Segment Disclosures (Details 1) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Segment revenues:
Revenues	$ 1,799	$ 2,069	$ 5,354	$ 5,496
Total assets by reporting segment
Total assets	50,819		50,819		$ 50,563
Reconciliation of Modified EBITDA to net income (loss):
Modified EBITDA	999	822	2,857	2,136
Accretion expense associated with asset retirement obligations for nonregulated operations	(6)	(4)	(21)	(13)
Depreciation and amortization expenses	(432)	(369)	(1,287)	(797)
Equity earnings (losses)	92	66	236	55
Gain on remeasurement of equity-method investment	0	2,522	0	2,522
Impairment of equity-method investments	(461)	0	(461)	0
Other investing income (loss) - net	18	11	27	43
Proportional Modified Ebitda Equity Method Investments	(185)	(132)	(504)	(273)
Interest Expense	(263)	(210)	(776)	(513)
(Provision) benefit for income taxes	65	(998)	(48)	(1,133)
Income (loss) from discontinued operations, net of tax	0	0	0	4
Net income (loss)	(173)	1,708	23	2,031
Service [Member]
Segment revenues:
Revenues	1,239	1,127	3,677	2,771
Product [Member]
Segment revenues:
Revenues	560	942	1,677	2,725
Williams Partners [Member]
Total assets by reporting segment
Total assets	49,639		49,639		49,322
Reconciliation of Modified EBITDA to net income (loss):
Modified EBITDA	1,021	843	2,891	2,147
Equity earnings (losses)		(19)		(19)
Williams Partners [Member] | Service [Member]
Segment revenues:
Revenues	1,232	1,065	3,655	2,591
Williams Partners [Member] | Product [Member]
Segment revenues:
Revenues	560	942	1,677	2,725
Williams NGL & Petchem Services [Member]
Total assets by reporting segment
Total assets	802		802		612
Reconciliation of Modified EBITDA to net income (loss):
Modified EBITDA	(5)	(4)	(13)	(112)
Williams NGL & Petchem Services [Member] | Service [Member]
Segment revenues:
Revenues	1	0	2	0
Williams NGL & Petchem Services [Member] | Product [Member]
Segment revenues:
Revenues	0	0	0	0
Other [Member]
Total assets by reporting segment
Total assets	999		999		1,220
Reconciliation of Modified EBITDA to net income (loss):
Modified EBITDA	(17)	(17)	(21)	101
Other [Member] | Service [Member]
Segment revenues:
Revenues	6	62	20	180
Other [Member] | Product [Member]
Segment revenues:
Revenues	0	0	0	0
Operating Segments [Member] | Williams Partners [Member]
Segment revenues:
Revenues	1,792	2,008	5,333	5,317
Operating Segments [Member] | Williams Partners [Member] | Service [Member]
Segment revenues:
Revenues	1,232	1,066	3,655	2,592
Operating Segments [Member] | Williams Partners [Member] | Product [Member]
Segment revenues:
Revenues	560	942	1,678	2,725
Operating Segments [Member] | Williams NGL & Petchem Services [Member]
Segment revenues:
Revenues	1	0	2	0
Operating Segments [Member] | Williams NGL & Petchem Services [Member] | Service [Member]
Segment revenues:
Revenues	1	0	2	0
Operating Segments [Member] | Williams NGL & Petchem Services [Member] | Product [Member]
Segment revenues:
Revenues	0	0	0	0
Operating Segments [Member] | Other [Member]
Segment revenues:
Revenues	70	69	143	194
Operating Segments [Member] | Other [Member] | Service [Member]
Segment revenues:
Revenues	70	69	143	194
Operating Segments [Member] | Other [Member] | Product [Member]
Segment revenues:
Revenues	0	0	0	0
Intersegment Elimination [Member]
Segment revenues:
Revenues	(64)	(8)	(124)	(15)
Total assets by reporting segment
Total assets	(621)		(621)		$ (591)
Intersegment Elimination [Member] | Service [Member]
Segment revenues:
Revenues	(64)	(8)	(123)	(15)
Intersegment Elimination [Member] | Product [Member]
Segment revenues:
Revenues	0	0	(1)	0
Intersegment Elimination [Member] | Williams Partners [Member] | Service [Member]
Segment revenues:
Revenues	0	(1)	0	(1)
Intersegment Elimination [Member] | Williams Partners [Member] | Product [Member]
Segment revenues:
Revenues	0	0	(1)	0
Intersegment Elimination [Member] | Williams NGL & Petchem Services [Member] | Service [Member]
Segment revenues:
Revenues	0	0	0	0
Intersegment Elimination [Member] | Williams NGL & Petchem Services [Member] | Product [Member]
Segment revenues:
Revenues	0	0	0	0
Intersegment Elimination [Member] | Other [Member] | Service [Member]
Segment revenues:
Revenues	(64)	(7)	(123)	(14)
Intersegment Elimination [Member] | Other [Member] | Product [Member]
Segment revenues:
Revenues	$ 0	$ 0	$ 0	$ 0