Summary of Impaired Loans (Detail) - Financial Services - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	$ 29.1	$ 15.8
Associated allowance	(4.3)	(2.5)
Net carrying amount of impaired loans with specific reserve	24.8	13.3
Impaired loans with no specific reserve	6.8	16.7
Net carrying amount of impaired loans	31.6	30.0
Average recorded investment	33.5	34.1
Dealer | Wholesale
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	5.0	0.5
Associated allowance	(0.3)	(0.5)
Net carrying amount of impaired loans with specific reserve	4.7
Impaired loans with no specific reserve		4.4
Net carrying amount of impaired loans	4.7	4.4
Average recorded investment	4.4	8.8
Customer Retail | Fleet
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	21.7	12.7
Associated allowance	(3.5)	(1.5)
Net carrying amount of impaired loans with specific reserve	18.2	11.2
Impaired loans with no specific reserve	6.5	12.3
Net carrying amount of impaired loans	24.7	23.5
Average recorded investment	26.6	22.5
Customer Retail | Owner/Operator
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific reserve	2.4	2.6
Associated allowance	(0.5)	(0.5)
Net carrying amount of impaired loans with specific reserve	1.9	2.1
Impaired loans with no specific reserve	0.3
Net carrying amount of impaired loans	2.2	2.1
Average recorded investment	$ 2.5	$ 2.8