Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statements of Comprehensive Income [Abstract]
Net income (loss)	$ (52,781)	$ 6,227	$ (38,126)	$ 27,107
Other comprehensive income (loss):
Unrealized loss on marketable securities, net of tax	(22)		(22)
Comprehensive income (loss)	$ (52,803)	$ 6,227	$ (38,148)	$ 27,107