Risk Management and Fair Values (Derivative Instruments Designated as Cash Flow Hedges On Consolidated Statements Of Income) (Details) - Competitive Businesses Operating Revenues [Member] - Electricity Swaps And Options [Member] - Cash Flow Hedging [Member] $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
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)	$ 39
Unrealized Gain (Loss) on Derivatives	$ 2