Fair Value of Financial Instruments (Details-1) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Fair Value Measurement [Domain]
Liabilities:
Unamortized discount and debt issuance costs, net		$ 4,400	$ 4,500
Carrying Amount [Member]
Assets:
Cash and cash equivalents		17,451	23,481
Liabilities:
Short-term debt - commercial paper		3,000	0
Long-term debt	[1]	546,724	547,879
Fair Value [Member]
Assets:
Cash and cash equivalents		17,451	23,481
Liabilities:
Short-term debt - commercial paper		3,000	0
Long-term debt	[1]	604,568	611,909
MGE [Member] | Fair Value Measurement [Domain]
Liabilities:
Unamortized discount and debt issuance costs, net		4,400	4,500
MGE [Member] | Carrying Amount [Member]
Assets:
Cash and cash equivalents		3,321	3,196
Liabilities:
Short-term debt - commercial paper		3,000	0
Long-term debt	[1]	546,724	547,879
MGE [Member] | Fair Value [Member]
Assets:
Cash and cash equivalents		3,321	3,196
Liabilities:
Short-term debt - commercial paper		3,000	0
Long-term debt	[1]	$ 604,568	$ 611,909

[1] Includes long-term debt due within one year. Excludes debt issuance costs and unamortized discount of $4.4 million and $4.5 million as of March 31, 2020, and December 31, 2019, respectively.