Financing Receivables by Aging Category (Detail) - Financial Services - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 19,578.0	$ 19,293.1
Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	19,404.6	19,098.9
31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	51.4	80.8
Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	122.0	113.4
Dealer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	7,327.1	7,371.5
Dealer | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	4,947.3	4,944.1
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,379.8	2,427.4
Dealer | Current and up to 30 days past due | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	4,947.3	4,942.1
Dealer | Current and up to 30 days past due | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,379.8	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	12,250.9	11,921.6
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	10,924.3	10,638.1
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,326.6	1,283.5
Customer Retail | Current and up to 30 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	10,772.9	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	1,304.6	1,266.9
Customer Retail | 31 - 60 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	38.6	71.8
Customer Retail | 31 - 60 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	12.8	7.9
Customer Retail | Greater than 60 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	112.8	103.8
Customer Retail | Greater than 60 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 9.2	$ 8.7