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INCENTIVE PLANS - Performance Share Units (Details) - $ / shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Weighted- average grant date fair value per share (in dollars per share):      
Weighted-average market value (in dollars per share) $ 57.45 $ 37.35 $ 50.33
Performance Share Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Period used for calculation of performance goals 3 years    
Percentage of target shares earned 100.00%    
Number of shares of common stock equivalent to each target share   1  
Valuation Assumptions      
Expected volatility 25.79% 24.37% 27.13%
Expected dividend yield 1.30% 0.40% 0.08%
Unvested stock awards (in shares):      
Beginning of period (in shares) 1,844,560    
Granted (in shares) 500,609    
Canceled (in shares) (277,546)    
Payments (in shares) (280,897)    
End of period (in shares) 1,786,726 1,844,560  
Weighted- average grant date fair value per share (in dollars per share):      
Beginning of period (in dollars per share) $ 38.22    
Granted (in dollars per share) 59.22    
Canceled (in dollars per share) 48.34    
Payments (in dollars per share) 48.34    
End of period (in dollars per share) $ 40.94 $ 38.22  
Weighted-average market value (in dollars per share)   $ 27.03 $ 44.07
Minimum | Performance Share Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Percentage of target shares earned 0.00%    
Maximum | Performance Share Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Percentage of target shares earned 150.00%