Pre- and Post-Modification Amortized Cost Basis Balances for Finance Receivables Modified by Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	$ 74.7	$ 2.5
Post-Modification, Amortized Cost Basis	74.7	2.5
Customer Retail | Fleet
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	72.5	2.2
Post-Modification, Amortized Cost Basis	72.5	2.2
Customer Retail | Owner/Operator
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	2.2	0.3
Post-Modification, Amortized Cost Basis	$ 2.2	$ 0.3