CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 173,533	$ 67,303	$ (8,302)
Other comprehensive income (loss):
Foreign currency translation adjustment	43,379	(9,086)	(7,364)
Cash flow hedges:
Change in unrealized gains	(8,153)	0	0
Reclassification to earnings	0	0	(17)
Tax effect on cross-currency swap	(2,038)	0	0
Change in fair value of cash flow hedges	(10,191)	0	(17)
Available-for-sale securities:
Net unrealized gain (loss), net of taxes	(1,778)	(169)	73
Reclassification to earnings for realized net loss, net of taxes	0	9	36
Change in fair value of available-for-sale securities	(1,778)	(160)	109
Other comprehensive income (loss)	31,410	(9,246)	(7,272)
Comprehensive income (loss)	$ 204,943	$ 58,057	$ (15,574)