Property, Plant and Equipment (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment, Net, by Type [Abstract]
Total	$ 8,741	$ 8,204
Accumulated depreciation	2,907	2,839
Property, plant and equipment, net	5,834	5,365
Depreciation, Depletion and Amortization [Abstract]
Depreciation expense	280	265	257
Amortization of securitized regulatory assets	383	442	308
Other amortization	22	22	22
Total depreciation and amortization	685	729	587
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	29	23
Accretion expense	1	1
Revisions in estimates of cash flows	3	5
Ending balance	33	29	23
Increase (decrease) in revisions in estimates of cash flows	3	5
Transmission [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	1,926	1,851
Property, plant and equipment, useful life, weighted average (in years)	41
Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	5,848	5,548
Property, plant and equipment, useful life, weighted average (in years)	29
Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	$ 967	$ 805
Property, plant and equipment, useful life, weighted average (in years)	14