Fair Value Measurements (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Additional disclosure:
Fair Value, Level 1 to level 2 Transfers, Amount		$ 0	$ 0	$ 0	$ 0
Fair Value, Level 2 to level 1 Transfers, Amount		0	0	0	0
Impairment of equity-method investments		461	0	461	0
Williams Partners [Member]
Additional disclosure:
Asset impairment charges		2	$ 0	29	$ 17
Carrying Amount [Member]
Additional disclosure:
Notes receivable and other		8		8		$ 30
Long-term debt, including current portion	[1]	(22,180)		(22,180)		(20,887)
Guarantee		(30)		(30)		(31)
Carrying Amount [Member] | Former Venezuela Operations [Member]
Additional disclosure:
Notes Receivable, Fair Value Disclosure		0		0
Fair Value [Member]
Additional disclosure:
Notes receivable and other		12		12		57
Long-term debt, including current portion	[1]	(20,010)		(20,010)		(21,131)
Guarantee		(17)		(17)		(27)
Fair Value [Member] | Former Venezuela Operations [Member]
Additional disclosure:
Notes Receivable, Fair Value Disclosure		4		4
Level 1 [Member]
Additional disclosure:
Notes receivable and other		6		6		0
Long-term debt, including current portion	[1]	0		0		0
Guarantee		0		0		0
Level 2 [Member]
Additional disclosure:
Notes receivable and other		2		2		4
Long-term debt, including current portion	[1]	(20,010)		(20,010)		(21,131)
Guarantee		(17)		(17)		(27)
Level 3 [Member]
Additional disclosure:
Notes receivable and other		4		4		53
Long-term debt, including current portion	[1]	0		0		0
Guarantee		0		0		0
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member]
Measured on a recurring basis:
ARO Trust investments		63		63		48
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		3		3		3
Energy derivative liabilities		(2)		(2)		(2)
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		4		4
Fair Value, Measurements, Recurring [Member] | Fair Value [Member]
Measured on a recurring basis:
ARO Trust investments		63		63		48
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		3		3		3
Energy derivative liabilities		(2)		(2)		(2)
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		4		4
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Measured on a recurring basis:
ARO Trust investments		63		63		48
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		0		0		1
Energy derivative liabilities		0		0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Measured on a recurring basis:
ARO Trust investments		0		0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		1		1		0
Energy derivative liabilities		0		0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		4		4
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Measured on a recurring basis:
ARO Trust investments		0		0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		2		2		2
Energy derivative liabilities		(2)		(2)		$ (2)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		0		0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Williams Partners [Member]
Additional disclosure:
Asset impairment charges				20
Property, plant, and equipment, fair value		17		17
Delaware Basin Gas Gathering System [Member]
Additional disclosure:
Impairment of equity-method investments		458
Delaware Basin Gas Gathering System [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Williams Partners [Member]
Additional disclosure:
Impairment of equity-method investments		$ 458
Discount rate		11.80%
Fair value of investment		$ 1,020		1,020
Appalachia Midstream Investments [Member]
Additional disclosure:
Impairment of equity-method investments		3
Appalachia Midstream Investments [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Williams Partners [Member]
Additional disclosure:
Impairment of equity-method investments		$ 3
Discount rate		8.80%
Fair value of investment		$ 185		$ 185

[1] Excludes capital leases