Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Operating Activities:
Net Income	$ 120,569	$ 117,699	$ 110,952
Items not affecting cash:
Depreciation and amortization	108,581	100,352	85,549
Deferred income taxes	608	22,999	23,435
Provision for doubtful receivables	8,800	1,764	1,764
Employee benefit plan (credit) cost	606	(5,796)	(8,142)
Equity earnings in investments	(12,275)	(10,631)	(9,136)
Other items	1,483	(388)	(1,535)
Changes in working capital items:
Accounts receivable and unbilled revenues	(6,566)	11,174	(16,726)
Inventories	5,542	(850)	(22,226)
Prepaid taxes	3,921	(3,178)	1,082
Other current assets	9,972	5,028	(3,729)
Accounts payable	6,491	(5,208)	5,102
Deferred income taxes	18,501	0	0
Other current liabilities	(1,711)	(2,264)	(5,562)
Dividends from investments	8,834	8,508	7,090
Cash contributions to pension and other postretirement plans	(7,722)	(7,747)	(7,308)
Other noncurrent items, net	12,150	6,099	(6,875)
Cash Provided by Operating Activities	277,784	237,561	153,735
Investing Activities:
Capital expenditures	(236,925)	(222,071)	(175,030)
Capital contributions to investments	(4,792)	(6,995)	(5,185)
Other	230	(954)	70
Cash Used for Investing Activities	(241,487)	(230,020)	(180,145)
Financing Activities:
Issuance of common stock, net	31,605	0	0
Cash dividends paid on common stock	(63,596)	(60,393)	(57,500)
Repayment of long-term debt	(5,146)	(54,314)	(4,889)
Issuance of long-term debt	50,000	139,300	25,000
(Repayments of) proceeds from short-term debt	(38,000)	(32,500)	65,000
Other	(1,690)	(2,576)	(2,068)
Cash (Used for) Provided by Financing Activities	(26,827)	(10,483)	25,543
Change in cash, cash equivalents, and restricted cash:	9,470	(2,942)	(867)
Cash, cash equivalents, and restricted cash at beginning of period	15,026	17,968	18,835
Cash, cash equivalents, and restricted cash at end of period	24,496	15,026	17,968
MGE [Member]
Operating Activities:
Net Income	112,299	112,370	105,492
Items not affecting cash:
Depreciation and amortization	108,581	100,352	85,549
Deferred income taxes	(433)	21,536	22,767
Provision for doubtful receivables	8,800	1,764	1,764
Employee benefit plan (credit) cost	606	(5,796)	(8,142)
Other items	2,247	(241)	672
Changes in working capital items:
Accounts receivable and unbilled revenues	(6,582)	11,130	(16,697)
Inventories	5,542	(850)	(22,226)
Prepaid taxes	3,979	(3,871)	912
Other current assets	9,983	5,032	(3,774)
Accounts payable	6,495	(5,209)	5,104
Deferred income taxes	18,501	0	0
Accrued interest and taxes	2,540	1,413	(2,737)
Other current liabilities	(2,397)	(3,272)	(2,541)
Cash contributions to pension and other postretirement plans	(7,722)	(7,747)	(7,308)
Other noncurrent items, net	10,514	5,211	(7,768)
Cash Provided by Operating Activities	272,953	231,822	151,067
Investing Activities:
Capital expenditures	(236,925)	(222,071)	(175,030)
Other	(2,088)	(1,956)	(1,065)
Cash Used for Investing Activities	(239,013)	(224,027)	(176,095)
Financing Activities:
Cash dividends paid to parent by MGE	(34,500)	(41,000)	(33,500)
Distributions to parent from noncontrolling interest	(22,000)	(20,500)	(22,000)
Capital contributions from parent	30,750	0	0
Repayment of long-term debt	(5,146)	(54,314)	(4,889)
Issuance of long-term debt	50,000	139,300	25,000
(Repayments of) proceeds from short-term debt	(38,000)	(32,500)	65,000
Other	(1,690)	(2,576)	(1,881)
Cash (Used for) Provided by Financing Activities	(20,586)	(11,590)	27,730
Change in cash, cash equivalents, and restricted cash:	13,354	(3,795)	2,702
Cash, cash equivalents, and restricted cash at beginning of period	6,705	10,500	7,798
Cash, cash equivalents, and restricted cash at end of period	$ 20,059	$ 6,705	$ 10,500