Selected Balance Sheet Data - Property, Plant and Equipment (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 5,126	$ 4,877
Less accumulated depreciation	(1,687)	(1,640)
Property, plant and equipment, net	3,439	3,237
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,971	3,845
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	517	502
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	292	278
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 346	$ 252