Summary of Impaired Loans (Detail) - Financial Services - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017		Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	$ 24.4		$ 20.8
Associated allowance	(3.9)		(3.2)
Net carrying amount of impaired loans with specific reserve	20.5		17.6
Impaired loans with no specific reserve	14.4		11.0
Net carrying amount of impaired loans	34.9		28.6
Average recorded investment	37.4	[1]	34.0	[2]
Dealer | Wholesale
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	0.1		0.1
Associated allowance	(0.1)		(0.1)
Net carrying amount of impaired loans with specific reserve	0.0		0.0
Impaired loans with no specific reserve	0.0		0.0
Net carrying amount of impaired loans	0.0		0.0
Average recorded investment	1.8	[1]	4.4	[2]
Dealer | Retail
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	0.0		0.0
Associated allowance	0.0		0.0
Net carrying amount of impaired loans with specific reserve	0.0		0.0
Impaired loans with no specific reserve	4.1		0.0
Net carrying amount of impaired loans	4.1		0.0
Average recorded investment	3.6	[1]	0.0	[2]
Customer Retail | Fleet
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	22.0		18.9
Associated allowance	(3.3)		(2.8)
Net carrying amount of impaired loans with specific reserve	18.7		16.1
Impaired loans with no specific reserve	10.1		10.8
Net carrying amount of impaired loans	28.8		26.9
Average recorded investment	29.6	[1]	27.2	[2]
Customer Retail | Owner/Operator
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	2.3		1.8
Associated allowance	(0.5)		(0.3)
Net carrying amount of impaired loans with specific reserve	1.8		1.5
Impaired loans with no specific reserve	0.2		0.2
Net carrying amount of impaired loans	2.0		1.7
Average recorded investment	$ 2.4	[1]	$ 2.4	[2]

[1] Represents the average during the 12 months ended March 31, 2017.

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