Equity - Schedule of Distributions Declared and/or Paid (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended			14 Months Ended
	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, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	$ 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)	$ 0.277000	$ 0.26375	$ 0.25000	$ 0.23500	$ 0.2200	$ 0.2050	$ 0.1900	$ 0.1750	$ 1.02575	$ 0.7900	$ 0.1042	$ 0.1042
Aggregate percentage of general partner interest									2.00%
Shell Pipeline Company L P
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	$ 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	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	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	1.2	1.1	1.0	0.9	0.7	0.6	0.5	0.5				0.3
General Partner | General Partner IDR's
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid	$ 8.3	$ 6.0	$ 3.7	$ 2.0	$ 1.2	$ 0.4	$ 0.1	$ 0.0				$ 0.0