Annual report pursuant to Section 13 and 15(d)

Stock Option Plans (Additional Information) (Detail)

v3.8.0.1
Stock Option Plans (Additional Information) (Detail) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]        
Exercisable Options Outstanding Shares 797,861 613,665 424,688  
Weighted average exercise price per share $ 4.65 $ 4.83 $ 5.34  
Unvested Options Outstanding, Shares 712,383 470,633 598,101  
Unvested Options Outstanding, Weighted average exercise price $ 5.48 $ 4.67 $ 4.05  
Unvested Options Outstanding Weighted average remaining life (yrs) 8 years 8 months 12 days 8 years 4 months 24 days 7 years 4 months 24 days  
Weighted average remaining contractual term on unvested options 6 years 4 months 24 days 7 years 7 years 4 months 24 days  
Unrecognized stock compensation expense $ 3,517,878      
Weighted average recognition period 3 years      
Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Shares Authorized 2,555,387 2,111,673 1,767,084  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value $ 3,517,878 $ 2,776,068 $ 3,449,805  
Non Employee Director        
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]        
Percentage Of Stock Option Vesting Period 50.00%      
2014 Plan        
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]        
Percentage Of Stock Option Vesting Period 20.00%      
Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Shares Authorized 2,427,628 1,956,925 1,608,795 1,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Outstanding Stock Maximum 10.00%      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 100.00%