Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation - Summary of Activity Related to PSUs (Detail)

v3.10.0.1
Stock Based Compensation - Summary of Activity Related to PSUs (Detail) - Performance Shares [Member] - $ / shares
9 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Options, Outstanding 951,657  
PSUs granted 0 0
PSUs forfeited 0  
PSUs vested (80,098)  
Number of Options, Outstanding 871,559  
Weighted Average Grant Date Fair Value, Beginning Balance $ 2.65  
Weighted Average Grant Date Fair Value, PSUs granted 0  
Weighted Average Grant Date Fair Value, PSUs forfeited 0  
Weighted Average Grant Date Fair Value, PSUs vested 2.65  
Weighted Average Grant Date Fair Value, Ending Balance $ 2.65