(Deficit) Equity - Schedule of Number of Units Outstanding (Details) - shares							3 Months Ended			12 Months Ended
	Sep. 15, 2017	Jun. 09, 2016	May 23, 2016	Mar. 29, 2016	Nov. 17, 2015	May 18, 2015	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									154,941,269	180,936,167	154,941,269
Expiration of subordination period (in units)										0
Units issued in connection with private placement (in units)										5,402,985	765,307
Units issued in connection with public offering (in units)										5,275,510	25,229,591
Ending balance (in units)										191,614,662	180,936,167
Common Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Units issued in connection with private placement (in units)						7,692,308	5,200,000
Units issued in connection with public offering (in units)					9,200,000
General Partner
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									3,098,825	3,618,723	3,098,825
Expiration of subordination period (in units)										0
Units issued in connection with private placement (in units)						156,986	106,122	1,938	15,307	108,060	15,307
Units issued in connection with public offering (in units)	105,510	32,143		258,163	187,755					105,510	504,591
Ending balance (in units)										3,832,293	3,618,723
General Public | Common Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									62,892,308	88,367,308	62,892,308
Expiration of subordination period (in units)										0
Units issued in connection with private placement (in units)								94,925	750,000	5,294,925	750,000
Units issued in connection with public offering (in units)	5,170,000		1,575,000	12,650,000						5,170,000	24,725,000
Ending balance (in units)										98,832,233	88,367,308
Shell Pipeline Company L P | Common Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									21,475,068	21,475,068	21,475,068
Expiration of subordination period (in units)										67,475,068
Units issued in connection with private placement (in units)										0	0
Units issued in connection with public offering (in units)										0	0
Ending balance (in units)										88,950,136	21,475,068
Shell Pipeline Company L P | Subordinate Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)									67,475,068	67,475,068	67,475,068
Expiration of subordination period (in units)										(67,475,068)
Units issued in connection with private placement (in units)										0	0
Units issued in connection with public offering (in units)										0	0
Ending balance (in units)										0	67,475,068