v3.10.0.1
Document And Entity Information - shares
6 Months Ended
Jun. 30, 2018
Jul. 27, 2018
Document Information [Line Items]    
Entity Registrant Name LITHIA MOTORS INC  
Entity Central Index Key 0001023128  
Trading Symbol lad  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Document Type 10-Q  
Document Period End Date Jun. 30, 2018  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q2  
Amendment Flag false  
Class A common stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding (in shares)   23,206,001
Class B common stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding (in shares)   1,000,000