Stock-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended	6 Months Ended
	Dec. 31, 2019	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net proceeds from Issue of common stock			$ 12,289,000	$ 9,352,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of option Granted			0	14,000
Intrinsic value of restricted shares that vested		$ 0	$ 400,000
Number of restricted stock vested		$ 0	$ 400,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, Issued		8,167	44,966
Net proceeds from Issue of common stock		$ 36,000,000	$ 231,000,000
2019 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued, Employee Stock Purchase Plans	950,000	16,392	34,857
Percentage of voting power	5.00%
Description of employee stock purchase plan			Employees who participate in the ESPP may purchase shares by authorizing payroll deductions of up to 15% of their base compensation during an accumulation period. Unless the participating employee withdraws from participation, accumulated payroll deductions are used to purchase shares of common stock on the last business day of the accumulation period (the "Purchase Date") at a price equal to 85% of the lower of the fair market value on (i) the Purchase Date or (ii) the first day of such accumulation period. Under applicable tax rules, no employee may purchase more than $25,000 worth of common stock, valued at the start of the purchase period, under the ESPP in any calendar year.
Stock-based compensation expense		$ 30,000	$ 64,000
Accrued salary and related expenses		$ 94,000	$ 94,000
Black Scholes Model [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of option Granted		270,357	523,857