Long-Term Debt - Long-term Debt Components (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	May 29, 2015
Debt Instrument [Line Items]
Total	$ 1,349.8	$ 1,449.3
Debt issuance costs	(12.3)	(13.8)
Debt Instrument, Unamortized Discount, Noncurrent	0.8	1.4
Discount	0.3	1.4
Debt outstanding	1,336.7	1,434.1
Long-term Debt, Gross, Current Maturities	53.2	55.5
Debt Issuance Costs, Current, Net	0.2	0.4
Debt Instrument, Unamortized Discount, Current	(0.5)	0.0
Current portion of long-term debt	52.5	55.1
Long-term Debt, Gross, Excluding Current Maturities	1,296.6	1,393.8
Debt Issuance Costs, Noncurrent, Net	12.1	13.4
Long-term Debt, Excluding Current Maturities	1,284.2	1,379.0
Term Loan \| Term A Loan
Debt Instrument [Line Items]
Total	1,234.4	1,004.3
Debt issuance costs	(6.9)	(7.0)
Debt Instrument, Unamortized Discount, Noncurrent	0.0	0.0
Debt outstanding	1,227.5	997.3
Term Loan \| Term B Loan
Debt Instrument [Line Items]
Total	0.0	390.0
Debt issuance costs	0.0	(2.5)
Debt Instrument, Unamortized Discount, Noncurrent	0.0	1.4
Debt outstanding	0.0	386.1
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Total	82.5	55.0
Debt issuance costs	(5.4)	(4.3)
Debt Instrument, Unamortized Discount, Noncurrent	0.0	0.0
Debt outstanding	77.1	50.7
Senior Notes \| Senior Notes, issued at par
Debt Instrument [Line Items]
Total	32.9	0.0
Debt issuance costs	0.0	0.0
Debt Instrument, Unamortized Discount, Noncurrent	0.8	0.0
Debt outstanding	$ 32.1	$ 0.0	$ 390.0

Long-term Debt, Gross, Current Maturities

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Long-term Debt, Gross, Excluding Current Maturities

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount of debt discount to be amortized within one year or within the normal operating cycle, if longer.

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