v3.19.1
Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2018
 [1]
Sep. 30, 2018
 [1]
Jun. 30, 2018
 [1]
Mar. 31, 2018
 [1]
Dec. 31, 2017
 [1]
Sep. 30, 2017
 [1]
Jun. 30, 2017
 [1]
Mar. 31, 2017
 [1]
Dec. 31, 2018
Dec. 31, 2017
Numerator:                    
Net loss $ (6,925) $ (3,808) $ (1,730) $ (1,328) $ (653) $ (1,135) $ (1,665) $ (1,618) $ (13,791) $ (5,071)
Accretion of redeemable convertible preferred stock to redemption value                 (37,415) (14,093)
Net loss attributable to common stockholders $ (6,925) $ (3,808) $ (28,132) $ (12,341) $ (2,498) $ (604) $ (2,660) $ (13,402) $ (51,206) $ (19,164)
Denominator:                    
Weighted average common shares outstanding, basic and diluted                 16,922,225 8,773,880
Net loss per share attributable to common stockholders, basic and diluted                 $ (3.03) $ (2.18)
[1] The Company's statements of operations were impacted in the third and fourth quarter of 2018 by the recognition of $0.6 million and $1.1 million of stock-based compensation expense, respectively, related to performance-based RSU grants for which achievement of the performance condition became probable.