Summary of Significant Accounting Policies - Additional Information (Details)			3 Months Ended		12 Months Ended
		May 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) a	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)
Summary of Significant Accounting Policies [Line Items]
Research and development costs					$ 15,500,000	$ 16,000,000.0	$ 14,400,000
Cash and cash equivalents			$ 974,600,000		974,600,000	679,500,000
Cash equivalents			662,200,000		662,200,000	410,700,000
Other-than-temporary impairment charges on available-for-sale securities					0	0
Allowance for doubtful accounts			3,000,000.0		$ 3,000,000.0	3,000,000.0
Customer returns, allowances and earned discounts as a percentage of gross selling price					1.00%
Reserve for customer accounts receivable, percentage					1.00%
Reserve for customer deductions					$ 7,600,000	8,400,000
Interest capitalization, construction in progress					3,700,000	3,400,000	4,500,000
Depreciation expense					362,500,000	346,800,000	361,700,000
Incremental depreciation					$ 4,500,000	$ 300,000	14,500,000
Intangible asset, useful life, in years					9 years 1 month 6 days	9 years 10 months 24 days
Goodwill			863,500,000		$ 863,500,000	$ 918,700,000	917,300,000
Goodwill and intangible asset impairment					0	0	0
Goodwill impairment			0		55,200,000
Deferred financing costs			14,300,000		$ 14,300,000	16,300,000
Area leased under timberland cutting rights (acres) | a					71,000
Depletion expense					$ 3,100,000	2,700,000	7,600,000
Software amortization expense					1,100,000	900,000	2,100,000
Cloud computing arrangements			4,000,000.0		4,000,000.0
Operating lease liabilities			242,500,000		242,500,000	240,200,000
Other long-term assets
Summary of Significant Accounting Policies [Line Items]
Long-term lease costs capitalization (Cutting rights)			20,300,000		20,300,000	21,600,000
Net capitalized software costs			4,800,000		$ 4,800,000	1,400,000
Adjustments for New Accounting Pronouncement | Long-term debt
Summary of Significant Accounting Policies [Line Items]
Deferred financing costs						$ 14,300,000	16,300,000
ASU 2016-02
Summary of Significant Accounting Policies [Line Items]
Operating lease liabilities								$ 228,000,000
Paper Reporting Unit
Summary of Significant Accounting Policies [Line Items]
Goodwill impairment		$ 55,200,000		$ 55,200,000
Customer Relationships
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years	[1],[2]				9 years 1 month 6 days	10 years
Trademarks and Trade Names
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years					9 years 3 months 18 days	9 years 6 months
Paper
Summary of Significant Accounting Policies [Line Items]
Recoverability test results recoverable percentage		100.00%
Goodwill			0		$ 0	$ 55,200,000	$ 55,200,000
Goodwill impairment					$ 55,200,000
Minimum
Summary of Significant Accounting Policies [Line Items]
Term of senior credit facilities and notes, in years					10 years
Minimum | Customer Relationships
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years					10 years
Minimum | Trademarks and Trade Names
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years					5 years
Maximum
Summary of Significant Accounting Policies [Line Items]
Term of senior credit facilities and notes, in years					30 years
Maximum | Customer Relationships
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years					40 years
Maximum | Trademarks and Trade Names
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years					20 years
Foreign operations
Summary of Significant Accounting Policies [Line Items]
Cash and cash equivalents			$ 2,200,000		$ 2,200,000	$ 2,400,000

[1] During 2019, a corrugated products facility sold part of its operations which included existing inventory, certain production equipment, and customer relationships corresponding to the operations sold. As a result, the gross carrying amount for the customer relationships intangible asset was decreased by $0.7 million

[2] During the second quarter of 2020, the Company recorded a $4.5 million adjustment to decrease the remaining book value of the customer relationships intangible asset as a result of the closure of the San Lorenzo, California corrugated products facility.