Amortized Cost Basis of Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	$ 2,504.8	$ 2,067.7
Financed Receivables, By Origination Year, Current Fiscal Year	3,239.1	3,914.5
Financing Receivable, Originated One Year before Current Fiscal Year	2,967.7	2,639.0
Financing Receivable, Originated Two Years before Current Fiscal Year	1,936.5	1,808.4
Financing Receivable, Originated Three Years before Current Fiscal Year	1,126.6	923.3
Financing Receivable, Originated Four Years before Current Fiscal Year	463.9	382.8
Financed Receivables, By Origination Year, Prior	292.0	175.4
Finance Receivables, Total	12,530.6	11,911.1
Dealer
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,504.8	2,067.7
Financed Receivables, By Origination Year, Current Fiscal Year	374.2	441.4
Financing Receivable, Originated One Year before Current Fiscal Year	371.3	319.0
Financing Receivable, Originated Two Years before Current Fiscal Year	239.7	320.8
Financing Receivable, Originated Three Years before Current Fiscal Year	263.3	180.6
Financing Receivable, Originated Four Years before Current Fiscal Year	133.1	119.3
Financed Receivables, By Origination Year, Prior	141.1	98.0
Finance Receivables, Total	4,027.5	3,546.8
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,307.8	1,865.8
Finance Receivables, Total	2,307.8	1,865.8
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,304.8	1,859.7
Finance Receivables, Total	2,304.8	1,859.7
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	3.0	6.1
Finance Receivables, Total	3.0	6.1
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	197.0	201.9
Financed Receivables, By Origination Year, Current Fiscal Year	374.2	441.4
Financing Receivable, Originated One Year before Current Fiscal Year	371.3	319.0
Financing Receivable, Originated Two Years before Current Fiscal Year	239.7	320.8
Financing Receivable, Originated Three Years before Current Fiscal Year	263.3	180.6
Financing Receivable, Originated Four Years before Current Fiscal Year	133.1	119.3
Financed Receivables, By Origination Year, Prior	141.1	98.0
Finance Receivables, Total	1,719.7	1,681.0
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	197.0	201.9
Financed Receivables, By Origination Year, Current Fiscal Year	374.2	434.4
Financing Receivable, Originated One Year before Current Fiscal Year	371.3	315.4
Financing Receivable, Originated Two Years before Current Fiscal Year	239.7	311.7
Financing Receivable, Originated Three Years before Current Fiscal Year	263.3	176.0
Financing Receivable, Originated Four Years before Current Fiscal Year	133.1	118.2
Financed Receivables, By Origination Year, Prior	140.3	96.9
Finance Receivables, Total	1,718.9	1,654.5
Dealer | Retail | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year		7.0
Financing Receivable, Originated One Year before Current Fiscal Year		3.6
Financing Receivable, Originated Two Years before Current Fiscal Year		9.1
Financing Receivable, Originated Three Years before Current Fiscal Year		4.6
Financing Receivable, Originated Four Years before Current Fiscal Year		1.1
Finance Receivables, Total		25.4
Dealer | Retail | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Prior	0.8	1.1
Finance Receivables, Total	0.8	1.1
Customer Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	2,864.9	3,473.1
Financing Receivable, Originated One Year before Current Fiscal Year	2,596.4	2,320.0
Financing Receivable, Originated Two Years before Current Fiscal Year	1,696.8	1,487.6
Financing Receivable, Originated Three Years before Current Fiscal Year	863.3	742.7
Financing Receivable, Originated Four Years before Current Fiscal Year	330.8	263.5
Financed Receivables, By Origination Year, Prior	150.9	77.4
Finance Receivables, Total	8,503.1	8,364.3
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	2,477.6	2,860.3
Financing Receivable, Originated One Year before Current Fiscal Year	2,143.8	1,928.3
Financing Receivable, Originated Two Years before Current Fiscal Year	1,421.8	1,257.3
Financing Receivable, Originated Three Years before Current Fiscal Year	726.1	624.3
Financing Receivable, Originated Four Years before Current Fiscal Year	273.8	224.3
Financed Receivables, By Origination Year, Prior	137.2	67.1
Finance Receivables, Total	7,180.3	6,961.6
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	2,468.8	2,851.7
Financing Receivable, Originated One Year before Current Fiscal Year	2,121.2	1,913.3
Financing Receivable, Originated Two Years before Current Fiscal Year	1,404.3	1,227.0
Financing Receivable, Originated Three Years before Current Fiscal Year	702.3	608.4
Financing Receivable, Originated Four Years before Current Fiscal Year	264.2	220.4
Financed Receivables, By Origination Year, Prior	135.4	66.5
Finance Receivables, Total	7,096.2	6,887.3
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	2.4	2.6
Financing Receivable, Originated One Year before Current Fiscal Year	6.1	6.5
Financing Receivable, Originated Two Years before Current Fiscal Year	4.5	4.3
Financing Receivable, Originated Three Years before Current Fiscal Year	4.1	5.3
Financing Receivable, Originated Four Years before Current Fiscal Year	2.5	0.6
Financed Receivables, By Origination Year, Prior	0.6	0.2
Finance Receivables, Total	20.2	19.5
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	6.4	6.0
Financing Receivable, Originated One Year before Current Fiscal Year	16.5	8.5
Financing Receivable, Originated Two Years before Current Fiscal Year	13.0	26.0
Financing Receivable, Originated Three Years before Current Fiscal Year	19.7	10.6
Financing Receivable, Originated Four Years before Current Fiscal Year	7.1	3.3
Financed Receivables, By Origination Year, Prior	1.2	0.4
Finance Receivables, Total	63.9	54.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	387.3	612.8
Financing Receivable, Originated One Year before Current Fiscal Year	452.6	391.7
Financing Receivable, Originated Two Years before Current Fiscal Year	275.0	230.3
Financing Receivable, Originated Three Years before Current Fiscal Year	137.2	118.4
Financing Receivable, Originated Four Years before Current Fiscal Year	57.0	39.2
Financed Receivables, By Origination Year, Prior	13.7	10.3
Finance Receivables, Total	1,322.8	1,402.7
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	386.3	611.9
Financing Receivable, Originated One Year before Current Fiscal Year	451.4	389.9
Financing Receivable, Originated Two Years before Current Fiscal Year	273.3	228.1
Financing Receivable, Originated Three Years before Current Fiscal Year	135.7	116.0
Financing Receivable, Originated Four Years before Current Fiscal Year	56.0	38.6
Financed Receivables, By Origination Year, Prior	13.6	10.1
Finance Receivables, Total	1,316.3	1,394.6
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	0.9	0.7
Financing Receivable, Originated One Year before Current Fiscal Year	0.6	0.5
Financing Receivable, Originated Two Years before Current Fiscal Year	0.8	0.7
Financing Receivable, Originated Three Years before Current Fiscal Year	0.4	0.4
Financing Receivable, Originated Four Years before Current Fiscal Year	0.2	0.1
Finance Receivables, Total	2.9	2.4
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	0.1	0.2
Financing Receivable, Originated One Year before Current Fiscal Year	0.6	1.3
Financing Receivable, Originated Two Years before Current Fiscal Year	0.9	1.5
Financing Receivable, Originated Three Years before Current Fiscal Year	1.1	2.0
Financing Receivable, Originated Four Years before Current Fiscal Year	0.8	0.5
Financed Receivables, By Origination Year, Prior	0.1	0.2
Finance Receivables, Total	$ 3.6	$ 5.7