Property, Plant and Equipment (Components of PP&E) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 25,383	$ 25,242
Accumulated depreciation	(8,505)	(8,227)
Property, Plant and Equipment, Net	16,878	17,015
Electric generation and distribution facilities
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 22,869	22,875
Electric generation and distribution facilities | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	7 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	$ 1,612	1,651
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	72 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 319	310
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	25 years
Other
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 583	$ 406
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	44 years