Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 52,116	$ 38,147	$ 113,688
Other comprehensive (loss) income:
Foreign currency translation (losses) gains	(5,855)	2,724	(16,613)
Net unrealized (losses) gain on marketable securities	(211)	66	13
Other comprehensive (loss) income	(6,066)	2,790	(16,600)
Comprehensive income	$ 46,050	$ 40,937	$ 97,088