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				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Limited Partners Capital Account [Line Items]
Net income	$ 119.0	$ 137.0	$ 115.0	$ 65.0	$ 256.0	$ 180.0
Less: Net income attributable to noncontrolling interests	4.0		4.0		9.0	5.0
Net income attributable to the Partnership	115.0		111.0		247.0	175.0
Distributions declared	131.0		113.0		250.0	219.0
Income (less than) / in excess of distributions	(16.0)		(2.0)		(3.0)	(44.0)
General Partner
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership	30.0		32.0		57.0	59.0
Distributions declared	31.0		32.0		57.0	60.0
Income (less than) / in excess of distributions	(1.0)		0.0		0.0	(1.0)
Limited Partners’ Common Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership	85.0		79.0		190.0	116.0
Distributions declared	100.0		81.0		193.0	159.0
Income (less than) / in excess of distributions	$ (15.0)		$ (2.0)		$ (3.0)	$ (43.0)