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		$ (102,362)	$ (12,982)	$ (129,542)	$ (32,079)
Other comprehensive income (loss):
Foreign currency translation gains (losses)	[1]	(72)	35	(334)	1
Total other comprehensive income (loss)	[1]	(72)	35	(334)	1
Total comprehensive loss		$ (102,434)	$ (12,947)	$ (129,876)	$ (32,078)

[1] Net of tax effect which was not material.