Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Stockholder's Equity - Summary of Common Stock Shares Activity (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Common Stock Outstanding Roll Forward [Roll Forward]    
Beginning balance $ 31,225 $ 21,410
Beginning balance (in shares) 47,971,989  
Net loss $ (22,908) (4,002)
Stock-based compensation expense 492 425
Common stock issued through employee stock purchase plan 20 20
Common stock issued, net of expenses 2,509 18,998
Common stock issued for vested restricted stock units (8) (7)
Ending balance $ 11,330 36,844
Ending balance (in shares) 50,232,429  
Common Stock    
Common Stock Outstanding Roll Forward [Roll Forward]    
Beginning balance $ 48 $ 29
Beginning balance (in shares) 47,971,989 28,971,651
Net loss $ 0 $ 0
Stock-based compensation expense 0 0
Common stock issued through employee stock purchase plan $ 0 $ 0
Common stock issued through employee stock purchase plan (in shares) 19,259 13,591
Common stock issued, net of expenses $ 2 $ 18
Common stock issued, net of expenses (in shares) 2,226,569 17,852,193
Common stock issued for vested restricted stock units $ 0 $ 0
Common stock issued for vested restricted stock units (in shares) 14,612 6,006
Ending balance $ 50 $ 47
Ending balance (in shares) 50,232,429 46,843,441
Additional Paid-in Capital    
Common Stock Outstanding Roll Forward [Roll Forward]    
Beginning balance $ 248,895 $ 226,631
Net loss 0 0
Stock-based compensation expense 492 425
Common stock issued through employee stock purchase plan 20 20
Common stock issued, net of expenses 2,507 18,980
Common stock issued for vested restricted stock units (8) (7)
Ending balance 251,906 246,049
Accumulated Deficit    
Common Stock Outstanding Roll Forward [Roll Forward]    
Beginning balance (217,718) (205,250)
Net loss (22,908) (4,002)
Stock-based compensation expense 0 0
Common stock issued through employee stock purchase plan 0 0
Common stock issued, net of expenses 0 0
Common stock issued for vested restricted stock units 0 0
Ending balance $ (240,626) $ (209,252)