Other Expense, Net - Components of Other Income (Expense), Net (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset disposals and write-offs		$ (39.7)	$ (31.7)	$ (44.5)
Restructuring, Settlement and Impairment Provisions	[1]	(7.6)	(1.8)	(6.9)
Facilities closure and other costs	[2]	(1.0)	(7.9)	(0.1)
DeRidder and other litigation	[3]	(95.2)	0.0	0.0
DeRidder and other litigation insurance recoveries	[3]	95.2	0.0	0.0
Other		(23.2)	(1.5)	(10.0)
Total		$ (71.5)	$ (42.9)	$ (61.3)

[1] Includes charges related to the announced discontinuation of production of uncoated freesheet paper grades on the No. 3 machine at the Jackson, Alabama mill in the first quarter of 2021 associated with the permanent conversion of the machine to produce linerboard and other paper-to-containerboard conversion related activities.

[2] For 2024, includes charges consisting of closure costs related to corrugated products facilities, partially offset by income primarily related to a favorable lease buyout for a closed corrugated products facility. For 2023, includes charges consisting of closure costs related to corrugated products facilities and design centers, partially offset by a gain on sale of a corrugated products facility. For 2022, includes income primarily related to insurance proceeds received for a natural disaster at one of the corrugated products facilities and a gain on sale of assets related to a corrugated products facility, partially offset by closure costs related to corrugated products facilities.

[3] On April 24, 2024, a jury for the remaining DeRidder mill lawsuit that was tried in the U.S. District Court for the Middle District of Louisiana awarded plaintiffs compensatory damages plus interest. During the fourth quarter of 2024, the Company, certain of its insurers, and the plaintiffs agreed to settle the matter for $59.2 million. A description of the settlement is included in Note 19, Commitments, Guarantees, Indemnifications, and Legal Proceedings for additional detail. The remaining balance relates to other settlement amounts that are fully insured.