Allowance for Credit Losses (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	$ 139.0	$ 145.0
Provision for losses	7.5	10.5
Charge-offs	(8.8)	(10.8)
Recoveries	1.4	1.5
Currency translation	2.2	2.8
Ending Balance	141.3	149.0
Dealer wholesale financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	11.7	7.5
Provision for losses	2.7	0.5
Charge-offs		(0.5)
Currency translation	0.2	0.2
Ending Balance	14.6	7.7
Retail
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	127.3	137.5
Provision for losses	4.8	10.0
Charge-offs	(8.8)	(10.3)
Recoveries	1.4	1.5
Currency translation	2.0	2.6
Ending Balance	$ 126.7	$ 141.3