Property Plant and Equipment Property Plant and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 52,249	$ 48,927
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(15,659)	(15,000)
Property, Plant and Equipment, Net	36,944	34,329
Electric plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment	41,472	39,016
Natural gas plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment	6,210	5,800
Common and other property
Property, Plant and Equipment [Line Items]
Property, plant and equipment	2,154	2,013
Plant to be retired
Property, Plant and Equipment [Line Items]
Property, plant and equipment	322	11
CWIP
Property, Plant and Equipment [Line Items]
Property, plant and equipment	2,091	2,087
Nuclear fuel
Property, Plant and Equipment [Line Items]
Property, plant and equipment	2,771	2,697
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ (2,417)	$ (2,295)