Finance and Other Receivables - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Repossessed inventory	$ 10.8		$ 10.8		$ 16.0
Proceeds from the sales of repossessed assets			48.7	65.7
Financial Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Decrease in the recorded investment for loans and leases modified as TDRs	0.8		1.5
Post-Modification Recorded Investment	14.5	4.1	45.9	29.5
Loans accounted for as troubled debt restructurings	44.0		44.0		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	2.9		2.9		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	57.4		57.4		63.9
Post-Modification Recorded Investment	13.9	3.4	43.8	24.3
Recorded Investment, subsequently defaulted	7.7		7.7
Financial Services | Retail | Fleet | One Customer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, subsequently defaulted	4.8		4.8
Specific reserve			1.8
Financial Services | Retail | Owner/Operator
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment of finance receivables that are on non-accrual status	12.8		12.8		17.6
Post-Modification Recorded Investment	0.6	0.7	2.1	5.2
Recorded Investment, subsequently defaulted	$ 0.5		$ 0.5
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