Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating Activities:
Net Income	$ 135,889	$ 120,569	$ 117,699
Adjustments to reconcile net income to cash provided by operating activities
Depreciation and amortization	114,324	108,581	100,352
Deferred income taxes	7,623	608	22,999
Provision for doubtful receivables	8,800	8,800	1,764
Employee benefit plan (credit) cost	(5,045)	606	(5,796)
Cash contributions to pension and other postretirement plans	(7,979)	(7,722)	(7,747)
Equity earnings in investments	(13,009)	(12,275)	(10,631)
Dividends from investments	10,987	8,834	8,508
Changes in assets and liabilities
Accounts receivable and unbilled revenues	(21,754)	(6,566)	11,174
Inventories	5,071	5,542	(850)
Prepaid taxes	(924)	3,921	(3,178)
Other current assets	(3,095)	665	950
Accounts payable	8,483	6,491	(5,208)
Deferred income taxes	10,996	18,501	0
Other current liabilities	2,242	6,337	4,168
Regulatory assets and liabilities, net	9,625	6,572	(968)
Other, net	1,000	8,320	4,325
Cash Provided by Operating Activities	263,234	277,784	237,561
Investing Activities:
Capital expenditures	(343,220)	(236,925)	(222,071)
Capital contributions to investments	(9,496)	(4,792)	(6,995)
Other	2,155	230	(954)
Cash Used for Investing Activities	(350,561)	(241,487)	(230,020)
Financing Activities:
Issuance of common stock, net	3,750	31,605	0
Cash dividends paid on common stock	(67,587)	(63,596)	(60,393)
Repayment of long-term debt	(5,285)	(5,146)	(54,314)
Issuance of long-term debt	50,000	50,000	139,300
Proceeds from (repayments of) short-term debt	92,525	(38,000)	(32,500)
Other	(1,836)	(1,690)	(2,576)
Cash (Used for) Provided by Financing Activities	71,567	(26,827)	(10,483)
Change in cash, cash equivalents, and restricted cash:	(15,760)	9,470	(2,942)
Cash, cash equivalents, and restricted cash at beginning of period	24,496	15,026	17,968
Cash, cash equivalents, and restricted cash at end of period	8,736	24,496	15,026
MGE [Member]
Operating Activities:
Net Income	126,797	112,299	112,370
Adjustments to reconcile net income to cash provided by operating activities
Depreciation and amortization	114,324	108,581	100,352
Deferred income taxes	6,458	(433)	21,536
Provision for doubtful receivables	8,800	8,800	1,764
Employee benefit plan (credit) cost	(5,045)	606	(5,796)
Cash contributions to pension and other postretirement plans	(7,979)	(7,722)	(7,747)
Changes in assets and liabilities
Accounts receivable and unbilled revenues	(21,227)	(6,582)	11,130
Inventories	5,071	5,542	(850)
Prepaid taxes	(389)	3,979	(3,871)
Other current assets	(3,138)	676	954
Accounts payable	8,481	6,495	(5,209)
Deferred income taxes	10,996	18,501	0
Other current liabilities	(1,128)	8,191	4,573
Regulatory assets and liabilities, net	9,625	6,572	(968)
Other, net	3,005	7,448	3,584
Cash Provided by Operating Activities	254,651	272,953	231,822
Investing Activities:
Capital expenditures	(343,220)	(236,925)	(222,071)
Other	(2,326)	(2,088)	(1,956)
Cash Used for Investing Activities	(345,546)	(239,013)	(224,027)
Financing Activities:
Cash dividends paid to parent by MGE	(51,500)	(34,500)	(41,000)
Distributions to parent from noncontrolling interest	(16,250)	(22,000)	(20,500)
Capital contributions from parent	8,500	30,750	0
Repayment of long-term debt	(5,285)	(5,146)	(54,314)
Issuance of long-term debt	50,000	50,000	139,300
Proceeds from (repayments of) short-term debt	92,525	(38,000)	(32,500)
Other	(1,836)	(1,690)	(2,576)
Cash (Used for) Provided by Financing Activities	76,154	(20,586)	(11,590)
Change in cash, cash equivalents, and restricted cash:	(14,741)	13,354	(3,795)
Cash, cash equivalents, and restricted cash at beginning of period	20,059	6,705	10,500
Cash, cash equivalents, and restricted cash at end of period	$ 5,318	$ 20,059	$ 6,705