Annual report pursuant to Section 13 and 15(d)

Equity Incentive Plans, Employee Stock Purchase Plan and Stock-Based Compensation - Summary of Option Activity (Details)

v3.19.1
Equity Incentive Plans, Employee Stock Purchase Plan and Stock-Based Compensation - Summary of Option Activity (Details) - 2004 Plan and 2018 Equity Incentive Plan - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2016
Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Outstanding Options, Beginning Balance   796,907  
Options granted to purchase common stock 2,312,821 62,392  
Outstanding Options Exercised (20,009) (13,499)  
Outstanding Options Canceled (16,414) (10,480)  
Outstanding Options, Ending Balance 3,111,718 835,320 796,907
Outstanding Options Exercisable 896,818    
Outstanding Options Vested and expected to vest 896,818    
Weighted - Average Exercise Price, Beginning Balance   $ 10.05  
Weighted - Average Exercise Price, Granted $ 14.85 13.10  
Weighted - Average Exercise Price, Exercised 6.53 7.06  
Weighted - Average Exercise Price, Canceled 14.49 12.46  
Weighted - Average Exercise Price, Ending Balance 13.74 $ 10.31 $ 10.05
Weighted - Average Exercise Price, Exercisable 10.99    
Weighted - Average Exercise Price, Vested and expected to vest $ 10.99    
Weighted - Average Remaining Contract Term 8 years 9 months 3 days 6 years 10 months 2 days 7 years 7 months 9 days
Weighted - Average Remaining Contract Term, Exercisable 6 years 5 months 8 days    
Weighted - Average Remaining Contract Term, Vested and expected to vest 6 years 5 months 8 days    
Aggregate Intrinsic Value, Balance $ 1,088 $ 3,813 $ 2,685
Aggregate Intrinsic Value, Exercisable 1,088    
Aggregate Intrinsic Value, Vested and expected to vest $ 1,088