v3.10.0.1
Long-Term Debt - Schedule of Long Term Debt (Detail) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Dec. 21, 2017
Debt Instrument [Line Items]      
Outstanding borrowings $ 295,500 $ 291,000  
Senior secured credit facility, net 294,321 289,275  
Senior notes, net 84,411 84,185  
Total long-term debt 378,732 373,460  
Senior Notes [Member]      
Debt Instrument [Line Items]      
Principal 85,240 85,240  
Debt issuance costs (829) (1,055)  
Senior notes, net 84,411 84,185  
Senior Secured Credit Facility [Member]      
Debt Instrument [Line Items]      
Outstanding borrowings 295,500 291,000  
Debt issuance costs (1,179) (1,725) $ (1,000)
Senior secured credit facility, net $ 294,321 $ 289,275