CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (75,042)	$ (33,769)	$ (120,172)	$ (189,492)
Other comprehensive income (loss), net of taxes of $0 for all periods:
Foreign currency translation adjustment	1,520	3,607	(1,994)	6,595
Total comprehensive loss	$ (73,522)	$ (30,162)	$ (122,166)	$ (182,897)