Goodwill and Purchased Intangibles Assets - Schedule of Purchased Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Mar. 31, 2020
Acquired Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	$ 11,139	$ 13,691
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	15,316	15,316
Accumulated Amortization	(4,177)	(1,625)
Net Carrying Amount	$ 11,139	$ 13,691