Segment Information - Analysis of Operations by Reportable Segment (Parenthetical) (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended	12 Months Ended
		Oct. 31, 2021	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Goodwill impairment charge			$ 0.0
Charges for disposal of fixed assets				$ (9.1)	$ (15.2)	$ (6.1)
Acquisition and integration related costs	[1]			0.0	0.0	0.6
Gain on Sale of Transportation Assets						0.8
Business Combination Acquisition And Integration Related Costs	[1]			0.0	0.0	0.6
Debt Refinancing Cost		$ 58.9
Advance Packaging Corporation [Member]
Segment Reporting Information [Line Items]
Restructuring charges						0.4
Acquisition and integration related costs					1.0	0.5
Business Combination Acquisition And Integration Related Costs					1.0	0.5
Packaging
Segment Reporting Information [Line Items]
Restructuring charges				14.4
Acquisition and integration related costs						0.4
Business Combination Acquisition And Integration Related Costs						0.4
Corrugated Products Facilities
Segment Reporting Information [Line Items]
Restructuring charges					0.7
Jackson Alabama Mill [Member] | Corrugated Products Facilities
Segment Reporting Information [Line Items]
Adjustment of asset retirement obligation				$ 11.1		4.3
Jackson Alabama Mill [Member] | Paper
Segment Reporting Information [Line Items]
Restructuring charges						9.3
Adjustment of asset retirement obligation					5.3
Jackson Alabama Mill [Member] | Paper Reporting Unit
Segment Reporting Information [Line Items]
Restructuring charges					$ 8.8
San Lorenzo, California [Member]
Segment Reporting Information [Line Items]
Restructuring charges						$ 2.8

[1] Includes charges related to the December 2021 Advance Packaging Corporation acquisition.