Other Income (Expense), Net - Components of Other Income (Expense), Net (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset disposals and write-offs		$ (8.0)	$ (6.6)	$ (15.5)	$ (13.2)
Facilities closure and other costs	[1]	(0.1)	(2.4)	0.0	(7.1)
DeRidder litigation	[2]	(2.0)	0.0	(125.7)	0.0
DeRidder litigation insurance recovery	[2]	2.0	0.0	125.7	0.0
Other		(4.7)	(3.9)	(11.7)	(5.4)
Total		(12.2)	(14.7)	(34.8)	(27.2)
Jackson, Alabama Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Jackson mill conversion-related activities	[3]	$ 0.6	$ (1.8)	$ (7.6)	$ (1.5)

[1] For the three months ended June 30, 2024, includes charges consisting of closure costs related to corrugated products facilities. For the six months ended June 30, 2024, these charges were completely offset by income primarily related to a favorable lease buyout for a closed corrugated products facility during the first quarter of 2024. For 2023, includes charges consisting of 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. The amount of the verdict with interest is within the remaining limits of the Company's liability insurance policies. See Note 19, Commitments, Guarantees, Indemnifications, and Legal Proceedings for additional detail.

[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.