Share-Based Payment Awards - Employee Stock Purchase Plan - Additional Information (Detail) - USD ($)		3 Months Ended		9 Months Ended
	Jun. 25, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 22, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Employee stock purchase plan		$ 101,000	$ 107,000	$ 273,000	$ 294,000
Common stock, shares issued		28,771,264		28,771,264			18,139,981
Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Number of common stock, authorized for issuance	110,000					250,000
Price of common stock purchased twice a year under ESPP, percent	85.00%
Employee stock purchase plan	$ 25,000
Employee stock purchase plan, shares	5,000
Consecutive six month offering period	Aug. 01, 2019
Common stock, shares issued		43,365		43,365