Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (120,809)	$ (236,876)	$ (6,185)
Other comprehensive loss, net of income taxes:
Net unrealized gain (loss) on available-for-sale securities	5	(192)	0
Reclassification of net realized gains on available-for-sale securities included in net loss	(97)	0	0
Total other comprehensive loss	(92)	(192)	0
Comprehensive loss	$ (120,901)	$ (237,068)	$ (6,185)