Equity Incentive Plan - Additional Information (Detail) - USD ($)			1 Months Ended	12 Months Ended
	Aug. 23, 2018	Mar. 05, 2015	Feb. 28, 2018	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense				$ 3,600,000	$ 4,200,000
Unrecognized compensation expense recognition period				2 years 9 months 18 days
Allocated compensation expense				$ 3,500,000	$ 6,100,000
Grant date fair value of options granted				$ 0.89	$ 0.96
Options exercised				2,028,203	0
Options exercised, weighted average exercise price				$ 2.64
Total proceeds from option exercises				$ 5,351,323
Fair value of options vested				3,700,000	$ 6,000,000
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated compensation expense				2,100,000	3,600,000
Research and development expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated compensation expense				$ 1,400,000	$ 2,500,000
2015 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of fair market value on date of grant		100.00%
Award expiration period		10 years
Equity incentive plan, available percentage of common stock share issued and outstanding			12.50%
Number of shares available for grants				2,485,717
2016 Director Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grants				889,167
Increase in total number of common shares authorized	2,000,000
Number of common shares authorized	2,750,000
Number of shares available for initial grants	100,000
Annual grants stock option granted in future	50,000
Initial grants term	10 years
Annual grants term	10 years
Initial grants vesting period	1 year
Annual grants vesting period	1 year
Term of stock option awards				(i) increased the total number of shares of Common Stock authorized and reserved for issuance under the 2016 Director Plan by 2,000,000 shares to 2,750,000 shares: (ii) made “Initial Grants” upon a director’s initial appointment to the Board consisting of an immediate stock option grant of 100,000 shares at fair market value; and (iii) made “Annual Grants” for members who continue in service as members of the Board subsequent to each annual meeting of stockholders occurring subsequent to an Initial Grant, an annual stock option grant of 50,000 shares at fair market value. The Initial Grants and Annual Grants have a ten year term, subject to applicable termination or forfeiture provisions, and vest in equal quarterly increments over a one-year period from the date of grant. As of March 31, 2021, there were 889,167 shares available for grant under the 2016 Director Plan.
Equity Incentive Plan 2015 and 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value, options				$ 3,300,000
Share price (in dollars per share)				$ 1.78
Intrinsic value of the exercised option				$ 1,700,000