Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 20,778	$ 9,828	$ 78,793	$ 50,502
Other comprehensive income (loss), net of tax:
Foreign currency translation	4	0	5	(6)
Total other comprehensive income (loss), net of tax	4	0	5	(6)
Comprehensive income (loss)	$ 20,782	$ 9,828	$ 78,798	$ 50,496