Property, Plant and Equipment - Components of Property,Plant and Equipment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Land	$ 1.4	$ 1.4
Building and improvements	19.6	19.5
Pipeline and equipment	572.1	572.4
Other	6.0	5.6
Property, plant and equipment, gross	599.1	598.9
Accumulated depreciation	(222.1)	(216.2)
Property plant and equipment excluding construction in progress	377.0	382.7
Construction in progress	15.1	10.2
Property, plant and equipment, net	392.1	392.9
Costs related to assets under capital lease	22.8	22.8
Accumulated depreciation on assets under capital lease	$ 0.5	$ 0.1
Building and Improvements | Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, depreciable life	10 years
Building and Improvements | Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, depreciable life	40 years
Pipeline and Equipment | Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, depreciable life	10 years
Pipeline and Equipment | Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, depreciable life	30 years
Other | Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, depreciable life	5 years
Other | Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, depreciable life	25 years