Net Income Per Limited Partner Unit - Schedule of Basic and Diluted Net Income Per Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ 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
Distribution Made To Limited Partner [Line Items]
Distributions declared									$ 469.1	$ 292.3	$ 203.2
Income in excess of distributions									(5.0)	3.0	41.7
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
Net income per limited partner unit:
Basic and diluted (in dollars per share)	$ 0.45	$ 0.50	$ 0.35	$ 0.18	$ 0.35	$ 0.31	$ 0.29	$ 0.33
General Partner
Distribution Made To Limited Partner [Line Items]
Distributions declared									134.5	64.6	24.2
Income in excess of distributions									(0.1)	0.0	0.8
Net income attributable to the Partnership									134.4	64.6	25.0
Limited Partners' Common Units
Distribution Made To Limited Partner [Line Items]
Distributions declared									334.6	227.7	109.8
Income in excess of distributions									(4.9)	3.0	24.6
Net income attributable to the Partnership									$ 329.7	$ 230.7	$ 134.4
Weighted average units outstanding:
Basic and diluted (in shares)									220.3	180.4	101.9
Net income per limited partner unit:
Basic and diluted (in dollars per share)									$ 1.50	$ 1.28	$ 1.32
Limited Partner's Subordinated Units
Distribution Made To Limited Partner [Line Items]
Distributions declared									$ 0.0	$ 0.0	$ 69.2
Income in excess of distributions											16.3
Net income attributable to the Partnership											$ 85.5
Weighted average units outstanding:
Basic and diluted (in shares)											67.5
Net income per limited partner unit:
Basic and diluted (in dollars per share)											$ 1.27