CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 24,503	$ 8,875	$ 61,877	$ 21,785
Other comprehensive gain (loss):
Foreign currency translation gains (losses)	2,696	812	8,849	(887)
Net unrealized gains (losses) on marketable securities	10	(18)	(45)	132
Other comprehensive gain (loss)	2,706	794	8,804	(755)
Comprehensive income	$ 27,209	$ 9,669	$ 70,681	$ 21,030