Annual report pursuant to Section 13 and 15(d)

Stock Option Plans (Assumptions Used To Compute The Fair Value Of Stock Options) (Detail)

v3.8.0.1
Stock Option Plans (Assumptions Used To Compute The Fair Value Of Stock Options) (Detail) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Assumptions for Black-Scholes:      
Expected term in years   7 years 10 months 24 days  
Value of options granted:      
Number of options granted 534,500 116,750 374,000
Weighted average fair value per share $ 5.24 $ 5.73 $ 4.50
Fair value of options issued $ 2,803,329 $ 669,435 $ 1,684,179
Minimum [Member]      
Assumptions for Black-Scholes:      
Expected term in years 6 years 6 months   6 years
Volatility 122.80% 103.60% 114.40%
Risk-free interest rate 1.98% 1.27% 1.74%
Maximum [Member]      
Assumptions for Black-Scholes:      
Expected term in years 6 years 9 months 18 days   7 years 10 months 24 days
Volatility 133.00% 109.70% 113.50%
Risk-free interest rate 2.30% 1.68% 2.02%