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	$ 23	$ 20
Capitalized Computer Software, Amortization	71	68	65
Capitalized Computer Software, Gross	668	608
Capitalized Computer Software, Accumulated Amortization	384	313
Capital Leased Assets, Gross	35	32
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	$ 21	$ 20
Electric [Member]
Public Utility Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.40%	3.30%	3.30%
Gas [Member]
Public Utility Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	2.40%	2.40%	2.30%
Minimum [Member]
Public Utility Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Finite-Lived Intangible Assets, Useful Life	1 year
Maximum [Member]
Public Utility Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	55 years
Finite-Lived Intangible Assets, Useful Life	28 years
Computer Software, Intangible Asset [Member] | Minimum [Member]
Public Utility Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Useful Life	3 years
Computer Software, Intangible Asset [Member] | Maximum [Member]
Public Utility Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Useful Life	15 years