Revenue Recognition - Summary of Activity of Product Revenue Rebates and Discounts (Detail) $ in Thousands	12 Months Ended
	Mar. 31, 2019 USD ($)
Rebates and Discounts [Abstract]
Balance at March 31, 2018	$ 1,405
Credits related to prior period balance	(759)
Provision related to current period revenue	2,180
Credits related to current period revenue	(1,294)
Balance at March 31, 2019	$ 1,532