Income Tax Matters - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred income tax assets:
Loss and credit carryforwards	$ 17.3	$ 39.6
Defined benefit plans	3.1	3.6
Other assets	35.8	36.8
Lease assets	7.2	8.7
Inventories	39.8	29.5
Excess interest carryforward	10.2	14.0
Research & development capitalization	19.1	16.9
Valuation allowances	(5.5)	(2.7)
Total deferred income tax assets	127.0	146.4
Deferred income tax liabilities:
Property, plant and equipment	(133.3)	(142.6)
Lease liabilities	(7.2)	(8.7)
Undistributed foreign earnings	(3.4)	(3.0)
Total deferred income tax liabilities	(143.9)	(154.3)
Net deferred income tax liabilities	$ (16.9)	$ (7.9)