Stockholders' Equity - Additional Information (Detail) - USD ($)			9 Months Ended	12 Months Ended
	Sep. 21, 2021	Dec. 23, 2020	Sep. 30, 2021	Dec. 31, 2020	Mar. 31, 2021
Series X1 Non-voting Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred shares outstanding			108,070	108,070
Series X1 Preferred Stock [Member]
Class Of Stock [Line Items]
Warrants available for exercise			50,207.419
Shares of common stock issued upon conversion of each share of preferred stock			55.5556
Series X Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred shares outstanding			6,204	0
Common Stock [Member]
Class Of Stock [Line Items]
Common stock number of shares issued		1,004,111
Warrants available for exercise			1,145,631
Warrants issued	298,692
Common Stock [Member] | Series X1 Non-voting Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Warrants exercisable for exchange	5,376.456
Warrant Exchange Agreement and Exchange Agreements [Member] | Series X Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred shares outstanding				6,203.98
Warrant Exchange Agreement and Exchange Agreements [Member] | Common Stock [Member] | Series X Preferred Stock [Member]
Class Of Stock [Line Items]
Shares of common stock issued upon conversion of each share of preferred stock				344,663
Exchange Agreement [Member]
Class Of Stock [Line Items]
Warrants available for exercise			509,117
Jeffries LLC [Member] | Equity Distribution Agreement [Member]
Class Of Stock [Line Items]
Equity distribution agreement maximum value of common shares issuable					$ 75,000,000.0
Common stock number of shares issued			0
BVF Exchanging Stockholders, Series X Exchanging Stockholders [Member] | Series X Exchange Agreement [Member] | Series X Preferred Stock [Member]
Class Of Stock [Line Items]
Conversion of stock, shares issued				6,203.98
BVF Exchanging Stockholders, Series X Exchanging Stockholders [Member] | Series X Exchange Agreement [Member] | Common Stock [Member]
Class Of Stock [Line Items]
Conversion of stock, shares converted				344,666
BVF Exchanging Stockholders | Warrant Exchange Agreement and Exchange Agreements [Member] | Common Stock [Member]
Class Of Stock [Line Items]
Warrants to issue shares of common stock				509,117