Risk Management and Fair Values (Derivative Instruments Designated as Cash Flow Hedges On Consolidated Statements Of Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Effect of Derivative instruments designated as cash flow hedges on consolidated statements of income
Amount of gain reclassified from accumulated OCI into income (effective portion)	$ 47	$ 268	$ 168
Competitive Businesses Operating Revenues [Member] | Electricity Swaps And Options [Member] | Cash Flow Hedging [Member]
Effect of Derivative instruments designated as cash flow hedges on consolidated statements of income
Amount of gain (loss) recognized in AOCI (effective portion)	(190)	111	296
Amount of gain reclassified from accumulated OCI into income (effective portion)	$ 47	$ 268	$ 168