Commitments and Contingencies - Schedule of Environmental Remediation Reserve Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Environmental remediation reserve activity
Beginning remediation accrual balance	$ 3.2	$ 2.9	$ 5.0
Current period expenses	0.1	1.2	0.5
Cash expenditures	(0.5)	(0.9)	(2.6)
Ending remediation accrual balance	$ 2.8	$ 3.2	$ 2.9