Summary of Impaired Loans (Cash Basis Method) (Detail) - Financial Services - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Interest income recognized:
Interest income recognized on a cash basis	$ 0.4	$ 0.3	$ 1.0	$ 1.1
Customer Retail | Fleet
Interest income recognized:
Interest income recognized on a cash basis	0.4	0.2	1.0	0.8
Customer Retail | Owner/Operator
Interest income recognized:
Interest income recognized on a cash basis	$ 0.0	$ 0.1	$ 0.0	$ 0.3