Property, Plant And Equipment (Schedule Of Property Plant And Equipment) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Original Cost	$ 12,855	$ 12,120
Accumulated Depreciation	4,635	4,447
Net Book Value	8,220	7,673
Generation [Member]
Property, Plant and Equipment [Line Items]
Original Cost	108	105
Accumulated Depreciation	82	72
Net Book Value	26	33
Distribution [Member]
Property, Plant and Equipment [Line Items]
Original Cost	7,832	7,567
Accumulated Depreciation	2,848	2,749
Net Book Value	4,984	4,818
Transmission [Member]
Property, Plant and Equipment [Line Items]
Original Cost	2,462	2,307
Accumulated Depreciation	834	793
Net Book Value	1,628	1,514
Gas [Member]
Property, Plant and Equipment [Line Items]
Original Cost	429	413
Accumulated Depreciation	133	125
Net Book Value	296	288
Construction Work in Progress [Member]
Property, Plant and Equipment [Line Items]
Original Cost	742	553
Net Book Value	742	553
Non-operating and Other Property [Member]
Property, Plant and Equipment [Line Items]
Original Cost	1,282	1,175
Accumulated Depreciation	738	708
Net Book Value	$ 544	$ 467