CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Convertible preferred stock	Common A stock Common stock	Series B convertible Preferred Stock	Common stock ATM sales	Common stock Follow-on public offering	Common stock	Additional paid-in capital ATM sales	Additional paid-in capital Follow-on public offering	Additional paid-in capital Prefunded common stock warrants	Additional paid-in capital	Accumulated deficit Follow-on public offering	Accumulated deficit	Accumulated other comprehensive loss	ATM sales	Follow-on public offering	Prefunded common stock warrants	Total
Balance at Mar. 31, 2017	$ 31,609					$ 5				$ 259		$ (9,230)	$ (2,549)				$ (11,515)
Balance (in shares) at Mar. 31, 2017	1,064,553					4,973,439
Increase (decrease) in Stockholders' Equity
Issuance of series convertible preferred stock, net of issuance costs			$ 54,752
Issuance of series convertible preferred stock, net of issuance costs (in shares)			861,415
Foreign currency translation adjustment													2,376				2,376
Unrealized gain (loss) on short-term investments													(65)				(65)
Issuance of stock (in shares)		26,258
Stock options in exchange for consulting services										26							26
Stock options in exchange for consulting services (in shares)						7,788
Stock-based compensation expense										812							812
Net loss												(19,702)					(19,702)
Balance at Mar. 31, 2018	$ 86,361					$ 5				1,097		(28,932)	(238)				(28,068)
Balance (in shares) at Mar. 31, 2018	1,925,968					5,007,485
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment													(897)				(897)
Unrealized gain (loss) on short-term investments													80				80
Exercise of stock options						$ 1				205							206
Exercise of stock options (in shares)						110,427
Conversion of convertible preferred stock into common stock upon closing of initial public offering	$ (86,361)					$ 19				86,342							86,361
Conversion of convertible preferred stock into common stock upon closing of initial public offering (in shares)	(1,925,968)					19,157,360
Conversion of convertible preferred stock warrants into common stock warrants										7,094							7,094
Repurchase of class A common stock upon closing of initial public offering (in shares)						(26,258)
Issuance of stock					$ 7			$ 101,177							$ 101,184
Issuance of stock (in shares)					7,407,936
Stock-based compensation expense										2,730							2,730
Net loss												(30,834)					(30,834)
Balance at Mar. 31, 2019						$ 32				198,645		(59,766)	(1,055)				137,856
Balance (in shares) at Mar. 31, 2019						31,656,950
Increase (decrease) in Stockholders' Equity
Foreign currency translation adjustment													(236)				(236)
Unrealized gain (loss) on short-term investments													309				309
Exercise of stock options										551							$ 551
Exercise of stock options (in shares)						207,673											207,673
Impact of adoption of ASC 842											$ 93				93
Issuance of stock					$ 5		$ 4,431	$ 57,448	$ 28,145					$ 4,431	$ 57,453	$ 28,145
Issuance of stock (in shares)				287,559	4,516,561									287,559
Stock-based compensation expense										7,741							$ 7,741
Net loss												(52,625)					(52,625)
Balance at Mar. 31, 2020						$ 37				$ 296,961		$ (112,298)	$ (982)				$ 183,718
Balance (in shares) at Mar. 31, 2020						36,668,743