LONG-TERM DEBT - (Details) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Long-term debt      
Total $ 285,576   $ 349,944
Less: current portion (3,000)   (65,737)
Long-term debt 282,576   284,207
Repayment of outstanding principal balance 65,063 $ 5,064  
Term Loan B-1      
Long-term debt      
Total 285,576   287,207
Term Loan B-2      
Long-term debt      
Total     $ 62,737
Repayment of outstanding principal balance $ 60,900