| Document and Entity Information | Sep. 09, 2021 |
| Document And Entity Information [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Sep. 9, 2021 |
| Entity Registrant Name | AUTONATION, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity Central Index Key | 0000350698 |
| Entity File Number | 1-13107 |
| Entity Tax Identification Number | 73-1105145 |
| Entity Address, Address Line One | 200 SW 1st Ave |
| Entity Address, City or Town | Fort Lauderdale |
| Entity Address, State or Province | FL |
| Entity Address, Postal Zip Code | 33301 |
| City Area Code | 954 |
| Local Phone Number | 769-6000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, par value $0.01 per share |
| Trading Symbol | AN |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
