Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 46,197	$ (8,196)	$ 37,998	$ (27,099)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	(4,529)	10,170	(1,982)	12,572
Unrealized income (loss) on available for sale debt securities	15		(77)
Other comprehensive (loss) income, net of tax	(4,514)	10,170	(2,059)	12,572
Comprehensive income (loss)	$ 41,683	$ 1,974	$ 35,939	$ (14,527)