Investment in Sunrise Energy (Condensed Statement of Operations - Sunrise) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue		$ 65,767	$ 82,013	$ 210,216	$ 275,267
Expenses		(60,682)	(76,203)	(190,996)	(249,146)
Net income (loss)	[1]	$ 4,322	$ 5,144	16,337	19,588
Sunrise Energy [Member]
Revenue				1,293	1,773
Expenses				(1,822)	(1,725)
Net income (loss)				$ (529)	$ 48

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