XML 18 R1.htm IDEA: XBRL DOCUMENT v3.10.0.1
Document And Entity Information - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
Feb. 22, 2019
Jun. 30, 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    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Well-known Seasoned Issuer Yes    
Entity Public Float     $ 2,216,050
Document Type 10-K    
Document Period End Date Dec. 31, 2018    
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Emerging Growth Company false    
Entity Small Business false    
Entity Shell Company false    
Class B common stock      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   800,000  
Class A common stock      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   22,347,635