Amortized Cost Basis of Financing Receivables by Aging Category (Detail) - Financial Services - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, current and up to 30 days past due	$ 11,618.6	$ 11,990.8
Financing Receivables	11,692.0	12,055.8
31 - 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	39.6	31.7
Greater than 60 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	33.8	33.3
Dealer | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, current and up to 30 days past due	2,874.8	2,907.4
Financing Receivables	2,875.7	2,907.4
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, current and up to 30 days past due	1,630.3	1,645.6
Financing Receivables	1,630.3	1,645.6
Dealer | 31 - 60 days past due | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	0.9
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, current and up to 30 days past due	6,065.8	6,297.1
Financing Receivables	6,122.6	6,347.7
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, current and up to 30 days past due	1,047.7	1,140.7
Financing Receivables	1,063.4	1,155.1
Customer Retail | 31 - 60 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	29.4	23.0
Customer Retail | 31 - 60 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	9.3	8.7
Customer Retail | Greater than 60 days past due | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	27.4	27.6
Customer Retail | Greater than 60 days past due | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, past due	$ 6.4	$ 5.7