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DEBT - Schedule of Non-Recourse Notes Payable (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Debt Instrument [Line Items]
Proceeds from issuance of non-recourse notes payable	$ 329.4	$ 479.7
Non-recourse \| Asset Backed Funding Vehicles
Debt Instrument [Line Items]
Proceeds from issuance of non-recourse notes payable	329.4
Non-recourse notes payable \| Non-recourse
Debt Instrument [Line Items]
Long-term debt, gross	1,831.5
Aggregate principal amount	2,844.9
Non-recourse notes payable \| LAD Auto Receivables Trust 2021-1 Class A-D \| Non-recourse
Debt Instrument [Line Items]
Long-term debt, gross	82.6
Aggregate principal amount	$ 344.4
Non-recourse notes payable \| LAD Auto Receivables Trust 2021-1 Class A-D \| Non-recourse \| Minimum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	1.30%
Non-recourse notes payable \| LAD Auto Receivables Trust 2021-1 Class A-D \| Non-recourse \| Maximum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	3.99%
Non-recourse notes payable \| LAD Auto Receivables Trust 2022-1 Class A-C \| Non-recourse
Debt Instrument [Line Items]
Long-term debt, gross	$ 131.6
Aggregate principal amount	$ 298.1
Non-recourse notes payable \| LAD Auto Receivables Trust 2022-1 Class A-C \| Non-recourse \| Minimum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	5.21%
Non-recourse notes payable \| LAD Auto Receivables Trust 2022-1 Class A-C \| Non-recourse \| Maximum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	6.85%
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-1 Class A-D \| Non-recourse
Debt Instrument [Line Items]
Long-term debt, gross	$ 279.0
Aggregate principal amount	$ 479.7
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-1 Class A-D \| Non-recourse \| Minimum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	5.48%
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-1 Class A-D \| Non-recourse \| Maximum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	7.30%
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-2 Class A-D \| Non-recourse
Debt Instrument [Line Items]
Long-term debt, gross	$ 362.5
Aggregate principal amount	$ 556.7
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-2 Class A-D \| Non-recourse \| Minimum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	5.42%
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-2 Class A-D \| Non-recourse \| Maximum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	6.30%
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-3 Class A-D \| Non-recourse
Debt Instrument [Line Items]
Long-term debt, gross	$ 316.9
Aggregate principal amount	$ 415.4
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-3 Class A-D \| Non-recourse \| Minimum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	5.95%
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-3 Class A-D \| Non-recourse \| Maximum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	6.92%
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-4 Class A-D \| Non-recourse
Debt Instrument [Line Items]
Long-term debt, gross	$ 352.4
Aggregate principal amount	$ 421.2
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-4 Class A-D \| Non-recourse \| Minimum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	6.10%
Non-recourse notes payable \| LAD Auto Receivables Trust 2023-4 Class A-D \| Non-recourse \| Maximum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	7.37%
Non-recourse notes payable \| LAD Auto Receivables Trust 2024-1 Class A-D \| Non-recourse
Debt Instrument [Line Items]
Long-term debt, gross	$ 306.5
Aggregate principal amount	$ 329.4
Non-recourse notes payable \| LAD Auto Receivables Trust 2024-1 Class A-D \| Non-recourse \| Minimum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	5.17%
Non-recourse notes payable \| LAD Auto Receivables Trust 2024-1 Class A-D \| Non-recourse \| Maximum
Debt Instrument [Line Items]
Debt stated interest rate (as a percent)	6.15%