Amortized Cost Basis of Finance Receivables by Credit Quality Indicator and Portfolio Class (Detail) - Financial Services - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	$ 2,067.7	$ 2,033.1
Financed Receivables, By Origination Year, Current Fiscal Year	3,914.5	3,752.9
Financing Receivable, Originated One Year before Current Fiscal Year	2,639.0	2,843.0
Financing Receivable, Originated Two Years before Current Fiscal Year	1,808.4	1,736.5
Financing Receivable, Originated Three Years before Current Fiscal Year	923.3	840.4
Financing Receivable, Originated Four Years before Current Fiscal Year	382.8	381.5
Financed Receivables, By Origination Year, Prior	175.4	208.8
Finance Receivables, Total	11,911.1	11,796.2
Dealer
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	2,067.7	2,033.1
Financed Receivables, By Origination Year, Current Fiscal Year	441.4	509.4
Financing Receivable, Originated One Year before Current Fiscal Year	319.0	485.4
Financing Receivable, Originated Two Years before Current Fiscal Year	320.8	272.5
Financing Receivable, Originated Three Years before Current Fiscal Year	180.6	181.5
Financing Receivable, Originated Four Years before Current Fiscal Year	119.3	101.6
Financed Receivables, By Origination Year, Prior	98.0	132.0
Finance Receivables, Total	3,546.8	3,715.5
Dealer | Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	1,865.8	2,012.4
Finance Receivables, Total	1,865.8	2,012.4
Dealer | Wholesale | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	1,859.7	2,004.5
Finance Receivables, Total	1,859.7	2,004.5
Dealer | Wholesale | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	6.1	7.9
Finance Receivables, Total	6.1	7.9
Dealer | Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	201.9	20.7
Financed Receivables, By Origination Year, Current Fiscal Year	441.4	509.4
Financing Receivable, Originated One Year before Current Fiscal Year	319.0	485.4
Financing Receivable, Originated Two Years before Current Fiscal Year	320.8	272.5
Financing Receivable, Originated Three Years before Current Fiscal Year	180.6	181.5
Financing Receivable, Originated Four Years before Current Fiscal Year	119.3	101.6
Financed Receivables, By Origination Year, Prior	98.0	132.0
Finance Receivables, Total	1,681.0	1,703.1
Dealer | Retail | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Loans	201.9	20.7
Financed Receivables, By Origination Year, Current Fiscal Year	434.4	504.2
Financing Receivable, Originated One Year before Current Fiscal Year	315.4	474.9
Financing Receivable, Originated Two Years before Current Fiscal Year	311.7	268.0
Financing Receivable, Originated Three Years before Current Fiscal Year	176.0	180.1
Financing Receivable, Originated Four Years before Current Fiscal Year	118.2	100.4
Financed Receivables, By Origination Year, Prior	96.9	132.0
Finance Receivables, Total	1,654.5	1,680.3
Dealer | Retail | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	7.0	5.2
Financing Receivable, Originated One Year before Current Fiscal Year	3.6	10.5
Financing Receivable, Originated Two Years before Current Fiscal Year	9.1	4.5
Financing Receivable, Originated Three Years before Current Fiscal Year	4.6	1.4
Financing Receivable, Originated Four Years before Current Fiscal Year	1.1
Finance Receivables, Total	25.4	21.6
Dealer | Retail | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Originated Four Years before Current Fiscal Year		1.2
Financed Receivables, By Origination Year, Prior	1.1
Finance Receivables, Total	1.1	1.2
Customer Retail
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	3,473.1	3,243.5
Financing Receivable, Originated One Year before Current Fiscal Year	2,320.0	2,357.6
Financing Receivable, Originated Two Years before Current Fiscal Year	1,487.6	1,464.0
Financing Receivable, Originated Three Years before Current Fiscal Year	742.7	658.9
Financing Receivable, Originated Four Years before Current Fiscal Year	263.5	279.9
Financed Receivables, By Origination Year, Prior	77.4	76.8
Finance Receivables, Total	8,364.3	8,080.7
Customer Retail | Fleet
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	2,860.3	2,686.4
Financing Receivable, Originated One Year before Current Fiscal Year	1,928.3	1,976.4
Financing Receivable, Originated Two Years before Current Fiscal Year	1,257.3	1,233.7
Financing Receivable, Originated Three Years before Current Fiscal Year	624.3	551.8
Financing Receivable, Originated Four Years before Current Fiscal Year	224.3	238.1
Financed Receivables, By Origination Year, Prior	67.1	67.2
Finance Receivables, Total	6,961.6	6,753.6
Customer Retail | Fleet | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	2,851.7	2,664.9
Financing Receivable, Originated One Year before Current Fiscal Year	1,913.3	1,921.6
Financing Receivable, Originated Two Years before Current Fiscal Year	1,227.0	1,203.7
Financing Receivable, Originated Three Years before Current Fiscal Year	608.4	533.7
Financing Receivable, Originated Four Years before Current Fiscal Year	220.4	234.2
Financed Receivables, By Origination Year, Prior	66.5	65.2
Finance Receivables, Total	6,887.3	6,623.3
Customer Retail | Fleet | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	2.6	13.5
Financing Receivable, Originated One Year before Current Fiscal Year	6.5	17.8
Financing Receivable, Originated Two Years before Current Fiscal Year	4.3	11.8
Financing Receivable, Originated Three Years before Current Fiscal Year	5.3	5.9
Financing Receivable, Originated Four Years before Current Fiscal Year	0.6	1.5
Financed Receivables, By Origination Year, Prior	0.2	1.2
Finance Receivables, Total	19.5	51.7
Customer Retail | Fleet | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	6.0	8.0
Financing Receivable, Originated One Year before Current Fiscal Year	8.5	37.0
Financing Receivable, Originated Two Years before Current Fiscal Year	26.0	18.2
Financing Receivable, Originated Three Years before Current Fiscal Year	10.6	12.2
Financing Receivable, Originated Four Years before Current Fiscal Year	3.3	2.4
Financed Receivables, By Origination Year, Prior	0.4	0.8
Finance Receivables, Total	54.8	78.6
Customer Retail | Owner/Operator
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	612.8	557.1
Financing Receivable, Originated One Year before Current Fiscal Year	391.7	381.2
Financing Receivable, Originated Two Years before Current Fiscal Year	230.3	230.3
Financing Receivable, Originated Three Years before Current Fiscal Year	118.4	107.1
Financing Receivable, Originated Four Years before Current Fiscal Year	39.2	41.8
Financed Receivables, By Origination Year, Prior	10.3	9.6
Finance Receivables, Total	1,402.7	1,327.1
Customer Retail | Owner/Operator | Performing
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	611.9	554.6
Financing Receivable, Originated One Year before Current Fiscal Year	389.9	376.4
Financing Receivable, Originated Two Years before Current Fiscal Year	228.1	225.1
Financing Receivable, Originated Three Years before Current Fiscal Year	116.0	105.2
Financing Receivable, Originated Four Years before Current Fiscal Year	38.6	41.2
Financed Receivables, By Origination Year, Prior	10.1	9.1
Finance Receivables, Total	1,394.6	1,311.6
Customer Retail | Owner/Operator | Watch
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	0.7	1.6
Financing Receivable, Originated One Year before Current Fiscal Year	0.5	2.7
Financing Receivable, Originated Two Years before Current Fiscal Year	0.7	2.0
Financing Receivable, Originated Three Years before Current Fiscal Year	0.4	0.7
Financing Receivable, Originated Four Years before Current Fiscal Year	0.1	0.2
Financed Receivables, By Origination Year, Prior		0.2
Finance Receivables, Total	2.4	7.4
Customer Retail | Owner/Operator | At-risk
Financing Receivable, Recorded Investment [Line Items]
Financed Receivables, By Origination Year, Current Fiscal Year	0.2	0.9
Financing Receivable, Originated One Year before Current Fiscal Year	1.3	2.1
Financing Receivable, Originated Two Years before Current Fiscal Year	1.5	3.2
Financing Receivable, Originated Three Years before Current Fiscal Year	2.0	1.2
Financing Receivable, Originated Four Years before Current Fiscal Year	0.5	0.4
Financed Receivables, By Origination Year, Prior	0.2	0.3
Finance Receivables, Total	$ 5.7	$ 8.1