Segment Information - Analysis of Operations by Reportable Segment (Parenthetical) (Details) - USD ($)			3 Months Ended					12 Months Ended
		May 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Goodwill impairment charge			$ 0					$ 55,200,000
Charges for disposal of fixed assets								(6,800,000)	$ (8,200,000)	$ (5,800,000)
Acquisition and integration related costs	[1]									200,000
Debt Refinancing
Segment Reporting Information [Line Items]
Restructuring charges							$ 38,700,000		38,700,000
Paper Reporting Unit
Segment Reporting Information [Line Items]
Goodwill impairment charge		$ 55,200,000			$ 55,200,000
Packaging and Paper
Segment Reporting Information [Line Items]
Restructuring charges			$ 4,000,000.0	$ 3,300,000	20,400,000			27,300,000
Paper
Segment Reporting Information [Line Items]
Restructuring charges								800,000
Goodwill impairment charge								55,200,000
Packaging
Segment Reporting Information [Line Items]
Restructuring charges									300,000	1,600,000
Property damage and business interruption insurance										500,000
Acquisition and integration related costs										200,000
Corporate and Other
Segment Reporting Information [Line Items]
Restructuring charges										200,000
DeRidder, Louisiana Mill
Segment Reporting Information [Line Items]
Charges for disposal of fixed assets									3,000,000.0
DeRidder, Louisiana Mill | Packaging
Segment Reporting Information [Line Items]
Charges for disposal of fixed assets									3,000,000.0
Wallula, Washington Mill | Paper
Segment Reporting Information [Line Items]
Restructuring charges									200,000	17,700,000
Wallula, Washington Mill | Packaging
Segment Reporting Information [Line Items]
Restructuring charges									$ 800,000	$ 12,300,000
Hurricane Laura | DeRidder, Louisiana Mill
Segment Reporting Information [Line Items]
Charges related to the impact of Hurricane Laura				$ 10,000,000.0				10,000,000.0
COVID-19 | Packaging and Paper
Segment Reporting Information [Line Items]
Incremental out-of-pocket costs					$ 6,100,000	$ 800,000		6,300,000
COVID-19 | Paper
Segment Reporting Information [Line Items]
Incremental out-of-pocket costs								$ 600,000

[1] Includes charges for acquisition and integration costs related to recent acquisitions.