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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	$ 8.6	$ 1.7	$ 48.7	$ 2.5
Post-Modification, Amortized Cost Basis	8.6	1.7	48.7	2.5
Customer Retail | Fleet
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	7.5	1.6	46.5	2.2
Post-Modification, Amortized Cost Basis	7.5	1.6	46.5	2.2
Customer Retail | Owner/Operator
Financing Receivable, Modifications [Line Items]
Pre-Modification, Amortized Cost Basis	1.1	0.1	2.2	0.3
Post-Modification, Amortized Cost Basis	$ 1.1	$ 0.1	$ 2.2	$ 0.3