Amortized Cost Basis of Finance Receivables that are on Non-accrual Status (Detail) - Financial Services - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amortized cost basis of finance receivables that are on non-accrual status	$ 57.2	$ 87.9
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amortized cost basis of finance receivables that are on non-accrual status	1.2	1.2
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amortized cost basis of finance receivables that are on non-accrual status	49.1	78.6
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amortized cost basis of finance receivables that are on non-accrual status	$ 6.9	$ 8.1