Property, Plant, and Equipment (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 712	$ 658	$ 611
Property, Plant, and Equipment (Textuals)
Offsetting increase related to changes in the timing and method of abandonment on certain of Transco's natural gas storage caverns	13	39
Asset retirement obligation included in regulatory liabilties deferred income and other	511	507
Regulated [Member]
Property, Plant and Equipment [Line Items]
Amounts in excess of the original cost of the regulated facilities within our gas pipeline businesses	825	865
Period of straight-line amortization method	40
Property, Plant, and Equipment (Textuals)
Amounts in excess of the original cost of the regulated facilities within our gas pipeline businesses	$ 825	$ 865
Period of straight-line amortization method	40