CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (17,331)	$ (104,893)	$ (80,887)	$ (155,939)
Other comprehensive income (loss):
Foreign currency translation adjustment	(2,096)	(1,027)	(2,270)	(2,798)
Unrealized gain (loss) on marketable securities, net of tax	17	(42)	101	(734)
Total comprehensive loss	$ (19,410)	$ (105,962)	$ (83,056)	$ (159,471)