Annual report pursuant to Section 13 and 15(d)

Stock Incentive Plan - Stock Options Outstanding Additional Information (Detail)

v3.19.1
Stock Incentive Plan - Stock Options Outstanding Additional Information (Detail) - $ / shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Options 1,980,972 1,428,462
Weighted Average Contractual Life Remaining 4 years 1 month 6 days  
Weighted Average Exercise Price $ 4.63  
Exercisable Options 1,055,716  
Weighted Average Grant Date Fair Value $ 5.51  
Range of Exercise Prices From $2.38 to $3.37 [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Range of Exercise Prices, Lower Limit 2.38  
Range of Exercise Prices, Upper Limit $ 3.00  
Options 308,755  
Weighted Average Contractual Life Remaining 2 years 6 months  
Weighted Average Exercise Price $ 2.67  
Exercisable Options 240,755  
Weighted Average Grant Date Fair Value $ 2.65  
Range of Exercise Prices From $3.38 to $4.42 [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Range of Exercise Prices, Lower Limit 3.01  
Range of Exercise Prices, Upper Limit $ 3.28  
Options 571,000  
Weighted Average Contractual Life Remaining 6 years 8 months 12 days  
Weighted Average Exercise Price $ 3.25  
Range of Exercise Prices From $4.43 to $4.85 [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Range of Exercise Prices, Lower Limit 3.29  
Range of Exercise Prices, Upper Limit $ 4.63  
Options 75,750  
Weighted Average Contractual Life Remaining 6 years 4 months 24 days  
Weighted Average Exercise Price $ 3.73  
Exercisable Options 4,250  
Weighted Average Grant Date Fair Value $ 3.99  
Range of Exercise Prices From $4.86 to $6.65 [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Range of Exercise Prices, Lower Limit 4.64  
Range of Exercise Prices, Upper Limit $ 4.85  
Options 421,292  
Weighted Average Contractual Life Remaining 4 years 8 months 12 days  
Weighted Average Exercise Price $ 4.85  
Exercisable Options 212,036  
Weighted Average Grant Date Fair Value $ 4.85  
Range of Exercise Prices From $6.66 to $7.54 [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Range of Exercise Prices, Lower Limit 4.86  
Range of Exercise Prices, Upper Limit $ 6.65  
Options 34,625  
Weighted Average Contractual Life Remaining 1 year 1 month 6 days  
Weighted Average Exercise Price $ 5.39  
Exercisable Options 32,125  
Weighted Average Grant Date Fair Value $ 5.43  
Range of Exercise Prices From $7.55 to $8.76 [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Range of Exercise Prices, Lower Limit 6.66  
Range of Exercise Prices, Upper Limit $ 8.76  
Options 569,550  
Weighted Average Contractual Life Remaining 1 year 8 months 12 days  
Weighted Average Exercise Price $ 6.99  
Exercisable Options 566,550  
Weighted Average Grant Date Fair Value $ 6.99