Amortized Cost Basis of Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	$ 4,428.5	$ 2,978.3
Financing Receivable Originated In Current Fiscal Year	5,942.3	4,662.3
Financed Receivables, By Origination Year, Current Fiscal Year	3,587.6	2,783.1
Financing Receivable, Originated One Year before Current Fiscal Year	1,888.0	1,802.9
Financing Receivable, Originated Two Years before Current Fiscal Year	1,038.2	988.0
Financing Receivable, Originated Three Years before Current Fiscal Year	444.3	378.5
Financed Receivables, By Origination Year, Prior	199.3	194.5
Finance Receivables, Total	17,528.2	13,787.6
Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	0.2
Financing Receivable Originated In Current Fiscal Year	1.5
Financed Receivables, By Origination Year, Current Fiscal Year	10.5
Financing Receivable, Originated One Year before Current Fiscal Year	6.6
Financing Receivable, Originated Two Years before Current Fiscal Year	4.7
Financing Receivable, Originated Three Years before Current Fiscal Year	4.2
Financed Receivables, By Origination Year, Prior	0.9
Finance Receivables, Total	28.6
Dealer
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	4,428.5	2,978.3
Financing Receivable Originated In Current Fiscal Year	789.1	609.7
Financed Receivables, By Origination Year, Current Fiscal Year	520.0	348.6
Financing Receivable, Originated One Year before Current Fiscal Year	291.2	223.1
Financing Receivable, Originated Two Years before Current Fiscal Year	162.8	241.7
Financing Receivable, Originated Three Years before Current Fiscal Year	161.8	120.8
Financed Receivables, By Origination Year, Prior	125.2	121.8
Finance Receivables, Total	6,478.6	4,644.0
Dealer | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	0.2
Finance Receivables, Total	0.2
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	4,147.8	2,772.1
Finance Receivables, Total	4,147.8	2,772.1
Dealer | Wholesale | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	0.2
Finance Receivables, Total	0.2
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	4,129.8	2,766.0
Finance Receivables, Total	4,129.8	2,766.0
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	18.0	6.1
Finance Receivables, Total	18.0	6.1
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	280.7	206.2
Financing Receivable Originated In Current Fiscal Year	789.1	609.7
Financed Receivables, By Origination Year, Current Fiscal Year	520.0	348.6
Financing Receivable, Originated One Year before Current Fiscal Year	291.2	223.1
Financing Receivable, Originated Two Years before Current Fiscal Year	162.8	241.7
Financing Receivable, Originated Three Years before Current Fiscal Year	161.8	120.8
Financed Receivables, By Origination Year, Prior	125.2	121.8
Finance Receivables, Total	2,330.8	1,871.9
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	280.7	206.2
Financing Receivable Originated In Current Fiscal Year	789.1	609.7
Financed Receivables, By Origination Year, Current Fiscal Year	520.0	348.6
Financing Receivable, Originated One Year before Current Fiscal Year	291.2	223.1
Financing Receivable, Originated Two Years before Current Fiscal Year	162.8	241.7
Financing Receivable, Originated Three Years before Current Fiscal Year	161.8	120.8
Financed Receivables, By Origination Year, Prior	125.2	121.1
Finance Receivables, Total	2,330.8	1,871.2
Dealer | Retail | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Prior		0.7
Finance Receivables, Total		0.7
Customer Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	5,153.2	4,052.6
Financed Receivables, By Origination Year, Current Fiscal Year	3,067.6	2,434.5
Financing Receivable, Originated One Year before Current Fiscal Year	1,596.8	1,579.8
Financing Receivable, Originated Two Years before Current Fiscal Year	875.4	746.3
Financing Receivable, Originated Three Years before Current Fiscal Year	282.5	257.7
Financed Receivables, By Origination Year, Prior	74.1	72.7
Finance Receivables, Total	11,049.6	9,143.6
Customer Retail | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1.5
Financed Receivables, By Origination Year, Current Fiscal Year	10.5
Financing Receivable, Originated One Year before Current Fiscal Year	6.6
Financing Receivable, Originated Two Years before Current Fiscal Year	4.7
Financing Receivable, Originated Three Years before Current Fiscal Year	4.2
Financed Receivables, By Origination Year, Prior	0.9
Finance Receivables, Total	28.4
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	4,689.7	3,572.2
Financed Receivables, By Origination Year, Current Fiscal Year	2,730.2	2,006.9
Financing Receivable, Originated One Year before Current Fiscal Year	1,329.9	1,327.1
Financing Receivable, Originated Two Years before Current Fiscal Year	730.5	624.3
Financing Receivable, Originated Three Years before Current Fiscal Year	229.2	211.7
Financed Receivables, By Origination Year, Prior	65.1	66.6
Finance Receivables, Total	9,774.6	7,808.8
Customer Retail | Fleet | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1.0
Financed Receivables, By Origination Year, Current Fiscal Year	9.4
Financing Receivable, Originated One Year before Current Fiscal Year	5.1
Financing Receivable, Originated Two Years before Current Fiscal Year	4.2
Financing Receivable, Originated Three Years before Current Fiscal Year	4.2
Financed Receivables, By Origination Year, Prior	0.6
Finance Receivables, Total	24.5
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	4,601.7	3,558.0
Financed Receivables, By Origination Year, Current Fiscal Year	2,667.2	1,981.9
Financing Receivable, Originated One Year before Current Fiscal Year	1,309.5	1,306.5
Financing Receivable, Originated Two Years before Current Fiscal Year	719.2	603.7
Financing Receivable, Originated Three Years before Current Fiscal Year	226.7	203.4
Financed Receivables, By Origination Year, Prior	64.1	65.6
Finance Receivables, Total	9,588.4	7,719.1
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	46.0	7.5
Financed Receivables, By Origination Year, Current Fiscal Year	32.0	7.3
Financing Receivable, Originated One Year before Current Fiscal Year	7.5	1.8
Financing Receivable, Originated Two Years before Current Fiscal Year	5.7	3.4
Financing Receivable, Originated Three Years before Current Fiscal Year	1.3	2.4
Financed Receivables, By Origination Year, Prior	0.9	0.5
Finance Receivables, Total	93.4	22.9
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	42.0	6.7
Financed Receivables, By Origination Year, Current Fiscal Year	31.0	17.7
Financing Receivable, Originated One Year before Current Fiscal Year	12.9	18.8
Financing Receivable, Originated Two Years before Current Fiscal Year	5.6	17.2
Financing Receivable, Originated Three Years before Current Fiscal Year	1.2	5.9
Financed Receivables, By Origination Year, Prior	0.1	0.5
Finance Receivables, Total	92.8	66.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	463.5	480.4
Financed Receivables, By Origination Year, Current Fiscal Year	337.4	427.6
Financing Receivable, Originated One Year before Current Fiscal Year	266.9	252.7
Financing Receivable, Originated Two Years before Current Fiscal Year	144.9	122.0
Financing Receivable, Originated Three Years before Current Fiscal Year	53.3	46.0
Financed Receivables, By Origination Year, Prior	9.0	6.1
Finance Receivables, Total	1,275.0	1,334.8
Customer Retail | Owner/Operator | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.5
Financed Receivables, By Origination Year, Current Fiscal Year	1.1
Financing Receivable, Originated One Year before Current Fiscal Year	1.5
Financing Receivable, Originated Two Years before Current Fiscal Year	0.5
Financed Receivables, By Origination Year, Prior	0.3
Finance Receivables, Total	3.9
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	460.9	478.2
Financed Receivables, By Origination Year, Current Fiscal Year	332.9	425.9
Financing Receivable, Originated One Year before Current Fiscal Year	263.6	251.2
Financing Receivable, Originated Two Years before Current Fiscal Year	142.1	120.9
Financing Receivable, Originated Three Years before Current Fiscal Year	52.8	45.3
Financed Receivables, By Origination Year, Prior	8.6	6.0
Finance Receivables, Total	1,260.9	1,327.5
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	2.0	1.8
Financed Receivables, By Origination Year, Current Fiscal Year	3.2	0.9
Financing Receivable, Originated One Year before Current Fiscal Year	2.2	0.4
Financing Receivable, Originated Two Years before Current Fiscal Year	1.3	0.3
Financing Receivable, Originated Three Years before Current Fiscal Year	0.3
Financed Receivables, By Origination Year, Prior		0.1
Finance Receivables, Total	9.0	3.5
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.6	0.4
Financed Receivables, By Origination Year, Current Fiscal Year	1.3	0.8
Financing Receivable, Originated One Year before Current Fiscal Year	1.1	1.1
Financing Receivable, Originated Two Years before Current Fiscal Year	1.5	0.8
Financing Receivable, Originated Three Years before Current Fiscal Year	0.2	0.7
Financed Receivables, By Origination Year, Prior	0.4
Finance Receivables, Total	$ 5.1	$ 3.8