Other Income and Expenses (Details) - USD ($) $ in Millions				3 Months Ended		9 Months Ended
		Jul. 03, 2017	Feb. 23, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Gain (Loss) on Disposition of Assets				$ 1,095	$ 0	$ 1,095	$ 0
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums		$ 51	$ 53
Debt Instrument, Unamortized Premium		54	23
Debt Instrument, Unamortized Discount (Premium), Net		3	30	27		27
Williams Partners [Member]
Segment Reporting Information [Line Items]
Revenue adjustment associated with litigation							(15)
Other income (expense) - net [Member] | Williams Partners [Member]
Segment Reporting Information [Line Items]
Amortization of regulatory assets associated with asset retirement obligations				8	8	25	25
Accrual of regulatory liability related to overcollection of certain employee expenses				5	6	16	19
Net foreign currency exchange (gains) losses (1)	[1]			0	0	0	11
Gain (Loss) on Disposition of Assets				0	0	(12)	0
Gain (Loss) on Contract Termination				0	0	(15)	0
Project development costs				4	11	12	19
Other income (expense) - net [Member] | Other [Member]
Segment Reporting Information [Line Items]
Gain on sale of unused pipe				0	0	0	(10)
Selling, general, and administrative expenses [Member] | Other [Member]
Segment Reporting Information [Line Items]
Project development costs					16		61
Selling, general, and administrative expenses and Operating and maintenance expenses [Member] | Williams Partners [Member]
Segment Reporting Information [Line Items]
Severance and other related costs				5		18	$ 26
Approximate percentage of workforce reductions							10.00%
Other Nonoperating Income (Expense) [Member] | Williams Partners [Member]
Segment Reporting Information [Line Items]
Allowance for funds used during construction, capitalized cost of equity				17	17	55	$ 46
Deferred taxes on equity funds used during construction [Member] | Other [Member]
Segment Reporting Information [Line Items]
Allowance for funds used during construction, capitalized cost of equity				8	6	44	16
Canadian Operations [Member]
Segment Reporting Information [Line Items]
Loss on sale of Canadian operations (see Note 2)					(65)		(65)
Disposal Group, Not Discontinued Operations [Member] | Canadian Operations [Member] | Other income (expense) - net [Member] | Williams Partners [Member]
Segment Reporting Information [Line Items]
Loss on sale of Canadian operations (see Note 2)				4	32	0	32
Disposal Group, Not Discontinued Operations [Member] | Canadian Operations [Member] | Other income (expense) - net [Member] | Williams Ngl And Petchem Services [Member]
Segment Reporting Information [Line Items]
Loss on sale of Canadian operations (see Note 2)				0	33	1	33
Williams Partners L.P. [Member]
Segment Reporting Information [Line Items]
Loss on sale of Canadian operations (see Note 2)					(32)		(32)
4.875% Senior Unsecured Notes due 2023 [Member] | Williams Partners L.P. [Member]
Segment Reporting Information [Line Items]
Long-term debt retired		$ 1,400
Long-term debt interest rate		4.875%
6.125% Senior Unsecured Notes due 2022 [Member] | Williams Partners L.P. [Member]
Segment Reporting Information [Line Items]
Long-term debt retired			$ 750
Long-term debt interest rate			6.125%
Acquisition and Merger [Member] | Selling, general, and administrative expenses [Member] | Williams Partners [Member]
Segment Reporting Information [Line Items]
Business combination, merger related costs				$ 5	$ 21	$ 9	$ 40

[1] Primarily relates to gains and losses incurred on foreign currency transactions and the remeasurement of U.S. dollar denominated current assets and liabilities within our former Canadian operations.