Property Plant and Equipment Property Plant and Equipment (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment		$ 22,699	$ 21,279
Accumulated depreciation		5,229	5,124
Property, plant and equipment, net		17,470	16,155
Electric plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment		15,736	14,362
Natural gas plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment		5,037	4,631
Common and other property
Property, Plant and Equipment [Line Items]
Property, plant and equipment		1,191	1,113
Plant to be retired
Property, Plant and Equipment [Line Items]
Property, plant and equipment	[1]	225	260
CWIP
Property, Plant and Equipment [Line Items]
Property, plant and equipment		$ 510	$ 913

[1] Includes regulator-approved retirements of Comanche Units 1 and 2 and jointly owned Craig Unit 1. Also includes PSCo’s planned retirement of jointly owned Craig Unit 2.