Net Income Per Limited Partner Unit - Schedule of Allocation of Net Income to Arrive at Net Income Per Limited Partner Unit (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016		Sep. 30, 2017		Sep. 30, 2016
Limited Partners Capital Account [Line Items]
Net income	$ 74.5	$ 61.8	[1]	$ 218.2	[2],[3],[4]	$ 204.5	[1],[5]
Less: Net income attributable to Parent	0.0	3.0	[1]	3.0	[3]	11.4	[1]
Less: Net income attributable to noncontrolling interests	1.9	2.5	[1]	6.3	[3]	17.7	[1]
Net income attributable to the Partnership	72.6	56.3	[1]	208.9	[3]	175.4	[1]
Distributions declared	77.4	53.9		209.2		144.6
Income (less than) / in excess of distributions	(4.8)	2.4		(0.3)		30.8
General Partner
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership	17.6	7.2		44.0		15.3
Distributions declared	17.7	7.1		44.0		14.7
Income (less than) / in excess of distributions	(0.1)	0.1		0.0		0.6
Limited Partners' Common Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership	55.0	30.4		164.9		97.4
Distributions declared	59.7	29.0		165.2		79.4
Income (less than) / in excess of distributions	(4.7)	1.4		(0.3)		18.0
Limited Partner's Subordinated Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership		18.7				62.7
Distributions declared	$ 0.0	17.8		$ 0.0		50.5
Income (less than) / in excess of distributions		$ 0.9				$ 12.2

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

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

[3] 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.

[4] 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.

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