Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 8,892.2	$ 8,820.1
Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	8,781.9	8,713.0
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	63.9	56.5
Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	46.4	50.6
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,548.6	1,616.5
Dealer | Wholesale | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,504.4	1,576.9
Dealer | Wholesale | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	36.2	31.1
Dealer | Wholesale | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	8.0	8.5
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,503.0	1,525.6
Dealer | Retail | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,501.6	1,520.1
Dealer | Retail | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1.4	5.5
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,646.8	4,442.5
Customer Retail | Fleet | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,601.0	4,396.5
Customer Retail | Fleet | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	15.3	12.7
Customer Retail | Fleet | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	30.5	33.3
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,193.8	1,235.5
Customer Retail | Owner/Operator | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,174.9	1,219.5
Customer Retail | Owner/Operator | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	11.0	7.2
Customer Retail | Owner/Operator | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 7.9	$ 8.8