Annual report pursuant to Section 13 and 15(d)

Stock Option Plans (Summary of Stock Option Activity) (Detail)

v3.8.0.1
Stock Option Plans (Summary of Stock Option Activity) (Detail) - $ / shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Number of Options outstanding        
Outstanding, Beginning Balance 1,084,298 1,022,789    
Outstanding, Ending Balance 1,510,244 1,084,298 1,022,789  
Employee Stock Option [Member]        
Number of Options outstanding        
Outstanding, Beginning Balance 1,084,298 1,022,789 720,551  
Granted 534,500 116,750 374,000  
Exercised (63,187) (10,450) (15,833)  
Expired or Forfeited (45,367) (44,791) (55,929)  
Outstanding, Ending Balance 1,510,244 1,084,298 1,022,789 720,551
Weighted Average Exercise Price        
Outstanding, Beginning Balance $ 4.76 $ 4.59 $ 4.46  
Granted 5.74 6.6 5.67  
Exercised 2.89 3.46 2.6  
Expired or Forfeited 8.30 3.87 8.12  
Outstanding, Ending Balance $ 5.04 $ 4.76 $ 4.59 $ 4.46
Weighted Average Remaining Life (Years)        
Options Outstanding, Weighted Average Remaining Life (Years) 7 years 6 months 29 days 7 years 6 months 25 days 7 years 6 months 22 days 8 years 6 months 22 days