Equity Investment in Sunrise Energy (Condensed Statement of Operations - Sunrise) (Details) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014		Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Revenue	$ 64,853	$ 82,013	$ 95,253	$ 98,001	$ 100,622	$ 66,322		$ 38,460	$ 35,767	$ 340,120		$ 241,171		$ 153,870
Expenses										(312,550)		(230,470)		(124,272)
Net income	$ 544	$ 5,144	$ 6,853	$ 7,591	$ 9,393	$ (5,768)	[1]	$ 3,068	$ 3,526	20,132	[2]	10,219	[2]	22,423	[2]
Sunrise Energy [Member]
Revenue										2,284		3,203		3,399
Expenses										(2,432)		(2,707)		(2,141)
Net income										$ (148)		$ 496		$ 1,258

[1] Includes $8.9 million related to Vectren deal costs.

[2] *There is no material difference between net income and comprehensive income.