Fair Value of Financial Instruments (Details-2) - USD ($)		Mar. 31, 2021	Dec. 31, 2020
Liabilities:
Collateral posted against derivative positions		$ 0	$ 0
Recurring [Member]
Assets:
Derivatives	[1]	721,000	806,000
Total Assets		2,195,000	2,556,000
Liabilities:
Derivatives	[1]	11,780,000	14,795,000
Deferred compensation		3,581,000	3,509,000
Total liabilities		15,361,000	18,304,000
Recurring [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities		1,474,000	1,750,000
Recurring [Member] | Level 1 [Member]
Assets:
Derivatives	[1]	423,000	436,000
Total Assets		1,897,000	2,186,000
Liabilities:
Derivatives	[1]	115,000	370,000
Deferred compensation		0	0
Total liabilities		115,000	370,000
Recurring [Member] | Level 1 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities		1,474,000	1,750,000
Recurring [Member] | Level 2 [Member]
Assets:
Derivatives	[1]	0	0
Total Assets		0	0
Liabilities:
Derivatives	[1]	0	0
Deferred compensation		3,581,000	3,509,000
Total liabilities		3,581,000	3,509,000
Recurring [Member] | Level 2 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities		0	0
Recurring [Member] | Level 3 [Member]
Assets:
Derivatives	[1]	298,000	370,000
Total Assets		298,000	370,000
Liabilities:
Derivatives	[1]	11,665,000	14,425,000
Deferred compensation		0	0
Total liabilities		11,665,000	14,425,000
Recurring [Member] | Level 3 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities		0	0
MGE [Member] | Recurring [Member]
Assets:
Derivatives	[1]	721,000	806,000
Total Assets		1,152,000	1,409,000
Liabilities:
Derivatives	[1]	11,780,000	14,795,000
Deferred compensation		3,581,000	3,509,000
Total liabilities		15,361,000	18,304,000
MGE [Member] | Recurring [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities		431,000	603,000
MGE [Member] | Recurring [Member] | Level 1 [Member]
Assets:
Derivatives	[1]	423,000	436,000
Total Assets		854,000	1,039,000
Liabilities:
Derivatives	[1]	115,000	370,000
Deferred compensation		0	0
Total liabilities		115,000	370,000
MGE [Member] | Recurring [Member] | Level 1 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities		431,000	603,000
MGE [Member] | Recurring [Member] | Level 2 [Member]
Assets:
Derivatives	[1]	0	0
Total Assets		0	0
Liabilities:
Derivatives	[1]	0	0
Deferred compensation		3,581,000	3,509,000
Total liabilities		3,581,000	3,509,000
MGE [Member] | Recurring [Member] | Level 2 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities		0	0
MGE [Member] | Recurring [Member] | Level 3 [Member]
Assets:
Derivatives	[1]	298,000	370,000
Total Assets		298,000	370,000
Liabilities:
Derivatives	[1]	11,665,000	14,425,000
Deferred compensation		0	0
Total liabilities		11,665,000	14,425,000
MGE [Member] | Recurring [Member] | Level 3 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities		$ 0	$ 0

[1] These amounts are shown gross. No collateral was posted against derivative positions with counterparties as of March 31, 2021, or December 31, 2020.