Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 8,881.1	$ 8,820.1
Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	8,781.7	8,713.0
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	53.2	56.5
Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	46.2	50.6
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,679.2	1,616.5
Dealer | Wholesale | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,646.9	1,576.9
Dealer | Wholesale | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	25.8	31.1
Dealer | Wholesale | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	6.5	8.5
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,464.3	1,525.6
Dealer | Retail | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,463.3	1,520.1
Dealer | Retail | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1.0	5.5
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,527.1	4,442.5
Customer Retail | Fleet | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,479.2	4,396.5
Customer Retail | Fleet | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	15.7	12.7
Customer Retail | Fleet | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	32.2	33.3
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,210.5	1,235.5
Customer Retail | Owner/Operator | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,192.3	1,219.5
Customer Retail | Owner/Operator | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	10.7	7.2
Customer Retail | Owner/Operator | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 7.5	$ 8.8