Finance and Other Receivables - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Repossessed inventory	$ 13.8		$ 16.0
Proceeds from the sales of repossessed assets	16.2	21.6
Financial Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Decrease in the recorded investment for loans and leases modified as TDRs	0.7
Post-Modification Recorded Investment	12.2
Loans accounted for as troubled debt restructurings	27.7		26.0
Financial Services | Dealer wholesale financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment of finance receivables that are on non-accrual status	17.6		18.4
Financial Services | Retail | Fleet
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment of finance receivables that are on non-accrual status	57.3		63.9
Post-Modification Recorded Investment	11.2
Recorded Investment, subsequently defaulted	0.9
Financial Services | Retail | Owner/Operator
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment of finance receivables that are on non-accrual status	16.3		17.6
Post-Modification Recorded Investment	1.0
Recorded Investment, subsequently defaulted	$ 0.1
Financial Services | Loans Receivable | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable, collection period	36 months
Financial Services | Loans Receivable | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable, collection period	60 months