Environmental (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Loss Contingencies [Line Items]
Environmental remediation costs	$ 300,000	$ 0
Accrued environmental liability	$ 102,300,000		$ 103,700,000
Estimated time frame to remediate contigency	30
Other Noncurrent Liabilities [Member]
Loss Contingencies [Line Items]
Accrued environmental liability	$ 88,100,000		$ 89,600,000