Income Taxes (Tables)

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Schedule of Income Tax Expense (Benefit) for Continuing Operations

Income tax expense (benefit) for continuing operations consisted of the following:

	Year ended December 31,
(dollars in millions)	2024			2023			2022
Current:
Federal	$	—		$	—		$	—
State and local		0.1			—			—
Foreign		—			—			—
Total current		0.1			—			—
Deferred:
Federal		(47.0	)		(48.3	)		(31.0	)
State and local		(11.8	)		(7.0	)		(6.6	)
Foreign		—			—			—
Total deferred		(58.8	)		(55.3	)		(37.6	)
Valuation allowance		44.8			38.9			29.6
Total	$	(13.9	)	$	(16.4	)	$	(8.0	)

Schedule of Effective Income Tax Rate Reconciliation

The following is a reconciliation of the statutory federal income tax rate with the effective tax rate for each period:

	Year ended December 31,
	2024			2023			2022
U.S. federal statutory rate		21.0	%		21.0	%		21.0	%
State and local income taxes, net of federal income tax		2.9			3.2			3.1
Non-Deductible meals and entertainment		(0.2	)		(0.2	)		(0.2	)
State net operating loss adjustments		1.1			(0.7	)		0.4
Change in valuation allowance, net of federal income tax		(18.9	)		(17.4	)		(19.0	)
Change in uncertain tax positions		—			0.2			—
Research and development credits		0.5			1.1			—
Other differences, net		(0.6	)		—			(0.2	)
Effective tax rate		5.8	%		7.2	%		5.1	%

Schedule of Income Tax (Benefit) Provision Charged to Continuing Operations or Accumulated Other Comprehensive Income

The income tax (benefit) provision was charged to continuing operations or accumulated other comprehensive income as follows:

	Year ended December 31,
(dollars in millions)	2024			2023			2022
Income tax (benefit) provision related to:
Continuing operations	$	(13.9	)	$	(16.4	)	$	(8.0	)
Accumulated other comprehensive (loss) income		0.6			(0.7	)	7.6

Schedule of Deferred Tax Assets and Liabilities

The components of our deferred tax assets and liabilities were as follows:

	December 31,
(dollars in millions)	2024			2023
Deferred tax assets:
Net operating loss carryforwards	$	177.6		$	206.4
Finance and operating lease obligations		17.1			18.9
Pension and postretirement benefits		28.3			32.8
Employee benefits		3.3			3.8
Interest limitation		76.1			41.5
State tax credit		1.6			1.6
Deferred revenue		26.0			9.1
Other		13.5			13.2
Total deferred tax assets		343.5			327.3
Valuation allowance		(82.9	)		(28.0	)
Total deferred tax assets, net of valuation allowance	$	260.6		$	299.3
Deferred tax liabilities:
Property, plant and equipment and intangibles	$	(270.9	)	$	(293.0	)
Other		(10.0	)		(8.2	)
Total deferred tax liabilities		(280.9	)		(301.2	)
Net deferred tax liabilities	$	(20.3	)	$	(1.9	)

Schedule of Reconciliation of Unrecognized Tax Benefits

A reconciliation of the unrecognized tax benefits is as follows:

	Year ended December 31,
(dollars in millions)	2024		2023		2022
Balance, beginning of year	$	19.4	$	19.3	$	19.3
Change in tax positions for the current year		48.4		0.1		—
Balance, end of year	$	67.8	$	19.4	$	19.3