Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.3
DERIVATIVE INSTRUMENTS (Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value) (Details) - USD ($)
$ in Millions
Sep. 30, 2019
Dec. 31, 2018
Derivatives, Fair Value [Line Items]    
Derivative assets $ 72.8 $ 91.5
Derivative liability 32.6 3.7
Not Designated as Hedging Instrument [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 72.8 91.4
Derivative liability 30.2 0.0
Fair Value, Inputs, Level 2 [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 0.0 0.1
Derivative liability 2.4 3.7
Fair Value, Inputs, Level 3 [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 72.8 91.4
Derivative liability 30.2 0.0
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Derivative Asset [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 0.0 0.1
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Derivative Liability [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability 2.4 3.7
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Customer Supply Agreement [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 71.2 89.3
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 1.6 2.1
Derivative liability $ 30.2  
Valuation, Market Approach [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Derivative Liability [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability   $ 0.0