Amortized Cost Basis of Finance Receivables and Charge-offs by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	$ 4,664.7	$ 4,428.5
Financing Receivable Originated In Current Fiscal Year	1,384.8	5,942.3
Financing Receivable, Originated One Year before Current Fiscal Year	5,499.9	3,587.6
Financing Receivable, Originated Two Years before Current Fiscal Year	3,286.5	1,888.0
Financing Receivable, Originated Three Years before Current Fiscal Year	1,639.8	1,038.2
Financing Receivable, Originated Four Years before Current Fiscal Year	875.3	444.3
Financed Receivables, By Origination Year, Prior	483.4	199.3
Finance Receivables, Total	17,834.4	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	0.2	1.5
Financing Receivable, Originated One Year before Current Fiscal Year	1.7	10.5
Financing Receivable, Originated Two Years before Current Fiscal Year	4.0	6.6
Financing Receivable, Originated Three Years before Current Fiscal Year	0.8	4.7
Financing Receivable, Originated Four Years before Current Fiscal Year	0.7	4.2
Financed Receivables, By Origination Year, Prior	3.0	0.9
Finance Receivables, Total	10.4	28.6
Dealer
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	4,664.7	4,428.5
Financing Receivable Originated In Current Fiscal Year	147.4	789.1
Financing Receivable, Originated One Year before Current Fiscal Year	762.7	520.0
Financing Receivable, Originated Two Years before Current Fiscal Year	517.5	291.2
Financing Receivable, Originated Three Years before Current Fiscal Year	242.6	162.8
Financing Receivable, Originated Four Years before Current Fiscal Year	148.7	161.8
Financed Receivables, By Origination Year, Prior	241.0	125.2
Finance Receivables, Total	6,724.6	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	4,352.2	4,147.8
Finance Receivables, Total	4,352.2	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	4,346.8	4,129.8
Finance Receivables, Total	4,346.8	4,129.8
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	5.4	18.0
Finance Receivables, Total	5.4	18.0
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	312.5	280.7
Financing Receivable Originated In Current Fiscal Year	147.4	789.1
Financing Receivable, Originated One Year before Current Fiscal Year	762.7	520.0
Financing Receivable, Originated Two Years before Current Fiscal Year	517.5	291.2
Financing Receivable, Originated Three Years before Current Fiscal Year	242.6	162.8
Financing Receivable, Originated Four Years before Current Fiscal Year	148.7	161.8
Financed Receivables, By Origination Year, Prior	241.0	125.2
Finance Receivables, Total	2,372.4	2,330.8
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	312.5	280.7
Financing Receivable Originated In Current Fiscal Year	147.4	789.1
Financing Receivable, Originated One Year before Current Fiscal Year	762.7	520.0
Financing Receivable, Originated Two Years before Current Fiscal Year	517.5	291.2
Financing Receivable, Originated Three Years before Current Fiscal Year	242.6	162.8
Financing Receivable, Originated Four Years before Current Fiscal Year	148.7	161.8
Financed Receivables, By Origination Year, Prior	241.0	125.2
Finance Receivables, Total	2,372.4	2,330.8
Customer Retail
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1,237.4	5,153.2
Financing Receivable, Originated One Year before Current Fiscal Year	4,737.2	3,067.6
Financing Receivable, Originated Two Years before Current Fiscal Year	2,769.0	1,596.8
Financing Receivable, Originated Three Years before Current Fiscal Year	1,397.2	875.4
Financing Receivable, Originated Four Years before Current Fiscal Year	726.6	282.5
Financed Receivables, By Origination Year, Prior	242.4	74.1
Finance Receivables, Total	11,109.8	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	1,115.6	4,689.7
Financing Receivable, Originated One Year before Current Fiscal Year	4,319.8	2,730.2
Financing Receivable, Originated Two Years before Current Fiscal Year	2,467.9	1,329.9
Financing Receivable, Originated Three Years before Current Fiscal Year	1,165.0	730.5
Financing Receivable, Originated Four Years before Current Fiscal Year	605.2	229.2
Financed Receivables, By Origination Year, Prior	198.4	65.1
Finance Receivables, Total	9,871.9	9,774.6
Customer Retail | Fleet | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.2	1.0
Financing Receivable, Originated One Year before Current Fiscal Year	1.2	9.4
Financing Receivable, Originated Two Years before Current Fiscal Year	3.6	5.1
Financing Receivable, Originated Three Years before Current Fiscal Year	0.4	4.2
Financing Receivable, Originated Four Years before Current Fiscal Year	0.2	4.2
Financed Receivables, By Origination Year, Prior	2.8	0.6
Finance Receivables, Total	8.4	24.5
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1,112.2	4,601.7
Financing Receivable, Originated One Year before Current Fiscal Year	4,207.4	2,667.2
Financing Receivable, Originated Two Years before Current Fiscal Year	2,413.3	1,309.5
Financing Receivable, Originated Three Years before Current Fiscal Year	1,149.4	719.2
Financing Receivable, Originated Four Years before Current Fiscal Year	591.9	226.7
Financed Receivables, By Origination Year, Prior	194.5	64.1
Finance Receivables, Total	9,668.7	9,588.4
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1.8	46.0
Financing Receivable, Originated One Year before Current Fiscal Year	27.1	32.0
Financing Receivable, Originated Two Years before Current Fiscal Year	23.7	7.5
Financing Receivable, Originated Three Years before Current Fiscal Year	5.6	5.7
Financing Receivable, Originated Four Years before Current Fiscal Year	3.7	1.3
Financed Receivables, By Origination Year, Prior	3.1	0.9
Finance Receivables, Total	65.0	93.4
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1.6	42.0
Financing Receivable, Originated One Year before Current Fiscal Year	85.3	31.0
Financing Receivable, Originated Two Years before Current Fiscal Year	30.9	12.9
Financing Receivable, Originated Three Years before Current Fiscal Year	10.0	5.6
Financing Receivable, Originated Four Years before Current Fiscal Year	9.6	1.2
Financed Receivables, By Origination Year, Prior	0.8	0.1
Finance Receivables, Total	138.2	92.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	121.8	463.5
Financing Receivable, Originated One Year before Current Fiscal Year	417.4	337.4
Financing Receivable, Originated Two Years before Current Fiscal Year	301.1	266.9
Financing Receivable, Originated Three Years before Current Fiscal Year	232.2	144.9
Financing Receivable, Originated Four Years before Current Fiscal Year	121.4	53.3
Financed Receivables, By Origination Year, Prior	44.0	9.0
Finance Receivables, Total	1,237.9	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	0.5	1.1
Financing Receivable, Originated Two Years before Current Fiscal Year	0.4	1.5
Financing Receivable, Originated Three Years before Current Fiscal Year	0.4	0.5
Financing Receivable, Originated Four Years before Current Fiscal Year	0.5
Financed Receivables, By Origination Year, Prior	0.2	0.3
Finance Receivables, Total	2.0	3.9
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	121.8	460.9
Financing Receivable, Originated One Year before Current Fiscal Year	409.2	332.9
Financing Receivable, Originated Two Years before Current Fiscal Year	292.8	263.6
Financing Receivable, Originated Three Years before Current Fiscal Year	228.5	142.1
Financing Receivable, Originated Four Years before Current Fiscal Year	117.8	52.8
Financed Receivables, By Origination Year, Prior	43.1	8.6
Finance Receivables, Total	1,213.2	1,260.9
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		2.0
Financing Receivable, Originated One Year before Current Fiscal Year	7.2	3.2
Financing Receivable, Originated Two Years before Current Fiscal Year	6.3	2.2
Financing Receivable, Originated Three Years before Current Fiscal Year	2.4	1.3
Financing Receivable, Originated Four Years before Current Fiscal Year	1.6	0.3
Financed Receivables, By Origination Year, Prior	0.4
Finance Receivables, Total	17.9	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	1.0	1.3
Financing Receivable, Originated Two Years before Current Fiscal Year	2.0	1.1
Financing Receivable, Originated Three Years before Current Fiscal Year	1.3	1.5
Financing Receivable, Originated Four Years before Current Fiscal Year	2.0	0.2
Financed Receivables, By Origination Year, Prior	0.5	0.4
Finance Receivables, Total	$ 6.8	$ 5.1