Financing Receivables by Aging Category (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	$ 8,822.4	$ 8,776.2
31 - 60 days past due	30.3	17.2
Greater than 60 days past due	24.5	26.7
Financing Receivables	8,877.2	8,820.1
Dealer | Wholesale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	1,631.8	1,611.7
31 - 60 days past due	6.2	1.7
Greater than 60 days past due	5.0	3.1
Financing Receivables	1,643.0	1,616.5
Dealer | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	1,512.8	1,525.6
Financing Receivables	1,512.8	1,525.6
Customer Retail | Fleet
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	4,516.1	4,417.5
31 - 60 days past due	16.4	9.2
Greater than 60 days past due	10.9	15.8
Financing Receivables	4,543.4	4,442.5
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current and up to 30 days past due	1,161.7	1,221.4
31 - 60 days past due	7.7	6.3
Greater than 60 days past due	8.6	7.8
Financing Receivables	$ 1,178.0	$ 1,235.5