Inventories (Detail) - Truck, Parts and Other - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Inventory [Line Items]
Finished products	$ 610.0	$ 584.6
Work in process and raw materials	801.9	754.9
Inventories, gross	1,411.9	1,339.5
Less LIFO reserve	(190.0)	(186.3)
Inventories, net	$ 1,221.9	$ 1,153.2

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 by which inventory stated at last-in first-out (LIFO) is less than (in excess of) inventory stated at other inventory cost methods.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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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The aggregate carrying amount as of the balance sheet date of items held by the entity which are partially completed at the time of measurement and unprocessed items that will go through the production process and become part of the final product. Includes supplies used directly or indirectly in the manufacturing or production process. This element may be used when the reporting entity combines work in process and raw materials into an aggregate amount.

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