Amortized Cost Basis of Financing Receivables by Aging Category (Detail) - Financial Services - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 12,539.7	$ 11,911.1
Current and up to 30 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	12,493.8	11,882.5
31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	25.0	11.5
Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	20.9	17.1
Dealer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	3,964.1	3,546.8
Dealer | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,202.5	1,865.8
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,761.6	1,681.0
Dealer | Current and up to 30 days past due | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2,202.5	1,865.4
Dealer | Current and up to 30 days past due | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,761.6	1,681.0
Dealer | 31 - 60 days past due | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable		0.4
Customer Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	8,575.6	8,364.3
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	7,200.2	6,961.6
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,375.4	1,402.7
Customer Retail | Current and up to 30 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	7,161.4	6,939.7
Customer Retail | Current and up to 30 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	1,368.3	1,396.4
Customer Retail | 31 - 60 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	22.2	9.3
Customer Retail | 31 - 60 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	2.8	1.8
Customer Retail | Greater than 60 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	16.6	12.6
Customer Retail | Greater than 60 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance Receivable	$ 4.3	$ 4.5