XML 15 R43.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Description Of Business (Narrative) (Details) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2019 loan | Sep. 30, 2019 loan | Dec. 31, 2019 USD ($) loan portfolio_segment
Description Of Business [Abstract] |  |  |
Number of Portfolio Segments | portfolio_segment |  |  | 2
Number of consumers required to group advances | 50 | 100 |
Number of Consumer Loans assigned to receive accelerated Dealer Holdback payment |  |  | 100
Servicing fee percentage in collections |  |  | 20.00%
Number Of Consumer Loans Assigned To Receive Dealer Holdback Payment |  |  | 100
One-time enrollment fee in program | $ |  |  | $ 9,850
Percentage of enrollment fee of first accelerated dealer holdback payment |  |  | 50.00%

X
- Definition Description Of Business [Abstract] + References No definition available. + Details
Name: | cacc_DescriptionOfBusinessAbstract
Namespace Prefix: | cacc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Consumer Loans Assigned To Receive Accelerated Dealer Holdback Payment + References No definition available. + Details
Name: | cacc_NumberOfConsumerLoansAssignedToReceiveAcceleratedDealerHoldbackPayment
Namespace Prefix: | cacc_
Data Type: | xbrli:positiveIntegerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Consumer Loans Assigned To Receive Dealer Holdback Payment + References No definition available. + Details
Name: | cacc_NumberOfConsumerLoansAssignedToReceiveDealerHoldbackPayment
Namespace Prefix: | cacc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Consumers Required To Group Advances + References No definition available. + Details
Name: | cacc_NumberOfConsumersRequiredToGroupAdvances
Namespace Prefix: | cacc_
Data Type: | xbrli:positiveIntegerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Portfolio Segments + References No definition available. + Details
Name: | cacc_NumberofPortfolioSegments
Namespace Prefix: | cacc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage Of Revenue From Enrollment And Registration Fees In Program + References No definition available. + Details
Name: | cacc_PercentageOfRevenueFromEnrollmentAndRegistrationFeesInProgram
Namespace Prefix: | cacc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Revenue From Enrollment And Registration Fees In Program + References No definition available. + Details
Name: | cacc_RevenueFromEnrollmentAndRegistrationFeesInProgram
Namespace Prefix: | cacc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Service fee income as a percentage of collections. + References No definition available. + Details
Name: | cacc_ServiceFeeIncomeAsPercentageOfCollections
Namespace Prefix: | cacc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration