CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss		$ (154,740)	$ (24,010)	$ (76,350)
Other comprehensive income (loss):
Foreign currency translation gains (losses)	[1]	(306)	(68)	87
Currency translation adjustment upon subsidiary liquidation	[1]	0	0	1,397
Total other comprehensive income (loss)	[1]	(306)	(68)	1,484
Total comprehensive loss		$ (155,046)	$ (24,078)	$ (74,866)

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