Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 9,250.7	$ 9,286.5
Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	9,133.4	9,160.9
Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	48.8	56.6
At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	68.5	69.0
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,912.0	1,950.1
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,892.0	1,922.4
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	15.4	22.7
Dealer | Wholesale | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4.6	5.0
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,493.2	1,561.3
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,493.2	1,561.3
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,853.4	4,761.4
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,774.7	4,680.6
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	25.1	27.0
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	53.6	53.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	992.1	1,013.7
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	973.5	996.6
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	8.3	6.9
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 10.3	$ 10.2