad-based benchmark, the S&P 500 and its comparative benchmarks, the S&P 500 Utilities Index and the Lipper Utility Fund Average. The potential for accelerated electric demand growth driven by technological innovation (artificial intelligence, data centers), electrification and manufacturing onshoring led to a momentum shift into power stocks. Shares of non-regulated power plant owners and developers surged on the AI-data center theme. Our Fund holds lower weights in the more volatile power names as well as a more diversified holdings list across the utility universe. |
| Performance Past Does Not Indicate Future [Text] | Past performance does not guarantee future results. |
| Line Graph [Table Text Block] | The Gabelli Utilities Fund - Class C S&P 500 Index S&P 500 Utilities Index Lipper Utility Fund Average 6/14 10,000 10,000 10,000 10,000 6/15 9,237 10,742 9,710 9,480 6/16 10,430 11,171 12,766 10,882 6/17 10,705 13,170 13,081 11,219 6/18 10,790 15,063 13,527 11,888 6/19 11,906 16,632 16,101 13,667 6/20 10,499 17,881 15,762 12,834 6/21 12,541 25,175 18,247 15,150 6/22 12,688 22,501 20,857 16,484 6/23 12,007 26,910 20,089 16,422 6/24 11,951 33,519 21,660 17,901 |
| Average Annual Return [Table Text Block] | Fund 6 months 1 Year 5 Year 10 Year The Gabelli Utilities Fund - Class C 3.15% (0.47)% 1.05% 2.78% S&P 500 Index 15.29% 24.56% 15.05% 12.86% S&P 500 Utilities Index 9.44% 7.82% 6.11% 8.04% Lipper Utility Fund Average 8.50% 9.01% 5.55% 6.00% |
| No Deduction of Taxes [Text Block] | The table and graph presented above do not reflect the deduction of taxes a shareholder would pay on fund distributions or the redemption of fund shares. |
| Performance Table Market Index Changed [Text Block] | |
| Updated Performance Information Location [Text Block] | Updated Location: Visit www.confluence.com/funds for more recent performance information. |
| AssetsNet | $ 1,452,187,602 |
| Holdings Count | Holding | 220 |
| Advisory Fees Paid, Amount | $ 7,382,681 |
| InvestmentCompanyPortfolioTurnover | 0% |
| Additional Fund Statistics [Text Block] | Fund Statistics Total Net Assets $1,452,187,602 Number of Portfolio Holdings 220 Portfolio Turnover Rate 0% Management Fees $7,382,681 |
| Holdings [Text Block] | Industry Allocation (% of net assets) Industry Weighting . Energy and Utilities 86.6% Communications 8.3% Other 4.8% U.S. Government Obligations 0.1% Other Assets and Liabilities (Net) 0.2% |
| Largest Holdings [Text Block] | Top 10 Holdings (% of net assets) Top 10 NextEra Energy Inc. 8.9% National Fuel Gas Co. 5.8% Southwest Gas Holdings Inc. 3.7% The AES Corp. 3.6% American Electric Power Co. Inc. 3.6% Evergy Inc. 3.3% WEC Energy Group Inc. 2.8% ONEOK Inc. 2.7% Eversource Energy 2.6% Otter Tail Corp. 2.5% |
| Material Fund Change [Text Block] | |
| Updated Prospectus Phone Number | 800-GABELLI (800-422-3554) |
| Updated Prospectus Email Address | info@gabelli.com</span>" id="sjs-B70"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">info@gabelli.com</span> |
| Updated Prospectus Web Address | www.gabelli.com</span>" id="sjs-B71"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| C000002901 | |
| Shareholder Report [Line Items] | |
| Fund Name | The Gabelli Utilities Fund |
| Class Name | Class C1 |
| Trading Symbol | GAUCX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about The Gabelli Utilities Fund (the Fund) for the period of January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at www.gabelli.com |
| Additional Information Phone Number | 800-GABELLI (800-422-3554) |
| Additional Information Website | www.gabelli.com</span>" id="sjs-B81"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| Expenses [Text Block] | What were the Fund costs for the last six months? (based on a hypothetical $10,000 investment) Class Name Costs of a $10k Investment Costs Paid as a % of a $10k Investment The Gabelli Utilities Fund - Class C1 $3,488,435,200 70152048.53% |
| Expenses Paid, Amount | $ 3,488,435,200 |
| Expense Ratio, Percent | 70,152,048.53% |
| Factors Affecting Performance [Text Block] | How did the Fund perform? During the six months ended June 30, 2024, the Gabelli Utilities Fund underperformed its broad-based benchmark, the S&P 500 and its comparative benchmarks, the S&P 500 Utilities Index and the Lipper Utility Fund Average. The potential for accelerated electric demand growth driven by technological innovation (artificial intelligence, data centers), electrification and manufacturing onshoring led to a momentum shift into power stocks. Shares of non-regulated power plant owners and developers surged on the AI-data center theme. Our Fund holds lower weights in the more volatile power names as well as a more diversified holdings list across the utility universe. |
| Performance Past Does Not Indicate Future [Text] | Past performance does not guarantee future results. |
| Line Graph [Table Text Block] | S&P 500 Index S&P 500 Utilities Index Lipper Utility Fund Average 6/14 0 0 0 6/15 0 0 0 6/16 0 0 0 6/17 0 0 0 6/18 0 0 0 6/19 0 0 0 6/20 0 0 0 6/21 0 0 0 6/22 0 0 0 6/23 0 0 0 6/24 0 0 0 |
| Average Annual Return [Table Text Block] | Fund 6 months 1 Year 5 Year 10 Year S&P 500 Index 15.29% 24.56% 15.05% 12.86% S&P 500 Utilities Index 9.44% 7.82% 6.11% 8.04% Lipper Utility Fund Average 8.50% 9.01% 5.55% 6.00% |
| No Deduction of Taxes [Text Block] | The table and graph presented above do not reflect the deduction of taxes a shareholder would pay on fund distributions or the redemption of fund shares. |
| Performance Table Market Index Changed [Text Block] | |
| Updated Performance Information Location [Text Block] | Updated Location: Visit www.confluence.com/funds for more recent performance information. |
| AssetsNet | $ 1,452,187,602 |
| Holdings Count | Holding | 220 |
| Advisory Fees Paid, Amount | $ 7,382,681 |
| InvestmentCompanyPortfolioTurnover | 0% |
| Additional Fund Statistics [Text Block] | Fund Statistics Total Net Assets $1,452,187,602 Number of Portfolio Holdings 220 Portfolio Turnover Rate 0% Management Fees $7,382,681 |
| Holdings [Text Block] | Industry Allocation (% of net assets) Industry Weighting . Energy and Utilities 86.6% Communications 8.3% Other 4.8% U.S. Government Obligations 0.1% Other Assets and Liabilities (Net) 0.2% |
| Largest Holdings [Text Block] | Top 10 Holdings (% of net assets) Top 10 NextEra Energy Inc. 8.9% National Fuel Gas Co. 5.8% Southwest Gas Holdings Inc. 3.7% The AES Corp. 3.6% American Electric Power Co. Inc. 3.6% Evergy Inc. 3.3% WEC Energy Group Inc. 2.8% ONEOK Inc. 2.7% Eversource Energy 2.6% Otter Tail Corp. 2.5% |
| Material Fund Change [Text Block] | |
| Updated Prospectus Phone Number | 800-GABELLI (800-422-3554) |
| Updated Prospectus Email Address | info@gabelli.com</span>" id="sjs-B101"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">info@gabelli.com</span> |
| Updated Prospectus Web Address | www.gabelli.com</span>" id="sjs-B102"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| C000034315 | |
| Shareholder Report [Line Items] | |
| Fund Name | The Gabelli Utilities Fund |
| Class Name | Class I |
| Trading Symbol | GAUIX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about The Gabelli Utilities Fund (the Fund) for the period of January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at www.gabelli.com |
| Additional Information Phone Number | 800-GABELLI (800-422-3554) |
| Additional Information Website | www.gabelli.com</span>" id="sjs-B112"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| Expenses [Text Block] | What were the Fund costs for the last six months? (based on a hypothetical $10,000 investment) Class Name Costs of a $10k Investment Costs Paid as a % of a $10k Investment The Gabelli Utilities Fund - Class I $59 1.15% |
| Expenses Paid, Amount | $ 59 |
| Expense Ratio, Percent | 1.15% |
| Factors Affecting Performance [Text Block] | How did the Fund perform? During the six months ended June 30, 2024, the Gabelli Utilities Fund underperformed its broad-based benchmark, the S&P 500 and its comparative benchmarks, the S&P 500 Utilities Index and the Lipper Utility Fund Average. The potential for accelerated electric demand growth driven by technological innovation (artificial intelligence, data centers), electrification and manufacturing onshoring led to a momentum shift into power stocks. Shares of non-regulated power plant owners and developers surged on the AI-data center theme. Our Fund holds lower weights in the more volatile power names as well as a more diversified holdings list across the utility universe. |
| Performance Past Does Not Indicate Future [Text] | Past performance does not guarantee future results. |
| Line Graph [Table Text Block] | The Gabelli Utilities Fund - Class I S&P 500 Index S&P 500 Utilities Index Lipper Utility Fund Average 6/14 10,000 10,000 10,000 10,000 6/15 9,429 10,742 9,710 9,480 6/16 10,852 11,171 12,766 10,882 6/17 11,347 13,170 13,081 11,219 6/18 11,681 15,063 13,527 11,888 6/19 13,125 16,632 16,101 13,667 6/20 11,801 17,881 15,762 12,834 6/21 14,378 25,175 18,247 15,150 6/22 14,843 22,501 20,857 16,484 6/23 14,342 26,910 20,089 16,422 6/24 14,561 33,519 21,660 17,901 |
| Average Annual Return [Table Text Block] | Fund 6 months 1 Year 5 Year 10 Year The Gabelli Utilities Fund - Class I 4.81% 1.53% 2.10% 3.83% S&P 500 Index 15.29% 24.56% 15.05% 12.86% S&P 500 Utilities Index 9.44% 7.82% 6.11% 8.04% Lipper Utility Fund Average 8.50% 9.01% 5.55% 6.00% |
| No Deduction of Taxes [Text Block] | The table and graph presented above do not reflect the deduction of taxes a shareholder would pay on fund distributions or the redemption of fund shares. |
| Performance Table Market Index Changed [Text Block] | |
| Updated Performance Information Location [Text Block] | Updated Location: Visit www.confluence.com/funds for more recent performance information. |
| AssetsNet | $ 1,452,187,602 |
| Holdings Count | Holding | 220 |
| Advisory Fees Paid, Amount | $ 7,382,681 |
| InvestmentCompanyPortfolioTurnover | 0% |
| Additional Fund Statistics [Text Block] | Fund Statistics Total Net Assets $1,452,187,602 Number of Portfolio Holdings 220 Portfolio Turnover Rate 0% Management Fees $7,382,681 |
| Holdings [Text Block] | Industry Allocation (% of net assets) Industry Weighting . Energy and Utilities 86.6% Communications 8.3% Other 4.8% U.S. Government Obligations 0.1% Other Assets and Liabilities (Net) 0.2% |
| Largest Holdings [Text Block] | Top 10 Holdings (% of net assets) Top 10 NextEra Energy Inc. 8.9% National Fuel Gas Co. 5.8% Southwest Gas Holdings Inc. 3.7% The AES Corp. 3.6% American Electric Power Co. Inc. 3.6% Evergy Inc. 3.3% WEC Energy Group Inc. 2.8% ONEOK Inc. 2.7% Eversource Energy 2.6% Otter Tail Corp. 2.5% |
| Material Fund Change [Text Block] | |
| Updated Prospectus Phone Number | 800-GABELLI (800-422-3554) |
| Updated Prospectus Email Address | info@gabelli.com</span>" id="sjs-B132"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">info@gabelli.com</span> |
| Updated Prospectus Web Address | www.gabelli.com</span>" id="sjs-B133"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| C000002898 | |
| Shareholder Report [Line Items] | |
| Fund Name | The Gabelli Utilities Fund |
| Class Name | Class A |
| Trading Symbol | GAUAX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about The Gabelli Utilities Fund (the Fund) for the period of January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at www.gabelli.com |
| Additional Information Phone Number | 800-GABELLI (800-422-3554) |
| Additional Information Website | www.gabelli.com</span>" id="sjs-B143"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| Expenses [Text Block] | What were the Fund costs for the last six months? (based on a hypothetical $10,000 investment) Class Name Costs of a $10k Investment Costs Paid as a % of a $10k Investment The Gabelli Utilities Fund - Class A $71 1.40% |
| Expenses Paid, Amount | $ 71 |
| Expense Ratio, Percent | 1.40% |
| Factors Affecting Performance [Text Block] | How did the Fund perform? During the six months ended June 30, 2024, the Gabelli Utilities Fund underperformed its broad-based benchmark, the S&P 500 and its comparative benchmarks, the S&P 500 Utilities Index and the Lipper Utility Fund Average. The potential for accelerated electric demand growth driven by technological innovation (artificial intelligence, data centers), electrification and manufacturing onshoring led to a momentum shift into power stocks. Shares of non-regulated power plant owners and developers surged on the AI-data center theme. Our Fund holds lower weights in the more volatile power names as well as a more diversified holdings list across the utility universe. |
| Performance Past Does Not Indicate Future [Text] | Past performance does not guarantee future results. |
| Line Graph [Table Text Block] | The Gabelli Utilities Fund - Class A S&P 500 Index S&P 500 Utilities Index Lipper Utility Fund Average 6/14 10,000 10,000 10,000 10,000 6/15 9,330 10,742 9,710 9,480 6/16 9,600 11,171 12,766 10,882 6/17 9,442 13,170 13,081 11,219 6/18 9,129 15,063 13,527 11,888 6/19 9,653 16,632 16,101 13,667 6/20 8,155 17,881 15,762 12,834 6/21 9,333 25,175 18,247 15,150 6/22 9,061 22,501 20,857 16,484 6/23 8,226 26,910 20,089 16,422 6/24 7,855 33,519 21,660 17,901 |
| Average Annual Return [Table Text Block] | Fund 6 months 1 Year 5 Year 10 Year The Gabelli Utilities Fund - Class A (1.38)% (4.51)% 0.62% 2.96% S&P 500 Index 15.29% 24.56% 15.05% 12.86% S&P 500 Utilities Index 9.44% 7.82% 6.11% 8.04% Lipper Utility Fund Average 8.50% 9.01% 5.55% 6.00% |
| No Deduction of Taxes [Text Block] | The table and graph presented above do not reflect the deduction of taxes a shareholder would pay on fund distributions or the redemption of fund shares. |
| Performance Table Market Index Changed [Text Block] | |
| Updated Performance Information Location [Text Block] | Updated Location: Visit www.confluence.com/funds for more recent performance information. |
| AssetsNet | $ 1,452,187,602 |
| Holdings Count | Holding | 220 |
| Advisory Fees Paid, Amount | $ 7,382,681 |
| InvestmentCompanyPortfolioTurnover | 0% |
| Additional Fund Statistics [Text Block] | Fund Statistics Total Net Assets $1,452,187,602 Number of Portfolio Holdings 220 Portfolio Turnover Rate 0% Management Fees $7,382,681 |
| Holdings [Text Block] | Industry Allocation (% of net assets) Industry Weighting . Energy and Utilities 86.6% Communications 8.3% Other 4.8% U.S. Government Obligations 0.1% Other Assets and Liabilities (Net) 0.2% |
| Largest Holdings [Text Block] | Top 10 Holdings (% of net assets) Top 10 NextEra Energy Inc. 8.9% National Fuel Gas Co. 5.8% Southwest Gas Holdings Inc. 3.7% The AES Corp. 3.6% American Electric Power Co. Inc. 3.6% Evergy Inc. 3.3% WEC Energy Group Inc. 2.8% ONEOK Inc. 2.7% Eversource Energy 2.6% Otter Tail Corp. 2.5% |
| Material Fund Change [Text Block] | |
| Updated Prospectus Phone Number | 800-GABELLI (800-422-3554) |
| Updated Prospectus Email Address | info@gabelli.com</span>" id="sjs-B163"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">info@gabelli.com</span> |
| Updated Prospectus Web Address | www.gabelli.com</span>" id="sjs-B164"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: justify;">www.gabelli.com</span> |
| Shareholder Report, Line Graph (Details) - USD ($) | 2 Months Ended | 6 Months Ended | ||||||||||
| Jun. 30, 2014 | Jun. 30, 2014 | Jun. 30, 2024 | Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2016 | Jun. 30, 2015 | |
| C000002899 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | The Gabelli Utilities Fund - Class AAA | |||||||||||
| C000239633 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | The Gabelli Utilities Fund - Class C | |||||||||||
| C000034315 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | The Gabelli Utilities Fund - Class I | |||||||||||
| C000002898 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | The Gabelli Utilities Fund - Class A | |||||||||||
| S&P 500 Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Account Value | $ 10,000 | $ 10,000 | $ 33,519 | $ 26,910 | $ 22,501 | $ 25,175 | $ 17,881 | $ 16,632 | $ 15,063 | $ 13,170 | $ 11,171 | $ 10,742 |
| S&P 500 Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Account Value | 10,000 | 10,000 | 33,519 | 26,910 | 22,501 | 25,175 | 17,881 | 16,632 | 15,063 | 13,170 | 11,171 | 10,742 |
| S&P 500 Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Account Value | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| S&P 500 Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Account Value | 10,000 | 10,000 | 33,519 | 26,910 | 22,501 | 25,175 | 17,881 | 16,632 | 15,063 | 13,170 | 11,171 | 10,742 |
| S&P 500 Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Account Value | $ 10,000 | $ 10,000 | $ 33,519 | $ 26,910 | $ 22,501 | $ 25,175 | $ 17,881 | $ 16,632 | $ 15,063 | $ 13,170 | $ 11,171 | $ 10,742 |
| Shareholder Report, Average Annual Return (Details) | 2 Months Ended | 6 Months Ended | 12 Months Ended | 60 Months Ended | 120 Months Ended | |
| Jun. 30, 2014 | Jun. 30, 2024 | Jun. 30, 2014 | Jun. 30, 2024 | Jun. 30, 2024 | Jun. 30, 2024 | |
| C000002899 | ||||||
| Average Annual Return [Line Items] | ||||||
| Line Graph and Table Measure Name | The Gabelli Utilities Fund - Class AAA | |||||
| C000239633 | ||||||
| Average Annual Return [Line Items] | ||||||
| Line Graph and Table Measure Name | The Gabelli Utilities Fund - Class C | |||||
| Average Annual Return, Percent | 3.15% | (0.47%) | 1.05% | 2.78% | ||
| C000034315 | ||||||
| Average Annual Return [Line Items] | ||||||
| Line Graph and Table Measure Name | The Gabelli Utilities Fund - Class I | |||||
| C000002898 | ||||||
| Average Annual Return [Line Items] | ||||||
| Line Graph and Table Measure Name | The Gabelli Utilities Fund - Class A | |||||
| Average Annual Return, Percent | (1.38%) | (4.51%) | 0.62% | 2.96% | ||
| Without Sales Load [Member] | C000002899 | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 4.59% | 1.30% | 1.84% | 3.57% | ||
| Without Sales Load [Member] | C000034315 | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 4.81% | 1.53% | 2.10% | 3.83% | ||
| S&P 500 Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 15.29% | 24.56% | 15.05% | 12.86% | ||
| S&P 500 Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 15.29% | 24.56% | 15.05% | 12.86% | ||
| S&P 500 Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 15.29% | 24.56% | 15.05% | 12.86% | ||
| S&P 500 Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 15.29% | 24.56% | 15.05% | 12.86% | ||
| S&P 500 Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 15.29% | 24.56% | 15.05% | 12.86% | ||
| S&P 500 Utilities Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 9.44% | 7.82% | 6.11% | 8.04% | ||
| Lipper Utility Fund Average | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 8.50% | 9.01% | 5.55% | 6% | ||
| S&P 500 Utilities Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 9.44% | 7.82% | 6.11% | 8.04% | ||
| Lipper Utility Fund Average | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 8.50% | 9.01% | 5.55% | 6% | ||
| S&P 500 Utilities Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 9.44% | 7.82% | 6.11% | 8.04% | ||
| Lipper Utility Fund Average | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 8.50% | 9.01% | 5.55% | 6% | ||
| S&P 500 Utilities Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 9.44% | 7.82% | 6.11% | 8.04% | ||
| Lipper Utility Fund Average | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 8.50% | 9.01% | 5.55% | 6% | ||
| S&P 500 Utilities Index | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 9.44% | 7.82% | 6.11% | 8.04% | ||
| Lipper Utility Fund Average | ||||||
| Average Annual Return [Line Items] | ||||||
| Average Annual Return, Percent | 8.50% | 9.01% | 5.55% | 6% | ||
| Shareholder Report, Holdings (Details) | Jun. 30, 2024 |
| C000002899 | NextEra Energy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.90% |
| C000002899 | National Fuel Gas Co. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| C000002899 | Southwest Gas Holdings Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| C000002899 | The AES Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000002899 | American Electric Power Co. Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000002899 | Evergy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.30% |
| C000002899 | WEC Energy Group Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| C000002899 | ONEOK Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000002899 | Eversource Energy | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.60% |
| C000002899 | Otter Tail Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| C000002899 | InvestmentType_Common Stocks | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 99.70% |
| C000002899 | InvestmentType_U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000002899 | InvestmentType_Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000002899 | Energy and Utilities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 86.60% |
| C000002899 | Communications | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| C000002899 | Other | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.80% |
| C000002899 | U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000002899 | Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000239633 | NextEra Energy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.90% |
| C000239633 | National Fuel Gas Co. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| C000239633 | Southwest Gas Holdings Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| C000239633 | The AES Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000239633 | American Electric Power Co. Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000239633 | Evergy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.30% |
| C000239633 | WEC Energy Group Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| C000239633 | ONEOK Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000239633 | Eversource Energy | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.60% |
| C000239633 | Otter Tail Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| C000239633 | InvestmentType_Common Stocks | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 99.70% |
| C000239633 | InvestmentType_U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000239633 | InvestmentType_Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000239633 | Energy and Utilities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 86.60% |
| C000239633 | Communications | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| C000239633 | Other | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.80% |
| C000239633 | U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000239633 | Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000002901 | NextEra Energy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.90% |
| C000002901 | National Fuel Gas Co. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| C000002901 | Southwest Gas Holdings Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| C000002901 | The AES Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000002901 | American Electric Power Co. Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000002901 | Evergy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.30% |
| C000002901 | WEC Energy Group Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| C000002901 | ONEOK Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000002901 | Eversource Energy | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.60% |
| C000002901 | Otter Tail Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| C000002901 | InvestmentType_Common Stocks | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 99.70% |
| C000002901 | InvestmentType_U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000002901 | InvestmentType_Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000002901 | Energy and Utilities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 86.60% |
| C000002901 | Communications | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| C000002901 | Other | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.80% |
| C000002901 | U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000002901 | Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000034315 | NextEra Energy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.90% |
| C000034315 | National Fuel Gas Co. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| C000034315 | Southwest Gas Holdings Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| C000034315 | The AES Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000034315 | American Electric Power Co. Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000034315 | Evergy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.30% |
| C000034315 | WEC Energy Group Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| C000034315 | ONEOK Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000034315 | Eversource Energy | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.60% |
| C000034315 | Otter Tail Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| C000034315 | InvestmentType_Common Stocks | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 99.70% |
| C000034315 | InvestmentType_U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000034315 | InvestmentType_Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000034315 | Energy and Utilities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 86.60% |
| C000034315 | Communications | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| C000034315 | Other | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.80% |
| C000034315 | U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000034315 | Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000002898 | NextEra Energy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.90% |
| C000002898 | National Fuel Gas Co. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| C000002898 | Southwest Gas Holdings Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| C000002898 | The AES Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000002898 | American Electric Power Co. Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000002898 | Evergy Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.30% |
| C000002898 | WEC Energy Group Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| C000002898 | ONEOK Inc. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000002898 | Eversource Energy | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.60% |
| C000002898 | Otter Tail Corp. | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| C000002898 | InvestmentType_Common Stocks | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 99.70% |
| C000002898 | InvestmentType_U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000002898 | InvestmentType_Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000002898 | Energy and Utilities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 86.60% |
| C000002898 | Communications | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| C000002898 | Other | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.80% |
| C000002898 | U.S. Government Obligations | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000002898 | Other Assets and Liabilities (Net) | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
