Equity - Schedule of Distributions Declared and/or Paid (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended									9 Months Ended
	Sep. 15, 2017	Jun. 09, 2016	Mar. 29, 2016	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016		Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017		Sep. 30, 2016	[1]
Distribution Made To Limited Partner [Line Items]
Aggregate percentage of general partner interest													2.00%
Distributions declared and/or paid				$ 77.4	$ 68.2	$ 63.6	$ 58.6	$ 53.9		$ 49.0	$ 41.7	$ 35.3
Distributions paid per limited partner unit (in dollars per share)				$ 0.3180	$ 0.30410	$ 0.291	$ 0.27700	$ 0.26375	[1]	$ 0.2500	$ 0.2350	$ 0.2200	$ 0.9131	[2]	$ 0.74880
Shell Pipeline Company L P
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid				$ 0.0	$ 0.0	$ 0.0	$ 18.7	$ 17.8		$ 16.9	$ 15.8	$ 14.8
Common Units | General Public
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid				31.4	26.9	25.7	24.5	23.3		22.0	17.9	13.9
Common Units | Shell Pipeline Company L P
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid				$ 28.3	$ 27.0	25.9	5.9	5.7		5.4	$ 5.1	4.7
General Partner
Distribution Made To Limited Partner [Line Items]
Aggregate percentage of general partner interest	2.00%	2.00%	2.00%	2.00%	2.00%						2.00%		2.00%
Distributions declared and/or paid				$ 1.5	$ 1.4	1.3	1.2	1.1		1.0	$ 0.9	0.7
General Partner | IDR's
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid				$ 16.2	$ 12.9	$ 10.7	$ 8.3	$ 6.0		$ 3.7	$ 2.0	$ 1.2

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

[2] 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.