Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

v3.10.0.1
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2018
Oct. 23, 2018
Document Information [Line Items]    
Entity Registrant Name SONIC AUTOMOTIVE INC  
Entity Central Index Key 0001043509  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Document Type 10-Q  
Document Period End Date Sep. 30, 2018  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q3  
Trading Symbol SAH  
Amendment Flag false  
Entity Emerging Growth Company false  
Entity Small Business false  
Class A Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   30,721,226
Class B Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   12,029,375