Financing Receivables by Aging Category (Detail) - Financial Services - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 19,563.1	$ 19,798.5
Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	19,260.4	19,416.7
31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	87.2	159.7
Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	215.5	222.1
Dealer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	6,491.9	6,584.4
Dealer \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	4,000.9	4,126.3
Dealer \| Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,491.0	2,458.1
Dealer \| Current and up to 30 days past due \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	3,997.2	4,117.7
Dealer \| Current and up to 30 days past due \| Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,491.0	2,458.1
Dealer \| 31 - 60 days past due \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1.1	5.0
Dealer \| Greater than 60 days past due \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2.6	3.6
Customer Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	13,071.2	13,214.1
Customer Retail \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	11,546.4	11,750.5
Customer Retail \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,524.8	1,463.6
Customer Retail \| Current and up to 30 days past due \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	11,269.9	11,412.2
Customer Retail \| Current and up to 30 days past due \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,502.3	1,428.7
Customer Retail \| 31 - 60 days past due \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	78.1	137.9
Customer Retail \| 31 - 60 days past due \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	8.0	16.8
Customer Retail \| Greater than 60 days past due \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	198.4	200.4
Customer Retail \| Greater than 60 days past due \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 14.5	$ 18.1