Financing Receivables by Aging Category (Detail) - Financial Services - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 18,089.5	$ 17,528.2
Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	17,925.1	17,381.3
31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	54.5	84.5
Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	109.9	62.4
Dealer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	6,794.9	6,478.6
Dealer | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	4,478.3	4,147.8
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,316.6	2,330.8
Dealer | Current and up to 30 days past due | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	4,478.3	4,131.7
Dealer | Current and up to 30 days past due | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,316.6	2,330.8
Dealer | 31 - 60 days past due | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable		15.0
Dealer | Greater than 60 days past due | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable		1.1
Customer Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	11,294.6	11,049.6
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	10,028.1	9,774.6
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,266.5	1,275.0
Customer Retail | Current and up to 30 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	9,879.8	9,656.4
Customer Retail | Current and up to 30 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,250.4	1,262.4
Customer Retail | 31 - 60 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	44.7	61.0
Customer Retail | 31 - 60 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	9.8	8.5
Customer Retail | Greater than 60 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	103.6	57.2
Customer Retail | Greater than 60 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 6.3	$ 4.1