Goodwill and Purchased Intangibles Assets - Schedule of Purchased Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	$ 13,415	$ 13,855
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	18,716	18,716
Accumulated Amortization	(5,301)	(4,861)
Net Carrying Amount	$ 13,415	$ 13,855