Annual report pursuant to Section 13 and 15(d)

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

v3.8.0.1
Equity Incentive Plan - Schedule of Additional Information About Stock Options Outstanding (Details) - $ / shares
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted Average Exercise Price (in dollars per share) $ 2.79 $ 4.57 $ 4.57
$2.23 - $5.00      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted Average Exercise Price (in dollars per share) 3.65    
$5.01 - $7.50      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted Average Exercise Price (in dollars per share) 6.96    
$7.51 - $8.27      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted Average Exercise Price (in dollars per share) $ 7.86    
Equity Incentive Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options Outstanding (in shares) 1,232,236 1,385,204 1,332,323
Weighted Average Remaining Life (in years) 6 years 9 months 18 days 7 years 6 months 8 years 4 months 24 days
Weighted Average Exercise Price (in dollars per share) $ 6.44 $ 6.89 $ 6.94
Options Exercisable (in shares) 910,436 862,354  
Equity Incentive Plan [Member] | $2.23 - $5.00      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options Outstanding (in shares) 318,170    
Weighted Average Remaining Life (in years) 7 years 2 months 12 days    
Options Exercisable (in shares) 226,495    
Equity Incentive Plan [Member] | $5.01 - $7.50      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options Outstanding (in shares) 453,528    
Weighted Average Remaining Life (in years) 6 years 6 months    
Options Exercisable (in shares) 340,078    
Equity Incentive Plan [Member] | $7.51 - $8.27      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options Outstanding (in shares) 460,538    
Weighted Average Remaining Life (in years) 6 years 10 months 24 days    
Options Exercisable (in shares) 343,863