Acquisitions and Divestitures - Additional Information (Details) - USD ($) $ in Millions													1 Months Ended	2 Months Ended	3 Months Ended			5 Months Ended	9 Months Ended
		Sep. 15, 2017	May 10, 2017	Apr. 28, 2017	Mar. 01, 2017	Sep. 27, 2016	Aug. 09, 2016	Jun. 09, 2016	May 23, 2016	Mar. 29, 2016	May 12, 2015	Nov. 03, 2014	May 31, 2017	Jun. 30, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2017		Sep. 30, 2016	[2]
Business Acquisition [Line Items]
Historical carrying value of property, plant and equipment acquired															$ 9.9
April 2017 Divestiture																			$ 0.8	[1]	$ 0.0
Proceeds from April 2017 divestiture	[3]																		20.2
Net proceeds from public offering	[3]																		$ 283.7
Units issued in connection with public offering (in shares)																			5,275,510
Contributions from general partner																			$ 5.8	[1]	9.8
Aggregate percentage of general partner interest																			2.00%
Capital distributions to general partner, cash																			$ 429.3	[1]	$ 599.2
Shell Treasury Center West Inc | Five Year Fixed Facility
Business Acquisition [Line Items]
Debt instrument term																			5 years
Shell Treasury Center West Inc | Five Year Revolver
Business Acquisition [Line Items]
Debt instrument term		5 years								5 years					5 years		5 years		5 years
General Partner
Business Acquisition [Line Items]
Units issued in connection with public offering (in shares)		105,510						32,143		258,163									105,510
Contributions from general partner								$ 1.1		$ 8.2					$ 2.9	$ 0.1	$ 0.5
Aggregate percentage of general partner interest		2.00%						2.00%		2.00%					2.00%	2.00%	2.00%		2.00%
Shell Pipeline Company L P | Common Units
Business Acquisition [Line Items]
Units issued in connection with public offering (in shares)																			0
Shell Pipeline Company L P | General Partner
Business Acquisition [Line Items]
Proceeds from April 2017 divestiture																			$ 18.7
Net proceeds from public offering																			$ 5.8
Zydeco Pipeline Company LLC (“Zydeco”) | Disposed of by sale
Business Acquisition [Line Items]
April 2017 Divestiture				$ 21.0
Net assets divested				0.8
Proceeds from April 2017 divestiture				20.2
Zydeco Pipeline Company LLC (“Zydeco”) | Disposed of by sale | Shell Pipeline Company L P
Business Acquisition [Line Items]
April 2017 Divestiture				$ 19.4
Revolving Credit Facility | Shell Treasury Center West Inc | Five Year Revolver
Business Acquisition [Line Items]
Debt instrument term						5 years				5 years	5 years	5 years							5 years
Fixed Facility | Shell Treasury Center West Inc | Five Year Fixed Facility
Business Acquisition [Line Items]
Debt instrument term					5 years														5 years
Delta
Business Acquisition [Line Items]
Interest acquired			100.00%
May 2017 Acquisition
Business Acquisition [Line Items]
Consideration transferred			$ 630.0
Consideration, cash on hand			50.0
Transaction costs			0.8
Purchase option and right of refusal, shutdown period (in years)													2 years
Capital distributions to general partner			$ 429.3
Revenue related to the assets acquired																		$ 40.1
Net earnings related to the assets acquired														$ 18.9
May 2017 Acquisition | Shell Treasury Center West Inc | Five Year Fixed Facility
Business Acquisition [Line Items]
Debt instrument term			5 years
May 2017 Acquisition | Shell Treasury Center West Inc | Five Year Revolver
Business Acquisition [Line Items]
Debt instrument term			5 years
May 2017 Acquisition | Revolving Credit Facility | Shell Treasury Center West Inc | Five Year Revolver
Business Acquisition [Line Items]
Consideration, funded with borrowings			$ 73.1
Debt instrument term			5 years						5 years
May 2017 Acquisition | Fixed Facility | Shell Treasury Center West Inc | Five Year Fixed Facility
Business Acquisition [Line Items]
Consideration, funded with borrowings			$ 506.9
Debt instrument term																			5 years
Na Kika
Business Acquisition [Line Items]
Interest acquired			100.00%
Refinery Gas Pipeline
Business Acquisition [Line Items]
Interest acquired			100.00%
Zydeco Pipeline Company LLC (“Zydeco”)
Business Acquisition [Line Items]
Interest acquired									30.00%
August 2016 Acquisition
Business Acquisition [Line Items]
Interest acquired							2.62%
Consideration transferred							$ 26.2
Consideration, cash on hand							26.3
Transaction costs							$ 0.1
Explorer Pipeline Company
Business Acquisition [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners							35.97%
Bengal
Business Acquisition [Line Items]
Interest acquired									1.00%
Colonial Pipeline Company (“Colonial”)
Business Acquisition [Line Items]
Interest acquired									3.00%
May 2016 Acquisition
Business Acquisition [Line Items]
Consideration transferred									$ 700.0
Consideration, cash on hand									50.4
Transaction costs									0.4
Capital distributions to general partner									606.3
Capital distributions to general partner, cash									599.2
Other non-cash capital distributions to general partner									$ 7.1
May 2016 Acquisition | Shell Treasury Center West Inc | Five Year Revolver
Business Acquisition [Line Items]
Debt instrument term									5 years
May 2016 Acquisition | Common Units
Business Acquisition [Line Items]
Net proceeds from public offering									$ 345.8
Units issued in connection with public offering (in shares)									10,500,000
May 2016 Acquisition | General Partner
Business Acquisition [Line Items]
Units issued in connection with public offering (in shares)									214,285
Contributions from general partner									$ 7.1
Aggregate percentage of general partner interest									2.00%
May 2016 Acquisition | Revolving Credit Facility | Shell Treasury Center West Inc | Five Year Revolver
Business Acquisition [Line Items]
Consideration, funded with borrowings									$ 296.7

[1] The financial information for the nine months ended September 30, 2017 reflects adjustments for the acquisition of the Shell Delta,Na Kika and Refinery Gas Pipeline Operations from January 1, 2017 through May 9, 2017.

[2] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations.

[3] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations.