Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 17,451	$ 23,481
Accounts receivable, less reserves	39,352	40,482
Other accounts receivables, less reserves	8,722	7,940
Unbilled revenues	22,633	25,899
Materials and supplies, at average cost	27,647	26,287
Fuel for electric generation, at average cost	8,354	8,358
Stored natural gas, at average cost	4,723	10,637
Prepaid taxes	11,888	16,892
Regulatory assets - current	12,182	11,432
Other current assets	9,241	10,233
Total Current Assets	162,193	181,641
Other long-term receivables	1,754	1,811
Regulatory assets	131,319	134,314
Pension benefit asset	16,480	13,630
Other deferred assets and other	18,518	19,093
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,524,782	1,530,199
Construction work in progress	128,321	112,484
Total Property, Plant, and Equipment	1,653,103	1,642,683
Investments	89,330	88,492
Total Assets	2,072,697	2,081,664
Current Liabilities:
Long-term debt due within one year	19,686	19,659
Short-term debt	3,000	0
Accounts payable	39,188	55,161
Accrued interest and taxes	7,568	7,244
Accrued payroll related items	9,243	12,752
Regulatory liabilities - current	11,369	9,228
Derivative liabilities	10,740	10,100
Other current liabilities	10,212	14,676
Total Current Liabilities	111,006	128,820
Other Credits:
Deferred income taxes	246,028	243,302
Investment tax credit - deferred	742	763
Regulatory liabilities	163,399	164,965
Accrued pension and other postretirement benefits	68,647	68,665
Derivative liabilities	12,870	15,340
Finance lease liabilities	17,581	17,379
Other deferred liabilities and other	60,318	63,013
Total Other Credits	569,585	573,427
Capitalization:
Common shareholders equity	869,492	855,676	$ 816,644
Long-term debt	522,614	523,741
Total Capitalization	1,392,106	1,379,417
Commitments and contingencies (see Footnote 8)
Total Liabilities and Capitalization	2,072,697	2,081,664
MGE [Member]
Current Assets:
Cash and cash equivalents	3,321	3,196
Accounts receivable, less reserves	39,352	40,482
Affiliate receivables	645	530
Other accounts receivables, less reserves	8,718	7,936
Unbilled revenues	22,633	25,899
Materials and supplies, at average cost	27,647	26,287
Fuel for electric generation, at average cost	8,354	8,358
Stored natural gas, at average cost	4,723	10,637
Prepaid taxes	11,786	15,463
Regulatory assets - current	12,182	11,432
Other current assets	8,767	10,065
Total Current Assets	148,128	160,285
Affiliate receivable long-term	2,515	2,648
Regulatory assets	131,319	134,314
Pension benefit asset	16,480	13,630
Other deferred assets and other	19,048	19,680
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,524,810	1,530,227
Construction work in progress	128,321	112,484
Total Property, Plant, and Equipment	1,653,131	1,642,711
Investments	227	209
Total Assets	1,970,848	1,973,477
Current Liabilities:
Long-term debt due within one year	19,686	19,659
Short-term debt	3,000	0
Accounts payable	38,897	54,845
Accrued interest and taxes	10,088	8,754
Accrued payroll related items	9,243	12,752
Regulatory liabilities - current	11,369	9,228
Derivative liabilities	10,740	10,100
Other current liabilities	10,212	12,683
Total Current Liabilities	113,235	128,021
Other Credits:
Deferred income taxes	216,310	214,041
Investment tax credit - deferred	742	763
Regulatory liabilities	163,399	164,965
Accrued pension and other postretirement benefits	68,647	68,665
Derivative liabilities	12,870	15,340
Finance lease liabilities	17,581	17,379
Other deferred liabilities and other	60,304	62,973
Total Other Credits	539,853	544,126
Capitalization:
Common shareholders equity	656,350	637,286
Noncontrolling interest	138,796	140,303
Total Equity	795,146	777,589	689,810
Long-term debt	522,614	523,741
Total Capitalization	1,317,760	1,301,330
Commitments and contingencies (see Footnote 8)
Total Liabilities and Capitalization	$ 1,970,848	$ 1,973,477