Segment Disclosures Recon from Segment to Consolidated - Assets and Investments (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 49,020	$ 50,455
Equity Method Investments	7,336	8,400
Operating Segments [Member] | Williams Partners [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	47,870	49,248
Equity Method Investments	7,336	8,399
Operating Segments [Member] | Williams Ngl And Petchem Services [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	835	612
Equity Method Investments	0	0
Operating Segments [Member] | Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	850	1,186
Equity Method Investments	0	1
Intersegment Eliminations [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	(535)	(591)
Equity Method Investments	$ 0	$ 0