Financial Risk Management Activities (Schedule Of Derivative Instruments Not Designated As Hedging Instruments And Their Impact On Condensed Consolidated Statements Of Operations) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives not designated as hedging instruments	$ 163	$ (62)	$ (3)
Operating Revenues [Member] | Energy-Related Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives not designated as hedging instruments	205	(53)	128
Energy Costs [Member] | Energy-Related Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives not designated as hedging instruments	(42)	(9)	(144)
Other Income [Member] | Derivatives In NDT Funds [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives not designated as hedging instruments	$ 0	$ 0	$ 13