(Deficit) Equity - Schedule of Number of Units Outstanding (Details) - shares					1 Months Ended	3 Months Ended			12 Months Ended
	Sep. 15, 2017	Jun. 09, 2016	May 23, 2016	Mar. 29, 2016	Nov. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									191,614,662	180,936,167
Expiration of subordination period (in units)										0
Units issued in connection with private placement (in units)										5,402,985
Units issued in connection with public offering (in units)									36,764,707	5,275,510
Ending balance (in units)									228,379,369	191,614,662
Common Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Units issued in connection with private placement (in units)					1,000,000,000.00	5,200,000
General Partner
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									3,832,293	3,618,723
Expiration of subordination period (in units)										0
Units issued in connection with private placement (in units)						106,122	1,938	15,307		108,060
Units issued in connection with public offering (in units)	105,510	32,143		258,163					735,295	105,510
Ending balance (in units)									4,567,588	3,832,293
General Public | Common Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									98,832,233	88,367,308
Expiration of subordination period (in units)										0
Units issued in connection with private placement (in units)							94,925	750,000		5,294,925
Units issued in connection with public offering (in units)	5,170,000		1,575,000	12,650,000					25,000,000	5,170,000
Ending balance (in units)									123,832,233	98,832,233
Shell Pipeline Company L P | Common Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									88,950,136	21,475,068
Expiration of subordination period (in units)										67,475,068
Units issued in connection with private placement (in units)										0
Units issued in connection with public offering (in units)									11,029,412	0
Ending balance (in units)									99,979,548	88,950,136
Shell Pipeline Company L P | Subordinate Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									0	67,475,068
Expiration of subordination period (in units)										(67,475,068)
Units issued in connection with private placement (in units)										0
Units issued in connection with public offering (in units)									0	0
Ending balance (in units)									0	0