FINANCE RECEIVABLES - Schedule of Finance Receivables by FICO Score (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Line Items]
Total finance receivables	$ 4,153.1	$ 3,971.1
Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	554.0	1,675.4
Fiscal year before current fiscal year	1,542.7	1,173.3
Two years before current fiscal year	1,046.9	782.7
Three years before current fiscal year	691.9	148.7
Four years before current fiscal year	127.8	14.2
Five years before current fiscal year	11.5
Total finance receivables	3,974.8	3,794.3
Other Finance Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Total finance receivables	178.3	176.8
Less than 599 \| Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	13.0	53.0
Fiscal year before current fiscal year	48.8	39.7
Two years before current fiscal year	34.7	22.4
Three years before current fiscal year	19.2	9.9
Four years before current fiscal year	8.3	1.4
Five years before current fiscal year	1.0
Total finance receivables	125.0	126.4
FICO Score, 600 to 699 \| Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	154.3	534.1
Fiscal year before current fiscal year	499.9	406.2
Two years before current fiscal year	362.4	298.8
Three years before current fiscal year	263.2	90.2
Four years before current fiscal year	77.4	8.3
Five years before current fiscal year	6.8
Total finance receivables	1,364.0	1,337.6
FICO Score, 700 to 774 \| Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	185.2	560.2
Fiscal year before current fiscal year	519.1	402.5
Two years before current fiscal year	361.6	284.9
Three years before current fiscal year	253.2	39.5
Four years before current fiscal year	34.2	3.2
Five years before current fiscal year	2.7
Total finance receivables	1,356.0	1,290.3
FICO Score, Greater than 775 \| Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	201.5	528.1
Fiscal year before current fiscal year	474.9	324.9
Two years before current fiscal year	288.2	176.6
Three years before current fiscal year	156.3	9.1
Four years before current fiscal year	7.9	1.3
Five years before current fiscal year	1.0
Total finance receivables	$ 1,129.8	$ 1,040.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable classified as noncurrent. Excludes net investment in lease.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
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Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
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-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 6
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 3B
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