Financing Receivables by Aging Category (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	$ 9,023.8	$ 8,776.2
31 - 60 days past due	18.1	17.2
Greater than 60 days past due	23.2	26.7
Financing Receivables	9,065.1	8,820.1
Dealer | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	1,752.9	1,611.7
31 - 60 days past due	0.6	1.7
Greater than 60 days past due	2.3	3.1
Financing Receivables	1,755.8	1,616.5
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	1,606.5	1,525.6
Financing Receivables	1,606.5	1,525.6
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	4,464.4	4,417.5
31 - 60 days past due	10.6	9.2
Greater than 60 days past due	12.5	15.8
Financing Receivables	4,487.5	4,442.5
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	1,200.0	1,221.4
31 - 60 days past due	6.9	6.3
Greater than 60 days past due	8.4	7.8
Financing Receivables	$ 1,215.3	$ 1,235.5