Derivatives And Risk Management (Derivative Instruments Summary) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Derivatives, Fair Value [Line Items]
Asset	$ 86,233	$ 35,105
Liability	(215,126)	(99,530)
Net Asset (Liability)	(128,893)	(64,425)
Other Current Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability	(16,253)
Net Asset (Liability)	(16,253)
Other Current Assets [Member] | Foreign Currency Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	32	116
Net Asset (Liability)	32	116
Other Intangibles, Property And Investments-Net [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset		127
Net Asset (Liability)		127
Other Non-Current Liabilities And Deferred Credits [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability	(2,642)	(53)
Net Asset (Liability)	(2,642)	(53)
Other Non-Current Liabilities And Deferred Credits [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	44,308	1,386
Liability	(84,838)	(32,371)
Net Asset (Liability)	(40,530)	(30,985)
Current Utility Energy Commodity Derivative Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	1,618	6,293
Liability	(479)	(3,701)
Net Asset (Liability)	1,139	2,592
Non-Current Utility Energy Commodity Derivative Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	185	21,249
Liability		(5,988)
Net Asset (Liability)	185	15,261
Current Utility Energy Commodity Derivative Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	40,090	5,934
Liability	(110,914)	(57,417)
Net Asset (Liability)	$ (70,824)	$ (51,483)