Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Activities:
Net Income	$ 110,952	$ 105,761	$ 92,418
Items not affecting cash:
Depreciation and amortization	85,549	76,983	74,188
Deferred income taxes	23,435	4,837	10,363
Provision for doubtful receivables	1,764	1,550	1,415
Employee benefit plan (credit) cost	(8,142)	(2,203)	(3,716)
Equity earnings in investments	(9,136)	(9,270)	(10,221)
Other items	(1,535)	120	(2,750)
Changes in working capital items:
Accounts receivable and unbilled revenues	(16,726)	(24,651)	(5,451)
Inventories	(22,226)	(6,342)	(842)
Prepaid taxes	1,082	(5,035)	1,713
Other current assets	(3,729)	(192)	(1,057)
Accounts payable	5,102	2,729	14,353
Other current liabilities	(5,562)	(6,734)	(5,635)
Dividends from investments	7,090	7,832	8,998
Cash contributions to pension and other postretirement plans	(7,308)	(6,935)	(6,296)
Other noncurrent items, net	(6,875)	(923)	4,963
Cash Provided by Operating Activities	153,735	137,527	172,443
Investing Activities:
Capital expenditures	(175,030)	(153,169)	(203,139)
Capital contributions to investments	(5,185)	(4,027)	(5,601)
Other	70	221	(1,672)
Cash Used for Investing Activities	(180,145)	(156,975)	(210,412)
Financing Activities:
Issuance of common stock, net	0	0	79,635
Cash dividends paid on common stock	(57,500)	(54,788)	(51,729)
Repayment of long-term debt	(4,889)	(4,771)	(38,959)
Issuance of long-term debt	25,000	100,000	19,300
Proceeds from (repayments of) short-term debt	65,000	(47,000)	52,500
Other	(2,068)	(2,197)	(1,553)
Cash Provided by (Used for) Financing Activities	25,543	(8,756)	59,194
Change in cash, cash equivalents, and restricted cash:	(867)	(28,204)	21,225
Cash, cash equivalents, and restricted cash at beginning of period	18,835	47,039	25,814
Cash, cash equivalents, and restricted cash at end of period	17,968	18,835	47,039
Supplemential Disclosures of Cash Flow Information:
Interest paid	25,957	23,502	23,898
Income taxes paid	7,966	4,000	8,127
Income taxes received	(4,800)	0	0
Significant noncash investing activities:
Accrued capital expenditures	5,970	14,414	5,719
MGE [Member]
Operating Activities:
Net Income	105,492	100,782	85,523
Items not affecting cash:
Depreciation and amortization	85,549	76,983	74,188
Deferred income taxes	22,767	3,654	8,543
Provision for doubtful receivables	1,764	1,550	1,415
Employee benefit plan (credit) cost	(8,142)	(2,203)	(3,716)
Other items	672	2,002	(1,828)
Changes in working capital items:
Accounts receivable and unbilled revenues	(16,697)	(24,680)	(5,453)
Inventories	(22,226)	(6,342)	(842)
Prepaid taxes	912	(4,531)	616
Other current assets	(3,774)	(148)	(1,157)
Accounts payable	5,104	2,775	14,603
Accrued interest and taxes	(2,737)	244	1,651
Other current liabilities	(2,541)	(11,107)	(4,909)
Cash contributions to pension and other postretirement plans	(7,308)	(6,935)	(6,296)
Other noncurrent items, net	(7,768)	(1,804)	3,980
Cash Provided by Operating Activities	151,067	130,240	166,318
Investing Activities:
Capital expenditures	(175,030)	(153,169)	(203,139)
Other	(1,065)	(1,709)	(2,122)
Cash Used for Investing Activities	(176,095)	(154,878)	(205,261)
Financing Activities:
Cash dividends paid to parent by MGE	(33,500)	(5,000)	0
Distributions to parent from noncontrolling interest	(22,000)	(15,000)	(21,500)
Capital contributions from parent	0	0	30,000
Repayment of long-term debt	(4,889)	(4,771)	(38,959)
Issuance of long-term debt	25,000	100,000	19,300
Proceeds from (repayments of) short-term debt	65,000	(47,000)	52,500
Other	(1,881)	(2,197)	(1,523)
Cash Provided by (Used for) Financing Activities	27,730	26,032	39,818
Change in cash, cash equivalents, and restricted cash:	2,702	1,394	875
Cash, cash equivalents, and restricted cash at beginning of period	7,798	6,404	5,529
Cash, cash equivalents, and restricted cash at end of period	10,500	7,798	6,404
Supplemential Disclosures of Cash Flow Information:
Interest paid	25,957	23,502	23,898
Significant noncash investing activities:
Accrued capital expenditures	$ 5,970	$ 14,414	$ 5,719