Divestitures (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
	Jul. 06, 2017	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Oct. 26, 2017	Dec. 31, 2016
Williams Olefins, L.L.C. [Member]
Income Statement and Additional Disclosures by Disposal Groups [Line Items]
Disposal Group, Consideration	$ 2,084
Gain (Loss) on Disposition of Business		$ 1,095
Income (Loss) from Individually Significant Component Disposed of Attributable to Parent, before Income Tax [Abstract]
Income (loss) before income taxes of disposal group		1	$ 61		$ 26	$ 109
Income (loss) before income taxes of disposal group attributable to the Williams Companies, Inc.		1	36		19	65
Williams Olefins, L.L.C. [Member] | Subsequent Event [Member]
Income Statement and Additional Disclosures by Disposal Groups [Line Items]
Disposal Group, Consideration							$ 12
Canadian Operations [Member]
Income Statement and Additional Disclosures by Disposal Groups [Line Items]
Disposal Group, Consideration								$ 1,020
Cash								31
Income (Loss) from Individually Significant Component Disposed of Attributable to Parent, before Income Tax [Abstract]
Income (loss) before income taxes of disposal group		0	(9)		0	(98)
Income (loss) before income taxes of disposal group attributable to the Williams Companies, Inc.		$ 0	(16)		$ 0	(95)
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down				$ 747
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal			65			65
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments			15			15
Reduction In Incentive Distribution Rights Payment [Member]
Income Statement and Additional Disclosures by Disposal Groups [Line Items]
Disposal Group, Consideration								$ 150
Williams Partners L.P. [Member]
Income (Loss) from Individually Significant Component Disposed of Attributable to Parent, before Income Tax [Abstract]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal			32			32
Williams Partners L.P. [Member] | Variable Interest Term Loan due 2018 [Member]
Income (Loss) from Individually Significant Component Disposed of Attributable to Parent, before Income Tax [Abstract]
Extinguishment of Debt, Amount	$ 850
Other [Member]
Income (Loss) from Individually Significant Component Disposed of Attributable to Parent, before Income Tax [Abstract]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal			$ 33			$ 33
Geismar [Member] | NGL And Petchem Services [Member]
Income Statement and Additional Disclosures by Disposal Groups [Line Items]
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest					88.50%