Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
		Dec. 31, 2019 USD ($) a	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)		Jan. 01, 2019 USD ($)
Summary of Significant Accounting Policies [Line Items]
Research and development costs		$ 16,000,000.0	$ 14,400,000	$ 12,800,000
Cash and cash equivalents		679,500,000	361,500,000
Cash equivalents		410,700,000	311,100,000
Other-than-temporary impairment charges on available-for-sale securities		0
Marketable debt securities			0
Allowance for doubtful accounts		$ 4,200,000	4,600,000
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		$ 8,400,000	9,000,000.0
Interest capitalization, construction in progress		3,400,000	4,500,000	2,500,000
Depreciation expense		346,800,000	361,700,000	347,800,000
Incremental depreciation		$ 300,000	$ 14,500,000	10,500,000
Intangible asset, useful life, in years		9 years 10 months 24 days	10 years 9 months 18 days
Goodwill		$ 918,700,000	$ 917,300,000	883,200,000	[1],[2]
Goodwill and intangible asset impairment		0	0	0
Deferred financing costs		$ 16,300,000	12,600,000
Area leased under timberland cutting rights (acres) | a		73,000
Area leased where fiber farms are operated (acres) | a		3,000
Net loss on impairment of assets			3,100,000	13,500,000
Depletion expense		$ 2,700,000	7,600,000	5,200,000
Software amortization expense		900,000	2,100,000	$ 2,300,000
Operating lease liabilities		240,200,000
Other long-term assets
Summary of Significant Accounting Policies [Line Items]
Long-term lease costs capitalization (Cutting rights)		21,600,000	22,400,000
Net capitalized software costs		1,400,000	1,600,000
Adjustments for New Accounting Pronouncement | Long-term debt
Summary of Significant Accounting Policies [Line Items]
Deferred financing costs		$ 16,300,000	$ 12,600,000
ASU 2016-02
Summary of Significant Accounting Policies [Line Items]
Operating lease liabilities						$ 228,000,000
Customer Relationships
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years	[3],[4]	10 years	10 years 10 months 24 days
Trademarks and Trade Names
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years	[4]	9 years 6 months	10 years 1 month 6 days
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		$ 2,400,000	$ 2,300,000

[1] During 2018, the Company recorded a $5.5 million adjustment to increase the goodwill balance for the Company’s October 2017 acquisition of Sacramento Container

[2] In connection with the October 2018 acquisition of Englander, the Company recorded $28.6 million of goodwill in the Packaging segment in 2018.

[3] 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.

[4] In connection with the October 2018 acquisition of Englander, the Company recorded intangible assets of $13.2 million for customer relationships, $0.8 million for trade names, and $0.1 million for other intangibles