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
	Mar. 31, 2016	Mar. 31, 2015
Limited Partners Capital Account [Line Items]
Net income	$ 68.0	$ 49.1	[1],[2]
Less: Net income attributable to Parent	0.0	7.7	[2]
Net income attributable to the Partnership	55.3	23.6	[2]
Distribution declared	41.7	24.1
Income in excess of distributions	13.6	(0.5)
General Partner
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership	3.1	0.5
Distribution declared	2.9	0.5
Income in excess of distributions	0.2	0.0
Limited Partners' Common Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership	30.5	11.6
Distribution declared	23.0	11.8
Income in excess of distributions	7.5	(0.2)
Limited Partner's Subordinated Units
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership	21.7	11.5
Distribution declared	15.8	11.8
Income in excess of distributions	5.9	(0.3)
Noncontrolling Interest
Limited Partners Capital Account [Line Items]
Net income	12.7
Less: Net income attributable to noncontrolling interests	$ 12.7	$ 17.8	[2]

[1] (1) The 2015 financial information has been retrospectively adjusted for the acquisition of the Shell Auger and Lockport Operations.

[2] (1) The 2015 financial information has been retrospectively adjusted for the acquisition of the Shell Auger and Lockport Operations.