Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Stock Option Activity (Detail)

v3.8.0.1
Stockholders' Equity - Stock Option Activity (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 9 Months Ended 12 Months Ended
Sep. 30, 2017
Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Number of shares, Options exercised (20,000)  
Weighted Average Exercise Price, Options expired $ 1.37  
Total Weighted Average Intrinsic Value, Options vested and exercisable $ 1,620,046  
Number of shares, Options vested and expected to vest 1,130,501  
Number of shares, Options vested and expected to vest 1,100,501 1,130,501
Number of shares, Options vested and exercisable 1,085,501  
Weighted average exercise price, Options vested and expected to vest $ 3.73  
Weighted average exercise price, Options vested and expected to vest 3.78 $ 3.73
Weighted average exercise price, Options vested and exercisable $ 3.75  
Total Weighted average intrinsic value, Options vested and expected to vest $ 602,451  
Total Weighted average intrinsic value, Options vested and expected to vest $ 1,620,046 $ 602,451
Weighted average remaining contractual life (years), Options vested and expected to vest 4 years 2 months 16 days 4 years 11 months 5 days
Weighted average remaining contractual life (years), Options vested and exercisable 4 years 2 months 5 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value $ 61,000