Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income (loss)	$ 18,979	$ 4,370	$ (33,063)
Other comprehensive income (loss), before tax:
Foreign currency translation adjustments	1,732	(7,168)
Unrealized gains on marketable securities:
Other comprehensive income (loss), before tax	1,732	(7,168)	(8,592)
Income tax expense (benefit) related to components of other comprehensive income (loss)	13	(362)	0
Other comprehensive income (loss), net of tax	1,719	(6,806)	(8,592)
Comprehensive income (loss)	$ 20,697	$ (2,436)	$ (41,655)