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, 2017
Dec. 31, 2016
Fair Value, Assets Measured On Recurring Basis, Unobservable Input Reconciliation [Roll Forward]    
Beginning balance - January 1 $ 31.6 $ 7.8
Total gains    
Included in earnings 195.8 103.8
Settlements (188.0) (80.0)
Transfers into Level 3 0.0 0.0
Transfers out of Level 3 0.0 0.0
Ending balance - December 31 39.4 31.6
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 39.4 23.7
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]    
Beginning balance - January 1 (0.5) (3.4)
Total gains    
Included in earnings (91.1) (14.1)
Settlements 89.2 17.0
Transfers into Level 3 0.0 0.0
Transfers out of Level 3 0.0 0.0
Ending balance - September 30 (2.4) (0.5)
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 $ (2.4) $ (0.5)