Annual report pursuant to Section 13 and 15(d)

PENSIONS AND OTHER POSTRETIREMENT BENEFITS ( Fair Value of Recurring) (Details)

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PENSIONS AND OTHER POSTRETIREMENT BENEFITS ( Fair Value of Recurring) (Details) - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets $ 215.6 $ 202.4 $ 193.4
Hedge Funds [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 37.4 40.6 40.7
Private Equity Funds [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 39.8 36.1 33.1
Real Estate [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 65.5 61.9 57.5
Other Postretirement Benefit Plan, Defined Benefit [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 262.5 253.0 250.6
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 40.0 35.9  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 35.2 33.5 32.5
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 187.3 183.6  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fixed Income Investments [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 204.1 197.9  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fixed Income Investments [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 40.0 35.9  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fixed Income Investments [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fixed Income Investments [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 164.1 162.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Hedge Funds [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 11.4 11.2  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 11.4 11.2 11.2
Other Postretirement Benefit Plan, Defined Benefit [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Private Equity Funds [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 3.9 4.3  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 3.9 4.3 5.5
Other Postretirement Benefit Plan, Defined Benefit [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Structured Credit [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 7.9 6.9  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Structured Credit [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Structured Credit [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 7.9 6.9 5.8
Other Postretirement Benefit Plan, Defined Benefit [Member] | Structured Credit [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Real Estate [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 12.0 11.1  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Real Estate [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 12.0 11.1 $ 10.0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Real Estate [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Cash [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.2 0.2  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Cash [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Cash [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | Cash [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.2 0.2  
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Small Mid Cap [Member] | Equity Securities [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 2.8 2.7  
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Small Mid Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Small Mid Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Small Mid Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 2.8 2.7  
Other Postretirement Benefit Plan, Defined Benefit [Member] | International [Member] | Equity Securities [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 8.8 8.1  
Other Postretirement Benefit Plan, Defined Benefit [Member] | International [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | International [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | International [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 8.8 8.1  
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Large Cap [Member] | Equity Securities [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 11.4 10.6  
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Large Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Large Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Large Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets $ 11.4 $ 10.6