Property, Plant and Equipment, Net - NPC (Details) - NPC - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Plant, net	$ 6,612	$ 6,559
Construction work-in-progress	217	142
Property, plant and equipment, net	6,829	6,701
Regulated
Property, Plant and Equipment [Line Items]
Generation	3,780	3,690
Transmission	1,493	1,468
Distribution	3,878	3,771
General and intangible	810	791
Utility plant in service	9,961	9,720
Accumulated depreciation and amortization	(3,350)	(3,162)
Plant, net	$ 6,611	6,558
Regulated | Minimum
Property, Plant and Equipment [Line Items]
Useful life, generation	30 years
Useful life, transmission	45 years
Useful life, distribution	20 years
Useful life, other	5 years
Regulated | Maximum
Property, Plant and Equipment [Line Items]
Useful life, generation	55 years
Useful life, transmission	70 years
Useful life, distribution	65 years
Useful life, other	65 years
Nonregulated
Property, Plant and Equipment [Line Items]
Plant, net	$ 1	$ 1
Useful life, other	45 years