Environmental and Other Contingencies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended	39 Months Ended
Mar. 31, 2018	Dec. 31, 2015	Mar. 31, 2018
Environmental and Other Contingencies [Abstract]
Remediation costs	$ 3.8	$ 43.9
Payments for environmental liabilities			$ 39.7
Remediation accrual	7.1		$ 7.1
Proceeds from insurance settlement	$ 15.0

Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
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-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

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- Definition

The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13296-110859

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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- References

No definition available.

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Cash outflows made during the period for environmental remediation activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Subparagraph (f)
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Amount of cash inflow for proceeds from settlement of insurance claim, classified as operating activities. Excludes insurance settlement classified as investing activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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