Selected Balance Sheet Data - Property, Plant and Equipment (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 4,203	$ 4,138
Less accumulated depreciation	(1,502)	(1,478)
Property, plant and equipment, net	2,701	2,660
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,408	3,348
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	428	423
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	243	233
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 124	$ 134

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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