Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 13,927	$ 136,422	$ (488,585)	$ (28,901)
Derivative financial instruments:
Unrealized holding loss		(40)		(1,574)
Reclassification adjustment for loss (gain) included in net income (loss)		268	(3)	5,085
Investments in marketable securities:
Unrealized holding loss	(1)	(2,440)	(6,559)	(2,733)
Reclassification adjustment for loss included in net income (loss)			11,600
Total other comprehensive (loss) gain	(1)	(2,212)	5,038	778
Comprehensive income (loss)	$ 13,926	$ 134,210	$ (483,547)	$ (28,123)