Property, Plant and Equipment (Details Textuals) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Public Utility Property, Plant and Equipment [Line Items]
AFUDC capitalized	$ 21	$ 19
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.40%	3.30%	3.30%
Capitalized Computer Software, Amortization	64	62	58
Capitalized Computer Software, Gross	572	515
Capitalized Computer Software, Accumulated Amortization	323	259
Capital Leased Assets, Gross	9	6
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	$ 1	$ 3
Electric Generation Equipment [Member]
Public Utility Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	40
Electric Distribution [Member]
Public Utility Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	41
Minimum [Member] | Computer Software, Intangible Asset [Member]
Public Utility Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Maximum [Member] | Computer Software, Intangible Asset [Member]
Public Utility Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years