Long-term Debt (Tables)

6 Months Ended

Jun. 30, 2023

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments

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

Debt Instrument (defined below, as applicable)	June 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	23.5		23.6
Less: Debt issuance costs	(9.0)		(9.8)
	334.5		333.8
Less: Current portion of long-term debt	13.0		13.2
Long-term debt	$	321.5	$	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 June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
	(Dollars in millions)
Indebtedness	$	5.3	$	24.0	$	11.7	$	49.9
Financial assurance instruments	8.0		13.6		20.0		27.1
Interest expense	$	13.3	$	37.6	$	31.7	$	77.0
Cash paid for interest	$	22.9	$	40.6	$	41.9	$	77.8
Non-cash interest expense	$	1.7	$	5.2	$	3.3	$	9.0