Summary of Impaired Loans (Detail) - Financial Services - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2017		Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	$ 24.2		$ 20.8
Associated allowance	(4.6)		(3.2)
Net carrying amount of impaired loans with specific reserve	19.6		17.6
Impaired loans with no specific reserve	14.9		11.0
Net carrying amount of impaired loans	34.5		28.6
Average recorded investment	37.6	[1]	34.7	[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	0.9	[1]	4.2	[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	3.9		0.0
Net carrying amount of impaired loans	3.9		0.0
Average recorded investment	3.8	[1]	0.0	[2]
Customer Retail | Fleet
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	22.4		18.9
Associated allowance	(4.1)		(2.8)
Net carrying amount of impaired loans with specific reserve	18.3		16.1
Impaired loans with no specific reserve	10.8		10.8
Net carrying amount of impaired loans	29.1		26.9
Average recorded investment	30.7	[1]	28.1	[2]
Customer Retail | Owner/Operator
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	1.7		1.8
Associated allowance	(0.4)		(0.3)
Net carrying amount of impaired loans with specific reserve	1.3		1.5
Impaired loans with no specific reserve	0.2		0.2
Net carrying amount of impaired loans	1.5		1.7
Average recorded investment	$ 2.2	[1]	$ 2.4	[2]

[1] Represents the average during the 12 months ended June 30, 2017.

[2] Represents the average during the 12 months ended June 30, 2016.