Assets Held for Sale (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jul. 06, 2017	Dec. 31, 2016
Income Statement and Additional Disclosures by Disposal Groups [Line Items]
Disposal Group, Including Discontinued Operation, Liabilities, Current		$ 36		$ 36			$ 0
Williams Partners [Member]
Income Statement and Additional Disclosures by Disposal Groups [Line Items]
Assets Held-for-sale, Not Part of Disposal Group		4		4
Williams Olefins, L.L.C. [Member]
Income Statement and Additional Disclosures by Disposal Groups [Line Items]
Disposal Group, Including Discontinued Operation, Other Assets, Current		72		72
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		903		903
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent		25		25
Disposal Group, Including Discontinued Operation, Assets		1,000		1,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Current		35		35
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		1		1
Disposal Group, Including Discontinued Operation, Liabilities, Current		36		36
Income (Loss) from Individually Significant Component Disposed of Attributable to Parent, before Income Tax [Abstract]
Income (loss) before income taxes of disposal group		2	$ 30	25	$ 48
Income (loss) before income taxes of disposal group attributable to the Williams Companies, Inc.		$ 2	$ 18	$ 19	$ 29
Williams Olefins, L.L.C. [Member] | Subsequent Event [Member]
Income Statement and Additional Disclosures by Disposal Groups [Line Items]
Disposal Group, Consideration						$ 2,084
Gain (Loss) on Disposition of Business	$ 1,100