Amortized Cost Basis of Finance Receivables and Charge-offs by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	$ 3,947.5	$ 2,978.3
Financing Receivable Originated In Current Fiscal Year	4,385.8	4,662.3
Financing Receivable, Originated One Year before Current Fiscal Year	3,808.0	2,783.1
Financing Receivable, Originated Two Years before Current Fiscal Year	2,082.6	1,802.9
Financing Receivable, Originated Three Years before Current Fiscal Year	1,191.2	988.0
Financing Receivable, Originated Four Years before Current Fiscal Year	557.7	378.5
Financed Receivables, By Origination Year, Prior	261.1	194.5
Finance Receivables, Total	16,233.9	13,787.6
Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.2
Financing Receivable, Originated One Year before Current Fiscal Year	5.4
Financing Receivable, Originated Two Years before Current Fiscal Year	5.4
Financing Receivable, Originated Three Years before Current Fiscal Year	3.9
Financing Receivable, Originated Four Years before Current Fiscal Year	0.4
Financed Receivables, By Origination Year, Prior	0.7
Finance Receivables, Total	16.0
Dealer
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	3,947.5	2,978.3
Financing Receivable Originated In Current Fiscal Year	556.1	609.7
Financing Receivable, Originated One Year before Current Fiscal Year	542.8	348.6
Financing Receivable, Originated Two Years before Current Fiscal Year	315.3	223.1
Financing Receivable, Originated Three Years before Current Fiscal Year	177.2	241.7
Financing Receivable, Originated Four Years before Current Fiscal Year	182.7	120.8
Financed Receivables, By Origination Year, Prior	152.5	121.8
Finance Receivables, Total	5,874.1	4,644.0
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	3,783.2	2,772.1
Finance Receivables, Total	3,783.2	2,772.1
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	3,782.1	2,766.0
Finance Receivables, Total	3,782.1	2,766.0
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	1.1	6.1
Finance Receivables, Total	1.1	6.1
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	164.3	206.2
Financing Receivable Originated In Current Fiscal Year	556.1	609.7
Financing Receivable, Originated One Year before Current Fiscal Year	542.8	348.6
Financing Receivable, Originated Two Years before Current Fiscal Year	315.3	223.1
Financing Receivable, Originated Three Years before Current Fiscal Year	177.2	241.7
Financing Receivable, Originated Four Years before Current Fiscal Year	182.7	120.8
Financed Receivables, By Origination Year, Prior	152.5	121.8
Finance Receivables, Total	2,090.9	1,871.9
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	164.3	206.2
Financing Receivable Originated In Current Fiscal Year	556.1	609.7
Financing Receivable, Originated One Year before Current Fiscal Year	542.8	348.6
Financing Receivable, Originated Two Years before Current Fiscal Year	315.3	223.1
Financing Receivable, Originated Three Years before Current Fiscal Year	177.2	241.7
Financing Receivable, Originated Four Years before Current Fiscal Year	182.7	120.8
Financed Receivables, By Origination Year, Prior	152.5	121.1
Finance Receivables, Total	2,090.9	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	3,829.7	4,052.6
Financing Receivable, Originated One Year before Current Fiscal Year	3,265.2	2,434.5
Financing Receivable, Originated Two Years before Current Fiscal Year	1,767.3	1,579.8
Financing Receivable, Originated Three Years before Current Fiscal Year	1,014.0	746.3
Financing Receivable, Originated Four Years before Current Fiscal Year	375.0	257.7
Financed Receivables, By Origination Year, Prior	108.6	72.7
Finance Receivables, Total	10,359.8	9,143.6
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	3,503.9	3,572.2
Financing Receivable, Originated One Year before Current Fiscal Year	2,904.2	2,006.9
Financing Receivable, Originated Two Years before Current Fiscal Year	1,469.4	1,327.1
Financing Receivable, Originated Three Years before Current Fiscal Year	843.6	624.3
Financing Receivable, Originated Four Years before Current Fiscal Year	307.6	211.7
Financed Receivables, By Origination Year, Prior	93.0	66.6
Finance Receivables, Total	9,121.7	7,808.8
Customer Retail | Fleet | Charge Offs Of Finance Receivables
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Originated One Year before Current Fiscal Year	4.4
Financing Receivable, Originated Two Years before Current Fiscal Year	4.4
Financing Receivable, Originated Three Years before Current Fiscal Year	3.6
Financing Receivable, Originated Four Years before Current Fiscal Year	0.4
Financed Receivables, By Origination Year, Prior	0.4
Finance Receivables, Total	13.2
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	3,460.9	3,558.0
Financing Receivable, Originated One Year before Current Fiscal Year	2,866.1	1,981.9
Financing Receivable, Originated Two Years before Current Fiscal Year	1,455.3	1,306.5
Financing Receivable, Originated Three Years before Current Fiscal Year	836.6	603.7
Financing Receivable, Originated Four Years before Current Fiscal Year	294.9	203.4
Financed Receivables, By Origination Year, Prior	91.8	65.6
Finance Receivables, Total	9,005.6	7,719.1
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	34.4	7.5
Financing Receivable, Originated One Year before Current Fiscal Year	14.9	7.3
Financing Receivable, Originated Two Years before Current Fiscal Year	2.6	1.8
Financing Receivable, Originated Three Years before Current Fiscal Year	1.0	3.4
Financing Receivable, Originated Four Years before Current Fiscal Year	1.1	2.4
Financed Receivables, By Origination Year, Prior	0.9	0.5
Finance Receivables, Total	54.9	22.9
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	8.6	6.7
Financing Receivable, Originated One Year before Current Fiscal Year	23.2	17.7
Financing Receivable, Originated Two Years before Current Fiscal Year	11.5	18.8
Financing Receivable, Originated Three Years before Current Fiscal Year	6.0	17.2
Financing Receivable, Originated Four Years before Current Fiscal Year	11.6	5.9
Financed Receivables, By Origination Year, Prior	0.3	0.5
Finance Receivables, Total	61.2	66.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	325.8	480.4
Financing Receivable, Originated One Year before Current Fiscal Year	361.0	427.6
Financing Receivable, Originated Two Years before Current Fiscal Year	297.9	252.7
Financing Receivable, Originated Three Years before Current Fiscal Year	170.4	122.0
Financing Receivable, Originated Four Years before Current Fiscal Year	67.4	46.0
Financed Receivables, By Origination Year, Prior	15.6	6.1
Finance Receivables, Total	1,238.1	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	0.2
Financing Receivable, Originated One Year before Current Fiscal Year	1.0
Financing Receivable, Originated Two Years before Current Fiscal Year	1.0
Financing Receivable, Originated Three Years before Current Fiscal Year	0.3
Financed Receivables, By Origination Year, Prior	0.3
Finance Receivables, Total	2.8
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	325.4	478.2
Financing Receivable, Originated One Year before Current Fiscal Year	357.4	425.9
Financing Receivable, Originated Two Years before Current Fiscal Year	293.9	251.2
Financing Receivable, Originated Three Years before Current Fiscal Year	167.2	120.9
Financing Receivable, Originated Four Years before Current Fiscal Year	66.6	45.3
Financed Receivables, By Origination Year, Prior	15.1	6.0
Finance Receivables, Total	1,225.6	1,327.5
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.3	1.8
Financing Receivable, Originated One Year before Current Fiscal Year	2.1	0.9
Financing Receivable, Originated Two Years before Current Fiscal Year	1.8	0.4
Financing Receivable, Originated Three Years before Current Fiscal Year	1.1	0.3
Financing Receivable, Originated Four Years before Current Fiscal Year	0.1
Financed Receivables, By Origination Year, Prior	0.2	0.1
Finance Receivables, Total	5.6	3.5
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	0.1	0.4
Financing Receivable, Originated One Year before Current Fiscal Year	1.5	0.8
Financing Receivable, Originated Two Years before Current Fiscal Year	2.2	1.1
Financing Receivable, Originated Three Years before Current Fiscal Year	2.1	0.8
Financing Receivable, Originated Four Years before Current Fiscal Year	0.7	0.7
Financed Receivables, By Origination Year, Prior	0.3
Finance Receivables, Total	$ 6.9	$ 3.8