Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Partners Capital [Abstract]
Net income (loss)	$ (911)	$ 5,093	$ 4,698	$ (4,381)
Other comprehensive income (loss):
Change in foreign currency translation adjustment	(29,855)	11,508	(6,721)	16,989
Net change in unrealized gains (losses) on available-for-sale marketable debt securities, net of tax	134	(4)	107	19
Other comprehensive income (loss), net of tax	(29,721)	11,504	(6,614)	17,008
Comprehensive income (loss)	$ (30,632)	$ 16,597	$ (1,916)	$ 12,627