Financing Arrangements (Components of Long-Term Debt) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt, principal amount	$ 1,367.6	$ 1,323.5
Long-term debt, unamortized discount and debt issuance cost	13.7	14.5
Total long-term debt	1,353.9	1,309.0
Less short-term and current portion of long-term debt, Principal Amount	35.1	32.6
Less short-term and current portion of long-term debt, Unamortized discount and debt issuance cost	0.0	0.0
Less short-term and current portion of long-term debt	35.1	32.6
Total long-term debt, net of current portion, Principal Amount	1,332.5	1,290.9
Total long-term debt, net of current portion, Unamortized discount and debt issuance cost	13.7	14.5
Total long-term debt, net of current portion	1,318.8	1,276.4
Capital lease obligations included in other debt	17.8	17.8
Senior secured revolving credit facility due 2022 | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt, principal amount	94.2	56.5
Long-term debt, unamortized discount and debt issuance cost	0.0	0.0
Total long-term debt	$ 94.2	$ 56.5
Weighted average interest rate	3.22%	2.77%
Senior secured term loan due 2022 | Secured Debt
Debt Instrument [Line Items]
Long-term debt, principal amount	$ 635.9	$ 637.5
Long-term debt, unamortized discount and debt issuance cost	8.0	8.5
Total long-term debt	$ 627.9	$ 629.0
Weighted average interest rate	3.59%	3.27%
5.25% senior notes due 2023 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, principal amount	$ 600.0	$ 600.0
Long-term debt, unamortized discount and debt issuance cost	5.7	6.0
Total long-term debt	$ 594.3	$ 594.0
Weighted average interest rate	5.25%	5.25%
Interest rate of senior notes due 2023	5.25%
Other debt
Debt Instrument [Line Items]
Long-term debt, principal amount	$ 37.5	$ 29.5
Long-term debt, unamortized discount and debt issuance cost	0.0	0.0
Total long-term debt	$ 37.5	$ 29.5