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STOCK BASED COMPENSATION - Narrative (Detail)
$ in Millions
9 Months Ended 12 Months Ended
Sep. 30, 2018
USD ($)
shares
Dec. 31, 2017
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Aggregate unamortized outstanding stock based compensation | $ $ 24.2 $ 19.8
Number of shares issued for each share of Class B Common Stock and TMM Unit converted (in shares) 1  
Performance-based RSUs    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Award vesting period (in years) 3 years  
Stock options    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expiration period (in years) 10 years  
2013 Omnibus Equity Award Plan    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Aggregate common stock available for future grants (in shares) 8,336,911  
Minimum | Time-Based RSUs    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Award vesting period (in years) 3 years  
Maximum | Time-Based RSUs    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Award vesting period (in years) 4 years  
Capital Units | Conversion Of TMM Holdings Class M Units    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Common stock conversion ratio (in units) 1