v2.4.0.8
Risk Management Activities (The Effect Of Derivative Instruments Reclassified To Statements Of Consolidated Income) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Jun. 30, 2013
Jun. 30, 2012
Cash Flow Hedging [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in OCI Derivative (Effective Portion) $ (0.1) $ 0.7 $ 0 $ 1.4
Amount of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) (0.4) (0.9) (0.7) (2.1)
Fair Value Hedging [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in Income on Derivatives 0.2 0.8 (9.5) (8.2)
Amount of Gain Recognized in Income on Related Hedged Items (0.2) (0.8) 9.5 8.2
Not Designated as Hedging Instrument [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in Income on Derivatives 7.7 17.2 1.3 (5.2)
Interest Expense [Member] | Cash Flow Hedging [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) (0.4) (0.7) (0.8) (1.3)
Cost Of Sales [Member] | Cash Flow Hedging [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) 0 (0.2) 0.1 (0.8)
Commodity Price Risk Programs [Member] | Cash Flow Hedging [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in OCI Derivative (Effective Portion) (0.1) 0.3 0 0.6
Commodity Price Risk Programs [Member] | Not Designated as Hedging Instrument [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Losses recognized in income, deferred (7.6) (4.7) (1.0) (15.1)
Commodity Price Risk Programs [Member] | Gas Distribution Revenues [Member] | Not Designated as Hedging Instrument [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in Income on Derivatives (0.1) (0.1) 0 0.3
Commodity Price Risk Programs [Member] | Other Revenues [Member] | Not Designated as Hedging Instrument [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in Income on Derivatives 10.8 7.7 22.8 6.0
Commodity Price Risk Programs [Member] | Cost Of Sales [Member] | Not Designated as Hedging Instrument [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in Income on Derivatives (3.0) 9.6 (21.5) (11.5)
Interest Rate Risk Activities [Member] | Cash Flow Hedging [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in OCI Derivative (Effective Portion) 0 0.4 0 0.8
Interest Rate Risk Activities [Member] | Interest Expense [Member] | Fair Value Hedging [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in Income on Derivatives 0.2 0.8 (9.5) (8.2)
Fixed Rate Debt Hedges [Member] | Interest Expense [Member] | Fair Value Hedging [Member]
       
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain Recognized in Income on Related Hedged Items $ (0.2) $ (0.8) $ 9.5 $ 8.2