Annual report pursuant to Section 13 and 15(d)

Equity Incentive Plan - Schedule of Additional Information About Stock Options Outstanding (Details)

v3.19.1
Equity Incentive Plan - Schedule of Additional Information About Stock Options Outstanding (Details) - $ / shares
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted Average Exercise Price (in dollars per share) $ 2.62 $ 2.79 $ 4.57
Equity Incentive Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options Outstanding (in shares) 1,470,447 1,232,236 1,385,204
Weighted Average Remaining Life (in years) 6 years 9 months 18 days 7 years 6 months  
Weighted Average Exercise Price (in dollars per share) $ 5.08 $ 6.44 $ 6.89
Options Exercisable (in shares) 1,401,522 910,436  
Equity Incentive Plan [Member] | $1.22 – $2.50      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options Outstanding (in shares) 451,139    
Weighted Average Remaining Life (in years) 9 years 2 months 12 days    
Weighted Average Exercise Price (in dollars per share) $ 1.37    
Options Exercisable (in shares) 429,314    
Equity Incentive Plan [Member] | $2.51 – $5.00      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options Outstanding (in shares) 190,942    
Weighted Average Remaining Life (in years) 6 years 4 months 24 days    
Weighted Average Exercise Price (in dollars per share) $ 3.72    
Options Exercisable (in shares) 168,942    
Equity Incentive Plan [Member] | $5.01 – $7.50      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options Outstanding (in shares) 385,828    
Weighted Average Remaining Life (in years) 5 years 3 months 18 days    
Weighted Average Exercise Price (in dollars per share) $ 6.91    
Options Exercisable (in shares) 371,753    
Equity Incentive Plan [Member] | $7.51 – $8.27      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options Outstanding (in shares) 442,538    
Weighted Average Remaining Life (in years) 5 years 10 months 24 days    
Weighted Average Exercise Price (in dollars per share) $ 7.86    
Options Exercisable (in shares) 431,513