Amortized Cost Basis of Finance Receivables and Charge-offs by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	$ 4,680.7	$ 4,428.5
Financing Receivable Originated In Current Fiscal Year	2,914.8	5,942.3
Financing Receivable, Originated One Year before Current Fiscal Year	5,052.7	3,587.6
Financing Receivable, Originated Two Years before Current Fiscal Year	2,923.3	1,888.0
Financing Receivable, Originated Three Years before Current Fiscal Year	1,428.6	1,038.2
Financing Receivable, Originated Four Years before Current Fiscal Year	716.7	444.3
Financed Receivables, By Origination Year, Prior	372.7	199.3
Finance Receivables, Total	18,089.5	17,528.2
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	0.6	1.5
Financing Receivable, Originated One Year before Current Fiscal Year	5.5	10.5
Financing Receivable, Originated Two Years before Current Fiscal Year	6.5	6.6
Financing Receivable, Originated Three Years before Current Fiscal Year	4.2	4.7
Financing Receivable, Originated Four Years before Current Fiscal Year	2.7	4.2
Financed Receivables, By Origination Year, Prior	4.8	0.9
Finance Receivables, Total	24.3	28.6
Dealer
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	4,680.7	4,428.5
Financing Receivable Originated In Current Fiscal Year	326.5	789.1
Financing Receivable, Originated One Year before Current Fiscal Year	748.7	520.0
Financing Receivable, Originated Two Years before Current Fiscal Year	468.3	291.2
Financing Receivable, Originated Three Years before Current Fiscal Year	230.6	162.8
Financing Receivable, Originated Four Years before Current Fiscal Year	135.0	161.8
Financed Receivables, By Origination Year, Prior	205.1	125.2
Finance Receivables, Total	6,794.9	6,478.6
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	4,478.3	4,147.8
Finance Receivables, Total	4,478.3	4,147.8
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	4,474.5	4,129.8
Finance Receivables, Total	4,474.5	4,129.8
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	3.8	18.0
Finance Receivables, Total	3.8	18.0
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	202.4	280.7
Financing Receivable Originated In Current Fiscal Year	326.5	789.1
Financing Receivable, Originated One Year before Current Fiscal Year	748.7	520.0
Financing Receivable, Originated Two Years before Current Fiscal Year	468.3	291.2
Financing Receivable, Originated Three Years before Current Fiscal Year	230.6	162.8
Financing Receivable, Originated Four Years before Current Fiscal Year	135.0	161.8
Financed Receivables, By Origination Year, Prior	205.1	125.2
Finance Receivables, Total	2,316.6	2,330.8
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	202.4	280.7
Financing Receivable Originated In Current Fiscal Year	326.5	789.1
Financing Receivable, Originated One Year before Current Fiscal Year	748.7	520.0
Financing Receivable, Originated Two Years before Current Fiscal Year	468.3	291.2
Financing Receivable, Originated Three Years before Current Fiscal Year	230.6	162.8
Financing Receivable, Originated Four Years before Current Fiscal Year	135.0	161.8
Financed Receivables, By Origination Year, Prior	205.1	125.2
Finance Receivables, Total	2,316.6	2,330.8
Customer Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	2,588.3	5,153.2
Financing Receivable, Originated One Year before Current Fiscal Year	4,304.0	3,067.6
Financing Receivable, Originated Two Years before Current Fiscal Year	2,455.0	1,596.8
Financing Receivable, Originated Three Years before Current Fiscal Year	1,198.0	875.4
Financing Receivable, Originated Four Years before Current Fiscal Year	581.7	282.5
Financed Receivables, By Origination Year, Prior	167.6	74.1
Finance Receivables, Total	11,294.6	11,049.6
Customer Retail | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		1.5
Financing Receivable, Originated One Year before Current Fiscal Year		10.5
Financing Receivable, Originated Two Years before Current Fiscal Year		6.6
Financing Receivable, Originated Three Years before Current Fiscal Year		4.7
Financing Receivable, Originated Four 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	2,310.8	4,689.7
Financing Receivable, Originated One Year before Current Fiscal Year	3,918.9	2,730.2
Financing Receivable, Originated Two Years before Current Fiscal Year	2,180.3	1,329.9
Financing Receivable, Originated Three Years before Current Fiscal Year	994.4	730.5
Financing Receivable, Originated Four Years before Current Fiscal Year	484.7	229.2
Financed Receivables, By Origination Year, Prior	139.0	65.1
Finance Receivables, Total	10,028.1	9,774.6
Customer Retail | Fleet | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.6	1.0
Financing Receivable, Originated One Year before Current Fiscal Year	4.5	9.4
Financing Receivable, Originated Two Years before Current Fiscal Year	5.2	5.1
Financing Receivable, Originated Three Years before Current Fiscal Year	3.8	4.2
Financing Receivable, Originated Four Years before Current Fiscal Year	2.3	4.2
Financed Receivables, By Origination Year, Prior	4.2	0.6
Finance Receivables, Total	20.6	24.5
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	2,235.3	4,601.7
Financing Receivable, Originated One Year before Current Fiscal Year	3,790.6	2,667.2
Financing Receivable, Originated Two Years before Current Fiscal Year	2,111.1	1,309.5
Financing Receivable, Originated Three Years before Current Fiscal Year	962.7	719.2
Financing Receivable, Originated Four Years before Current Fiscal Year	476.5	226.7
Financed Receivables, By Origination Year, Prior	137.1	64.1
Finance Receivables, Total	9,713.3	9,588.4
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	3.3	46.0
Financing Receivable, Originated One Year before Current Fiscal Year	32.6	32.0
Financing Receivable, Originated Two Years before Current Fiscal Year	19.2	7.5
Financing Receivable, Originated Three Years before Current Fiscal Year	6.5	5.7
Financing Receivable, Originated Four Years before Current Fiscal Year	1.4	1.3
Financed Receivables, By Origination Year, Prior	1.2	0.9
Finance Receivables, Total	64.2	93.4
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	72.2	42.0
Financing Receivable, Originated One Year before Current Fiscal Year	95.7	31.0
Financing Receivable, Originated Two Years before Current Fiscal Year	50.0	12.9
Financing Receivable, Originated Three Years before Current Fiscal Year	25.2	5.6
Financing Receivable, Originated Four Years before Current Fiscal Year	6.8	1.2
Financed Receivables, By Origination Year, Prior	0.7	0.1
Finance Receivables, Total	250.6	92.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	277.5	463.5
Financing Receivable, Originated One Year before Current Fiscal Year	385.1	337.4
Financing Receivable, Originated Two Years before Current Fiscal Year	274.7	266.9
Financing Receivable, Originated Three Years before Current Fiscal Year	203.6	144.9
Financing Receivable, Originated Four Years before Current Fiscal Year	97.0	53.3
Financed Receivables, By Origination Year, Prior	28.6	9.0
Finance Receivables, Total	1,266.5	1,275.0
Customer Retail | Owner/Operator | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		0.5
Financing Receivable, Originated One Year before Current Fiscal Year	1.0	1.1
Financing Receivable, Originated Two Years before Current Fiscal Year	1.3	1.5
Financing Receivable, Originated Three Years before Current Fiscal Year	0.4	0.5
Financing Receivable, Originated Four Years before Current Fiscal Year	0.4
Financed Receivables, By Origination Year, Prior	0.6	0.3
Finance Receivables, Total	3.7	3.9
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	274.6	460.9
Financing Receivable, Originated One Year before Current Fiscal Year	374.7	332.9
Financing Receivable, Originated Two Years before Current Fiscal Year	264.9	263.6
Financing Receivable, Originated Three Years before Current Fiscal Year	198.1	142.1
Financing Receivable, Originated Four Years before Current Fiscal Year	92.8	52.8
Financed Receivables, By Origination Year, Prior	27.8	8.6
Finance Receivables, Total	1,232.9	1,260.9
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	2.9	2.0
Financing Receivable, Originated One Year before Current Fiscal Year	9.5	3.2
Financing Receivable, Originated Two Years before Current Fiscal Year	7.6	2.2
Financing Receivable, Originated Three Years before Current Fiscal Year	4.3	1.3
Financing Receivable, Originated Four Years before Current Fiscal Year	2.3	0.3
Financed Receivables, By Origination Year, Prior	0.5
Finance Receivables, Total	27.1	9.0
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		0.6
Financing Receivable, Originated One Year before Current Fiscal Year	0.9	1.3
Financing Receivable, Originated Two Years before Current Fiscal Year	2.2	1.1
Financing Receivable, Originated Three Years before Current Fiscal Year	1.2	1.5
Financing Receivable, Originated Four Years before Current Fiscal Year	1.9	0.2
Financed Receivables, By Origination Year, Prior	0.3	0.4
Finance Receivables, Total	$ 6.5	$ 5.1