Risk Management, Derivative Instruments And Hedging Activities (Cash Flow Hedges - Location And Amount Of Pre-Tax Losses Recognized In Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Total Pre-tax (Losses) Gains Recorded in AOCI	$ (88)	$ 2
Total Pre-tax (Losses) Reclassified from AOCI into Earnings	(5)	(3)
Fuel Used In Electric Generation And Purchased Power-Non-Regulated [Member]
Total Pre-tax (Losses) Reclassified from AOCI into Earnings		2
Interest Rate Contracts [Member]
Total Pre-tax (Losses) Gains Recorded in AOCI	(88)	2
Total Pre-tax (Losses) Reclassified from AOCI into Earnings	$ (5)	$ (5)