Environmental and Other Contingencies (Narrative) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2015
Contingencies Disclosure [Line Items]
Remediation costs		$ 43,900,000
Remediation accrual	$ 5,800,000
Canada [Member]
Contingencies Disclosure [Line Items]
Payments for environmental liabilities	$ 130,000