Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (7,326)	$ (10,537)	$ (21,417)	$ (28,783)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of zero tax	(1,790)	(8,482)	1,147	(2,380)
Unrealized gains on available-for-sale securities, net of zero tax	0	0	0	1
Total other comprehensive income (loss)	(1,790)	(8,482)	1,147	(2,379)
Comprehensive loss	$ (9,116)	$ (19,019)	$ (20,270)	$ (31,162)