Amortized Cost Basis for Finance Receivables that are on Non-accrual Status (Detail) - Financial Services - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amortized cost basis for finance receivables that are on non-accrual status	$ 87.9	$ 49.7
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amortized cost basis for finance receivables that are on non-accrual status	1.2	2.3
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amortized cost basis for finance receivables that are on non-accrual status	78.6	40.2
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amortized cost basis for finance receivables that are on non-accrual status	$ 8.1	$ 7.2