Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 117,702	$ 95,959
Accounts receivable, less reserves	39,750	39,887
Other accounts receivables, less reserves	5,896	8,530
Unbilled revenues	25,335	29,846
Materials and supplies, at average cost	19,668	18,561
Fossil fuel, at average cost	8,827	9,757
Stored natural gas, at average cost	4,710	12,819
Prepaid taxes	12,468	26,636
Regulatory assets - current	7,581	6,414
Assets held for sale	2,338	14,813
Other current assets	9,819	12,293
Total Current Assets	254,094	275,515
Regulatory assets	153,126	158,485
Pension and other postretirement benefit asset	2,568	2,020
Other deferred assets and other	6,489	6,691
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,249,648	1,245,269
Construction work in progress	37,588	36,790
Total Property, Plant, and Equipment	1,287,236	1,282,059
Investments	81,806	76,290
Total Assets	1,785,319	1,801,060
Current Liabilities:
Long-term debt due within one year	4,381	4,333
Accounts payable	36,865	47,799
Accrued interest and taxes	8,254	5,495
Accrued payroll related items	7,848	11,892
Regulatory liabilities - current	11,658	6,910
Derivative liabilities	8,259	7,620
Other current liabilities	6,249	19,456
Total Current Liabilities	83,514	103,505
Other Credits:
Deferred income taxes	380,276	383,813
Investment tax credit - deferred	927	947
Regulatory liabilities	23,266	22,173
Accrued pension and other postretirement benefits	67,481	74,347
Derivative liabilities	40,430	42,970
Other deferred liabilities and other	65,131	66,426
Total Other Credits	577,511	590,676
Capitalization:
Common shareholders equity	732,825	724,088
Long-term debt	391,469	382,791
Total Capitalization	1,124,294	1,106,879
Commitments and contingencies (see Footnote 7)
Total Liabilities and Capitalization	1,785,319	1,801,060
MGE [Member]
Current Assets:
Cash and cash equivalents	23,098	10,768
Accounts receivable, less reserves	39,750	39,887
Affiliate receivables	1,149	539
Other accounts receivables, less reserves	5,796	6,363
Unbilled revenues	25,335	29,846
Materials and supplies, at average cost	19,668	18,561
Fossil fuel, at average cost	8,827	9,757
Stored natural gas, at average cost	4,710	12,819
Prepaid taxes	12,449	25,798
Regulatory assets - current	7,581	6,414
Assets held for sale	2,338	14,813
Other current assets	9,805	12,268
Total Current Assets	160,506	187,833
Affiliate receivable long-term	4,104	4,236
Regulatory assets	153,126	158,485
Pension and other postretirement benefit asset	2,568	2,020
Other deferred assets and other	4,200	4,353
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,249,676	1,244,648
Construction work in progress	37,588	36,790
Total Property, Plant, and Equipment	1,287,264	1,281,438
Investments	476	487
Total Assets	1,612,244	1,638,852
Current Liabilities:
Long-term debt due within one year	4,381	4,333
Accounts payable	36,865	47,790
Accrued interest and taxes	8,598	5,440
Accrued payroll related items	7,848	11,892
Regulatory liabilities - current	11,658	6,910
Derivative liabilities	8,259	7,620
Other current liabilities	6,028	19,347
Total Current Liabilities	83,637	103,332
Other Credits:
Deferred income taxes	339,477	343,117
Investment tax credit - deferred	927	947
Regulatory liabilities	23,266	22,173
Accrued pension and other postretirement benefits	67,481	74,347
Derivative liabilities	40,430	42,970
Other deferred liabilities and other	65,131	66,426
Total Other Credits	536,712	549,980
Capitalization:
Common shareholders equity	484,872	487,084
Noncontrolling interest	115,554	115,665
Total Equity	600,426	602,749
Long-term debt	391,469	382,791
Total Capitalization	991,895	985,540
Commitments and contingencies (see Footnote 7)
Total Liabilities and Capitalization	$ 1,612,244	$ 1,638,852