Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (11,522)	$ 2,310
Other comprehensive income:
Foreign currency translation adjustments net of zero tax	2,468	2,065
Unrealized gains on available-for-sale securities, net of zero tax	3	28
Total other comprehensive income	2,471	2,093
Comprehensive income (loss)	$ (9,051)	$ 4,403