Pre- and Post-Modification Amortized Cost Basis Balances for Finance Receivables Modified by Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	$ 5.5	$ 23.5
Post-Modification, Amortized Cost Basis	5.4	23.5
Customer Retail | Fleet
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	4.6	23.4
Post-Modification, Amortized Cost Basis	4.5	23.4
Customer Retail | Owner/Operator
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	0.9	0.1
Post-Modification, Amortized Cost Basis	$ 0.9	$ 0.1