Other Income and Expenses (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Gains on asset retirements	[1]	$ (67)	$ 39
Regulatory Charges In Operating Expense Resulting From Tax Reform		0	(17)	$ 674
Gain on sale of Refinery Grade Propylene Splitter		(2)	692	1,095
Debt Instrument, Unamortized Discount (Premium), Net		58	62
Regulatory charges resulting from Tax Reform (Note 1)		0	15	(776)
Other Operating Income (Expense) [Member] | Atlantic Gulf [Member]
Segment Reporting Information [Line Items]
Amortization of regulatory assets associated with asset retirement obligations		21	33	33
Accrual of regulatory liability related to overcollection of certain employee expenses		(17)	22	22
Project development costs related to Constitution		3	4	16
Regulatory Charge Resulting From Tax Rate Change		(26)	0	0
Gains on asset retirements		0	(12)	0
Other Operating Income (Expense) [Member] | West [Member]
Segment Reporting Information [Line Items]
Regulatory Charges In Operating Expense Resulting From Tax Reform		24	24	0
Gains on contract settlements and terminations		0	0	(15)
Other Operating Income (Expense) [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Regulatory Benefit Resulting From Tax Rate Change		12	(37)	0
Gain on sale of Refinery Grade Propylene Splitter		0	0	(12)
Selling, general and administrative expenses [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Noncash Contribution Expense			35
WPZ Merger			20
Selling, general, and administrative expenses and Operating and maintenance expenses [Member] | Atlantic Gulf [Member]
Segment Reporting Information [Line Items]
Severance and other related costs		32	0	0
Selling, general, and administrative expenses and Operating and maintenance expenses [Member] | Northeast G And P [Member]
Segment Reporting Information [Line Items]
Severance and other related costs		7	0	0
Selling, general, and administrative expenses and Operating and maintenance expenses [Member] | West [Member]
Segment Reporting Information [Line Items]
Severance and other related costs		17	0	0
Selling, general, and administrative expenses and Operating and maintenance expenses [Member] | Other [Member]
Segment Reporting Information [Line Items]
Severance and other related costs		1	0	22
Other income (expense) - net [Member]
Segment Reporting Information [Line Items]
Regulatory Charges In Operating Expense Resulting From Tax Reform			(17)
Regulatory charges resulting from Tax Reform (Note 1)				(102)
Other income (expense) - net [Member] | Atlantic Gulf [Member]
Segment Reporting Information [Line Items]
Allowance for funds used during construction, capitalized cost of equity		29	87	70
Regulatory charges resulting from Tax Reform (Note 1)		0	0	(33)
Other income (expense) - net [Member] | West [Member]
Segment Reporting Information [Line Items]
Regulatory charges resulting from Tax Reform (Note 1)		0	0	(6)
Other income (expense) - net [Member] | Other [Member]
Segment Reporting Information [Line Items]
Debt Instrument, Unamortized Discount (Premium), Net		0	(7)	27
Regulatory charges resulting from Tax Reform (Note 1)		0	(1)	(63)
Deferred Taxes On Equity Funds Used During Construction [Member] | Other [Member]
Segment Reporting Information [Line Items]
Allowance for funds used during construction, capitalized cost of equity		9	35	52
Pension Plan [Member]
Segment Reporting Information [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		(1)	(23)	(71)
Pension Plan [Member] | Other income (expense) - net [Member]
Segment Reporting Information [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement			(23)	(71)
Pension Plan [Member] | Other income (expense) - net [Member] | Atlantic Gulf [Member]
Segment Reporting Information [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		0	(7)	(15)
Pension Plan [Member] | Other income (expense) - net [Member] | Northeast G And P [Member]
Segment Reporting Information [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		0	(4)	(7)
Pension Plan [Member] | Other income (expense) - net [Member] | West [Member]
Segment Reporting Information [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		0	(6)	(13)
Pension Plan [Member] | Other income (expense) - net [Member] | Other [Member]
Segment Reporting Information [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		0	(5)	(35)
Northwest Pipeline LLC [Member] | Other Operating Income (Expense) [Member] | West [Member]
Segment Reporting Information [Line Items]
Tangible Asset Impairment Charges		$ 0	$ 12	$ 0

[1] Several factors are considered in the annual review process, including inflation rates, current estimates for removal cost, market risk premiums, discount rates, and the estimated remaining useful life of the assets. The 2019 revisions reflect changes in removal cost estimates, decreases in the estimated remaining useful life of certain assets, increases in inflation rates, and decreases in the discount rates used in the annual review process. The 2018 revisions reflect changes in removal cost estimates, decreases in the estimated remaining useful life of certain assets, and increases in the discount rates used in the annual review process.