Income Taxes - Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Lease obligations		$ 71.9	$ 72.8
Employee benefits and compensation		53.3	44.8
Accrued liabilities		31.6	30.4
Net operating loss carryforwards		12.6	16.2
Restricted stock and performance units		10.4	9.8
Inventories		8.8	13.4
Capital loss and general business credit carryforwards		0.4	0.4
Derivatives		0.1	0.1
Pension and postretirement benefits		0.0	12.7
Gross deferred tax assets		189.1	200.6
Valuation allowance	[1]	(0.3)	(0.3)
Net deferred tax assets		188.8	200.3
Deferred tax liabilities:
Property, plant and equipment		(598.8)	(609.2)
Goodwill and intangible assets		(81.8)	(79.0)
Right-of-use assets		(68.9)	(70.1)
Pension and postretirement benefits		(1.2)	0.0
Total deferred tax liabilities		(750.7)	(758.3)
Net deferred tax liabilities		$ (561.9)	$ (558.0)

[1] Deferred tax assets are reduced by a valuation allowance when it is more likely than not that some portion of the deferred tax assets will not be realized. Both the 2024 and 2023 valuation allowances relate to capital losses. We do not expect to generate capital gains before the capital losses expire. If or when recognized, the tax benefits relating to the reversal of any or all of the valuation allowance would be recognized as a benefit to income tax expense.