Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Summarizes Fortress warrant activities (Detail)

v3.8.0.1
Stockholders' Equity - Summarizes Fortress warrant activities (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Subsidiary or Equity Method Investee [Line Items]    
Weighted average remaining contractual life, Forfeited (years) 0 years  
Warrant [Member]    
Subsidiary or Equity Method Investee [Line Items]    
Number of shares, Outstanding 2,774,189  
Number of shares, Granted 0  
Forfeited 0  
Number of shares, Outstanding 2,774,189 2,774,189
Number of shares, Exercisable 869,189  
Weighted average exercise price, Outstanding $ 3.3  
Weighted average exercise price, Granted 0  
Weighted average exercise price, Forfeited 0  
Weighted average exercise price, Outstanding 3.3 $ 3.3
Weighted average exercise price, Exercisable $ 3.96  
Total weighted average intrinsic value, Outstanding $ 2,204,530  
Total weighted average intrinsic value, Granted 0  
Total weighted average intrinsic value, Forfeited 0  
Total weighted average intrinsic value, Outstanding 3,586,975 $ 2,204,530
Total weighted average intrinsic value, Exercisable $ 634,225  
Weighted average remaining contractual life, Granted (years) 0 years  
Weighted average remaining contractual life (years), Outstanding 4 years 2 months 19 days 4 years 5 months 19 days
Weighted average remaining contractual life, Exercisable (years) 3 years 9 months 22 days