C000002899C000239633C000034315C000002898S&P 500 IndexS&P 500 Index_40605S&P 500 IndexS&P 500 Index_50133S&P 500 IndexS&P 500 Index_40608S&P 500 IndexS&P 500 Index_40606S&P 500 Utilities IndexS&P 500 Utilities Index_40605Lipper Utility Fund AverageLipper Utility Fund Average_40605S&P 500 Utilities IndexS&P 500 Utilities Index_50133Lipper Utility Fund AverageLipper Utility Fund Average_50133S&P 500 Utilities IndexS&P 500 Utilities Index_40608Lipper Utility Fund AverageLipper Utility Fund Average_40608S&P 500 Utilities IndexS&P 500 Utilities Index_40606Lipper Utility Fund AverageLipper Utility Fund Average_40606NextEra Energy Inc.National Fuel Gas Co.American Electric Power Co. Inc.Evergy Inc.WEC Energy Group Inc.Southwest Gas Holdings Inc.Ameren Corp.The AES Corp.ONEOK Inc.Eversource EnergyInvestmentType_Common StocksInvestmentType_U.S. Government ObligationsUtilitiesOtherCommunication ServicesU.S. Government ObligationsClosed-End FundsNo Trading Symbol [Flag]AssetsNetInvestmentCompanyPortfolioTurnover