Financing Receivables by Aging Category (Detail) - Financial Services - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 20,163.6	$ 19,293.1
Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	19,981.4	19,098.9
31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	89.7	80.8
Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	92.5	113.4
Dealer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	7,179.2	7,371.5
Dealer \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	4,799.0	4,944.1
Dealer \| Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,380.2	2,427.4
Dealer \| Current and up to 30 days past due \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	4,799.0	4,942.1
Dealer \| Current and up to 30 days past due \| Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,380.2	2,427.4
Dealer \| 31 - 60 days past due \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable		1.1
Dealer \| Greater than 60 days past due \| Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable		0.9
Customer Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	12,984.4	11,921.6
Customer Retail \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	11,567.8	10,638.1
Customer Retail \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,416.6	1,283.5
Customer Retail \| Current and up to 30 days past due \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	11,412.8	10,462.5
Customer Retail \| Current and up to 30 days past due \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,389.4	1,266.9
Customer Retail \| 31 - 60 days past due \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	75.7	71.8
Customer Retail \| 31 - 60 days past due \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	14.0	7.9
Customer Retail \| Greater than 60 days past due \| Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	79.3	103.8
Customer Retail \| Greater than 60 days past due \| Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 13.2	$ 8.7