Employee Benefit Plan, Description of Plan (Details) - EBP 001 [Member] - USD ($)	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
EBP, Description of Plan [Line Items]
EBP, Required Minimum Age To Participate In Plan	18 years
EBP, Participant Contribution Pretax Minimum Annual Compensation To Total Compensation Percentage	1.00%
EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage	75.00%
EBP, Participant Contribution, Automatic, Deferral Rate	6.00%
EBP, Participant Additional Contribution Automatic Deferral Rate	1.00%
EBP, Participant Contribution Maximum Automatic Deferral Rate	10.00%
EBP, Employer Contribution, Matching Percentage	100.00%
EBP, Employer Contribution, Participant Compensation Matched, Percentage	4.00%
EBP, Additional Employer Contribution Matching Percentage	50.00%
EBP, Additional Employer Contribution Participant Compensation Matched Percentage	2.00%
EBP, Employer Contribution Maximum Participant Compensation Matched Percentage	5.00%
EBP, Employer Contribution Vesting Service Period	2 years
EBP, Forfeited Nonvested Account, Decrease from Employer Contribution	$ 579,939
EBP, Forfeited Nonvested Account	$ 33,917	$ 66,554
EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage	50.00%
EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount	$ 50,000
EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount	$ 1,000
EBP, Participant Loan Basis Spread On Variable Rate	1.00%
EBP, Asset Held for Investment, Participant Loan, Interest Rate	4.25%	3.25%
EBP, Participant Maximum Loan Interest Rate	9.50%	9.50%
EBP, Note Receivable From Participant Maximum Borrowing Term	5 years
EBP, Note Receivable From Participant Principal Residence Maximum Borrowing Term	10 years
EBP, Required Minimum Distributions Commencement Age	73 years
EBP, Lump Sum Payable Margin On Termination	$ 7,000

EBP, Employer Contribution Vesting Service Period

No definition available.

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- Definition

EBPNoteReceivableFromParticipantMaximumBorrowingTerm

+ References

No definition available.

+ Details

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- Definition

EBPNoteReceivableFromParticipantPrincipalResidenceMaximumBorrowingTerm

+ References

No definition available.

+ Details

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- Definition

EBP Participant Loan Basis Spread On Variable Rate

+ References

No definition available.

+ Details

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Namespace Prefix:	cacc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP Required Minimum Distributions Commencement Age

+ References

No definition available.

+ Details

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- Definition

EBP Required Minimum Age To Participate In Plan

+ References

No definition available.

+ Details

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- Definition

Employee Benefit Plan Additional Employer Contribution Matching Percentage

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee Benefit Plan Additional Employer Contribution Participant Compensation Matched Percentage

+ References

No definition available.

+ Details

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- Definition

Employee Benefit Plan Employer Contribution Maximum Participant Compensation Matched Percentage

+ References

No definition available.

+ Details

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- Definition

EmployeeBenefitPlanLumpSumPayableMarginOnTermination

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Employee Benefit Plan Participant Additional Contribution Automatic Deferral Rate

+ References

No definition available.

+ Details

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- Definition

Employee Benefit Plan Participant Contribution Maximum Automatic Deferral Rate

+ References

No definition available.

+ Details

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- Definition

EmployeeBenefitPlanParticipantContributionPretaxMinimumAnnualCompensationToTotalCompensationPercentage

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

EmployeeBenefitPlanParticipantMaximumLoanInterestRate

+ References

No definition available.

+ Details

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Namespace Prefix:	cacc_
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Period Type:	duration

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

+ Details

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- Definition

Percentage of employer matching contribution on eligible participant contribution to employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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Period Type:	duration

- Definition

Percentage of participant compensation eligible for employer matching contribution for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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Period Type:	duration

- Definition

Amount of plan asset, in forfeited nonvested account, no longer allocated to participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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Balance Type:	debit
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- Definition

Amount of decrease in forfeited nonvested account of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) from employer contribution.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 962
-SubTopic 325
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478873/962-325-55-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (j)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-04(5)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

+ Details

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- Definition

Amount of maximum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow.

+ References

+ Details

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- Definition

Percentage of maximum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow to total participant account balance.

+ References

+ Details

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- Definition

Amount of minimum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow.

+ References

+ Details

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- Definition

Percentage of eligible compensation contributed for participant automatically enrolled in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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- Definition

Percentage of maximum pretax annual compensation that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), is permitted to contribute to total pretax annual compensation.

+ References

+ Details

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- Definition

Interest rate on participant loan in schedule of asset held for investment of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Employee Retirement Income Security Act of 1974
-Number 2520
-Section 103
-Subsection 10
-Paragraph b
-Subparagraph (1)(i)(D)
-Publisher DOL-EBSA

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-05(a)(Schedule I))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

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