Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.3
Stockholder's Equity - Summary of Common Stock Shares Activity (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Common Stock Outstanding Roll Forward [Roll Forward]        
Beginning balance $ 10,402 $ 26,553 $ 31,225 $ 21,410
Beginning balance (in shares)     47,971,989  
Net loss (7,941) 351 $ (39,252) (14,410)
Stock-based compensation expense 449 458 1,387 1,351
Common stock issued through employee stock purchase plan 17 21 37 39
Common stock issued, net of expenses 3,206 498 9,761 19,498
Common stock issued for April 2019 conversion of Notes     2,984  
Common stock issued for exercise of stock options 12   $ 12  
Common stock issued for exercise of stock options (in shares)     22,500  
Common stock issued for vested restricted stock units (2) (2) $ (11) (9)
Ending balance $ 6,143 27,879 $ 6,143 27,879
Ending balance (in shares) 57,362,453   57,362,453  
Common Stock        
Common Stock Outstanding Roll Forward [Roll Forward]        
Beginning balance $ 54 $ 47 $ 48 $ 29
Beginning balance (in shares) 54,520,131 46,844,072 47,971,989 28,971,651
Net loss $ 0 $ 0 $ 0 $ 0
Stock-based compensation expense 0 0 0 0
Common stock issued through employee stock purchase plan $ 0 $ 0 $ 0 $ 0
Common stock issued through employee stock purchase plan (in shares) 17,588 17,770 36,847 31,361
Common stock issued, net of expenses $ 3 $ 0 $ 7 $ 18
Common stock issued, net of expenses (in shares) 2,799,111 328,871 7,686,589 18,181,064
Common stock issued for April 2019 conversion of Notes     $ 2  
Common stock issued for April 2019 conversion of Notes (in shares)     1,626,000  
Common stock issued for exercise of stock options $ 0   $ 0  
Common stock issued for exercise of stock options (in shares) 22,500   22,500  
Common stock issued for vested restricted stock units $ 0 $ 0 $ 0 $ 0
Common stock issued for vested restricted stock units (in shares) 3,123 2,349 18,528 8,986
Ending balance $ 57 $ 47 $ 57 $ 47
Ending balance (in shares) 57,362,453 47,193,062 57,362,453 47,193,062
Additional Paid-in Capital        
Common Stock Outstanding Roll Forward [Roll Forward]        
Beginning balance $ 259,377 $ 246,517 $ 248,895 $ 226,631
Net loss 0 0 0 0
Stock-based compensation expense 449 458 1,387 1,351
Common stock issued through employee stock purchase plan 17 21 37 39
Common stock issued, net of expenses 3,203 498 9,754 19,480
Common stock issued for April 2019 conversion of Notes     2,982  
Common stock issued for exercise of stock options 12   12  
Common stock issued for vested restricted stock units (2) (2) (11) (9)
Ending balance 263,056 247,492 263,056 247,492
Accumulated Deficit        
Common Stock Outstanding Roll Forward [Roll Forward]        
Beginning balance (249,029) (220,011) (217,718) (205,250)
Net loss (7,941) 351 (39,252) (14,410)
Stock-based compensation expense 0 0 0 0
Common stock issued through employee stock purchase plan 0 0 0 0
Common stock issued, net of expenses 0 0 0 0
Common stock issued for April 2019 conversion of Notes     0  
Common stock issued for exercise of stock options 0   0  
Common stock issued for vested restricted stock units 0 0 0 0
Ending balance $ (256,970) $ (219,660) $ (256,970) $ (219,660)