Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 51,642	$ 23,481
Accounts receivable, less reserves	33,879	40,482
Other accounts receivables, less reserves	7,658	7,940
Unbilled revenues	23,118	25,899
Materials and supplies, at average cost	31,076	26,287
Fuel for electric generation, at average cost	8,008	8,358
Stored natural gas, at average cost	6,998	10,637
Prepaid taxes	14,887	16,892
Regulatory assets - current	10,475	11,432
Other current assets	30,009	10,233
Total Current Assets	217,750	181,641
Other long-term receivables	1,673	1,811
Regulatory assets	129,775	134,314
Pension benefit asset	19,109	13,630
Other deferred assets and other	17,555	19,093
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,524,617	1,530,199
Construction work in progress	161,542	112,484
Total Property, Plant, and Equipment	1,686,159	1,642,683
Investments	91,698	88,492
Total Assets	2,163,719	2,081,664
Current Liabilities:
Long-term debt due within one year	19,714	19,659
Accounts payable	40,701	55,161
Accrued interest and taxes	8,696	7,244
Accrued payroll related items	11,688	12,752
Regulatory liabilities - current	8,121	9,228
Derivative liabilities	10,430	10,100
Other current liabilities	10,273	14,676
Total Current Liabilities	109,623	128,820
Other Credits:
Deferred income taxes	251,050	243,302
Investment tax credit - deferred	721	763
Regulatory liabilities	166,469	164,965
Accrued pension and other postretirement benefits	68,550	68,665
Derivative liabilities	9,950	15,340
Finance lease liabilities	17,725	17,379
Other deferred liabilities and other	63,004	63,013
Total Other Credits	577,469	573,427
Capitalization:
Common shareholders equity	955,171	855,676	$ 816,644
Long-term debt	521,456	523,741
Total Capitalization	1,476,627	1,379,417
Commitments and contingencies (see Footnote 8)
Total Liabilities and Capitalization	2,163,719	2,081,664
MGE [Member]
Current Assets:
Cash and cash equivalents	18,002	3,196
Accounts receivable, less reserves	33,879	40,482
Affiliate receivables	787	530
Other accounts receivables, less reserves	7,644	7,936
Unbilled revenues	23,118	25,899
Materials and supplies, at average cost	31,076	26,287
Fuel for electric generation, at average cost	8,008	8,358
Stored natural gas, at average cost	6,998	10,637
Prepaid taxes	15,591	15,463
Regulatory assets - current	10,475	11,432
Other current assets	9,934	10,065
Total Current Assets	165,512	160,285
Affiliate receivable long-term	2,383	2,648
Regulatory assets	129,775	134,314
Pension benefit asset	19,109	13,630
Other deferred assets and other	18,040	19,680
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,524,645	1,530,227
Construction work in progress	161,542	112,484
Total Property, Plant, and Equipment	1,686,187	1,642,711
Investments	213	209
Total Assets	2,021,219	1,973,477
Current Liabilities:
Long-term debt due within one year	19,714	19,659
Accounts payable	40,563	54,845
Accrued interest and taxes	11,791	8,754
Accrued payroll related items	11,688	12,752
Regulatory liabilities - current	8,121	9,228
Derivative liabilities	10,430	10,100
Other current liabilities	10,273	12,683
Total Current Liabilities	112,580	128,021
Other Credits:
Deferred income taxes	220,734	214,041
Investment tax credit - deferred	721	763
Regulatory liabilities	166,469	164,965
Accrued pension and other postretirement benefits	68,550	68,665
Derivative liabilities	9,950	15,340
Finance lease liabilities	17,725	17,379
Other deferred liabilities and other	62,987	62,973
Total Other Credits	547,136	544,126
Capitalization:
Common shareholders equity	696,983	637,286
Noncontrolling interest	143,064	140,303
Total Equity	840,047	777,589	689,810
Long-term debt	521,456	523,741
Total Capitalization	1,361,503	1,301,330
Commitments and contingencies (see Footnote 8)
Total Liabilities and Capitalization	$ 2,021,219	$ 1,973,477