(Deficit) Equity - At-the-Market Program (Details) - USD ($)								3 Months Ended			12 Months Ended
		Sep. 15, 2017	Jun. 09, 2016	May 23, 2016	Mar. 29, 2016	Mar. 02, 2016	May 18, 2015	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Class of Stock [Line Items]
Issuance of common units, maximum (in units)						$ 300,000,000
Units issued in connection with private placement (in units)											5,402,985	765,307
Net proceeds from private equity placement											$ 0	$ 0	[1]	$ 297,400,000	[1]
Consideration for units issued in connection with private placement											$ 5,800,000	$ 9,800,000	[1]	6,100,000	[1]
Aggregate percentage of interest											2.00%
Net proceeds from public offerings	[2]													$ 297,400,000
364 Day Revolver
Class of Stock [Line Items]
Debt instrument term											364 days
Shell Treasury Center West Inc | Five Year Revolver
Class of Stock [Line Items]
Debt instrument term		5 years						5 years			5 years
Shell Treasury Center West Inc | 364 Day Revolver
Class of Stock [Line Items]
Debt instrument term					364 days						364 days
May 2016 Acquisition
Class of Stock [Line Items]
Consideration for units issued in connection with private placement				$ 7,100,000
Common Units
Class of Stock [Line Items]
Units issued in connection with private placement (in units)							7,692,308	5,200,000
Net proceeds from private equity placement							$ 297,400,000	$ 139,800,000
Gross proceed issuance of private placement offering							$ 300,000,000	$ 140,200,000
Common units per share (in units per share)							$ 39.00	$ 26.96
Placement fees (less than)							$ 2,600,000	$ 400,000
Consideration for units issued in connection with private placement							$ 6,100,000
General Partner
Class of Stock [Line Items]
Units issued in connection with private placement (in units)							156,986	106,122	1,938	15,307	108,060	15,307
Consideration for units issued in connection with private placement			$ 1,100,000		$ 8,200,000			$ 2,900,000	$ 100,000	$ 500,000
General Public | Common Units
Class of Stock [Line Items]
Units issued in connection with private placement (in units)									94,925	750,000	5,294,925	750,000
Gross proceed issuance of private placement offering									$ 3,000,000	$ 25,500,000
Common units per share (in units per share)		$ 26.14	$ 33.25	$ 33.25	$ 31.75				$ 31.51	$ 34.00
Placement fees (less than)			$ 100,000	$ 400,000	$ 200,000				$ 100,000	$ 100,000
Net proceeds from public offerings									$ 2,900,000	$ 25,400,000
Shell Pipeline Company L P | Common Units
Class of Stock [Line Items]
Units issued in connection with private placement (in units)											0	0
Shell Pipeline Company L P | General Partner
Class of Stock [Line Items]
Aggregate percentage of interest											2.00%
Shell Pipeline Company L P | General Partner | May 2016 Acquisition
Class of Stock [Line Items]
Aggregate percentage of interest											2.00%

[1] The financial information presented has been retrospectively adjusted for acquisitions of businesses under common control.

[2] The financial information presented has been retrospectively adjusted for acquisitions of businesses under common control.