Shareholders' Equity - Additional Information (Detail) - USD ($)				3 Months Ended	9 Months Ended
	Dec. 10, 2020	Sep. 30, 2020	Sep. 29, 2020	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	May 31, 2019
Common stock, shares issued					16,933,000		16,735,000
Preferred stock, shares issued					10,000		10,000
Preferred stock, par value					$ 0.001		$ 0.001
Equity Distribution Agreement
Common Stock Capital Value Reserved For Future Issuance					$ 6,932,000
Series B convertible Preferred Stock [Member]
Stock issuance costs		$ 84,000
Preferred stock, shares issued		17,000		17,000		17,000
Preferred stock, par value		$ 0.001		$ 0.001		$ 0.001
Proceeds from issuance of preferred stock		$ 16,970,000
Common stock issued upon conversion of preferred stock	1,198,000
Preferred stock conversion price	$ 14.37
Common Stock [Member]
Cash proceeds from sale of common stock			$ 36,530,000			$ 2,263,000
Stock issuance costs			$ 190,000			$ 394,000
Issuance of common stock				2,676,000	0	2,704,000
Sale of common stock, sales agent commissions						$ 61,000
Common Stock [Member] | Equity Distribution Agreement With Average Price Of 16.80 [Member]
Common stock price per share		$ 16.80		$ 16.80		$ 16.80
Cash proceeds from sale of common stock						$ 2,718,000
Issuance of common stock						162,000
Common Stock [Member] | Maximum [Member]
Aggregate offering price of common stock								$ 30,000,000
Common Stock [Member] | Private Placement [Member]
Common stock, shares issued			2,542,000
Common stock price per share			$ 14.37