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, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Limited Partners Capital Account [Line Items]
Net income	$ 146.0	$ 119.0	$ 137.0	$ 155.0	$ 115.0	$ 65.0	$ 402.0	$ 335.0
Less: Net income attributable to noncontrolling interests	5.0			6.0			14.0	11.0
Net income attributable to the Partnership	141.0			149.0			388.0	324.0
Distributions declared	140.0			121.0			390.0	340.0
Income (less than) / in excess of distributions	1.0			28.0			(2.0)	(16.0)
General Partner
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership	36.0			37.0			93.0	96.0
Distributions declared	36.0			36.0			93.0	96.0
Income (less than) / in excess of distributions	0.0			1.0			0.0	0.0
Limited Partners’ Common Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership	105.0			112.0			295.0	228.0
Distributions declared	104.0			85.0			297.0	244.0
Income (less than) / in excess of distributions	$ 1.0			$ 27.0			$ (2.0)	$ (16.0)