FINANCE RECEIVABLES - Schedule of Financing Receivable Credit Quality Indicators (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Total finance receivables	$ 3,524.3	$ 3,348.7
Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	434.2	1,707.2
Fiscal year before current fiscal year	1,584.9	1,188.6
Two years before current fiscal year	1,079.7	248.9
Three years before current fiscal year	221.0	27.1
Four years before current fiscal year	23.4
Total finance receivables	3,343.2	3,171.8
Other Finance Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Total finance receivables	181.1	176.9
Less than 599 \| Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	16.8	62.2
Fiscal year before current fiscal year	57.3	39.0
Two years before current fiscal year	34.0	17.6
Three years before current fiscal year	15.6	2.4
Four years before current fiscal year	2.1
Total finance receivables	125.8	121.2
FICO Score, 600 to 699 \| Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	140.3	586.6
Fiscal year before current fiscal year	549.1	463.6
Two years before current fiscal year	418.8	152.7
Three years before current fiscal year	135.3	16.1
Four years before current fiscal year	13.9
Total finance receivables	1,257.4	1,219.0
FICO Score, 700 to 774 \| Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	135.4	568.1
Fiscal year before current fiscal year	532.7	422.5
Two years before current fiscal year	386.5	63.9
Three years before current fiscal year	57.0	5.9
Four years before current fiscal year	5.1
Total finance receivables	1,116.7	1,060.4
FICO Score, Greater than 775 \| Auto Loan Receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Current year	141.7	490.3
Fiscal year before current fiscal year	445.8	263.5
Two years before current fiscal year	240.4	14.7
Three years before current fiscal year	13.1	2.7
Four years before current fiscal year	2.3
Total finance receivables	$ 843.3	$ 771.2

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/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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

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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
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Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.

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