Summary of Impaired Loans and Specific Reserve (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2014		Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	$ 19.4		$ 22.4
Associated allowance	(3.2)		(4.1)
Net carrying amount of impaired loans	16.2		18.3
Average recorded investment	33.7	[1]	42.2	[2]
Dealer | Wholesale
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	3.0		8.5
Associated allowance	(1.1)		(1.4)
Net carrying amount of impaired loans	1.9		7.1
Average recorded investment	8.9	[1]	4.8	[2]
Customer Retail | Fleet
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	13.6		10.8
Associated allowance	(1.6)		(2.1)
Net carrying amount of impaired loans	12.0		8.7
Average recorded investment	21.6	[1]	31.4	[2]
Customer Retail | Owner/Operator
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	2.8		3.1
Associated allowance	(0.5)		(0.6)
Net carrying amount of impaired loans	2.3		2.5
Average recorded investment	$ 3.2	[1]	$ 6.0	[2]

[1] Represents the average during the 12 months ended September 30, 2014.

[2] Represents the average during the 12 months ended September 30, 2013.