Property, Plant and Equipment - Components of Property, Plant and Equipment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Land	$ 1.4	$ 1.4
Building and improvements	20.7	20.2
Pipeline and equipment	591.4	589.7
Other	6.7	6.0
Property, plant and equipment, gross	620.2	617.3
Accumulated depreciation	(245.7)	(239.5)
Property plant and equipment excluding construction in progress	374.5	377.8
Construction in progress	29.3	20.2
Property, plant and equipment, net	403.8	398.0
Costs related to assets under capital lease	22.8	22.8
Accumulated depreciation on assets under capital lease	$ 1.9	$ 1.6
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