Equity - Public Offerings (Details) - USD ($) $ / shares in Units, $ in Millions							3 Months Ended	12 Months Ended
	Jun. 09, 2016	May 23, 2016	Mar. 29, 2016	Nov. 17, 2015	May 18, 2015	Nov. 03, 2014	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Units issued in connection with public offering (in units)						137,704,220		25,229,591	9,387,755
Net proceeds from public equity offerings								$ 818.1	$ 296.8	$ 0.0
Underwriter fees										46.3
Aggregate percentage of general partner interest								2.00%
Net proceeds from public offerings								$ 818.1	296.8
Consideration for units issued in connection with private placement								$ 9.8	$ 6.1	$ 0.0
May 2016 Acquisition
Class of Stock [Line Items]
Consideration for units issued in connection with private placement		$ 7.1
Shell Treasury Center West Inc | Five Year Revolver
Class of Stock [Line Items]
Debt instrument term								5 years
Shell Treasury Center West Inc | 364 Day Revolver
Class of Stock [Line Items]
Debt instrument term								364 days
Common Units
Class of Stock [Line Items]
Units issued in connection with public offering (in units)				9,200,000
Net proceeds from public equity offerings				$ 296.8
Gross proceeds from public offering				299.4
Underwriter fees				$ 2.6
Common units per share (in units per share)					$ 39.00
Placement fees					$ 2.6
Common Units | May 2016 Acquisition
Class of Stock [Line Items]
Units issued in connection with public offering (in units)		10,500,000
Net proceeds from public offerings		$ 345.8
Common Units | General Public
Class of Stock [Line Items]
Units issued in connection with public offering (in units)		1,575,000	12,650,000			46,000,000		24,725,000	9,200,000
Gross proceeds from public offering	$ 52.4	$ 349.1	$ 401.6
Underwriter fees	0.5	$ 2.9	6.3
Net proceeds from public offerings	$ 51.8		$ 395.1
Common units per share (in units per share)	$ 33.25	$ 33.25	$ 31.75				$ 34.00
Placement fees	$ 0.1	$ 0.4	$ 0.2				$ 0.1
Common Units | Shell Pipeline Company L P
Class of Stock [Line Items]
Units issued in connection with public offering (in units)						21,475,068		0	0
General Partner
Class of Stock [Line Items]
Units issued in connection with public offering (in units)	32,143		258,163			2,754,084		504,591	187,755
Consideration for units issued in connection with private placement	$ 1.1		$ 8.2		$ 6.1		$ 0.5
General Partner | May 2016 Acquisition
Class of Stock [Line Items]
Units issued in connection with public offering (in units)		214,285
General Partner | Pecten
Class of Stock [Line Items]
Units issued in connection with public offering (in units)				187,755
General Partner | Shell Pipeline Company L P | May 2016 Acquisition
Class of Stock [Line Items]
Aggregate percentage of general partner interest								2.00%