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Other Income and Expenses (Details) - USD ($) $ in Millions	3 Months Ended
Other Income and Expenses (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 28, 2018
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Debt Instrument, Unamortized Discount (Premium), Net	$ 0		$ (7)
Other income (expense) - net [Member] \| Corporate and Other [Member]
Segment Reporting Information [Line Items]
Benefit of regulatory asset associated with increase in Transco's estimated deferred state income tax rate following WPZ Merger	12	$ 0
Other income (expense) - net [Member] \| West [Member]
Segment Reporting Information [Line Items]
Tangible Asset Impairment Charges	12	0
Other Nonoperating Income (Expense) [Member] \| Atlantic Gulf [Member]
Segment Reporting Information [Line Items]
Allowance for funds used during construction, capitalized cost of equity	$ 7	$ 20