Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 9,286.5	$ 9,065.1
Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	9,160.9	8,970.7
Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	56.6	45.8
At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	69.0	48.6
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,950.1	1,755.8
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,922.4	1,739.5
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	22.7	11.4
Dealer | Wholesale | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	5.0	4.9
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,561.3	1,606.5
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,561.3	1,606.4
Dealer | Retail | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables		0.1
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,761.4	4,487.5
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,680.6	4,430.9
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	27.0	21.8
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	53.8	34.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,013.7	1,215.3
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	996.6	1,193.9
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	6.9	12.5
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 10.2	$ 8.9