Segment Disclosures Reconciliation of Segment Modified EBITDA to Consolidated Net Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ 1,150	$ 918
Accretion expense associated with asset retirement obligations for nonregulated operations	(7)	(7)
Depreciation and amortization expenses	(442)	(445)
Equity earnings (losses)	107	97
Impairment of equity-method investments (Note 10)	0	(112)
Other investing income (loss) – net (Note 3)	272	18
Proportional Modified EBITDA of equity-method investments	(194)	(189)
Interest expense	(280)	(291)
(Provision) benefit for income taxes	(37)	(2)
Net income (loss)	569	(13)
Operating Segments [Member] | Williams Partners [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	1,132	955
Operating Segments [Member] | Other [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ 18	$ (37)