Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.2
Stockholder's Equity - Summary of Common Stock Shares Activity (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Common Stock Outstanding Roll Forward [Roll Forward]        
Beginning balance $ 6,455 $ 11,330 $ 12,895 $ 31,225
Beginning balance (in shares)     9,741,372  
Net loss (6,381) (8,403) $ (13,383) (31,311)
Stock-based compensation expense 410 446 $ 821 938
Common stock issued for exercise of stock options 0      
Common stock issued for exercise of stock options (in shares)     166  
Common stock issued, net of expenses 2,463 4,046 $ 2,669 6,556
Common stock issued through employee stock purchase and stock option plans     18  
Common stock issued through employee stock purchase plan       21
Common stock issued for Commitment Shares 602   602  
Common stock issued for vested restricted stock units 0 (1) (73) (11)
Ending balance $ 6,333 10,402 $ 6,333 10,402
Ending balance (in shares) 10,478,927   10,478,927  
April 2020 Notes        
Common Stock Outstanding Roll Forward [Roll Forward]        
Common stock issued for conversion of Notes $ 2,784   $ 2,784  
March 2019 Notes        
Common Stock Outstanding Roll Forward [Roll Forward]        
Common stock issued for conversion of Notes   2,984   2,984
Common Stock        
Common Stock Outstanding Roll Forward [Roll Forward]        
Beginning balance $ 10 $ 5 $ 10 $ 5
Beginning balance (in shares) 9,787,604 5,023,242 9,741,372 4,797,198
Net loss $ 0 $ 0 $ 0 $ 0
Stock-based compensation expense 0 0 0 0
Common stock issued for exercise of stock options $ 0      
Common stock issued for exercise of stock options (in shares) 151      
Common stock issued, net of expenses $ 0 $ 0 $ 0 $ 0
Common stock issued, net of expenses (in shares) 303,038 266,090 331,565 488,747
Common stock issued through employee stock purchase and stock option plans     $ 0  
Common stock issued through employee stock purchase and stock option plans (in shares)     2,368  
Common stock issued through employee stock purchase plan       $ 0
Common stock issued through employee stock purchase plan (in shares)       1,926
Common stock issued for Commitment Shares $ 0   $ 0  
Common stock issued for Commitment Shares (in shares) 70,910   70,910  
Common stock issued for vested restricted stock units $ 0 $ 0 $ 0 $ 0
Common stock issued for vested restricted stock units (in shares) 762 79 16,250 1,540
Ending balance $ 10 $ 5 $ 10 $ 5
Ending balance (in shares) 10,478,927 5,452,011 10,478,927 5,452,011
Common Stock | April 2020 Notes        
Common Stock Outstanding Roll Forward [Roll Forward]        
Common stock issued for conversion of Notes $ 0   $ 0  
Common stock issued for conversion of Notes (in shares) 316,461   316,461  
Common Stock | March 2019 Notes        
Common Stock Outstanding Roll Forward [Roll Forward]        
Common stock issued for conversion of Notes   $ 0   $ 0
Common stock issued for conversion of Notes (in shares)   162,600   162,600
Additional Paid-in Capital        
Common Stock Outstanding Roll Forward [Roll Forward]        
Beginning balance $ 284,875 $ 251,951 $ 284,313 $ 248,938
Net loss 0 0 0 0
Stock-based compensation expense 410 446 821 938
Common stock issued for exercise of stock options 0      
Common stock issued, net of expenses 2,463 4,046 2,669 6,556
Common stock issued through employee stock purchase and stock option plans     18  
Common stock issued through employee stock purchase plan       21
Common stock issued for Commitment Shares 602   602  
Common stock issued for vested restricted stock units 0 (1) (73) (11)
Ending balance 291,134 259,426 291,134 259,426
Additional Paid-in Capital | April 2020 Notes        
Common Stock Outstanding Roll Forward [Roll Forward]        
Common stock issued for conversion of Notes 2,784   2,784  
Additional Paid-in Capital | March 2019 Notes        
Common Stock Outstanding Roll Forward [Roll Forward]        
Common stock issued for conversion of Notes   2,984   2,984
Accumulated Deficit        
Common Stock Outstanding Roll Forward [Roll Forward]        
Beginning balance (278,430) (240,626) (271,428) (217,718)
Net loss (6,381) (8,403) (13,383) (31,311)
Stock-based compensation expense 0 0 0 0
Common stock issued for exercise of stock options 0      
Common stock issued, net of expenses 0 0 0 0
Common stock issued through employee stock purchase and stock option plans     0  
Common stock issued through employee stock purchase plan       0
Common stock issued for Commitment Shares 0   0  
Common stock issued for vested restricted stock units 0 0 0 0
Ending balance (284,811) (249,029) (284,811) (249,029)
Accumulated Deficit | April 2020 Notes        
Common Stock Outstanding Roll Forward [Roll Forward]        
Common stock issued for conversion of Notes $ 0   $ 0  
Accumulated Deficit | March 2019 Notes        
Common Stock Outstanding Roll Forward [Roll Forward]        
Common stock issued for conversion of Notes   $ 0   $ 0