0001161728 mgee:MgeMember 2021-10-15 2021-10-15 0001161728 2021-10-15 2021-10-15 false 0001161728 false 0000061339 8-K 2021-10-15 000-49965 MGE Energy, Inc. WI 133 South Blair Street Madison WI 53788 608 252-7000 39-2040501 000-1125 Madison Gas and Electric Company WI 133 South Blair Street Madison WI 53788 608 252-7000 39-0444025 false false false false false false Common Stock, $1 Par Value Per Share MGEE NASDAQ