Selected Balance Sheet Data, Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 59,383	$ 55,844
Less accumulated depreciation and amortization		(17,456)	(16,735)
Property, plant and equipment, net		42,227	39,483
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		46,531	44,355
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		6,899	6,560
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		2,401	2,341
Plant to be retired
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	[1]	287	259
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		3,265	2,329
Nuclear fuel
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		2,930	2,909
Less accumulated depreciation and amortization		$ (2,630)	$ (2,535)

[1] The CPUC has approved early retirement of PSCo’s Comanche Units 1 and 2 in approximately 2022 and 2025, respectively, and PSCo’s Craig 1 in approximately 2025. Amounts are presented net of accumulated depreciation.