Segment Disclosures (Details 1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Segment revenues:
Revenues	$ 1,839	$ 1,678	$ 3,555	$ 3,427
Total assets by reporting segment
Total assets	51,163		51,163		$ 50,563
Reconciliation of Modified EBITDA to net income (loss):
Modified EBITDA	1,046	648	1,858	1,314
Accretion expense associated with asset retirement obligations for nonregulated operations	(9)	(6)	(15)	(9)
Depreciation and amortization expenses	(428)	(214)	(855)	(428)
Equity earnings (losses)	93	37	144	(11)
Other investing income (loss) - net	9	18	9	32
Proportional Modified Ebitda Equity Method Investments	(183)	(113)	(319)	(141)
Interest Expense	(262)	(163)	(513)	(303)
(Provision) benefit for income taxes	(83)	(84)	(113)	(135)
Income (loss) from discontinued operations, net of tax	0	4	0	4
Net income (loss)	183	127	196	323
Service [Member]
Segment revenues:
Revenues	1,241	825	2,438	1,644
Product [Member]
Segment revenues:
Revenues	598	853	1,117	1,783
Williams Partners [Member]
Total assets by reporting segment
Total assets	50,040		50,040		49,322
Reconciliation of Modified EBITDA to net income (loss):
Modified EBITDA	1,053	596	1,870	1,304
Williams Partners [Member] | Service [Member]
Segment revenues:
Revenues	1,231	763	2,423	1,526
Williams Partners [Member] | Product [Member]
Segment revenues:
Revenues	598	853	1,117	1,783
Williams NGL & Petchem Services [Member]
Total assets by reporting segment
Total assets	731		731		612
Reconciliation of Modified EBITDA to net income (loss):
Modified EBITDA	(3)	(8)	(8)	(108)
Williams NGL & Petchem Services [Member] | Service [Member]
Segment revenues:
Revenues	1	0	1	0
Williams NGL & Petchem Services [Member] | Product [Member]
Segment revenues:
Revenues	0	0	0	0
Other [Member]
Total assets by reporting segment
Total assets	1,064		1,064		1,220
Reconciliation of Modified EBITDA to net income (loss):
Modified EBITDA	(4)	60	(4)	118
Other [Member] | Service [Member]
Segment revenues:
Revenues	9	62	14	118
Other [Member] | Product [Member]
Segment revenues:
Revenues	0	0	0	0
Operating Segments [Member] | Williams Partners [Member]
Segment revenues:
Revenues	1,830	1,616	3,541	3,309
Operating Segments [Member] | Williams Partners [Member] | Service [Member]
Segment revenues:
Revenues	1,231	763	2,423	1,526
Operating Segments [Member] | Williams Partners [Member] | Product [Member]
Segment revenues:
Revenues	599	853	1,118	1,783
Operating Segments [Member] | Williams NGL & Petchem Services [Member]
Segment revenues:
Revenues	1	0	1	0
Operating Segments [Member] | Williams NGL & Petchem Services [Member] | Service [Member]
Segment revenues:
Revenues	1	0	1	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	47	66	73	125
Operating Segments [Member] | Other [Member] | Service [Member]
Segment revenues:
Revenues	47	66	73	125
Operating Segments [Member] | Other [Member] | Product [Member]
Segment revenues:
Revenues	0	0	0	0
Intersegment Elimination [Member]
Segment revenues:
Revenues	(39)	(4)	(60)	(7)
Total assets by reporting segment
Total assets	(672)		(672)		$ (591)
Intersegment Elimination [Member] | Service [Member]
Segment revenues:
Revenues	(38)	(4)	(59)	(7)
Intersegment Elimination [Member] | Product [Member]
Segment revenues:
Revenues	(1)	0	(1)	0
Intersegment Elimination [Member] | Williams Partners [Member] | Service [Member]
Segment revenues:
Revenues	0	0	0	0
Intersegment Elimination [Member] | Williams Partners [Member] | Product [Member]
Segment revenues:
Revenues	(1)	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	(38)	(4)	(59)	(7)
Intersegment Elimination [Member] | Other [Member] | Product [Member]
Segment revenues:
Revenues	$ 0	$ 0	$ 0	$ 0