Derivatives And Risk Management (Derivative Instruments Summary) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Asset	$ 27,487	$ 86,233
Liability	(135,525)	(215,126)
Net Asset (Liability)	(108,038)	(128,893)
Other Current Assets [Member] | Foreign Currency Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset		32
Net Asset (Liability)		32
Other Current Liabilities [Member] | Foreign Currency Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability	(25)
Net Asset (Liability)	(25)
Other Current Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability	(9,241)	(16,253)
Net Asset (Liability)	(9,241)	(16,253)
Other Intangibles, Property And Investments - Net [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	5,084
Net Asset (Liability)	5,084
Other Non-Current Liabilities And Deferred Credits [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability		(2,642)
Net Asset (Liability)		(2,642)
Other Non-Current Liabilities And Deferred Credits [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	1,147	44,308
Liability	(35,864)	(84,838)
Net Asset (Liability)	(34,717)	(40,530)
Current Utility Energy Commodity Derivative Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	2,647	1,618
Liability	(365)	(479)
Net Asset (Liability)	2,282	1,139
Non-Current Utility Energy Commodity Derivative Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	8,148	185
Liability	(5,965)
Net Asset (Liability)	2,183	185
Current Utility Energy Commodity Derivative Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	10,461	40,090
Liability	(84,065)	(110,914)
Net Asset (Liability)	$ (73,604)	$ (70,824)