CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 109,848	$ (63,160)	$ 56,061	$ (115,835)
Other comprehensive income (loss):
Net unrealized loss on marketable securities	(1,923)	0	(5,909)	0
Cumulative translation adjustment, net of tax of $0	(12)	(77)	(44)	159
Defined benefit pension obligation, net of tax of $0	36	(495)	91	(418)
Reclassification of cumulative translation adjustment and pension obligation adjustments to earnings upon sale of European operations	2,939	0	2,939	0
Other comprehensive income (loss)	1,040	(572)	(2,923)	(259)
Comprehensive income (loss)	$ 110,888	$ (63,732)	$ 53,138	$ (116,094)