Asset Sales Impairments and Other Accruals (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended					9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Mar. 31, 2011 Other [Member]	Sep. 30, 2010 Other [Member]	Jun. 30, 2010 Other [Member]	Sep. 30, 2011 Exploration & Production [Member]	Sep. 30, 2010 Exploration & Production [Member]	Sep. 30, 2011 Exploration & Production [Member] Correction Charge For Estimated Annual Compression Service [Member]	Sep. 30, 2011 Williams Partners [Member] Charges related to leak at underground natural gas storage facility [Member]	Sep. 30, 2011 Williams Partners [Member] Charges related to leak at underground natural gas storage facility [Member]	Sep. 30, 2010 Noncontrolling Interests [Member]	Sep. 30, 2010 Accelerated Amortization Of Debt Costs [Member]
Component of Other Expense, Nonoperating [Line Items]
Early debt retirement costs	$ 0	$ 0	$ 0	$ 606
Other transaction costs				45									7
Other income (expense) - net	0	4	(4)	12										4
Equity Method Investment, Realized Gain (Loss) on Disposal					11	30	13
Number Of quarterly payments					6
Exploratory dry hole costs								12	15
Impairment of Leasehold								50
Quantifying Misstatement in Current Year Financial Statements, Amount										14
Costs and operating expenses	$ 2,025	$ 1,748	$ 5,871	$ 5,382							$ 6	$ 13