Segment Disclosures Recon from Segment to Consolidated - Modified EBITDA (Details 1) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Modified EBITDA by segment to Net Income Loss
Modified Ebitda		$ 3,891	$ 3,232	$ 2,611
Asset Retirement Obligation Accretion Expense For Nonregulated Operations		(28)	(18)	(15)
Depreciation and amortization expenses		(1,738)	(1,176)	(815)
Impairment of goodwill	$ (1,098)	(1,098)	0	0
Equity earnings (losses)		335	144	134
Gain on remeasurement of equity-method investment		0	2,544	0
Impairment of equity-method investments		(1,359)	0	0
Other investing income (loss) – net		27	43	81
Proportional Modified Ebitda Equity Method Investments		(699)	(438)	(406)
Interest Expense		(1,044)	(747)	(510)
(Provision) benefit for income taxes		399	(1,249)	(401)
Income (loss) from discontinued operations, net of tax		0	4	(11)
Net income (loss)		(1,314)	2,339	668
Williams Partners [Member]
Reconciliation of Modified EBITDA by segment to Net Income Loss
Impairment of goodwill		(1,098)
Operating Segments [Member] | Williams Partners [Member]
Reconciliation of Modified EBITDA by segment to Net Income Loss
Modified Ebitda		4,003	3,244	2,447
Proportional Modified Ebitda Equity Method Investments		(699)	(431)	(209)
Operating Segments [Member] | Williams NGL & Petchem Services [Member]
Reconciliation of Modified EBITDA by segment to Net Income Loss
Modified Ebitda		(83)	(115)	(33)
Proportional Modified Ebitda Equity Method Investments		0	78	0
Operating Segments [Member] | Other [Member]
Reconciliation of Modified EBITDA by segment to Net Income Loss
Modified Ebitda		(29)	103	197
Proportional Modified Ebitda Equity Method Investments		$ 0	$ (85)	$ (197)