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SHARE-BASED COMPENSATION - Long term equity compensation plan narrative (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
May 31, 2017
Restricted Stock And Restricted Stock Units        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Fair value of restricted stock and cash settled awards vested $ 125 $ 67 $ 75  
Unrecognized compensation costs $ 94 $ 85    
Weighted average period for recognition of share based compensation 2 years 4 months 45 days 2 years 3 months 27 days    
Share based compensation expense incurred $ 68 $ 74 59  
Tax benefit related to share-based compensation costs incurred 15 16 $ 15  
Restricted Stock And Restricted Stock Units | Cash Settled        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Cash settled awards 22 $ 48    
Restricted Stock Units (RSUs)        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Tax benefit related to share-based compensation costs incurred $ 7      
2007 Long-term Equity Compensation Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Maximum number of shares to be issued under the plan (in shares)       3,400,000.0
Number of awards available for grant under plan (in shares) 3,274,004      
2007 Long-term Equity Compensation Plan | Share Settled        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Period of time subsequent to a change in control during which plan allows for accelerated vesting of awards for certain terminations 2 years      
2014 Long Term Equity Compensation Plan | Restricted Stock And Restricted Stock Units        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Fair value of restricted stock and cash settled awards vested $ 44      
Vesting period 3 years