Segment Disclosures Reconciliation of Segment Modified EBITDA to Consolidated Net Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ 1,120	$ 1,150
Accretion expense associated with asset retirement obligations for nonregulated operations	(8)	(7)
Depreciation and amortization expenses	(431)	(442)
Equity earnings (losses)	82	107
Other investing income (loss) – net	(4)	(272)
Proportional Modified EBITDA of equity-method investments	(169)	(194)
Interest expense	(273)	(280)
(Provision) benefit for income taxes	(55)	(37)
Net income (loss)	270	569
Operating Segments [Member] | Williams Partners [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	1,107	1,132
Operating Segments [Member] | Other [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ 13	$ 18