Inventories, Net - Schedule of Inventories Net (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Finished products	$ 661.4	$ 667.0
Products in process	26.2	37.1
Raw materials	37.9	35.3
Supplies and expendable parts	151.1	149.9
Inventories, Gross	876.6	889.3
Less: Allowances	(186.6)	(180.3)
Total	$ 690.0	$ 709.0

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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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Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

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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 of valuation reserve for inventory.

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Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed 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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