Operating Revenues (Revenues Disaggregated) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating revenues	$ 267	$ 302
Pipelines
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating revenues	111	109
Terminals
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating revenues	43	40
Storage, processing and other revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating revenues	$ 113	$ 153