CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
Net income (loss)	$ (88,720)	$ (75,738)	$ 131,762
Unrealized gains (losses) on available-for-sale securities:
Unrealized gains (losses) on available-for-sale securities, net of tax	35	(17)	(30)
Comprehensive income (loss)	$ (88,685)	$ (75,755)	$ 131,732