Fair Value Measurements Nonrecurring Measurements (Details) - USD ($) $ in Millions		3 Months Ended							9 Months Ended
		Sep. 30, 2017		Jun. 30, 2017	[4]	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017		Sep. 30, 2016
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges		$ 1,210				$ 1			$ 1,236		$ 811
Impairment of equity-method investments		0				$ 0			0		112
Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Disposal Group, Not Discontinued Operation, Loss (Gain) on writedown							$ 747
Williams Partners [Member] | Delaware Basin Gas Gathering System [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of equity-method investments											59
Impairment Of Certain Assets [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets									1,236		811
Fair Value, Measurements, Nonrecurring [Member] | Impairment Of Certain Assets [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets	[1]								11		16
Fair Value, Measurements, Nonrecurring [Member] | Impairment Of Equity-Method Investments [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of equity-method investments											112
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	[2]						18
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Property Plant And Equipment, net [Member] | Other [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair Value of Property, Plant, and Equipment		32	[3]	$ 18					32	[3]
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Assets Held For Sale [Member] | Williams Partners [Member] | Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Assets Held-for-sale, Long-Lived, Fair Value Disclosure	[5]						924
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Assets Held For Sale [Member] | Other [Member] | Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Assets Held-for-sale, Long-Lived, Fair Value Disclosure	[5]						206
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair value of investment								$ 0
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	[6]							$ 1,294
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								13.00%
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								13.30%
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets									1,225		$ 795
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets	[2]						48
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Williams Partners [Member] | Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Disposal Group, Not Discontinued Operation, Loss (Gain) on writedown	[5]						341
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Other [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets		68	[3]	$ 23
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Other [Member] | Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Disposal Group, Not Discontinued Operation, Loss (Gain) on writedown	[5]						$ 406
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Equity-Method Investments [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of equity-method investments								$ 3
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Equity-Method Investments [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of equity-method investments	[6]							$ 109
Mid Continent [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Property Plant And Equipment, Net And Intangible Assets, Net Of Accumulated Amortization [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Property Plant And Equipment And Intangibles, Fair Value Disclosure	[7]	$ 439							439
Discount rate		10.20%
Mid Continent [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges	[7]	$ 1,019
Marcellus South [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Property Plant And Equipment, Net And Intangible Assets, Net Of Accumulated Amortization [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Property Plant And Equipment And Intangibles, Fair Value Disclosure	[8]	$ 21							$ 21
Discount rate		11.10%
Marcellus South [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges	[8]	$ 115

[1] Reflects multiple individually insignificant impairments and write-downs 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 lower than the carrying value.

[2] Relates to certain gathering assets within the Mid-Continent region. The estimated fair value was determined by a market approach based on our analysis of observable inputs in the principal market.

[3] Relates to an NGL pipeline near the Houston Ship Channel region which we anticipate will be underutilized for the foreseeable future. The estimated fair value was primarily determined by using a market approach based on our analysis of observable inputs in the principal market.

[4] Relates primarily to project development costs associated with an olefins pipeline project in the Gulf Coast region, the likelihood of completion of which is now considered remote. The estimated fair value of the remaining pipe and equipment considered a market approach based on our analysis of observable inputs in the principal market, as well as an estimate of replacement cost.

[5] Relates to our Canadian operations. We designated these operations as held for sale as of June 30, 2016. As a result, we measured the fair value of the disposal group, resulting in an impairment charge. The estimated fair value was determined by a market approach based primarily on inputs received in the marketing process and reflected our estimate of the potential assumed proceeds. We disposed of our Canadian operations through a sale during the third quarter of 2016.

[6] Relates to Williams Partners’ previously owned interest in DBJV and current equity-method investment in Laurel Mountain. Our carrying values in these equity-method investments had been written down to fair value at December 31, 2015. Our first-quarter 2016 analysis reflected higher discount rates for both of these equity-method investments, along with lower natural gas prices for Laurel Mountain. We estimated the fair value of these equity-method 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 13.0 percent to 13.3 percent and reflected increases in our estimated cost of capital, revised estimates of expected future cash flows, and risks associated with the underlying businesses.

[7] Relates to certain gathering operations in the Mid-Continent region. During the third quarter of 2017, we received solicitations and engaged in negotiations for the sale of certain of these assets which led to our impairment evaluation. The estimated fair value was determined using an income approach and incorporated market inputs based on ongoing negotiations for a potential sale of a portion of the underlying assets. For the income approach, we utilized a discount rate of 10.2 percent, reflecting an estimate of our cost of capital and risks associated with the underlying assets.

[8] Relates to certain gathering operations in the Marcellus South region resulting from an anticipated decline in future volumes following a third-quarter 2017 shut-in by the primary producer. The estimated fair value was determined by the income approach utilizing a discount rate of 11.1 percent, reflecting an estimate of our cost of capital and risks associated with the underlying assets.