Long-term Debt - Schedule of Debt (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Debt Instrument [Line Items]
Finance lease obligations	$ 22.1		$ 22.1		$ 23.6
Less: Unamortized debt issuance costs	(8.5)		(8.5)		(9.8)
Total debt	333.6		333.6		333.8
Less: Current portion of long-term debt	12.7		12.7		13.2
Long-term debt	320.9		320.9		320.6
Interest expense	13.8	$ 33.8	45.5	$ 110.8
Interest Paid, Capitalized, Investing Activities	14.8	26.4	56.7	104.2
Other Noncash Income (Expense)	0.7	4.6
Noncash interest expense, net			4.0	13.6
Financial assurance instruments
Debt Instrument [Line Items]
Interest expense	8.9	13.0	28.9	40.1
Indebtedness
Debt Instrument [Line Items]
Interest expense	4.9	$ 20.8	16.6	$ 70.7
Senior Notes | 3.250% Convertible Senior Notes due March 2028 (2028 Convertible Notes)
Debt Instrument [Line Items]
Long-term debt	$ 320.0		$ 320.0		$ 320.0
Stated interest rate	3.25%		3.25%