Amortized Cost Basis of Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	$ 2,584.1	$ 2,067.7
Financed Receivables, By Origination Year, Current Fiscal Year	2,296.6	3,914.5
Financing Receivable, Originated One Year before Current Fiscal Year	3,295.2	2,639.0
Financing Receivable, Originated Two Years before Current Fiscal Year	2,221.4	1,808.4
Financing Receivable, Originated Three Years before Current Fiscal Year	1,322.6	923.3
Financing Receivable, Originated Four Years before Current Fiscal Year	593.9	382.8
Financed Receivables, By Origination Year, Prior	324.1	175.4
Finance Receivables, Total	12,637.9	11,911.1
Dealer
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,584.1	2,067.7
Financed Receivables, By Origination Year, Current Fiscal Year	295.1	441.4
Financing Receivable, Originated One Year before Current Fiscal Year	390.7	319.0
Financing Receivable, Originated Two Years before Current Fiscal Year	258.6	320.8
Financing Receivable, Originated Three Years before Current Fiscal Year	284.3	180.6
Financing Receivable, Originated Four Years before Current Fiscal Year	147.0	119.3
Financed Receivables, By Origination Year, Prior	164.2	98.0
Finance Receivables, Total	4,124.0	3,546.8
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,385.8	1,865.8
Finance Receivables, Total	2,385.8	1,865.8
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,379.6	1,859.7
Finance Receivables, Total	2,379.6	1,859.7
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	6.2	6.1
Finance Receivables, Total	6.2	6.1
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	198.3	201.9
Financed Receivables, By Origination Year, Current Fiscal Year	295.1	441.4
Financing Receivable, Originated One Year before Current Fiscal Year	390.7	319.0
Financing Receivable, Originated Two Years before Current Fiscal Year	258.6	320.8
Financing Receivable, Originated Three Years before Current Fiscal Year	284.3	180.6
Financing Receivable, Originated Four Years before Current Fiscal Year	147.0	119.3
Financed Receivables, By Origination Year, Prior	164.2	98.0
Finance Receivables, Total	1,738.2	1,681.0
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	198.3	201.9
Financed Receivables, By Origination Year, Current Fiscal Year	295.1	434.4
Financing Receivable, Originated One Year before Current Fiscal Year	390.7	315.4
Financing Receivable, Originated Two Years before Current Fiscal Year	258.6	311.7
Financing Receivable, Originated Three Years before Current Fiscal Year	284.3	176.0
Financing Receivable, Originated Four Years before Current Fiscal Year	147.0	118.2
Financed Receivables, By Origination Year, Prior	163.3	96.9
Finance Receivables, Total	1,737.3	1,654.5
Dealer | Retail | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year		7.0
Financing Receivable, Originated One Year before Current Fiscal Year		3.6
Financing Receivable, Originated Two Years before Current Fiscal Year		9.1
Financing Receivable, Originated Three Years before Current Fiscal Year		4.6
Financing Receivable, Originated Four Years before Current Fiscal Year		1.1
Finance Receivables, Total		25.4
Dealer | Retail | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Prior	0.9	1.1
Finance Receivables, Total	0.9	1.1
Customer Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	2,001.5	3,473.1
Financing Receivable, Originated One Year before Current Fiscal Year	2,904.5	2,320.0
Financing Receivable, Originated Two Years before Current Fiscal Year	1,962.8	1,487.6
Financing Receivable, Originated Three Years before Current Fiscal Year	1,038.3	742.7
Financing Receivable, Originated Four Years before Current Fiscal Year	446.9	263.5
Financed Receivables, By Origination Year, Prior	159.9	77.4
Finance Receivables, Total	8,513.9	8,364.3
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	1,736.0	2,860.3
Financing Receivable, Originated One Year before Current Fiscal Year	2,398.9	1,928.3
Financing Receivable, Originated Two Years before Current Fiscal Year	1,652.1	1,257.3
Financing Receivable, Originated Three Years before Current Fiscal Year	878.8	624.3
Financing Receivable, Originated Four Years before Current Fiscal Year	377.1	224.3
Financed Receivables, By Origination Year, Prior	141.8	67.1
Finance Receivables, Total	7,184.7	6,961.6
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	1,734.3	2,851.7
Financing Receivable, Originated One Year before Current Fiscal Year	2,378.3	1,913.3
Financing Receivable, Originated Two Years before Current Fiscal Year	1,634.1	1,227.0
Financing Receivable, Originated Three Years before Current Fiscal Year	841.4	608.4
Financing Receivable, Originated Four Years before Current Fiscal Year	365.3	220.4
Financed Receivables, By Origination Year, Prior	139.3	66.5
Finance Receivables, Total	7,092.7	6,887.3
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	1.1	2.6
Financing Receivable, Originated One Year before Current Fiscal Year	10.0	6.5
Financing Receivable, Originated Two Years before Current Fiscal Year	3.6	4.3
Financing Receivable, Originated Three Years before Current Fiscal Year	8.6	5.3
Financing Receivable, Originated Four Years before Current Fiscal Year	3.6	0.6
Financed Receivables, By Origination Year, Prior	0.8	0.2
Finance Receivables, Total	27.7	19.5
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	0.6	6.0
Financing Receivable, Originated One Year before Current Fiscal Year	10.6	8.5
Financing Receivable, Originated Two Years before Current Fiscal Year	14.4	26.0
Financing Receivable, Originated Three Years before Current Fiscal Year	28.8	10.6
Financing Receivable, Originated Four Years before Current Fiscal Year	8.2	3.3
Financed Receivables, By Origination Year, Prior	1.7	0.4
Finance Receivables, Total	64.3	54.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	265.5	612.8
Financing Receivable, Originated One Year before Current Fiscal Year	505.6	391.7
Financing Receivable, Originated Two Years before Current Fiscal Year	310.7	230.3
Financing Receivable, Originated Three Years before Current Fiscal Year	159.5	118.4
Financing Receivable, Originated Four Years before Current Fiscal Year	69.8	39.2
Financed Receivables, By Origination Year, Prior	18.1	10.3
Finance Receivables, Total	1,329.2	1,402.7
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	265.3	611.9
Financing Receivable, Originated One Year before Current Fiscal Year	504.3	389.9
Financing Receivable, Originated Two Years before Current Fiscal Year	308.8	228.1
Financing Receivable, Originated Three Years before Current Fiscal Year	158.0	116.0
Financing Receivable, Originated Four Years before Current Fiscal Year	68.8	38.6
Financed Receivables, By Origination Year, Prior	18.0	10.1
Finance Receivables, Total	1,323.2	1,394.6
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	0.2	0.7
Financing Receivable, Originated One Year before Current Fiscal Year	0.8	0.5
Financing Receivable, Originated Two Years before Current Fiscal Year	0.9	0.7
Financing Receivable, Originated Three Years before Current Fiscal Year	0.6	0.4
Financing Receivable, Originated Four Years before Current Fiscal Year	0.2	0.1
Finance Receivables, Total	2.7	2.4
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year		0.2
Financing Receivable, Originated One Year before Current Fiscal Year	0.5	1.3
Financing Receivable, Originated Two Years before Current Fiscal Year	1.0	1.5
Financing Receivable, Originated Three Years before Current Fiscal Year	0.9	2.0
Financing Receivable, Originated Four Years before Current Fiscal Year	0.8	0.5
Financed Receivables, By Origination Year, Prior	0.1	0.2
Finance Receivables, Total	$ 3.3	$ 5.7