Long-term Debt (Tables)

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments

The Company’s total indebtedness as of September 30, 2023 and December 31, 2022 consisted of the following:

Debt Instrument (defined below, as applicable)	September 30, 2023		December 31, 2022
	(Dollars in millions)
3.250% Convertible Senior Notes due March 2028 (2028 Convertible Notes)	$	320.0	$	320.0
Finance lease obligations	22.1		23.6
Less: Debt issuance costs	(8.5)		(9.8)
	333.6		333.8
Less: Current portion of long-term debt	12.7		13.2
Long-term debt	$	320.9	$	320.6

Schedule of Interest Charges

Additionally, the table sets forth the amount of cash paid for interest and the amount of non-cash interest expense primarily related to the amortization of debt issuance costs.

	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
	(Dollars in millions)
Indebtedness	$	4.9	$	20.8	$	16.6	$	70.7
Financial assurance instruments	8.9		13.0		28.9		40.1
Interest expense	$	13.8	$	33.8	$	45.5	$	110.8
Cash paid for interest	$	14.8	$	26.4	$	56.7	$	104.2
Non-cash interest expense	$	0.7	$	4.6	$	4.0	$	13.6