Summary of Impaired Loans and Specific Reserve (Cash Basis Method) (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest income recognized:
Interest income recognized on a cash basis	$ 1.7	$ 3.9	$ 2.1
Dealer | Wholesale
Interest income recognized:
Interest income recognized on a cash basis	0.1	0.1	0.1
Customer Retail | Fleet
Interest income recognized:
Interest income recognized on a cash basis	1.2	2.9	1.2
Customer Retail | Owner/Operator
Interest income recognized:
Interest income recognized on a cash basis	$ 0.4	$ 0.9	$ 0.8