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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Limited Partners Capital Account [Line Items]
Net income	$ 148.0	$ 154.2	$ 115.4	$ 64.8	$ 102.5	$ 99.5	$ 91.7	$ 98.1	$ 482.4	$ 391.8	$ 377.5
Net income attributable to the Parent									0.0	77.3	102.3
Net income attributable to noncontrolling interests									18.3	19.2	30.3
Net income attributable to the Partnership	$ 141.1	$ 148.3	$ 110.7	$ 64.0	$ 86.4	$ 72.6	$ 65.5	$ 70.8	464.1	295.3	244.9
Partner distribution declared									469.1	292.3	203.2
Income in excess of distributions									(5.0)	3.0	41.7
General Partner
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership									134.4	64.6	25.0
Partner distribution declared									134.5	64.6	24.2
Income in excess of distributions									(0.1)	0.0	0.8
Limited Partners' Common Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership									329.7	230.7	134.4
Partner distribution declared									334.6	227.7	109.8
Income in excess of distributions									(4.9)	3.0	24.6
Limited Partner's Subordinated Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership											85.5
Partner distribution declared									$ 0.0	$ 0.0	69.2
Income in excess of distributions											$ 16.3