Debt and Credit Arrangements - Interest Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Debt Instrument
Interest expense, debt	$ 80.3		$ 128.5
Revolving Credit Facility
Debt Instrument
Interest expense, debt	46.0	$ 5.0	54.1	$ 8.3
Senior Secured And Unsecured Notes
Debt Instrument
Interest income	0.6		20.7
Senior Secured Notes Due 2030 | Secured Debt
Debt Instrument
Interest expense, debt	27.4		54.8
Senior Unsecured Notes Due 2031 | Unsecured Debt
Debt Instrument
Interest expense, debt	12.1		24.2
Term Loan Due 2030 | Revolving Credit Facility
Debt Instrument
Interest expense, debt	34.2	0.0	39.7	0.0
Convertible Notes, due 2024 | Convertible Debt
Debt Instrument
Interest expense, debt	0.7		1.3
Senior secured revolving credit facility due October 2026 | Revolving Credit Facility
Debt Instrument
Interest expense, debt	$ 11.8	$ 5.0	$ 14.4	$ 8.3