Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 7,766.4	$ 7,287.7
Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	7,572.6	7,075.7
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	85.8	97.6
Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	108.0	114.4
Dealer wholesale financing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,805.9	1,517.0
Dealer wholesale financing | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,744.1	1,451.9
Dealer wholesale financing | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	43.7	46.7
Dealer wholesale financing | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	18.1	18.4
Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,560.6	4,376.5
Retail | Fleet | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,459.3	4,262.8
Retail | Fleet | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	28.8	37.2
Retail | Fleet | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	72.5	76.5
Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,399.9	1,394.2
Retail | Owner/Operator | Pass
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,369.2	1,361.0
Retail | Owner/Operator | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	13.3	13.7
Retail | Owner/Operator | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 17.4	$ 19.5