Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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Debt - Long-term debt (Details) - USD ($) $ in Millions	9 Months Ended
Debt - Long-term debt (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Oct. 01, 2017
Financing Arrangements
Less current maturities	$ (28.1)	$ (22.5)
Total long-term debt	350.7	$ 474.6
Principal payments during each of the next five years and thereafter
Letters of credit outstanding	$ 25.8		$ 25.7
5.05% Senior notes due 2020
Financing Arrangements
Interest rate (as a percent)	5.05%
Letters of credit
Financing Arrangements
Term of letters of credit from the date of issuance	1 year