Quarterly Results of Operations (Unaudited) - Summary of Quarterly Financial Data (Parenthetical) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019
U.S. federal
Quarterly Financial Data [Line Items]
Restructuring charges, diluted per share				$ 0.02
Income tax benefit related to enactment of Tax Cuts and Jobs Act				$ 2,000
Integration Costs Related to Recent Acquisitions
Quarterly Financial Data [Line Items]
Restructuring charges				100	$ 100
Restructuring charges, after tax				$ 100	$ 10
Restructuring charges, diluted per share				$ 0.00	$ 0.00
Corrugated Products Facility Closure
Quarterly Financial Data [Line Items]
Restructuring charges	$ 300				$ 500
Restructuring charges, after tax	$ 200				$ 400
Restructuring charges, diluted per share	$ 0.00				$ 0.00
Debt Refinancing
Quarterly Financial Data [Line Items]
Restructuring charges	$ 38,700							$ 38,700
Treasury Lock
Quarterly Financial Data [Line Items]
Restructuring charges, after tax	$ 25,900
Restructuring charges, diluted per share	$ 0.28
Income tax benefit from stranded tax effects in accumulated OCI related to write-off of remaining treasury lock	$ 3,200
Packaging And Corporate And Other
Quarterly Financial Data [Line Items]
Restructuring charges	400	$ 3,000	$ 600		$ 1,300	$ 200	$ 300
Restructuring charges, after tax					$ 1,000	$ 200	$ 200
Restructuring charges, diluted per share					$ 0.01	$ 0.00	$ 0.00
Wallula, Washington Mill
Quarterly Financial Data [Line Items]
Restructuring charges				$ 3,600	$ 4,000	$ 13,600	$ 8,800
Restructuring charges, after tax	$ 300	$ 2,300	$ 500	$ 2,700	$ 2,900	$ 10,200	$ 6,600
Restructuring charges, diluted per share	$ 0.00	$ 0.02	$ 0.01	$ 0.03	$ 0.04	$ 0.11	$ 0.07