Annual report pursuant to Section 13 and 15(d)

FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value, Assets and Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation) (Details)

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FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value, Assets and Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2018
Dec. 31, 2017
Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]        
Derivative assets $ 91.5 $ 91.5 $ 37.9 $ 49.5
Fair Value, Assets Measured On Recurring Basis, Unobservable Input Reconciliation [Roll Forward]        
Beginning balance - January 1 37.9 49.5 30.1  
Total gains        
Included in earnings   428.7 176.2  
Settlements   (386.8) (168.4)  
Ending balance - December 31 91.4 91.4 37.9  
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) on assets still held at the reporting date 91.4   37.9  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]        
Beginning balance - January 1 (1.7)   0.0  
Total gains        
Included in earnings (6.1)   (55.6)  
Settlements 7.8   53.9  
Ending balance - September 30 0.0 0.0 (1.7)  
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) on liabilities still held at the reporting date 0.0   $ (1.7)  
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]        
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]        
Derivative assets $ 30.8 $ 30.8   $ 11.6