LONG-TERM DEBT AND LEASE OBLIGATIONS - Senior Secured and Senior Secured Notes (Details) - USD ($)
$ in Millions
1 Months Ended 3 Months Ended
Mar. 31, 2018
Mar. 31, 2018
Mar. 31, 2017
LONG-TERM DEBT AND LEASE OBLIGATIONS      
Loss from early extinguishment of debt   $ 1 $ 0
Senior Notes      
LONG-TERM DEBT AND LEASE OBLIGATIONS      
Repurchase of debt $ 51    
Repurchase of debt, accrued and unpaid interest 1    
Loss from early extinguishment of debt   (1)  
Senior Notes | 6.750% due 2023      
LONG-TERM DEBT AND LEASE OBLIGATIONS      
Repurchased face amount $ 28 $ 28  
Interest rate, stated percentage 6.75% 6.75%  
Senior Notes | 7.000% due 2025      
LONG-TERM DEBT AND LEASE OBLIGATIONS      
Repurchased face amount $ 22 $ 22  
Interest rate, stated percentage 7.00% 7.00%