Accounting Policies - Stock Based Compensation (Details) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) item $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares
Stock-based compensation
Number of stock-based compensation plans \| item	1
Total unrecognized compensation costs related to unvested stock-based compensation arrangements	$ 14.8
Total weighted average remaining term of unrecognized compensation costs	1 year 6 months 26 days
Compensation cost recognized	$ 13.9	$ 13.4	$ 10.9
Number of Reportable Segments \| item	3
Impact on both basic and diluted net income per common share for recognition of total stock-based compensation expense (in dollars per share) \| $ / shares	$ 0.28	$ 0.29	$ 0.25
Cost of goods sold.
Stock-based compensation
Compensation cost recognized	$ 0.8	$ 0.9	$ 0.4
Selling, general and administrative expenses
Stock-based compensation
Compensation cost recognized	12.5	10.5
Stock options
Stock-based compensation
Tax benefit recorded for the compensation expense	0.1	0.8	0.3
Other Stock-based Plans
Stock-based compensation
Tax benefit recorded for the compensation expense	$ 3.9	$ 2.8	$ 2.0

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Unrecognized cost of unvested share-based compensation awards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Represents the impact on both basic and diluted net income per common share for recognition of total stock-based compensation expense.

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