| Document | Jul. 30, 2020 | Apr. 29, 2020 |
| Cover [Abstract] | ||
| Document Type | 8-K | |
| Document Period End Date | Jul. 30, 2020 | |
| Entity Registrant Name | SONIC AUTOMOTIVE, INC. | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Entity Emerging Growth Company | false | |
| Title of 12(b) Security | Class A Common Stock, par value $0.01 per share | |
| Entity File Number | 1-13395 | |
| Entity Incorporation, State or Country Code | DE | |
| Entity Tax Identification Number | 56-2010790 | |
| Entity Address, Address Line One | 4401 Colwick Road | |
| Entity Address, City or Town | Charlotte, | |
| Entity Address, State or Province | NC | |
| Entity Address, Postal Zip Code | 28211 | |
| City Area Code | (704) | |
| Local Phone Number | 566-2400 | |
| Pre-commencement Issuer Tender Offer | false | |
| Trading Symbol | SAH | |
| Security Exchange Name | NYSE | |
| Amendment Flag | false | |
| Entity Central Index Key | 0001043509 |
