Fair Value Measurements Nonrecurring Measurements (Details) - USD ($) $ in Millions		3 Months Ended										9 Months Ended		12 Months Ended
		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015	[3]	Dec. 31, 2014		Jun. 30, 2014	[3]	Sep. 30, 2015		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of goodwill		$ 1,098												$ 1,098		$ 0		$ 0
Impairment of equity-method investments														1,359		0		$ 0
Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of goodwill														1,098
Property, plant, and equipment, net [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets														209		52
Fair Value, Measurements, Nonrecurring [Member] | Property, plant, and equipment, net [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets	[1]													31		10
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Goodwill [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of goodwill		$ 1,098										$ 0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Goodwill [Member] | Williams Partners [Member] | Minimum [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Discount rate		10.00%
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Goodwill [Member] | Williams Partners [Member] | Maximum [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Discount rate		13.00%
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Goodwill [Member] | West [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of goodwill		$ 0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Property, plant, and equipment, net [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets														178		42
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Property, plant, and equipment, net [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair value of property, plant, and equipment		13	[2]			$ 17		$ 32	[3]	$ 46				13	[2]	32	[3]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	[4]							1								$ 1
Impairment of certain assets		94	[2]			$ 20		13	[3]	$ 17
Impairment of Long-Lived Assets to be Disposed of	[4]							$ 12
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Property, plant, and equipment, net [Member] | Williams Ngl And Petchem Services [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair value of property, plant, and equipment	[5]	40												40
Impairment of certain assets	[5]	64
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair value of investment		4,017	[6]	$ 1,203	[7]							$ 1,203	[7]	4,017	[6]
Impairment of equity-method investments		$ 890	[6]	$ 461	[7]									1,359
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member] | Williams Partners [Member] | Minimum [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Discount rate		10.80%
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member] | Williams Partners [Member] | Maximum [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Discount rate		14.40%
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member] | Williams Partners [Member] | Delaware Basin Gas Gathering System [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Discount rate				11.80%
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member] | Williams Partners [Member] | Appalachia Midstream Investments [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Discount rate				8.80%
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member] | Williams Partners [Member] | Other Investments [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair value of investment		$ 58												$ 58
Impairment of equity-method investments		$ 8

[1] Reflects multiple individually insignificant impairments of other certain assets that may no longer be in use or are surplus in nature for which the fair value was determined to be zero or an insignificant salvage value. These impairment charges are recorded in Other (income) expense – net within Costs and expenses in the Consolidated Statement of Operations

[2] Reflects an impairment charge within our Williams Partners segment associated with previously capitalized project development costs for a gas processing plant, the completion of which is now considered remote due to unfavorable impact of low natural gas prices on customer drilling activities. These impairment charges are recorded in Other (income) expense – net within Costs and expenses in the Consolidated Statement of Operations.The assessed fair value primarily represents the estimated salvage value of certain equipment measured using a market approach based on our analysis of observable inputs in the principal market and is reported in Property, plant, and equipment – net in the Consolidated Balance Sheet.

[3] Reflects impairment charges for our Williams Partners segment associated with certain surplus equipment. Certain of these assets were previously presented as held for sale, but are now considered held for use and reported in Property, plant, and equipment – net in the Consolidated Balance Sheet at December 31, 2015. The estimated fair value was determined by a market approach based on our analysis of observable inputs in the principal market. These impairment charges are recorded in Other (income) expense – net within Costs and expenses in the Consolidated Statement of Operations.

[4] Reflects impairment charges for our Williams Partners segment associated with certain surplus equipment considered held for sale and reported in Other current assets and deferred charges in the Consolidated Balance Sheet. The estimated fair value was determined by a market approach based on our analysis of observable inputs in the principal market. These impairment charges are recorded in Other (income) expense – net within Costs and expenses in the Consolidated Statement of Operations.

[5] Reflects an impairment charge within our Williams NGL & Petchem Services segment associated with previously capitalized project development costs for an olefins pipeline project, the completion of which is now considered remote due to the lack of customer interest. These impairment charges are recorded in Other (income) expense – net within Costs and expenses in the Consolidated Statement of Operations. The assessed fair value primarily represents the estimated value of unused pipeline measured using a market approach based on our analysis of observable inputs in the principal market and is reported in Property, plant, and equipment – net in the Consolidated Balance Sheet.

[6] Reflects other-than-temporary impairment charges related to Williams Partners’ equity-method investments in the Delaware basin gas gathering system, certain of the Appalachia Midstream Investments, UEOM, and Laurel Mountain, reflected within Impairment of equity-method investments in the Consolidated Statement of Operations. We estimated the fair value of these investments using an income approach based on expected future cash flows and appropriate discount rates. The determination of estimated future cash flows involved significant assumptions regarding gathering volumes and related capital spending. Discount rates utilized ranged from 10.8 percent to 14.4 percent and reflected further fourth quarter increases in our cost of capital, revised estimates of expected future cash flows, and risks associated with the underlying businesses.

[7] Reflects other-than-temporary impairment charges related to Williams Partners’ equity-method investments in the Delaware basin gas gathering system and certain of the Appalachia Midstream Investments reflected within Impairment of equity-method investments in the Consolidated Statement of Operations. The historical carrying value of these investments was initially recorded based on estimated fair value during the third quarter of 2014 in conjunction with the ACMP Acquisition. We estimated the fair value of these investments using an income approach based on expected future cash flows and appropriate discount rates. The determination of estimated future cash flows involved significant assumptions regarding gathering volumes and related capital spending. Discount rates utilized were 11.8 percent and 8.8 percent for the Delaware basin gas gathering system and certain of the Appalachia Midstream Investments, respectively, and reflected our cost of capital as impacted by market conditions, and risks associated with the underlying businesses.