(Deficit) Equity - Public Offerings and Private Placement (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 06, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Net proceeds from equity offerings				$ 973
Underwriter fees		$ 2	$ 0	0
Contributions from general partner	$ 14			20
Consideration for units issued in connection with private placement		$ 0	$ 0	20
Five Year Revolver Due December 2022
Class of Stock [Line Items]
Debt instrument term		5 years
Repayments of Debt		$ 726
Five Year Revolver due July 2023
Class of Stock [Line Items]
Debt instrument term		5 years
Repayments of Debt		$ 247
Common Units
Class of Stock [Line Items]
Units issued in connection with private placement (in units)	11,029,412	1,000,000,000
Common units per share (in units per share)	$ 27.20
Payment of equity issuance costs	$ 300
Consideration for units issued in connection with private placement	$ 6
Common Units | General Public
Class of Stock [Line Items]
Units issued in connection with public offering (in units)	25,000,000
Net proceeds from equity offerings	$ 673
Gross proceeds from public offering	$ 680
Common units per share (in units per share)	$ 27.20
Underwriter fees	$ 6
Placement fees	$ 1
General Partner SPLC
Class of Stock [Line Items]
Units issued in connection with public offering (in units)	510,204
Units issued in connection with private placement (in units)	225,091
General Partner SPLC | Shell Pipeline Company L P
Class of Stock [Line Items]
Contributions from general partner				$ 20
General Partner SPLC | Shell Pipeline Company L P | General Partner Interest
Class of Stock [Line Items]
Aggregate percentage of interest	2.00%	2.00%