Summary of Significant Accounting Policies (Inventories) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Inventory, Finished Goods, Gross	$ 148.0	$ 137.0
Other Inventory, Supplies, Gross	100.1	97.7
Inventories	277.7	263.3
Raw Materials
Accounting Policies [Abstract]
Inventory, Raw Materials, Gross	13.7	17.2
Inventory [Line Items]
Inventory, Raw Materials, Gross	13.7	17.2
Inventory Pulp [Member]
Accounting Policies [Abstract]
Inventory, Raw Materials, Gross	15.9	11.5
Inventory [Line Items]
Inventory, Raw Materials, Gross	$ 15.9	$ 11.5

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Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount before valuation and LIFO reserves of other supplies used within the manufacturing or production process expected to be consumed within one year or operating cycle, if longer.

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