Changes in Valuation Allowance for Deferred Tax Assets (Detail) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Valuation Allowance [Line Items]
Balance at beginning of year	$ 15,170	$ 1,302	$ 1,652
Increase	497	13,868
Decrease			(350)
Balance at end of year	$ 15,667	$ 15,170	$ 1,302