Reportable Segments Earnings (loss) from equity investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Earnings (loss) from equity investments and amortization of excess cost of equity investments, including loss on impairments of equity investments	$ 18	$ 522	$ 367
Operating Segments | Natural Gas Pipelines
Segment Reporting Information [Line Items]
Earnings (loss) from equity investments and amortization of excess cost of equity investments, including loss on impairments of equity investments	(101)	410	258
Operating Segments | Products Pipelines
Segment Reporting Information [Line Items]
Earnings (loss) from equity investments and amortization of excess cost of equity investments, including loss on impairments of equity investments	63	56	43
Operating Segments | Terminals
Segment Reporting Information [Line Items]
Earnings (loss) from equity investments and amortization of excess cost of equity investments, including loss on impairments of equity investments	23	22	24
Operating Segments | CO2
Segment Reporting Information [Line Items]
Earnings (loss) from equity investments and amortization of excess cost of equity investments, including loss on impairments of equity investments	$ 33	$ 34	$ 42