Fair Value of Financial Instruments (Details-2) - USD ($)	Dec. 31, 2020		Dec. 31, 2019
Assets:
Available-for-sale securities	$ 17,906,000		$ 14,546,000
Liabilities:
Collateral posted against derivative positions	0		1,500,000
Recurring [Member]
Assets:
Derivative assets, net	806,000		303,000
Total Assets	2,556,000		1,574,000
Liabilities:
Derivative liabilities, net	14,795,000	[1]	27,178,000	[2]
Deferred compensation	3,509,000		3,157,000
Total Liabilities	18,304,000		30,335,000
Recurring [Member] | Exchange-traded investments
Assets:
Available-for-sale securities	1,750,000		1,271,000
Recurring [Member] | Level 1 [Member]
Assets:
Derivative assets, net	436,000		189,000
Total Assets	2,186,000		1,460,000
Liabilities:
Derivative liabilities, net	370,000	[1]	608,000	[2]
Deferred compensation	0		0
Total Liabilities	370,000		608,000
Recurring [Member] | Level 1 [Member] | Exchange-traded investments
Assets:
Available-for-sale securities	1,750,000		1,271,000
Recurring [Member] | Level 2 [Member]
Assets:
Derivative assets, net	0		0
Total Assets	0		0
Liabilities:
Derivative liabilities, net	0	[1]	0	[2]
Deferred compensation	3,509,000		3,157,000
Total Liabilities	3,509,000		3,157,000
Recurring [Member] | Level 2 [Member] | Exchange-traded investments
Assets:
Available-for-sale securities	0		0
Recurring [Member] | Level 3 [Member]
Assets:
Derivative assets, net	370,000		114,000
Total Assets	370,000		114,000
Liabilities:
Derivative liabilities, net	14,425,000	[1]	26,570,000	[2]
Deferred compensation	0		0
Total Liabilities	14,425,000		26,570,000
Recurring [Member] | Level 3 [Member] | Exchange-traded investments
Assets:
Available-for-sale securities	0		0
MGE [Member]
Assets:
Available-for-sale securities	603,000		209,000
MGE [Member] | Recurring [Member]
Assets:
Derivative assets, net	806,000		303,000
Total Assets	1,409,000		512,000
Liabilities:
Derivative liabilities, net	14,795,000	[1]	27,178,000	[2]
Deferred compensation	3,509,000		3,157,000
Total Liabilities	18,304,000		30,335,000
MGE [Member] | Recurring [Member] | Exchange-traded investments
Assets:
Available-for-sale securities	603,000		209,000
MGE [Member] | Recurring [Member] | Level 1 [Member]
Assets:
Derivative assets, net	436,000		189,000
Total Assets	1,039,000		398,000
Liabilities:
Derivative liabilities, net	370,000	[1]	608,000	[2]
Deferred compensation	0		0
Total Liabilities	370,000		608,000
MGE [Member] | Recurring [Member] | Level 1 [Member] | Exchange-traded investments
Assets:
Available-for-sale securities	603,000		209,000
MGE [Member] | Recurring [Member] | Level 2 [Member]
Assets:
Derivative assets, net	0		0
Total Assets	0		0
Liabilities:
Derivative liabilities, net	0	[1]	0	[2]
Deferred compensation	3,509,000		3,157,000
Total Liabilities	3,509,000		3,157,000
MGE [Member] | Recurring [Member] | Level 2 [Member] | Exchange-traded investments
Assets:
Available-for-sale securities	0		0
MGE [Member] | Recurring [Member] | Level 3 [Member]
Assets:
Derivative assets, net	370,000		114,000
Total Assets	370,000		114,000
Liabilities:
Derivative liabilities, net	14,425,000	[1]	26,570,000	[2]
Deferred compensation	0		0
Total Liabilities	14,425,000		26,570,000
MGE [Member] | Recurring [Member] | Level 3 [Member] | Exchange-traded investments
Assets:
Available-for-sale securities	$ 0		$ 0

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

[2] These amounts are shown gross and exclude $1.5 million of collateral that was posted against derivative positions with counterparties as of December 31, 2019.