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								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, 2017		Dec. 31, 2016		Dec. 31, 2015
Limited Partners Capital Account [Line Items]
Net income	$ 102.5	$ 99.5	$ 91.7	$ 98.1	$ 95.5	$ 84.4	$ 98.6	$ 99.0	$ 391.8	[1]	$ 377.5	[1],[2],[3]	$ 374.0	[1],[2],[3]
Net income attributable to the Parent									77.3		102.3	[3]	133.8	[3]
Net income attributable to noncontrolling interests									19.2		30.3	[3]	73.1	[3]
Net income attributable to the Partnership	$ 86.4	$ 72.6	$ 65.5	$ 70.8	$ 69.5	$ 56.3	$ 63.8	$ 55.3	295.3		244.9	[3]	167.1	[3]
Partner distribution declared									292.3		203.2		117.4
Income in excess of distributions									3.0		41.7		49.7
General Partner
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership									64.6		25.0		5.0
Partner distribution declared									64.6		24.2		4.0
Income in excess of distributions									0.0		0.8		1.0
Limited Partners' Common Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership									230.7		134.4		85.5
Partner distribution declared									227.7		109.8		60.1
Income in excess of distributions									3.0		24.6		25.4
Limited Partner's Subordinated Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership											85.5		76.6
Partner distribution declared									$ 0.0		69.2		53.3
Income in excess of distributions											$ 16.3		$ 23.3

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

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

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