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Property, Plant And Equipment Property, Plant and Equipment (Schedule of Depreciation Provisions For Utility Plant as a Percentage of the Original Cost) (Details)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Electric Operations      
Property, Plant and Equipment [Line Items]      
Depreciation Provisions For Utility Plant Percentage 2.90% [1] 3.40% 3.30%
Gas Distribution Operations      
Property, Plant and Equipment [Line Items]      
Depreciation Provisions For Utility Plant Percentage 2.20% 2.10% 2.10%
[1] Lower depreciation rate in 2018 due to reduced EERM-related depreciation expense and higher depreciable base from transmission assets being placed into service in 2018.