Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Summary of Common Stock Shares Activity (Detail)

v3.22.1
Stockholders' Equity - Summary of Common Stock Shares Activity (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Common Stock Outstanding Roll Forward [Roll Forward]    
Beginning balance $ 41,258 $ 22,758
Beginning balance (in shares) 28,705,334  
Net loss $ (5,451) (4,676)
Stock-based compensation expense 922 398
Common stock issued, net of expenses 2,135  
Common stock issued through employee stock purchase plan 10 6
Common stock issued for vested restricted stock units (18) (15)
Vested Loan Agreement warrants 71  
Ending balance $ 38,927 25,924
Ending balance (in shares) 29,221,158  
April 2020 Notes    
Common Stock Outstanding Roll Forward [Roll Forward]    
Common stock issued for conversion of Notes   7,453
Common Stock    
Common Stock Outstanding Roll Forward [Roll Forward]    
Beginning balance $ 32 $ 20
Beginning balance (in shares) 28,705,334 19,663,698
Net loss $ 0 $ 0
Stock-based compensation expense 0 0
Common stock issued, net of expenses $ 0  
Common stock issued, net of expenses (in shares) 487,610  
Common stock issued through employee stock purchase plan $ 0 $ 0
Common stock issued through employee stock purchase (in shares) 3,120 2,184
Common stock issued for vested restricted stock units $ 0 $ 0
Common stock issued for vested restricted stock units (in shares) 25,094 675
Vested Loan Agreement warrants $ 0  
Ending balance $ 32 $ 21
Ending balance (in shares) 29,221,158 20,625,637
Common Stock | April 2020 Notes    
Common Stock Outstanding Roll Forward [Roll Forward]    
Common stock issued for conversion of Notes   $ 1
Common stock issued for conversion of Notes (in shares)   959,080
Additional Paid-in Capital    
Common Stock Outstanding Roll Forward [Roll Forward]    
Beginning balance $ 400,705 $ 349,351
Net loss 0 0
Stock-based compensation expense 922 398
Common stock issued, net of expenses 2,135  
Common stock issued through employee stock purchase plan 10 6
Common stock issued for vested restricted stock units (18) (15)
Vested Loan Agreement warrants 71  
Ending balance 403,825 357,192
Additional Paid-in Capital | April 2020 Notes    
Common Stock Outstanding Roll Forward [Roll Forward]    
Common stock issued for conversion of Notes   7,452
Accumulated Deficit    
Common Stock Outstanding Roll Forward [Roll Forward]    
Beginning balance (359,479) (326,613)
Net loss (5,451) (4,676)
Stock-based compensation expense 0 0
Common stock issued, net of expenses 0  
Common stock issued through employee stock purchase plan 0 0
Common stock issued for vested restricted stock units 0 0
Vested Loan Agreement warrants 0  
Ending balance $ (364,930) (331,289)
Accumulated Deficit | April 2020 Notes    
Common Stock Outstanding Roll Forward [Roll Forward]    
Common stock issued for conversion of Notes   $ 0