Summary of Impaired Loans (Detail) - Financial Services - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016		Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	$ 29.2		$ 29.1
Associated allowance	(2.8)		(4.3)
Net carrying amount of impaired loans with specific reserve	26.4		24.8
Impaired loans with no specific reserve	6.0		6.8
Net carrying amount of impaired loans	32.4		31.6
Average recorded investment	34.0	[1]	33.5	[2]
Dealer | Wholesale
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	4.6		5.0
Associated allowance	(0.3)		(0.3)
Net carrying amount of impaired loans with specific reserve	4.3		4.7
Net carrying amount of impaired loans	4.3		4.7
Average recorded investment	4.4	[1]	7.7	[2]
Customer Retail | Fleet
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	21.9		21.7
Associated allowance	(2.0)		(3.5)
Net carrying amount of impaired loans with specific reserve	19.9		18.2
Impaired loans with no specific reserve	5.8		6.5
Net carrying amount of impaired loans	25.7		24.7
Average recorded investment	27.2	[1]	23.2	[2]
Customer Retail | Owner/Operator
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	2.7		2.4
Associated allowance	(0.5)		(0.5)
Net carrying amount of impaired loans with specific reserve	2.2		1.9
Impaired loans with no specific reserve	0.2		0.3
Net carrying amount of impaired loans	2.4		2.2
Average recorded investment	$ 2.4	[1]	$ 2.6	[2]

[1] Represents the average during the 12 months ended March 31, 2016.

[2] Represents the average during the 12 months ended March 31, 2015.