Commitments and Contingencies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Loss Contingencies [Line Items]
Liabilities recognized for estimated environmental costs	$ 18.9		$ 19.3
Environmental expenses	2.5	$ 4.3
Receivables from insurance carriers related to environmental matters	4.8		7.2
Accounts Receivable [Member]
Loss Contingencies [Line Items]
Receivables from insurance carriers related to environmental matters	1.0		0.5
Other Noncurrent Assets [Member]
Loss Contingencies [Line Items]
Receivables from insurance carriers related to environmental matters	$ 3.8		$ 6.7