Property, Plant and Equipment (Components of PP&E) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 26,707	$ 25,383
Accumulated depreciation	(8,472)	(8,505)
Property, Plant and Equipment, Net	18,235	16,878
Electric generation and distribution facilities
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 24,239	22,869
Electric generation and distribution facilities | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Electric generation and distribution facilities | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Other buildings
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 1,507	1,612
Other buildings | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Other buildings | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	51 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 333	319
Furniture and Fixtures [Member] | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Fixtures [Member] | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	30 years
Other
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 628	$ 583
Other | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Other | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	39 years