Investing Activities (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended												1 Months Ended	12 Months Ended													12 Months Ended					1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended
	May 31, 2011	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009		Dec. 31, 2011 All Other Segments [Member]	Dec. 31, 2010 All Other Segments [Member]	Dec. 31, 2009 All Other Segments [Member]	Dec. 31, 2011 Williams Partners [Member]	Dec. 31, 2010 Williams Partners [Member]	Dec. 31, 2009 Williams Partners [Member]	Sep. 30, 2010 Overland Pass Pipeline Company LLC [Member]	Dec. 31, 2011 Overland Pass Pipeline Company LLC [Member]	Dec. 31, 2010 Overland Pass Pipeline Company LLC [Member]	Dec. 31, 2009 Overland Pass Pipeline Company LLC [Member]	Dec. 31, 2011 Gulfstream Natural Gas System LLC [Member]		Dec. 31, 2010 Gulfstream Natural Gas System LLC [Member]		Dec. 31, 2009 Gulfstream Natural Gas System LLC [Member]	Dec. 31, 2011 Gulfstream Natural Gas System LLC [Member] All Other Segments [Member]	May 31, 2011 Gulfstream Natural Gas System LLC [Member] All Other Segments [Member]	Dec. 31, 2011 Gulfstream Natural Gas System LLC [Member] Williams Partners [Member]	May 31, 2011 Gulfstream Natural Gas System LLC [Member] Williams Partners [Member]	May 31, 2011 Gulfstream Natural Gas System LLC [Member] Intercompany Transfer [Member]	Dec. 31, 2011 Discovery Producer Services LLC [Member]		Dec. 31, 2010 Discovery Producer Services LLC [Member]		Dec. 31, 2009 Discovery Producer Services LLC [Member]	Jun. 30, 2009 Laurel Mountain Midstream, LLC [Member]	Dec. 31, 2011 Laurel Mountain Midstream, LLC [Member]		Dec. 31, 2010 Laurel Mountain Midstream, LLC [Member]		Jun. 30, 2010 Accroven SRL sold [Member]	Dec. 31, 2011 Accroven SRL sold [Member]	Dec. 31, 2010 Accroven SRL sold [Member]	Dec. 31, 2009 Accroven SRL sold [Member]	Dec. 31, 2011 Aux Sable Liquid Products LP [Member]	Dec. 31, 2010 Aux Sable Liquid Products LP [Member]	Dec. 31, 2009 Aux Sable Liquid Products LP [Member]	Dec. 31, 2011 Other [Member]	Dec. 31, 2010 Other [Member]	Sep. 30, 2010 Overland Pass Pipeline Company LLC Acquired [Member]
Investing income
Income (loss) from equity method investments		$ 155	[1]	$ 143	[1]	$ 118	[1]	$ 13	$ 34	$ 37	$ 142	$ 109	$ 81					$ 12		$ 32		$ 30
Income (loss) from investments		7	[1]	43	[1]	(75)	[1]	11	43	(75)	0	0	0																										11	43	75
Impairment of cost-based investments		(1)		0		(11)
Interest income and other		7		2		6
Total investing income		168		188		38
Investments
Equity Method Investments		1,390		1,238				7	193	196	1,383	1,045	593		433	429		362	[2]	378	[2]							182	[3]	181	[3]			291	[3]	170	[3]								122	80
Cost method		1		2
Marketable equity securities		24		0
Total investments		1,415		1,240
Dividends and distributions
Equity method investment, dividends or distributions		193		175		282									19	0	0	84		81		223						40		44		32										35	28	15
Equity Method Investment, Ownership Percentage															50.00%			50.00%					1.00%	1.00%	49.00%	49.00%	24.50%	60.00%					51.00%	51.00%				50.00%									49.00%
Proceeds from Sale of Equity Method Investments	297																																					107
Equity Method Investment, payments to purchase or contributions														424																			133	137		43						30
Percentage of after tax discount rate included in weighted discounted cash flow analysis						20.00%
Distribution from company related to debt offering		0		0		148
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity		62
Summarized Financial Position of Equity Method Investments
Current assets		293		236
Noncurrent assets		4,409		3,976
Current liabilities		235		157
Noncurrent liabilities		1,257		1,294
Summarized Results of Operations of Equity Method Investments
Revenue		1,242		1,086		872
Operating income		623		587		409
Net income		460		429		317
Related Party Transactions [Abstract]
Revenue from Related Parties		23		41		27
Related Party Transaction, Expenses from Transactions with Related Party		234		220		158
Related party transaction, receivable		1		2
Related party transaction, payable		23		20
Related party transaction, operating fees		$ 57		$ 38		$ 23

[1] Items also included in segment profit (loss). (See Note 18.)

[2] As of December 31, 2011, 49 percent interest is held within Williams Partners, with the remaining 1 percent held within Other.

[3] We account for these investments under the equity method due to the significant participatory rights of our partners such that we do not control the investments.