Segment Disclosures Recon from Segment to Consolidated - Revenues (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		$ 7,360	$ 7,637		$ 6,860
Other financial information:
Additions to long-lived assets		3,336	20,756		3,731
Proportional Modified Ebitda Equity Method Investments		699	438		406
Service [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		5,164	4,116		2,939
Service [Member] | Williams Partners [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		5,134	3,887		2,914
Service [Member] | Williams Ngl And Petchem Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[1]	2	0		0
Service [Member] | Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		28	229		25
Product [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		2,196	3,521		3,921
Product [Member] | Williams Partners [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		2,196	3,521		3,921
Product [Member] | Williams Ngl And Petchem Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[1]	0	0		0
Product [Member] | Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		0	0		0
Operating Segments [Member] | Williams Partners [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		7,331	7,409		6,835
Other financial information:
Additions to long-lived assets		2,960	20,413	[2]	3,409
Proportional Modified Ebitda Equity Method Investments		699	431		209
Operating Segments [Member] | Williams Ngl And Petchem Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[1]	2	0		0
Other financial information:
Additions to long-lived assets		360	291		295
Proportional Modified Ebitda Equity Method Investments		0	(78)		0
Operating Segments [Member] | Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		186	259		36
Other financial information:
Additions to long-lived assets		28	54		27
Proportional Modified Ebitda Equity Method Investments		0	85		197
Operating Segments [Member] | Service [Member] | Williams Partners [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		5,135	3,888		2,914
Operating Segments [Member] | Service [Member] | Williams Ngl And Petchem Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[1]	2	0		0
Operating Segments [Member] | Service [Member] | Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		186	259		36
Operating Segments [Member] | Product [Member] | Williams Partners [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		2,196	3,521		3,921
Operating Segments [Member] | Product [Member] | Williams Ngl And Petchem Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[1]	0	0		0
Operating Segments [Member] | Product [Member] | Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		0	0		0
Intersegment Eliminations [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		(159)	(31)		(11)
Other financial information:
Additions to long-lived assets		(12)	(2)		0
Intersegment Eliminations [Member] | Service [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		(159)	(31)		(11)
Intersegment Eliminations [Member] | Service [Member] | Williams Partners [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		(1)	(1)		0
Intersegment Eliminations [Member] | Service [Member] | Williams Ngl And Petchem Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[1]	0	0		0
Intersegment Eliminations [Member] | Service [Member] | Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		(158)	(30)		(11)
Intersegment Eliminations [Member] | Product [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		0	0		0
Intersegment Eliminations [Member] | Product [Member] | Williams Partners [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		0	0		0
Intersegment Eliminations [Member] | Product [Member] | Williams Ngl And Petchem Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[1]	0	0		0
Intersegment Eliminations [Member] | Product [Member] | Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues		$ 0	$ 0		$ 0

[1] Includes certain projects under development and thus nominal reported revenues to date.

[2] 2014 Additions to long-lived assets within our Williams Partners segment primarily includes the acquisition-date fair value of long-lived assets from the ACMP Acquisition. (See Note 2 - Acquisitions.)