(Deficit) Equity - Schedule of Distributions Declared and/or Paid (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended													12 Months Ended
	Dec. 31, 2017	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, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2017	Dec. 31, 2016	[1]	Dec. 31, 2015	[1]
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	$ 83.1	$ 77.4	$ 68.2	$ 63.6	$ 58.6	$ 53.9	$ 49.0	$ 41.7	$ 35.3	$ 30.3	$ 27.7	$ 24.1	$ 14.4
Distributions per Limited Partner unit (in dollars per share)	$ 0.3330	$ 0.31800	$ 0.30410	$ 0.29100	$ 0.277000	$ 0.26375	$ 0.25000	$ 0.23500	$ 0.2200	$ 0.2050	$ 0.1900	$ 0.1750	$ 0.1042	$ 1.2461	$ 1.0258		$ 0.79
Aggregate percentage of interest														2.00%
Shell Pipeline Company L P
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 18.7	$ 17.8	$ 16.9	$ 15.8	$ 14.8	$ 13.9	$ 12.8	$ 11.8	$ 7.1
Common Units | General Public
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	32.9	31.4	26.9	25.7	24.5	23.3	22.0	17.9	13.9	11.0	10.2	8.0	4.8
Common Units | Shell Pipeline Company L P
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	29.6	28.3	27.0	25.9	5.9	5.7	5.4	5.1	4.7	4.4	4.1	3.8	2.2
General Partner
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	1.7	1.5	1.4	1.3	1.2	1.1	1.0	0.9	0.7	0.6	0.5	0.5	0.3
General Partner | Shell Pipeline Company L P
Distribution Made To Limited Partner [Line Items]
Aggregate percentage of interest														2.00%
General Partner | General Partner IDR's
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	$ 18.9	$ 16.2	$ 12.9	$ 10.7	$ 8.3	$ 6.0	$ 3.7	$ 2.0	$ 1.2	$ 0.4	$ 0.1	$ 0.0	$ 0.0

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