Carrying Amount and Fair Value of Financial Services Fixed-Rate Loans and Fixed-Rate Debt (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financial Services
Assets, carrying amount
Fixed-rate loans, carrying amount	$ 3,482.6	$ 3,361.7
Liabilities, carrying amount
Fixed-rate debt, carrying amount	4,029.0	3,277.2
Assets, Fair Value
Fixed-rate loans, Fair Value	3,537.4	3,434.8
Liabilities, Fair Value
Fixed-rate debt, Fair Value	4,076.6	3,350.5
Truck, Parts and Other
Liabilities, carrying amount
Fixed-rate debt, carrying amount	150.0	150.0
Liabilities, Fair Value
Fixed-rate debt, Fair Value	$ 153.5	$ 160.6

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- Details

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Glossary Loan

-URI http://asc.fasb.org/extlink&oid=6517073

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Amount of loan with fixed rate of interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

+ Details

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ References

No definition available.

+ Details

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