Debt Leases and Banking Arrangements (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Line of Credit Facility [Line Items]
Amount of unsecured credit facility	$ 2,400
Total rent expense	56	49	45
$ 900 million unsecured credit facility effective June 2011
Line of Credit Facility [Line Items]
Amount of unsecured credit facility	900
Additional amount by which credit facility can be increased	250
Total aggregate purchase price of acquisitions that increases debt to EBITDA Ratio	50
Commitment fee	0.25%
Loans outstanding	0
$ 900 million unsecured credit facility effective June 2011 | Maximum [Member]
Line of Credit Facility [Line Items]
Ratio of debt to EBITDA	4.5
Ratio Of Debt To Ebitda After Acquisition	5
$ 900 million unsecured credit facility effective June 2011 | Letter of Credit Capacity | Maximum [Member]
Line of Credit Facility [Line Items]
Amount of unsecured credit facility	700
$ 2 billion WPZ unsecured credit facility (terminated)
Line of Credit Facility [Line Items]
Amount of unsecured credit facility	2,000
Increase In The Credit Facility Capacity	400
$2.4 billion WPZ unsecured credit facility
Line of Credit Facility [Line Items]
Additional amount by which credit facility can be increased	400
Total aggregate purchase price of acquisitions that increases debt to EBITDA Ratio	50
Maximum amount each of Transco and Northwest Pipeline can borrow	$ 400
Commitment fee	0.20%
Ratio Of Debt To Capitalization For Transco And Northwest Pipeline	65.00%
$2.4 billion WPZ unsecured credit facility | Maximum [Member]
Line of Credit Facility [Line Items]
Ratio of debt to EBITDA	5
Ratio Of Debt To Ebitda After Acquisition	5.5