Common Stock - Sales Agreement (Detail) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
	Feb. 29, 2020 USD ($) item	Sep. 30, 2021 USD ($) shares	Sep. 30, 2021 USD ($) shares
Class of Stock [Line Items]
Total shares of common stock sold | shares		22,059	416,406
Gross proceeds		$ 540	$ 10,512
Commissions earned by placement agents		(22)	(422)
Issuance fees		(23)	(70)
Net proceeds		$ 495	$ 10,020
Sale Agreement (ATM)
Class of Stock [Line Items]
Number of agents | item	2
Maximum aggregate offering price of equity securities	$ 50,000
Percentage of commission	4.00%
Sales Agreement Agent [Member] | Sale Agreement (ATM)
Class of Stock [Line Items]
Percentage of commission	2.00%