Supplemental Balance Sheet Information (Tables)

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Supplemental Balance Sheet Information

	As of December 31,
	2025			2024 As Adjusted1
	(In millions of dollars)
Trade Receivables, Net
Billed trade receivables	$	395.8		$	320.5
Allowance for doubtful receivables		(0.6	)		(0.8	)
Trade receivables, net	$	395.2		$	319.7
Inventories
Finished products	$	156.1		$	130.0
Work-in-process		316.7			229.1
Raw materials		236.2			228.7
Operating supplies		16.2			14.1
Inventories	$	725.2		$	601.9
Property, Plant and Equipment, Net
Land and improvements	$	38.2		$	37.2
Buildings and leasehold improvements		302.6			256.3
Machinery and equipment2		1,586.7			1,337.4
Construction in progress		66.7			297.5
Property, plant and equipment, gross		1,994.2			1,928.4
Accumulated depreciation and amortization		(849.1	)		(767.5	)
Land held for sale		0.1			0.3
Property, plant and equipment, net	$	1,145.2		$	1,161.2
Other Assets
Assets to be conveyed associated with Warrick acquisition2	$	—		$	18.3
Restricted cash – Note 16		19.9			19.5
Long-term replacement parts		28.5			18.3
Net assets of Salaried VEBA – Note 5		9.7			—
Other		17.6			22.5
Other assets	$	75.7		$	78.6
.
Other Accrued Liabilities
Uncleared cash disbursements	$	45.8		$	24.5
Accrued income taxes and other taxes payable		7.8			11.1
Accrued annual contribution to Salaried VEBA – Note 5		2.9			0.7
Accrued interest		6.9			9.9
Current operating lease liabilities – Note 3		4.8			6.3
Current finance lease liabilities – Note 3		2.3			2.4
Current deferred compensation plan liabilities – Note 5		1.2			6.7
Other – Note 8		19.6			17.7
Other accrued liabilities	$	91.3		$	79.3
Long-Term Liabilities
Workers' compensation accrual	$	26.0		$	26.8
Long-term environmental accrual – Note 10		17.4			17.7
Other long-term liabilities		38.0			39.5
Long-term liabilities	$	81.4		$	84.0

1.Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 18 for further discussion.

2.During the year ended December 31, 2025, all of the remaining assets associated with our acquisition of Warrick were conveyed to us and placed in service. At December 31, 2025, such assets are presented within Machinery and equipment.