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Stockholders' Equity - Additional Information (Detail) - USD ($) |  | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Dec. 23, 2020 | Jun. 30, 2021 | Dec. 31, 2020 | Mar. 31, 2021
Series X1 Preferred Stock [Member] |  |  |  |
Class Of Stock [Line Items] |  |  |  |
Warrants available for exercise |  | 55,853.875 |  |
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 Warrants [Member] |  |  |  |
Class Of Stock [Line Items] |  |  |  |
Warrants available for exercise |  | 846,939 | 337,822 |
Common Stock [Member] |  |  |  |
Class Of Stock [Line Items] |  |  |  |
Common stock number of shares issued | 1,004,111 |  |  |
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 |

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