Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Summarizes Fortress warrant activities (Detail)

v3.10.0.1
Stockholders' Equity - Summarizes Fortress warrant activities (Detail) - Warrant [Member] - USD ($)
 9 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2017
Subsidiary or Equity Method Investee [Line Items]    
Number of shares, Outstanding 2,774,189  
Number of shares, Forfeited (20,000)  
Number of shares, Outstanding 2,754,189 2,774,189
Number of shares, Exercisable 849,189  
Weighted average exercise price, Outstanding $ 3.30  
Weighted average exercise price, Forfeited 5.72  
Weighted average exercise price, Outstanding 3.28 $ 3.30
Weighted average exercise price, Exercisable $ 3.92  
Total weighted average intrinsic value, Outstanding $ 2,204,530  
Total weighted average intrinsic value, Forfeited 0  
Total weighted average intrinsic value, Outstanding 13,800 $ 2,204,530
Total weighted average intrinsic value, Exercisable $ 13,800  
Weighted average remaining contractual life, Forfeited (years) 0 years  
Weighted average remaining contractual life (years), Outstanding 3 years 9 months 4 years 5 months 19 days
Weighted average remaining contractual life, Exercisable (years) 3 years 4 months 20 days