Debt (Narrative) (Details) - USD ($) $ in Millions				3 Months Ended	9 Months Ended
	Jun. 30, 2023	Mar. 20, 2023	May 04, 2022	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Mar. 31, 2023	Mar. 15, 2023	Dec. 31, 2022	Dec. 21, 2021	Dec. 21, 2016
Debt [Line Items]
Debt principal repaid					$ 603.3	$ 1,094.9
Current portion					41.2				$ 4.4
Deferred debt issue costs, non-current					4.3
Issuance cost capitalized							$ 20.5
Acquisition-related costs incurred							0.6
Loss on redemption of Notes					$ 3.3	$ 4.8
Term Loans
Debt [Line Items]
Maximum borrowing capacity									$ 2,700.0
Debt issuance costs							22.5
Deferred debt issue costs, non-current							$ 1.4
Revolving Credit Facility
Debt [Line Items]
Weighted average interest rate					4.00%				5.80%
2016 Notes | Unsecured Debt
Debt [Line Items]
Aggregate principal amount											$ 500.0
Interest rate					5.375%						5.375%
Redemption price percentage		100.00%
Loss on redemption of Notes		$ 3.3
2021 Notes | Unsecured Debt
Debt [Line Items]
Redemption price percentage			100.00%
Loss on redemption of Notes			$ 4.8
2021 USD Notes | Unsecured Debt
Debt [Line Items]
Aggregate principal amount										$ 600.0
Interest rate										4.75%
2021 CAD Notes | Unsecured Debt
Debt [Line Items]
Aggregate principal amount										$ 425.0
Interest rate										4.95%
2023 Notes
Debt [Line Items]
Debt issuance costs					$ 19.7
2023 Secured Notes | Secured Debt
Debt [Line Items]
Aggregate principal amount								$ 550.0
Interest rate					6.75%			6.75%
2023 Unsecured Notes | Unsecured Debt
Debt [Line Items]
Aggregate principal amount								$ 800.0
Interest rate					7.75%			7.75%
Revolving Credit Facility | Revolving credit facilities, Maturing September 2026
Debt [Line Items]
Maximum borrowing capacity					$ 730.1
Revolving Credit Facility | Revolving credit facilities, Maturing October 2023
Debt [Line Items]
Available borrowing capacity					5.0
Revolving Credit Facility | Revolving credit facilities, No Maturity
Debt [Line Items]
Available borrowing capacity					$ 5.0
DDTL Facility loan denominated in Canadian dollars, secured | Term Loans
Debt [Line Items]
Weighted average interest rate					5.86%
Annual amortization rate				5.00%
Aggregate principal amount		115.9
Bridge Loan Facility | Term Loans
Debt [Line Items]
Aggregate principal amount		2,800.0
Backstop Revolving Facility | Term Loans
Debt [Line Items]
Aggregate principal amount		750.0
Commitments									$ 88.9
USD TLA Facility | Term Loans
Debt [Line Items]
Maximum borrowing capacity									1,900.0
Weighted average interest rate					7.87%
Aggregate principal amount	$ 1,800.0	$ 1,800.0							$ 1,800.0
Quarterly instalments as percentage of principal amount outstanding (as percentage)	1.25%
Debt principal repaid	$ 100.0
Mandatory principal repayment repaid	22.8
Voluntary repayment repaid	$ 77.2
Current portion					$ 14.1
USD TLA Facility | Term Loans | SOFR
Debt [Line Items]
Variable interest rate (as percentage)		7.54%
CAD TLA Facility | Term Loans
Debt [Line Items]
Weighted average interest rate					7.83%
Annual amortization rate		5.00%