(Deficit) Equity - Schedule of Distributions Declared and/or Paid (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended						9 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	$ 162	$ 162	$ 140	$ 131	$ 119	$ 129
Distributions paid per limited partner unit (in dollars per share)	$ 0.460	$ 0.4600	$ 0.4450	$ 0.4300	$ 0.4150	$ 0.4000
Shell Midstream Partners L.P.
Distribution Made To Limited Partner [Line Items]
Aggregate percentage of general partner interest							2.00%
Zydeco Pipeline Company LLC (“Zydeco”)
Distribution Made To Limited Partner [Line Items]
Distributions to noncontrolling interest	$ 1				$ 1
Odyssey Pipeline L.L.C. (“Odyssey”)
Distribution Made To Limited Partner [Line Items]
Distributions to noncontrolling interest	4				2
Common Units | General Public
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	57	$ 57	$ 56	$ 53	51	$ 49
Common Units | Shell Pipeline Company L P
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	50	50	48	47	42	40
General Partner
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	3	3	3	3	3	3
General Partner | IDR's
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	$ 52	$ 52	$ 33	$ 28	$ 23	$ 37