Inventories Table (Detail) (Truck and Other, USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Truck and Other
Schedule of Inventory [Line Items]
Finished products	$ 489.3	$ 436.2
Work in process and raw materials	496.1	439.6
Inventory, Gross, Total	985.4	875.8
Less LIFO reserve	(166.6)	(165.4)
Inventories	$ 818.8	$ 710.4

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Carrying amount as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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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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Reflects the difference between (a) inventory at the lower of LIFO cost or market and (b) inventory at replacement cost or at the lower of some acceptable inventory accounting method (such as FIFO or average cost), or market. If material, reflects an excess of replacement or current cost over stated LIFO value parenthetically on the balance sheet or in a note to the financial statements.

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Carrying amount (lower of cost or market) as of the balance sheet date of inventories less all valuation and other allowances. Excludes noncurrent inventory balances (expected to remain on hand past one year or one 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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