Summary of Impaired Loans and Specific Reserve (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Impaired loans with specific reserve	$ 54.7				$ 57.8
Associated allowance	(10.8)				(10.8)
Net carrying amount of impaired loans	43.9				47.0
Average recorded investment	61.2	[1]	65.3	[1]
Interest income recognized on a cash basis	0.7	[2]	0.4	[2]
Dealer wholesale financing
Financing Receivable, Impaired [Line Items]
Impaired loans with specific reserve	18.1				18.4
Associated allowance	(2.8)				(2.2)
Net carrying amount of impaired loans	15.3				16.2
Average recorded investment	17.9	[1]	5.7	[1]
Retail | Fleet
Financing Receivable, Impaired [Line Items]
Impaired loans with specific reserve	26.9				27.9
Associated allowance	(6.0)				(6.0)
Net carrying amount of impaired loans	20.9				21.9
Average recorded investment	31.9	[1]	36.9	[1]
Interest income recognized on a cash basis	0.4	[2]	0.3	[2]
Retail | Owner/Operator
Financing Receivable, Impaired [Line Items]
Impaired loans with specific reserve	9.7				11.5
Associated allowance	(2.0)				(2.6)
Net carrying amount of impaired loans	7.7				8.9
Average recorded investment	11.4	[1]	22.7	[1]
Interest income recognized on a cash basis	$ 0.3	[2]	$ 0.1	[2]

[1] Represents the average during the 12 months ended March 31, 2012 and 2011.

[2] Represents the amounts recognized during the three months ended March 31, 2012 and 2011. All interest income recognized during the period these loans were considered impaired was recorded on a cash basis.