Selected Balance Sheet Data Balance Sheet Related Disclosures, Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions		Mar. 31, 2022	Dec. 31, 2021
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 10,214	$ 10,109
Accumulated depreciation		(2,323)	(2,271)
Property, plant and equipment, net		7,891	7,838
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		9,734	9,639
Plant to be Retired
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	[1]	285	299
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 195	$ 171

[1] Includes expected retirement of Tolk and conversion of Harrington to natural gas.