Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.2
DERIVATIVE INSTRUMENTS (Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value) (Details) - USD ($)
$ in Millions
Jun. 30, 2019
Dec. 31, 2018
Derivatives, Fair Value [Line Items]    
Derivative assets $ 118.3 $ 91.5
Derivative liability 2.6 3.7
Not Designated as Hedging Instrument [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 118.1 91.4
Derivative liability 0.0 0.0
Fair Value, Inputs, Level 2 [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 0.2 0.1
Fair Value, Inputs, Level 3 [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 118.1 91.4
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 0.2 0.1
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability 2.6 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 assets 102.4 89.3
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 15.7 2.1
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 $ 0.0 $ 0.0