Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE MEASUREMENTS (Fair Value of Assets and Liabilities) (Details)

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FAIR VALUE MEASUREMENTS (Fair Value of Assets and Liabilities) (Details) - USD ($)
$ in Millions
Mar. 31, 2018
Jan. 01, 2018
Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Cash equivalents $ 526.6   $ 616.9
Derivative assets 93.6 $ 51.0 39.4
Total Asset 620.2   656.3
Derivative Liability 4.4   2.7
Total Liability 4.4   2.7
Fair Value, Inputs, Level 1 [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Cash equivalents 36.0   66.3
Derivative assets 0.0   0.0
Total Asset 36.0   66.3
Derivative Liability 0.0   0.0
Total Liability 0.0   0.0
Fair Value, Inputs, Level 2 [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Cash equivalents 490.6   550.6
Derivative assets 0.0   0.0
Total Asset 490.6   550.6
Derivative Liability 0.2   0.3
Total Liability 0.2   0.3
Fair Value, Inputs, Level 3 [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Cash equivalents 0.0   0.0
Derivative assets 93.6   39.4
Total Asset 93.6   39.4
Derivative Liability 4.2   2.4
Total Liability $ 4.2   $ 2.4