Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Partners Capital [Abstract]
Net income (loss)	$ 10,200	$ 18,091	$ 14,898	$ 13,710
Other comprehensive income (loss):
Change in foreign currency translation adjustment	(3,141)	20,490	(9,863)	37,479
Net change in unrealized gains (losses) on available-for-sale marketable debt securities, net of tax	42	(27)	150	(8)
Other comprehensive income (loss), net of tax	(3,099)	20,463	(9,713)	37,471
Comprehensive income (loss)	$ 7,101	$ 38,554	$ 5,185	$ 51,181