Stockholders' Equity - Preferred stock warrants (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jul. 24, 2019	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2020
Preferred stock warrants
Loss from change in fair value of the warrant liability		$ (5,452)	$ (972)
Series seed preferred stock
Preferred stock warrants
Number of preferred stock warrants issued				50,000
Exercise price (in dollars per share)				$ 10.00
Fair value of the warrants to purchase shares of series seed preferred stock				$ 391
Preferred stock warrants, exercisable	497,344
Other income (expense), net
Preferred stock warrants
Loss from change in fair value of the warrant liability		$ (5,452)	$ (972)