Name:	cacc_CertainLoansAcquiredInTransferAccountedForAsLoansAccretableYield
Namespace Prefix:	cacc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Increases in the aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan due to the acquisition of similar loans during the period. This relates to loans with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

No definition available.

Name:	cacc_CertainLoansAcquiredInTransferAccountedForAsLoansAccretableYieldAdditions
Namespace Prefix:	cacc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Change in the estimate of cash flows expected to be collected, after acquisition of a loan, which results in an increase in accretable yield (for example, if actual cash flows are significantly greater than previously expected). This relates to loans with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

No definition available.

Name:	cacc_CertainLoansAcquiredInTransferAccountedForAsLoansAccretableYieldReclassificationsFromNonaccretableDifference
Namespace Prefix:	cacc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Certain Loans Acquired In Transfer Accounted For As Loans Accretable Yield Transfers

No definition available.

Name:	cacc_CertainLoansAcquiredInTransferAccountedForAsLoansAccretableYieldTransfers
Namespace Prefix:	cacc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The aggregate financial services revenue and operating interest income earned during the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(d))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5