Financing Arrangements - Components of Long-Term Debt (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	May 13, 2020
Debt Instrument [Line Items]
Principal Amount	$ 1,893.8	$ 1,242.8
Unamortized discount and debt issuance cost	19.9	13.5
Long-term Debt, Total	1,873.9	1,229.3
Less short-term and current portion of long-term debt, Principal Amount	18.7	18.4
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	18.7	18.4
Total long-term debt, gross, net of current	1,875.1	1,224.4
Debt excluding current, unamortized discount and debt issuance costs	19.9	13.5
Total long-term debt, net of current portion	1,855.2	1,210.9
Senior secured revolving credit facility due 2022 | Revolving Credit Facility
Debt Instrument [Line Items]
Principal Amount	0.0	0.0
Unamortized discount and debt issuance cost	0.0	0.0
Long-term Debt, Total	$ 0.0	$ 0.0
Weighted average interest rate	0.00%	3.90%
Senior secured term loan due 2026 | Secured Debt
Debt Instrument [Line Items]
Principal Amount	$ 619.6	$ 624.5
Unamortized discount and debt issuance cost	8.3	9.8
Long-term Debt, Total	$ 611.3	$ 614.7
Weighted average interest rate	2.51%	4.01%
5.25% Senior Notes Due 2023 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	5.25%	5.25%
Principal Amount	$ 600.0	$ 600.0
Unamortized discount and debt issuance cost	2.8	3.7
Long-term Debt, Total	$ 597.2	$ 596.3
Weighted average interest rate	5.25%	5.25%
5.75% Senior Notes Due 2025 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	5.75%		5.75%
Principal Amount	$ 650.0
Unamortized discount and debt issuance cost	8.8
Long-term Debt, Total	$ 641.2
Weighted average interest rate	5.75%
Other Debt
Debt Instrument [Line Items]
Principal Amount	$ 24.2	$ 18.3
Unamortized discount and debt issuance cost	0.0	0.0
Long-term Debt, Total	$ 24.2	$ 18.3