Segment Reporting Information, by Segment (Detail) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segment Reporting Information [Line Items]
Net sales and revenues	$ 3,960.7	$ 2,464.1	$ 7,244.3	$ 4,694.8
Investment income	9.9	4.3	17.9	8.8
Income (loss) before income taxes	353.2	148.6	639.5	244.6
Depreciation and amortization	169.0	151.4	331.4	316.8
Truck and Other
Segment Reporting Information [Line Items]
Net sales and revenues	3,702.7	2,224.8	6,745.3	4,209.1
Income (loss) before income taxes	286.4	110.3	514.4	173.7
Depreciation and amortization	81.4	68.3	162.0	141.9
Truck and Other \| Trucks
Segment Reporting Information [Line Items]
Total sales and revenues	3,947.3	2,274.7	7,130.4	4,331.0
Less intersegment sales and revenues	(272.9)	(71.2)	(437.9)	(161.8)
Net sales and revenues	3,674.4	2,203.5	6,692.5	4,169.2
Income (loss) before income taxes	290.3	114.2	531.0	180.8
Depreciation and amortization	79.1	66.0	157.5	137.4
Truck and Other \| Other products
Segment Reporting Information [Line Items]
Net sales and revenues	28.3	21.3	52.8	39.9
Income (loss) before income taxes	(3.9)	(3.9)	(16.6)	(7.1)
Depreciation and amortization	2.3	2.3	4.5	4.5
Financial Services
Segment Reporting Information [Line Items]
Net sales and revenues	258.0	239.3	499.0	485.7
Income (loss) before income taxes	56.9	34.0	107.2	62.1
Depreciation and amortization	$ 87.6	$ 83.1	$ 169.4	$ 174.9

The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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Amount of total revenue for the reportable segments, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy.

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