Fair Value of Financial Instruments (Details-1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Carrying Amount [Member]
Assets:
Cash and cash equivalents	$ 68,813		$ 46,357
Liabilities:
Long-Term debt	403,793	[1]	361,805	[1]
Fair Value [Member]
Assets:
Cash and cash equivalents	68,813		46,357
Liabilities:
Long-Term debt	432,010	[1]	427,456	[1]
MGE [Member] | Carrying Amount [Member]
Assets:
Cash and cash equivalents	14,808		6,350
Liabilities:
Long-Term debt	403,793	[1]	361,805	[1]
MGE [Member] | Fair Value [Member]
Assets:
Cash and cash equivalents	14,808		6,350
Liabilities:
Long-Term debt	$ 432,010	[1]	$ 427,456	[1]

[1] *Includes long-term debt due within one year.