Debt (Summary of Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Mar. 15, 2023	Dec. 31, 2022	Dec. 21, 2016
Debt [Line Items]
Short-term debt	$ 4.7		$ 29.1
Total long-term debt	3,122.2		581.5
Total debt	3,126.9		610.6
Current portion	41.2		4.4
Non-current portion	3,081.0		577.1
Term Loans
Debt [Line Items]
Less: unamortized debt issuance costs	$ (16.8)		(0.4)
DDTL Facility loan denominated in Canadian dollars, secured | Term Loans
Debt [Line Items]
Weighted average interest rate	5.86%
Long-term debt:	$ 0.0		85.5
CAD TLA Facility | Term Loans
Debt [Line Items]
Weighted average interest rate	7.83%
Long-term debt:	$ 82.1		0.0
USD TLA Facility | Term Loans
Debt [Line Items]
Weighted average interest rate	7.87%
Long-term debt:	$ 1,725.0		0.0
Current portion	$ 14.1
5.375% Senior unsecured notes due in January 2025 (the "2016 Notes") | Unsecured Debt
Debt [Line Items]
Interest rate	5.375%			5.375%
Long-term debt:	$ 0.0		500.0
Less: unamortized debt issuance costs	$ 0.0		(3.6)
6.75% Senior secured notes due in March 2028 (the "2023 Secured Notes") | Secured Debt
Debt [Line Items]
Interest rate	6.75%	6.75%
Long-term debt:	$ 550.0		0.0
Less: unamortized debt issuance costs	$ (7.2)		0.0
7.75% Senior unsecured notes due in March 2031 (the "2023 Unsecured Notes") | Unsecured Debt
Debt [Line Items]
Interest rate	7.75%	7.75%
Long-term debt:	$ 800.0		0.0
Less: unamortized debt issuance costs	$ (10.9)		$ 0.0