General, Description of Business and Basis of Presentation (Details) $ / shares in Units, $ in Millions			1 Months Ended					3 Months Ended		11 Months Ended	12 Months Ended
	Sep. 28, 2015 USD ($) $ / shares	Feb. 02, 2015	Feb. 26, 2016 USD ($)	Nov. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Oct. 31, 2014 USD ($)	Feb. 28, 2014 USD ($) shares	Dec. 31, 2015 shares	Jun. 30, 2014 USD ($)	Dec. 31, 2015	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Dec. 31, 2013 USD ($) $ / shares	Dec. 20, 2012
General and Description Of Business [Abstract]
Common Stock, Dividends, Per Share, Declared | $ / shares											$ 2.45	$ 1.9575	$ 1.4375
Basis Of Presentation [Abstract]
Master limited partnership, general partner ownership percentage														2.00%
Changes in ownership of consolidated subsidiaries, net											$ 94	$ 44	$ (243)
ETC Merger [Member]
General and Description Of Business [Abstract]
Common Stock, Dividends, Per Share, Declared | $ / shares	$ 0.10
WPZ Merger Agreement [Member]
General and Description Of Business [Abstract]
Termination Fee	$ 428
Maximum Reduction Of Quarterly Incentive Distributions	$ 209
Basis Of Presentation [Abstract]
Reduction in incentive distribution rights payment				$ 209
WPZ Merger Agreement [Member] | Subsequent Event [Member]
Basis Of Presentation [Abstract]
Reduction in incentive distribution rights payment			$ 209
Canada Dropdown [Member]
Basis Of Presentation [Abstract]
Proceeds from Divestiture of Businesses							$ 56		$ 31
Number Of Limited Partner Units Received1 | shares							25,577,521
Payments for Previous Acquisition						$ 56
Reduction in incentive distribution rights payment						$ 2
Noncontrolling Interest [Member]
Basis Of Presentation [Abstract]
Changes in ownership of consolidated subsidiaries, net											254	137	(652)
Capital in excess of par value [Member]
Basis Of Presentation [Abstract]
Changes in ownership of consolidated subsidiaries, net											(160)	$ (73)	$ 409
Deferred Income Taxes [Member]
Basis Of Presentation [Abstract]
Income Tax Effects Allocated Directly to Equity, Other											$ (94)
Gulfstream Natural Gas System, L.L.C.[Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								50.00%		50.00%	50.00%
Utica East Ohio Midstream, LLC [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								62.00%		62.00%	62.00%
Delaware Basin Gas Gathering System [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								50.00%		50.00%	50.00%
Laurel Mountain Midstream, LLC [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								69.00%		69.00%	69.00%
Discovery Producer Services LLC [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								60.00%		60.00%	60.00%
Overland Pass Pipeline Company LLC [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								50.00%		50.00%	50.00%
Energy Transfer Corp L P [Member]
General and Description Of Business [Abstract]
Master limited partnership ownership percentage	19.00%
Williams Partners L.P. [Member]
Basis Of Presentation [Abstract]
Master limited partnership, general partner ownership percentage							2.00%
Williams Partners L.P. [Member] | Access Midstream Partners Acquisition [Member] | Publicly Held WPZ Common Units into ACMP Common Units [Member]
General and Description Of Business [Abstract]
Conversion Ratio		0.86672
Williams Partners L.P. [Member] | Access Midstream Partners Acquisition [Member] | Privately Held WPZ Units Into ACMP Common Units [Member]
General and Description Of Business [Abstract]
Conversion Ratio		0.80036
Williams Partners L.P. [Member] | Access Midstream Partners Acquisition [Member] | ACMP Units Into Merged Partnership Units [Member]
General and Description Of Business [Abstract]
Conversion Ratio		1.06152
Williams Partners L.P. [Member] | Access Midstream Partners Acquisition [Member] | Class D WPZ Units Into WPZ Common Units [Member]
General and Description Of Business [Abstract]
Conversion Ratio		1
Williams Partners L.P. [Member] | Private Placement [Member]
Basis Of Presentation [Abstract]
Sale Of Stock Number Of Shares Issued In Transaction | shares								1,790,840
Williams Partners L.P. [Member] | General and Limited Partner [Member]
General and Description Of Business [Abstract]
Master limited partnership ownership percentage											60.00%
Williams Partners L.P. [Member] | General and Limited Partner [Member] | Access Midstream Partners Acquisition [Member]
General and Description Of Business [Abstract]
Master limited partnership ownership percentage										60.00%
Williams Partners [Member]
General and Description Of Business [Abstract]
Number Of Interstate Natural Gas Pipelines											2
Williams Partners [Member] | Gulfstream Natural Gas System, L.L.C.[Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								50.00%		50.00%	50.00%
Williams Partners [Member] | Utica East Ohio Midstream, LLC [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								62.00%		62.00%	62.00%
Basis Of Presentation [Abstract]
Reduction in incentive distribution rights payment					$ 2
Williams Partners [Member] | Delaware Basin Gas Gathering System [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								50.00%		50.00%	50.00%
Williams Partners [Member] | Laurel Mountain Midstream, LLC [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								69.00%		69.00%	69.00%
Williams Partners [Member] | Caiman Energy II [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								58.00%		58.00%	58.00%
Williams Partners [Member] | Discovery Producer Services LLC [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								60.00%		60.00%	60.00%
Williams Partners [Member] | Overland Pass Pipeline Company LLC [Member]
General and Description Of Business [Abstract]
Equity Method Investment, Ownership Percentage								50.00%		50.00%	50.00%
Williams Partners [Member] | Appalachia Midstream Services, LLC [Member]
General and Description Of Business [Abstract]
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest											45.00%
Williams Partners [Member] | Constitution Pipeline Company LLC [Member]
General and Description Of Business [Abstract]
Variable Interest Entity Ownership Percentage											41.00%
Stock Consideration [Member] | ETC Merger [Member]
General and Description Of Business [Abstract]
Conversion Ratio	1.8716
Cash Consideration [Member] | ETC Merger [Member]
General and Description Of Business [Abstract]
Business Acquisition, Share Price | $ / shares	$ 43.50
Mixed Consideration [Member] | ETC Merger [Member]
General and Description Of Business [Abstract]
Conversion Ratio	1.5274
Business Acquisition, Share Price | $ / shares	$ 8.00