Income Taxes - Schedule of Income (Loss) Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
U.S.	$ (100,341)	$ (31,664)	$ (29,436)
Foreign	67,404	5,433	8,688
Loss before income tax expense (benefit)	$ (32,937)	$ (26,231)	$ (20,748)