Average Annual Total Returns	12 Months Ended	60 Months Ended	120 Months Ended
Average Annual Total Returns	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2024
THE GABELLI UTILITIES FUND CLASS AAA
Prospectus [Line Items]
Average Annual Return, Percent	13.00%	2.54%	4.41%
THE GABELLI UTILITIES FUND CLASS AAA \| After Taxes on Distributions
Prospectus [Line Items]
Average Annual Return, Percent	10.82%	1.52%	3.44%
THE GABELLI UTILITIES FUND CLASS AAA \| After Taxes on Distributions and Sales
Prospectus [Line Items]
Average Annual Return, Percent	9.24%	1.91%	3.36%
THE GABELLI UTILITIES FUND CLASS A
Prospectus [Line Items]
Average Annual Return, Percent	6.66%	1.35%	3.79%
THE GABELLI UTILITIES FUND CLASS C
Prospectus [Line Items]
Average Annual Return, Percent	11.21%	1.78%	3.62%
THE GABELLI UTILITIES FUND CLASS I
Prospectus [Line Items]
Average Annual Return, Percent	13.25%	2.79%	4.66%
S P 500 Utilities Index [Member]
Prospectus [Line Items]
Average Annual Return, Percent	23.43%	6.61%	8.43%
Lipper Utility Fund Average [Member]
Prospectus [Line Items]
Average Annual Return, Percent	23.24%	6.73%	7.24%