Property, Plant and Equipment, Net - SPPC (Details) - SPPC - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Public Utility, Property, Plant and Equipment [Line Items]
Plant, net	$ 3,121	$ 3,027
Construction work- in-progress	219	137
Property, plant and equipment, net	$ 3,340	$ 3,164
Depreciation and amortization rate	3.10%	3.20%	3.10%
Regulated assets | Generation
Public Utility, Property, Plant and Equipment [Line Items]
Generation	$ 1,163	$ 1,130
Transmission	940	908
Distribution	1,846	1,754
General and intangible plant	$ 204	189
Regulated assets | Generation | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Useful life, generation	25 years
Useful life, transmission	50 years
Useful life, distribution	20 years
Useful life, other	5 years
Regulated assets | Generation | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Useful life, generation	60 years
Useful life, transmission	100 years
Useful life, distribution	100 years
Useful life, other	70 years
Regulated assets | Natural gas
Public Utility, Property, Plant and Equipment [Line Items]
Distribution	$ 438	429
General and intangible plant	$ 14	15
Regulated assets | Natural gas | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Useful life, distribution	35 years
Useful life, other	5 years
Regulated assets | Natural gas | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Useful life, distribution	70 years
Useful life, other	70 years
Regulated assets | Common Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Common general	$ 370	355
Utility plant in-service	4,975	4,780
Accumulated depreciation and amortization	(1,854)	(1,755)
Plant, net	$ 3,121	3,025
Regulated assets | Common Facilities | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Useful life, common general	5 years
Regulated assets | Common Facilities | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Useful life, common general	70 years
Nonregulated assets
Public Utility, Property, Plant and Equipment [Line Items]
Plant, net	$ 0	$ 2
Useful life, other	70 years