Property, Plant and Equipment (Details) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		$ 25,979	$ 24,923
Accumulated depreciation and amortization		(7,986)	(7,734)
Property, plant and equipment, net		18,300	17,478
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		20,716	20,114
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		2,216	2,100
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		1,298	1,156
Plant to be Retired (a)
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	[1]	616	646
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		1,133	907
Nuclear fuel
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		3,282	3,183
Accumulated depreciation and amortization		$ (2,975)	$ (2,894)

[1] Amounts include regulator-approved retirements of Sherco Units 1, 2, 3 and A.S. King. Amounts are reported net of accumulated depreciation.