Derivative Financial Instruments (Schedule Of Derivative Instruments) (Details)	3 Months Ended
	Mar. 31, 2012
Qualifies For Hedge Accounting Treatment [Member] | NYMEX - Cash Flow Hedges [Member]
Derivative [Line Items]
Hedge Type	Cash Flow Hedge
Hedge Purpose	To hedge the variability in cash flows related to a forecasted transaction.
Accounting Treatment	The effective portion of changes in the value of the hedge are recorded to accumulated other comprehensive income/loss and reclassified to earnings when the forecasted transaction occurs. Any ineffectiveness is recognized currently in earnings.
Qualifies For Hedge Accounting Treatment [Member] | NYMEX - Fair Value Hedges [Member]
Derivative [Line Items]
Hedge Type	Fair Value Hedge
Hedge Purpose	To hedge against changes in the fair value of a recognized asset or liability.
Accounting Treatment	The effective portion of changes in the value of the hedge are recorded as adjustments to the asset or liability being hedged. Any ineffectiveness is recognized currently in earnings.
Does Not Qualify For Hedge Accounting Treatment [Member] | NYMEX - Economic Hedges [Member]
Derivative [Line Items]
Hedge Type	Economic Hedge
Hedge Purpose	To effectively serve as either a fair value or a cash flow hedge; however, the derivative agreement does not qualify for hedge accounting treatment or is not designated as a hedge in accordance with Accounting Standards Codification ("ASC") 815, Derivatives and Hedging.
Accounting Treatment	Changes in the value of these agreements are recognized currently in earnings.