Recorded Investment for Finance Receivables that are on Non-accrual Status (Detail) - Financial Services - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded investment of finance receivables that are on non-accrual status	$ 41.0	$ 50.5
Dealer | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded investment of finance receivables that are on non-accrual status	0.1	0.1
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded investment of finance receivables that are on non-accrual status	32.4	44.4
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded investment of finance receivables that are on non-accrual status	$ 8.5	$ 6.0