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STOCK-BASED COMPENSATION - Summary of Stock Option Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]    
Outstanding Beginning Balance (in shares) 3,685,125  
Granted (in shares) 414,507  
Exercised (in shares) (842,704)  
Expired (in shares) (4,904)  
Forfeited (in shares) (86,637)  
Outstanding Ending Balance (in shares) 3,165,387 3,685,125
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]    
Beginning, Weighted-Average Exercise Price (in usd per share) $ 12.45  
Granted, Weighted-Average Exercise Price (in usd per share) 22.67  
Exercised, Weighted-Average Exercise Price (in usd per share) 10.25  
Expired, Weighted-Average Exercise Price (in usd per share) 8.03  
Forfeited, Weighted-Average Exercise Price (in usd per share) 17.23  
Ending, Weighted-Average Exercise Price (in usd per share) $ 14.26 $ 12.45
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]    
Outstanding, Weighted- Average Remaining Contractual Term (years) 5 years 10 months 17 days 6 years 18 days
Outstanding, Aggregate Intrinsic Value $ 29,142  
Outstanding, Aggregate Intrinsic Value $ 15,567 $ 29,142
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested [Abstract]    
Vested (in shares) 2,331,801  
Vested, Weighted-Average Exercise Price (in usd per share) $ 12.29  
Vested, Weighted-Average Remaining Contractual Term (years) 4 years 10 months 2 days  
Vested, Aggregate Intrinsic Value $ 13,939  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]    
Expected to vest (in shares) 833,586  
Expected to vest, Weighted-Average Exercise Price (in usd per share) $ 19.76  
Expected to vest, Weighted-Average Remaining Contractual Term (years) 1 year 10 months 9 days  
Expected to vest, Aggregate Intrinsic Value $ 1,087  
Fair value valuation, estimated fair market value of stock (in usd per share) $ 18.00 $ 20.04
Performance Shares [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]    
Outstanding Beginning Balance (in shares) 980,671  
Outstanding Ending Balance (in shares)   980,671