Amortized Cost Basis of Finance Receivables and Charge-offs by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	$ 5,174.5	$ 5,173.9
Financing Receivable Originated In Current Fiscal Year	1,320.6	5,577.5
Financing Receivable, Originated One Year before Current Fiscal Year	5,580.2	4,188.0
Financing Receivable, Originated Two Years before Current Fiscal Year	3,930.9	2,482.9
Financing Receivable, Originated Three Years before Current Fiscal Year	2,168.8	1,173.4
Financing Receivable, Originated Four Years before Current Fiscal Year	889.2	468.8
Financed Receivables, By Origination Year, Prior	513.8	228.6
Finance Receivables, Total	19,578.0	19,293.1
Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.2	1.0
Financing Receivable, Originated One Year before Current Fiscal Year	5.2	21.8
Financing Receivable, Originated Two Years before Current Fiscal Year	12.9	15.8
Financing Receivable, Originated Three Years before Current Fiscal Year	2.6	8.5
Financing Receivable, Originated Four Years before Current Fiscal Year	1.3	5.5
Financed Receivables, By Origination Year, Prior	0.8	8.6
Finance Receivables, Total	23.0	61.2
Dealer
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	5,174.5	5,173.9
Financing Receivable Originated In Current Fiscal Year	126.6	682.8
Financing Receivable, Originated One Year before Current Fiscal Year	650.1	664.6
Financing Receivable, Originated Two Years before Current Fiscal Year	609.2	410.7
Financing Receivable, Originated Three Years before Current Fiscal Year	384.7	194.9
Financing Receivable, Originated Four Years before Current Fiscal Year	177.1	102.6
Financed Receivables, By Origination Year, Prior	204.9	142.0
Finance Receivables, Total	7,327.1	7,371.5
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	4,947.3	4,944.1
Finance Receivables, Total	4,947.3	4,944.1
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	4,940.6	4,936.1
Finance Receivables, Total	4,940.6	4,936.1
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	6.7	7.1
Finance Receivables, Total	6.7	7.1
Dealer | Wholesale | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans		0.9
Finance Receivables, Total		0.9
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	227.2	229.8
Financing Receivable Originated In Current Fiscal Year	126.6	682.8
Financing Receivable, Originated One Year before Current Fiscal Year	650.1	664.6
Financing Receivable, Originated Two Years before Current Fiscal Year	609.2	410.7
Financing Receivable, Originated Three Years before Current Fiscal Year	384.7	194.9
Financing Receivable, Originated Four Years before Current Fiscal Year	177.1	102.6
Financed Receivables, By Origination Year, Prior	204.9	142.0
Finance Receivables, Total	2,379.8	2,427.4
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	227.2	229.8
Financing Receivable Originated In Current Fiscal Year	120.7	680.8
Financing Receivable, Originated One Year before Current Fiscal Year	648.1	641.5
Financing Receivable, Originated Two Years before Current Fiscal Year	595.3	404.6
Financing Receivable, Originated Three Years before Current Fiscal Year	379.0	192.8
Financing Receivable, Originated Four Years before Current Fiscal Year	175.3	98.0
Financed Receivables, By Origination Year, Prior	201.8	141.6
Finance Receivables, Total	2,347.4	2,389.1
Dealer | Retail | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	5.9	2.0
Financing Receivable, Originated One Year before Current Fiscal Year	2.0	23.1
Financing Receivable, Originated Two Years before Current Fiscal Year	13.9	6.1
Financing Receivable, Originated Three Years before Current Fiscal Year	5.7	2.1
Financing Receivable, Originated Four Years before Current Fiscal Year	1.8	4.6
Financed Receivables, By Origination Year, Prior	3.1	0.4
Finance Receivables, Total	32.4	38.3
Customer Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1,194.0	4,894.7
Financing Receivable, Originated One Year before Current Fiscal Year	4,930.1	3,523.4
Financing Receivable, Originated Two Years before Current Fiscal Year	3,321.7	2,072.2
Financing Receivable, Originated Three Years before Current Fiscal Year	1,784.1	978.5
Financing Receivable, Originated Four Years before Current Fiscal Year	712.1	366.2
Financed Receivables, By Origination Year, Prior	308.9	86.6
Finance Receivables, Total	12,250.9	11,921.6
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1,035.0	4,367.2
Financing Receivable, Originated One Year before Current Fiscal Year	4,406.1	3,205.8
Financing Receivable, Originated Two Years before Current Fiscal Year	3,033.0	1,855.8
Financing Receivable, Originated Three Years before Current Fiscal Year	1,593.6	829.6
Financing Receivable, Originated Four Years before Current Fiscal Year	595.5	306.3
Financed Receivables, By Origination Year, Prior	261.1	73.4
Finance Receivables, Total	10,924.3	10,638.1
Customer Retail | Fleet | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.1	0.9
Financing Receivable, Originated One Year before Current Fiscal Year	4.9	19.4
Financing Receivable, Originated Two Years before Current Fiscal Year	12.5	12.1
Financing Receivable, Originated Three Years before Current Fiscal Year	1.8	7.5
Financing Receivable, Originated Four Years before Current Fiscal Year	1.3	4.2
Financed Receivables, By Origination Year, Prior	0.6	7.8
Finance Receivables, Total	21.2	51.9
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1,027.2	4,306.5
Financing Receivable, Originated One Year before Current Fiscal Year	4,326.3	2,991.4
Financing Receivable, Originated Two Years before Current Fiscal Year	2,826.7	1,761.1
Financing Receivable, Originated Three Years before Current Fiscal Year	1,492.3	781.9
Financing Receivable, Originated Four Years before Current Fiscal Year	556.5	298.2
Financed Receivables, By Origination Year, Prior	255.7	71.0
Finance Receivables, Total	10,484.7	10,210.1
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	6.3	11.2
Financing Receivable, Originated One Year before Current Fiscal Year	19.2	17.6
Financing Receivable, Originated Two Years before Current Fiscal Year	48.7	13.9
Financing Receivable, Originated Three Years before Current Fiscal Year	46.0	5.8
Financing Receivable, Originated Four Years before Current Fiscal Year	24.2	2.1
Financed Receivables, By Origination Year, Prior	2.9	0.9
Finance Receivables, Total	147.3	51.5
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1.5	49.5
Financing Receivable, Originated One Year before Current Fiscal Year	60.6	196.8
Financing Receivable, Originated Two Years before Current Fiscal Year	157.6	80.8
Financing Receivable, Originated Three Years before Current Fiscal Year	55.3	41.9
Financing Receivable, Originated Four Years before Current Fiscal Year	14.8	6.0
Financed Receivables, By Origination Year, Prior	2.5	1.5
Finance Receivables, Total	292.3	376.5
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	159.0	527.5
Financing Receivable, Originated One Year before Current Fiscal Year	524.0	317.6
Financing Receivable, Originated Two Years before Current Fiscal Year	288.7	216.4
Financing Receivable, Originated Three Years before Current Fiscal Year	190.5	148.9
Financing Receivable, Originated Four Years before Current Fiscal Year	116.6	59.9
Financed Receivables, By Origination Year, Prior	47.8	13.2
Finance Receivables, Total	1,326.6	1,283.5
Customer Retail | Owner/Operator | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.1	0.1
Financing Receivable, Originated One Year before Current Fiscal Year	0.3	2.4
Financing Receivable, Originated Two Years before Current Fiscal Year	0.4	3.7
Financing Receivable, Originated Three Years before Current Fiscal Year	0.8	1.0
Financing Receivable, Originated Four Years before Current Fiscal Year		1.3
Financed Receivables, By Origination Year, Prior	0.2	0.8
Finance Receivables, Total	1.8	9.3
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	159.0	524.1
Financing Receivable, Originated One Year before Current Fiscal Year	517.7	303.7
Financing Receivable, Originated Two Years before Current Fiscal Year	277.4	206.2
Financing Receivable, Originated Three Years before Current Fiscal Year	183.4	145.1
Financing Receivable, Originated Four Years before Current Fiscal Year	113.5	57.6
Financed Receivables, By Origination Year, Prior	45.7	12.7
Finance Receivables, Total	1,296.7	1,249.4
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		2.5
Financing Receivable, Originated One Year before Current Fiscal Year	3.9	12.1
Financing Receivable, Originated Two Years before Current Fiscal Year	5.7	8.0
Financing Receivable, Originated Three Years before Current Fiscal Year	4.3	2.9
Financing Receivable, Originated Four Years before Current Fiscal Year	1.7	1.3
Financed Receivables, By Origination Year, Prior	0.9	0.4
Finance Receivables, Total	16.5	27.2
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		0.9
Financing Receivable, Originated One Year before Current Fiscal Year	2.4	1.8
Financing Receivable, Originated Two Years before Current Fiscal Year	5.6	2.2
Financing Receivable, Originated Three Years before Current Fiscal Year	2.8	0.9
Financing Receivable, Originated Four Years before Current Fiscal Year	1.4	1.0
Financed Receivables, By Origination Year, Prior	1.2	0.1
Finance Receivables, Total	$ 13.4	$ 6.9