Financing Arrangements - Long-term debt (Details) - USD ($) $ in Millions		12 Months Ended
	Jun. 18, 2010	Dec. 31, 2017	Dec. 31, 2016
Financing Arrangements
Total debt		$ 499.5	$ 653.6
Less debt issuance costs (deduction from liability)		(2.4)	(3.2)
Less current maturities		(22.5)	(139.1)
Total long-term debt		474.6	511.3
Principal payments during each of the next five years and thereafter
2018		22.5
2019		30.0
2020		105.0
2021		342.0
2022		0.0
Thereafter		0.0
Letters of credit outstanding		$ 25.7	$ 25.6
5.05% Senior notes due 2020
Financing Arrangements
Interest rate (as a percent)		5.05%	5.05%
Total debt		$ 75.0	$ 75.0
Amount drawn	$ 75.0
5.05% Senior notes due 2020 | Minimum
Financing Arrangements
Optional amount that the Company may prepay			1.0
Term Loan due February 2021
Financing Arrangements
Total debt		277.5	300.0
Term Loan due December 2017
Financing Arrangements
Total debt			115.8
Line of Credit matures February 2021
Financing Arrangements
Total debt		$ 147.0	162.0
Other consists primarily of European borrowings (at interest rates ranging from 1.1% to 6.0%)
Financing Arrangements
Total debt			$ 0.8
Other consists primarily of European borrowings (at interest rates ranging from 1.1% to 6.0%) | Minimum
Financing Arrangements
Interest rate (as a percent)		1.10%
Other consists primarily of European borrowings (at interest rates ranging from 1.1% to 6.0%) | Maximum
Financing Arrangements
Interest rate (as a percent)		6.00%
Letters of credit
Financing Arrangements
Term of letters of credit from the date of issuance		1 year