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		$ 24,007	$ 23,728
Accumulated depreciation and amortization		(7,768)	(7,606)
Property, plant and equipment, net		16,521	16,430
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		19,676	19,154
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		1,917	1,864
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		1,056	1,007
Plant to be Retired (a)
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	[1]	700	719
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		658	984
Nuclear fuel
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		3,085	3,081
Accumulated depreciation and amortization		$ (2,803)	$ (2,773)

[1] Includes regulator-approved retirements of Sherco Units 1, 2 and 3 and A.S. King.