Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 9,029.0	$ 9,286.5
Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	8,918.0	9,160.9
Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	43.5	56.6
At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	67.5	69.0
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,736.5	1,950.1
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,724.0	1,922.4
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	9.9	22.7
Dealer | Wholesale | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	2.6	5.0
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,446.8	1,561.3
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,446.8	1,561.3
Dealer | Retail | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	0.0	0.0
Dealer | Retail | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	0.0	0.0
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,865.8	4,761.4
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,783.7	4,680.6
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	26.0	27.0
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	56.1	53.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	979.9	1,013.7
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	963.5	996.6
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	7.6	6.9
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 8.8	$ 10.2