Investments (Details-1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Available-for-sale securities:
Cost basis	$ 1,964	$ 1,736
Gross unrealized gains	765	629
Fair Value	2,729	2,365
Equity method investments:
Equity method investments	68,872	65,587
Other Investments	159	0
Total investments	71,760	67,952
Results of Investment Liquidation [Abstract]
Proceeds from sale of investments	38	39	0
Gain (loss) on sale of investments	21	2	0
ATC [Member]
Equity method investments:
Equity method investments	67,673	64,488
Other Equity Method Investments [Member]
Equity method investments:
Equity method investments	1,199	1,099
MGE [Member]
Available-for-sale securities:
Cost basis	489	490
Gross unrealized gains	240	321
Fair Value	729	811
Equity method investments:
Equity method investments	67,673	64,488
Other Investments	0	0
Total investments	68,402	65,299
Results of Investment Liquidation [Abstract]
Proceeds from sale of investments	0	16	0
Gain (loss) on sale of investments	0	(3)	0
MGE [Member] | ATC [Member]
Equity method investments:
Equity method investments	67,673	64,488
MGE [Member] | Other Equity Method Investments [Member]
Equity method investments:
Equity method investments	$ 0	$ 0