Other Income (Expense), Net - Components of Other Income (Expense), Net (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset disposals and write-offs		$ (8.2)	$ (7.4)
Facilities closure and other (costs) income (a)	[1]	(2.3)	0.1
DeRidder litigation (b)	[2]	0.0	(123.7)
DeRidder litigation insurance recovery (b)	[2]	0.0	123.7
Other		(2.5)	(6.9)
Total		(13.0)	(22.5)
Jackson, Alabama Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Jackson mill conversion-related activities (c)	[3]	$ 0.0	$ (8.3)

[1] For 2025, includes charges consisting of closure costs related to corrugated products facilities. For 2024, includes income primarily related to a favorable lease buyout for a closed corrugated products facility, partially offset by closure costs related to corrugated products facilities and design centers.

[2] 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. The settlement amount has not yet been paid as of March 31, 2025. For more information, see Note 19, Commitments, Guarantees, Indemnifications, and Legal Proceedings, of the Notes to Consolidated Financial Statements in “Part II, Item 8. Financial Statements and Supplementary Data” of our 2024 Annual Report on Form 10-K.

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