Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 87,425	$ (255,709)
Derivative financial instruments:
Unrealized holding loss		(1,827)
Reclassification adjustment for (gain) loss included in net income	(1)	3,587
Investments in marketable securities:
Unrealized holding loss	(6,559)	(2,123)
Reclassification adjustment for gain included in net income	0	0
Total other comprehensive loss	(6,560)	(363)
Comprehensive income (loss)	$ 80,865	$ (256,072)