Amortized Cost Basis of Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	$ 2,391.1	$ 2,067.7
Financed Receivables, By Origination Year, Current Fiscal Year	1,248.6	3,914.5
Financing Receivable, Originated One Year before Current Fiscal Year	3,682.5	2,639.0
Financing Receivable, Originated Two Years before Current Fiscal Year	2,475.0	1,808.4
Financing Receivable, Originated Three Years before Current Fiscal Year	1,552.1	923.3
Financing Receivable, Originated Four Years before Current Fiscal Year	763.0	382.8
Financed Receivables, By Origination Year, Prior	427.4	175.4
Finance Receivables, Total	12,539.7	11,911.1
Dealer
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,391.1	2,067.7
Financed Receivables, By Origination Year, Current Fiscal Year	225.1	441.4
Financing Receivable, Originated One Year before Current Fiscal Year	410.7	319.0
Financing Receivable, Originated Two Years before Current Fiscal Year	274.9	320.8
Financing Receivable, Originated Three Years before Current Fiscal Year	303.4	180.6
Financing Receivable, Originated Four Years before Current Fiscal Year	165.9	119.3
Financed Receivables, By Origination Year, Prior	193.0	98.0
Finance Receivables, Total	3,964.1	3,546.8
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,202.5	1,865.8
Finance Receivables, Total	2,202.5	1,865.8
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,197.2	1,859.7
Finance Receivables, Total	2,197.2	1,859.7
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	5.3	6.1
Finance Receivables, Total	5.3	6.1
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	188.6	201.9
Financed Receivables, By Origination Year, Current Fiscal Year	225.1	441.4
Financing Receivable, Originated One Year before Current Fiscal Year	410.7	319.0
Financing Receivable, Originated Two Years before Current Fiscal Year	274.9	320.8
Financing Receivable, Originated Three Years before Current Fiscal Year	303.4	180.6
Financing Receivable, Originated Four Years before Current Fiscal Year	165.9	119.3
Financed Receivables, By Origination Year, Prior	193.0	98.0
Finance Receivables, Total	1,761.6	1,681.0
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	188.6	201.9
Financed Receivables, By Origination Year, Current Fiscal Year	225.1	434.4
Financing Receivable, Originated One Year before Current Fiscal Year	410.7	315.4
Financing Receivable, Originated Two Years before Current Fiscal Year	274.9	311.7
Financing Receivable, Originated Three Years before Current Fiscal Year	303.4	176.0
Financing Receivable, Originated Four Years before Current Fiscal Year	165.9	118.2
Financed Receivables, By Origination Year, Prior	191.8	96.9
Finance Receivables, Total	1,760.4	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	1.2	1.1
Finance Receivables, Total	1.2	1.1
Customer Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	1,023.5	3,473.1
Financing Receivable, Originated One Year before Current Fiscal Year	3,271.8	2,320.0
Financing Receivable, Originated Two Years before Current Fiscal Year	2,200.1	1,487.6
Financing Receivable, Originated Three Years before Current Fiscal Year	1,248.7	742.7
Financing Receivable, Originated Four Years before Current Fiscal Year	597.1	263.5
Financed Receivables, By Origination Year, Prior	234.4	77.4
Finance Receivables, Total	8,575.6	8,364.3
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	884.5	2,860.3
Financing Receivable, Originated One Year before Current Fiscal Year	2,704.6	1,928.3
Financing Receivable, Originated Two Years before Current Fiscal Year	1,848.2	1,257.3
Financing Receivable, Originated Three Years before Current Fiscal Year	1,055.1	624.3
Financing Receivable, Originated Four Years before Current Fiscal Year	504.0	224.3
Financed Receivables, By Origination Year, Prior	203.8	67.1
Finance Receivables, Total	7,200.2	6,961.6
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	883.7	2,851.7
Financing Receivable, Originated One Year before Current Fiscal Year	2,685.1	1,913.3
Financing Receivable, Originated Two Years before Current Fiscal Year	1,832.9	1,227.0
Financing Receivable, Originated Three Years before Current Fiscal Year	1,030.2	608.4
Financing Receivable, Originated Four Years before Current Fiscal Year	490.7	220.4
Financed Receivables, By Origination Year, Prior	200.5	66.5
Finance Receivables, Total	7,123.1	6,887.3
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	0.3	2.6
Financing Receivable, Originated One Year before Current Fiscal Year	9.8	6.5
Financing Receivable, Originated Two Years before Current Fiscal Year	9.9	4.3
Financing Receivable, Originated Three Years before Current Fiscal Year	3.2	5.3
Financing Receivable, Originated Four Years before Current Fiscal Year	4.4	0.6
Financed Receivables, By Origination Year, Prior	0.5	0.2
Finance Receivables, Total	28.1	19.5
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	0.5	6.0
Financing Receivable, Originated One Year before Current Fiscal Year	9.7	8.5
Financing Receivable, Originated Two Years before Current Fiscal Year	5.4	26.0
Financing Receivable, Originated Three Years before Current Fiscal Year	21.7	10.6
Financing Receivable, Originated Four Years before Current Fiscal Year	8.9	3.3
Financed Receivables, By Origination Year, Prior	2.8	0.4
Finance Receivables, Total	49.0	54.8
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	139.0	612.8
Financing Receivable, Originated One Year before Current Fiscal Year	567.2	391.7
Financing Receivable, Originated Two Years before Current Fiscal Year	351.9	230.3
Financing Receivable, Originated Three Years before Current Fiscal Year	193.6	118.4
Financing Receivable, Originated Four Years before Current Fiscal Year	93.1	39.2
Financed Receivables, By Origination Year, Prior	30.6	10.3
Finance Receivables, Total	1,375.4	1,402.7
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	139.0	611.9
Financing Receivable, Originated One Year before Current Fiscal Year	565.4	389.9
Financing Receivable, Originated Two Years before Current Fiscal Year	349.7	228.1
Financing Receivable, Originated Three Years before Current Fiscal Year	191.6	116.0
Financing Receivable, Originated Four Years before Current Fiscal Year	91.1	38.6
Financed Receivables, By Origination Year, Prior	30.1	10.1
Finance Receivables, Total	1,366.9	1,394.6
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year		0.7
Financing Receivable, Originated One Year before Current Fiscal Year	1.2	0.5
Financing Receivable, Originated Two Years before Current Fiscal Year	1.2	0.7
Financing Receivable, Originated Three Years before Current Fiscal Year	0.8	0.4
Financing Receivable, Originated Four Years before Current Fiscal Year	0.6	0.1
Financed Receivables, By Origination Year, Prior	0.1
Finance Receivables, Total	3.9	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	0.6	1.3
Financing Receivable, Originated Two Years before Current Fiscal Year	1.0	1.5
Financing Receivable, Originated Three Years before Current Fiscal Year	1.2	2.0
Financing Receivable, Originated Four Years before Current Fiscal Year	1.4	0.5
Financed Receivables, By Origination Year, Prior	0.4	0.2
Finance Receivables, Total	$ 4.6	$ 5.7