Property Plant and Equipment Major classes of property, plant and equipment (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment		$ 55,844	$ 52,249
Accumulated depreciation and amortization		(16,735)	(15,659)
Property, plant and equipment, net		39,483	36,944
Electric plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment		44,355	41,472
Natural gas plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment		6,560	6,210
Common and other property
Property, Plant and Equipment [Line Items]
Property, plant and equipment		2,341	2,154
Plant to be retired
Property, Plant and Equipment [Line Items]
Property, plant and equipment	[1]	259	322
CWIP
Property, Plant and Equipment [Line Items]
Property, plant and equipment		2,329	2,091
Nuclear fuel
Property, Plant and Equipment [Line Items]
Property, plant and equipment		2,909	2,771
Accumulated depreciation and amortization		$ (2,535)	$ (2,417)

[1] In 2018, the CPUC approved early retirement of PSCo’s Comanche Units 1 and 2 in approximately 2022 and 2025, respectively. PSCo also expects Craig Unit 1 to be retired early in 2025.  Amounts are presented net of accumulated depreciation.