Unaudited Condensed Consolidated Statements of Comprehensive 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 loss	$ (24,808)	$ (49,744)	$ (88,898)	$ (102,142)
Other comprehensive (loss) income:
Foreign currency translation	(35)	(124)	(1,375)	1,032
Other comprehensive (loss) income	(35)	(124)	(1,375)	1,032
Comprehensive loss	$ (24,843)	$ (49,868)	$ (90,273)	$ (101,110)