Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 8,922.1	$ 8,797.7
Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	8,825.1	8,710.8
Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	37.6	29.5
At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	59.4	57.4
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,625.1	1,528.5
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,618.7	1,519.3
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	6.3	9.1
Dealer | Wholesale | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	0.1	0.1
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,343.7	1,406.0
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,339.6	1,406.0
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	4.1	0.0
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,955.0	4,928.7
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	4,883.8	4,863.4
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	23.8	14.9
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	47.4	50.4
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	998.3	934.5
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	983.0	922.1
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	7.5	5.5
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 7.8	$ 6.9