Income Taxes - Reconciliation of (Provision for) Benefit from Income Taxes to Amount Computed by Applying Statutory Federal Income Tax Rate to Income (Loss) before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Provision Benefit For Income Taxes [Line Items]
Tax (provision) benefit at federal statutory rate	$ (5,457)	$ (300)	$ 23,201
State tax (provision) benefit, net of federal benefit	(5,067)	(1,093)	1,815
Tax credits, net of valuation allowance	24,272	25,153	26,836
Non-deductible compensation	(5,728)	(7,150)	(4,527)
Non-deductible meals and entertainment	(386)	(1,075)	(929)
Stock-based compensation	(9,901)	780	180
Foreign effective tax rate differential, net of valuation allowance	(3,046)	(5,707)	(1,552)
Unremitted subsidiary gains	(1,682)	(2,742)	(1,388)
Other	(86)	(504)	(1,938)
Total (provision for) benefit from income taxes	(9,441)	7,915	41,014
United States [Member]
Provision Benefit For Income Taxes [Line Items]
Change in effective tax rate		567
State [Member]
Provision Benefit For Income Taxes [Line Items]
Change in effective tax rate	$ (2,360)	$ (14)	$ (684)