Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 112,170	$ 52,116	$ 38,147
Other comprehensive income (loss):
Foreign currency translation gains (losses)	16,862	(5,855)	2,724
Net unrealized (losses) gain on marketable securities	(460)	(211)	66
Other comprehensive income (loss)	16,402	(6,066)	2,790
Comprehensive income	$ 128,572	$ 46,050	$ 40,937