| Cover | Dec. 09, 2019 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Dec. 9, 2019 |
| Entity Registrant Name | CREDIT ACCEPTANCE CORP |
| Entity Central Index Key | 0000885550 |
| Amendment Flag | false |
| Entity Incorporation, State or Country Code | MI |
| Entity File Number | 000-20202 |
| Entity Tax Identification Number | 38-1999511 |
| Entity Address, Address Line One | 25505 West Twelve Mile Road |
| Entity Address, City or Town | Southfield, |
| Entity Address, State or Province | MI |
| Entity Address, Postal Zip Code | 48034-8339 |
| City Area Code | 248 |
| Local Phone Number | 353-2700 |
| Title of 12(b) Security | Common Stock, $.01 par value |
| Trading Symbol | CACC |
| Security Exchange Name | NASDAQ |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
