| Document and Entity Information | Dec. 02, 2019 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001023128 |
| Document Type | 8-K |
| Document Period End Date | Dec. 2, 2019 |
| Entity Registrant Name | LITHIA MOTORS INC |
| Entity Incorporation State Country Code | OR |
| Entity File Number | 001-14733 |
| Entity Tax Identification Number | 93-0572810 |
| Entity Address, Address Line One | 150 N. Bartlett Street |
| Entity Address, City or Town | Medford |
| Entity Address, State or Province | OR |
| Entity Address, Postal Zip Code | 97501 |
| City Area Code | (541) |
| Local Phone Number | 776-6401 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Class A [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Class A common stock without par value |
| Trading Symbol | LAD |
| Security Exchange Name | NYSE |
| Common Class B [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Class B common stock without par value |
| Trading Symbol | LAD |
| Security Exchange Name | NYSE |
