Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

v3.10.0.1
Document and Entity Information - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2018
Feb. 20, 2019
Jun. 30, 2018
Document and Entity Information [Line Items]      
Document Type 10-K    
Document Period End Date Dec. 31, 2018    
Amendment Flag false    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Shell Company false    
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY    
Trading Symbol SAH    
Entity Registrant Name SONIC AUTOMOTIVE INC    
Entity Central Index Key 0001043509    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 599.3
Class A Common stock      
Document and Entity Information [Line Items]      
Entity Common Stock, Shares Outstanding   30,916,226  
Class B Common stock      
Document and Entity Information [Line Items]      
Entity Common Stock, Shares Outstanding   12,029,375