Quarterly report pursuant to Section 13 or 15(d)

DERIVATIVE INSTRUMENTS (Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value) (Details)

v3.19.1
DERIVATIVE INSTRUMENTS (Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value) (Details) - USD ($)
$ in Millions
Mar. 31, 2019
Dec. 31, 2018
Derivatives, Fair Value [Line Items]    
Derivative Asset $ 107.4 $ 91.5
Derivative liability 10.5 3.7
Not Designated as Hedging Instrument [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 106.7 91.4
Derivative liability 9.8 0.0
Fair Value, Inputs, Level 3 [Member] | Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Derivative Financial Instruments, Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 0.7 0.1
Fair Value, Inputs, Level 3 [Member] | Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability 0.7 3.7
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Customer Supply Agreement [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 106.4 89.3
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability 9.8  
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset $ 0.3 2.1
Derivative liability   $ 0.0