Financing Receivables by Aging Category (Detail) - Financial Services - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 19,345.6	$ 19,798.5
Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	19,008.5	19,416.7
31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	125.9	159.7
Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	211.2	222.1
Dealer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	6,202.9	6,584.4
Dealer \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	3,840.3	4,126.3
Dealer \| Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,362.6	2,458.1
Dealer \| Current and up to 30 days past due \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	3,838.9	4,117.7
Dealer \| Current and up to 30 days past due \| Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,362.6	2,458.1
Dealer \| 31 - 60 days past due \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1.0	5.0
Dealer \| Greater than 60 days past due \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	0.4	3.6
Customer Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	13,142.7	13,214.1
Customer Retail \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	11,625.0	11,750.5
Customer Retail \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,517.7	1,463.6
Customer Retail \| Current and up to 30 days past due \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	11,313.1	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	1,493.9	1,428.7
Customer Retail \| 31 - 60 days past due \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	114.1	137.9
Customer Retail \| 31 - 60 days past due \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	10.8	16.8
Customer Retail \| Greater than 60 days past due \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	197.8	200.4
Customer Retail \| Greater than 60 days past due \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 13.0	$ 18.1