Summary of Amortized Cost Basis of Financing Receivables by Aging Category (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	$ 8,651.9	$ 7,530.7
Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	8,625.3	7,523.2
31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	16.2	2.5
Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	10.4	5.0
Dealer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	3,585.8	2,761.2
Dealer | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	1,716.3	1,093.2
Dealer | Wholesale | Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	1,716.3	1,093.2
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	1,869.5	1,668.0
Dealer | Retail | Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	1,869.5	1,668.0
Customer Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	5,066.1	4,769.5
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	4,522.2	4,149.6
Customer Retail | Fleet | Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	4,500.1	4,143.7
Customer Retail | Fleet | 31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	13.4	1.1
Customer Retail | Fleet | Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	8.7	4.8
Customer Retail | Owner/Oparator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	543.9	619.9
Customer Retail | Owner/Oparator | Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	539.4	618.3
Customer Retail | Owner/Oparator | 31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	2.8	1.4
Customer Retail | Owner/Oparator | Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	$ 1.7	$ 0.2