Pre- and Post-Modification Amortized Cost Basis Balances for Finance Receivables Modified by Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	$ 1.0	$ 8.6	$ 6.8	$ 48.7
Post-Modification, Amortized Cost Basis	1.0	8.6	6.7	48.7
Customer Retail | Fleet
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	1.0	7.5	5.8	46.5
Post-Modification, Amortized Cost Basis	$ 1.0	7.5	5.7	46.5
Customer Retail | Owner/Operator
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis		1.1	1.0	2.2
Post-Modification, Amortized Cost Basis		$ 1.1	$ 1.0	$ 2.2