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Segment Disclosures (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment revenues:
Revenues	$ 1,716us-gaap_Revenues	$ 1,749us-gaap_Revenues
Total assets by reporting segment
Total assets	50,457us-gaap_Assets		50,563us-gaap_Assets
Reconciliation of Modified EBITDA to net income (loss):
Modified Ebitda	812wmb_ModifiedEbitda	666wmb_ModifiedEbitda
Accretion expense associated with asset retirement obligations for nonregulated operations	(6)	(3)
Depreciation and amortization expenses	(427)	(214)
Equity earnings (losses)	51	(48)
Other investing income (loss) - net	0us-gaap_InvestmentIncomeNonoperating	14us-gaap_InvestmentIncomeNonoperating
Proportional Modified Ebitda Equity Method Investments	(136)	(28)
Interest Expense	(251)us-gaap_InterestExpense	(140)us-gaap_InterestExpense
(Provision) benefit for income taxes	(30)us-gaap_IncomeTaxExpenseBenefit	(51)us-gaap_IncomeTaxExpenseBenefit
Net income (loss)	13us-gaap_ProfitLoss	196us-gaap_ProfitLoss
Service [Member]
Segment revenues:
Revenues	1,197	819
Product [Member]
Segment revenues:
Revenues	519	930
Williams Partners [Member]
Total assets by reporting segment
Total assets	49,284		49,322
Reconciliation of Modified EBITDA to net income (loss):
Modified Ebitda	817	708
Williams Partners [Member] \| Service [Member]
Segment revenues:
Revenues	1,192	763
Williams Partners [Member] \| Product [Member]
Segment revenues:
Revenues	519	930
Williams NGL & Petchem Services [Member]
Total assets by reporting segment
Total assets	656		612
Reconciliation of Modified EBITDA to net income (loss):
Modified Ebitda	(5)	(100)
Williams NGL & Petchem Services [Member] \| Service [Member]
Segment revenues:
Revenues	0	0
Williams NGL & Petchem Services [Member] \| Product [Member]
Segment revenues:
Revenues	0	0
Other [Member]
Total assets by reporting segment
Total assets	1,101		1,220
Reconciliation of Modified EBITDA to net income (loss):
Modified Ebitda	0	58
Other [Member] \| Service [Member]
Segment revenues:
Revenues	5	56
Other [Member] \| Product [Member]
Segment revenues:
Revenues	0	0
Operating Segments [Member] \| Williams Partners [Member]
Segment revenues:
Revenues	1,711	1,693
Operating Segments [Member] \| Williams Partners [Member] \| Service [Member]
Segment revenues:
Revenues	1,192	763
Operating Segments [Member] \| Williams Partners [Member] \| Product [Member]
Segment revenues:
Revenues	519	930
Operating Segments [Member] \| Williams NGL & Petchem Services [Member]
Segment revenues:
Revenues	0	0
Operating Segments [Member] \| Williams NGL & Petchem Services [Member] \| Service [Member]
Segment revenues:
Revenues	0	0
Operating Segments [Member] \| Williams NGL & Petchem Services [Member] \| Product [Member]
Segment revenues:
Revenues	0	0
Operating Segments [Member] \| Other [Member]
Segment revenues:
Revenues	26	59
Operating Segments [Member] \| Other [Member] \| Service [Member]
Segment revenues:
Revenues	26	59
Operating Segments [Member] \| Other [Member] \| Product [Member]
Segment revenues:
Revenues	0	0
Intersegment Elimination [Member]
Segment revenues:
Revenues	(21)	(3)
Total assets by reporting segment
Total assets	(584)		(591)
Intersegment Elimination [Member] \| Service [Member]
Segment revenues:
Revenues	(21)	(3)
Intersegment Elimination [Member] \| Product [Member]
Segment revenues:
Revenues	0	0
Intersegment Elimination [Member] \| Williams Partners [Member] \| Service [Member]
Segment revenues:
Revenues	0	0
Intersegment Elimination [Member] \| Williams Partners [Member] \| Product [Member]
Segment revenues:
Revenues	0	0
Intersegment Elimination [Member] \| Williams NGL & Petchem Services [Member] \| Service [Member]
Segment revenues:
Revenues	0	0
Intersegment Elimination [Member] \| Williams NGL & Petchem Services [Member] \| Product [Member]
Segment revenues:
Revenues	0	0
Intersegment Elimination [Member] \| Other [Member] \| Service [Member]
Segment revenues:
Revenues	(21)	(3)
Intersegment Elimination [Member] \| Other [Member] \| Product [Member]
Segment revenues:
Revenues	$ 0	$ 0