Summary of Significant Accouting Policies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and cash equivalents	$ 20.0	$ 22.5	$ 15.7
Restricted Cash, Current	1.4	0.0	0.0
Restricted Cash, Noncurrent	1.0	2.4	1.0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	22.4	24.9	16.7	$ 23.0
Logs, pulpwood, chips and sawdust	19.4	19.8
Pulp, paperboard and tissue products	168.9	159.5
Materials and supplies	93.1	86.9
Inventories	281.4	266.2
Property, Plant and Equipment, Gross	3,039.5	2,961.0
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,781.8	1,691.7
Property, plant and equipment, net	1,257.7	1,269.3
Depreciation	108.4	94.4	97.0
Interest Costs Capitalized	5.9	9.0	4.6
Net proceeds from divested assets		70.9
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		26.8
Receivables, net of allowance for doubtful accounts of $1.5 at December 31, 2019 and 2018	159.1	145.5
Accrued account purchase agreement liabilities	0.0	4.9
Goodwill, Impairment Loss	0.0	195.1	0.0
Sale of Accounts Receivable	159.3	68.8
Factoring Expense	1.0	0.2
Supply chain financing, amount outstanding		20.8
Other Assets
Escrow Deposit	1.4	1.4
Restricted Cash, Current [Member]
Escrow Deposit	1.4
Land and land Improvements
Property, Plant and Equipment, Gross	$ 109.9	95.3
Land and land Improvements | Minimum
Estimated useful life	10 years
Land and land Improvements | Maximum
Estimated useful life	40 years
Building and Building Improvements [Member]
Property, Plant and Equipment, Gross	$ 478.7	381.1
Building and Building Improvements [Member] | Minimum
Estimated useful life	10 years
Building and Building Improvements [Member] | Maximum
Estimated useful life	40 years
Machinery and Equipment
Property, Plant and Equipment, Gross	$ 2,441.7	2,211.3
Capital Leased Assets, Gross	$ 26.5		$ 26.1
Machinery and Equipment | Minimum
Estimated useful life	2 years
Machinery and Equipment | Maximum
Estimated useful life	25 years
Construction in Progress [Member]
Property, Plant and Equipment, Gross	$ 9.2	273.3
Trade Accounts Receivable [Member]
Receivables, net of allowance for doubtful accounts of $1.5 at December 31, 2019 and 2018	$ 157.1	$ 142.8