Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 102,916	$ 95,959
Accounts receivable, less reserves	35,252	39,887
Other accounts receivables, less reserves	7,024	8,530
Unbilled revenues	23,238	29,846
Materials and supplies, at average cost	20,354	18,561
Fossil fuel, at average cost	11,186	9,757
Stored natural gas, at average cost	9,607	12,819
Prepaid taxes	15,679	26,636
Regulatory assets - current	7,602	6,414
Assets held for sale	5,117	14,813
Other current assets	11,320	12,293
Total Current Assets	249,295	275,515
Regulatory assets	149,866	158,485
Pension and other postretirement benefit asset	2,984	2,020
Other deferred assets and other	6,228	6,691
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,262,674	1,245,269
Construction work in progress	36,511	36,790
Total Property, Plant, and Equipment	1,299,185	1,282,059
Investments	84,946	76,290
Total Assets	1,792,504	1,801,060
Current Liabilities:
Long-term debt due within one year	4,404	4,333
Accounts payable	34,047	47,799
Accrued interest and taxes	5,600	5,495
Accrued payroll related items	9,719	11,892
Regulatory liabilities - current	10,795	6,910
Derivative liabilities	9,000	7,620
Other current liabilities	10,075	19,456
Total Current Liabilities	83,640	103,505
Other Credits:
Deferred income taxes	385,210	383,813
Investment tax credit - deferred	906	947
Regulatory liabilities	23,579	22,173
Accrued pension and other postretirement benefits	66,800	74,347
Derivative liabilities	37,620	42,970
Other deferred liabilities and other	66,572	66,426
Total Other Credits	580,687	590,676
Capitalization:
Common shareholders equity	737,739	724,088
Long-term debt	390,438	382,791
Total Capitalization	1,128,177	1,106,879
Commitments and contingencies (see Footnote 7)
Total Liabilities and Capitalization	1,792,504	1,801,060
MGE [Member]
Current Assets:
Cash and cash equivalents	5,831	10,768
Accounts receivable, less reserves	35,252	39,887
Affiliate receivables	802	539
Other accounts receivables, less reserves	6,954	6,363
Unbilled revenues	23,238	29,846
Materials and supplies, at average cost	20,354	18,561
Fossil fuel, at average cost	11,186	9,757
Stored natural gas, at average cost	9,607	12,819
Prepaid taxes	15,905	25,798
Regulatory assets - current	7,602	6,414
Assets held for sale	5,117	14,813
Other current assets	11,312	12,268
Total Current Assets	153,160	187,833
Affiliate receivable long-term	3,971	4,236
Regulatory assets	149,866	158,485
Pension and other postretirement benefit asset	2,984	2,020
Other deferred assets and other	3,997	4,353
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,262,702	1,244,648
Construction work in progress	36,511	36,790
Total Property, Plant, and Equipment	1,299,213	1,281,438
Investments	434	487
Total Assets	1,613,625	1,638,852
Current Liabilities:
Long-term debt due within one year	4,404	4,333
Accounts payable	34,044	47,790
Accrued interest and taxes	6,298	5,440
Accrued payroll related items	9,719	11,892
Regulatory liabilities - current	10,795	6,910
Derivative liabilities	9,000	7,620
Other current liabilities	9,702	19,347
Total Current Liabilities	83,962	103,332
Other Credits:
Deferred income taxes	343,697	343,117
Investment tax credit - deferred	906	947
Regulatory liabilities	23,579	22,173
Accrued pension and other postretirement benefits	66,800	74,347
Derivative liabilities	37,620	42,970
Other deferred liabilities and other	66,572	66,426
Total Other Credits	539,174	549,980
Capitalization:
Common shareholders equity	483,601	487,084
Noncontrolling interest	116,450	115,665
Total Equity	600,051	602,749
Long-term debt	390,438	382,791
Total Capitalization	990,489	985,540
Commitments and contingencies (see Footnote 7)
Total Liabilities and Capitalization	$ 1,613,625	$ 1,638,852