Description of Business and Basis of Presentation (Details)	9 Months Ended
	Sep. 30, 2017 segment system	Dec. 31, 2016
Description Of Business And Basis Of Presentation [Line Items]
Number of pipeline systems	9
Number of refined products systems	3
Number of natural gas gathering pipeline systems	1
Number of gas pipeline systems	1
Number of crude tank storage and terminal systems	1
Number of reportable segments | segment	1
Pecten Midstream LLC (“Pecten”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	100.00%
Shell's Retained Ownership	0.00%
Sand Dollar Pipeline LLC (“Sand Dollar”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	100.00%
Shell's Retained Ownership	0.00%
Zydeco Pipeline Company LLC (“Zydeco”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	92.50%
Shell's Retained Ownership	7.50%
Bengal Pipeline Company LLC (“Bengal”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	50.00%	50.00%
Shell's Retained Ownership	0.00%
Odyssey Pipeline LLC (“Odyssey”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	49.00%	49.00%
Shell's Retained Ownership	22.00%
Mars Oil Pipeline Company LLC (“Mars”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	48.60%	48.60%
Shell's Retained Ownership	22.90%
Poseidon Oil Pipeline Company LLC (“Poseidon”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	36.00%	36.00%
Shell's Retained Ownership	0.00%
Proteus Oil Pipeline Company, LLC (“Proteus”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	10.00%	10.00%
Shell's Retained Ownership	0.00%
Endymion Oil Pipeline Company, LLC (“Endymion”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	10.00%	10.00%
Shell's Retained Ownership	0.00%
Colonial Pipeline Company (“Colonial”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	6.00%
Shell's Retained Ownership	10.12%
Explorer Pipeline Company (“Explorer”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	2.62%
Shell's Retained Ownership	35.97%
Cleopatra Gas Gathering Company, LLC (“Cleopatra”)
Description Of Business And Basis Of Presentation [Line Items]
SHLX Ownership	1.00%
Shell's Retained Ownership	0.00%