Summary of Amortized Cost Basis of Financing Receivables by Aging Category (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	$ 9,201.1	$ 7,530.7
Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	9,141.6	7,523.2
31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	50.1	2.5
Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	9.4	5.0
Dealer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	4,034.2	2,761.2
Dealer | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	1,953.3	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	1,953.3	1,093.2
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	2,080.9	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	2,080.9	1,668.0
Customer Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	5,166.9	4,769.5
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	4,642.2	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	4,589.2	4,143.7
Customer Retail | Fleet | 31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	45.3	1.1
Customer Retail | Fleet | Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	7.7	4.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	524.7	619.9
Customer Retail | Owner/Operator | Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	518.2	618.3
Customer Retail | Owner/Operator | 31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	4.8	1.4
Customer Retail | Owner/Operator | Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	$ 1.7	$ 0.2