Property, Plant and Equipment, Net Property, Plant and Equipment, Net (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Property, plant and equipment in service	$ 24,868		$ 24,024
Accumulated depreciation and amortization	(7,686)		(7,222)
Net property, plant and equipment In service	17,182		16,802
Construction work-in-progress	1,325		1,255
Total property, plant and equipment, net	18,507		18,057
Average depreciation and amortization rate	2.80%		2.80%		2.80%
Property, plant and equipment unallocated acquisition adjustments	159		159
Accumulated depreciation for unallocated acquisition adjustments	118		113
Minimum [Member]
Property, Plant and Equipment [Line Items]
Depreciable Life, Generation	20 years
Depreciable Life, Transmission	25 years
Depreciable Life, Distribution	20 years
Depreciable Life, Intangible plant	5 years	[1]
Depreciable Life, Other	5 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Depreciable Life, Generation	80 years
Depreciable Life, Transmission	75 years
Depreciable Life, Distribution	65 years
Depreciable Life, Intangible plant	65 years	[1]
Depreciable Life, Other	50 years
Generation [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment in service	11,058		10,952
Transmission [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment in service	5,235		4,732
Distribution [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment in service	6,030		5,859
Intangible plant [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment in service	857	[1]	850	[1]
Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment in service	1,688		1,631
Computer software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Depreciable Life, Intangible plant	5 years
Computer software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Depreciable Life, Intangible plant	10 years
Depreciable Assets [Member]
Property, Plant and Equipment [Line Items]
Change in Accounting Estimates, Impact on Future Periods	$ 40

[1] Computer software costs included in intangible plant are initially assigned a depreciable life of 5 to 10 years.