ACQUISITIONS - Schedule of Pro Forma Summary of All Acquisitions (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Revenue	$ 9,276.3	$ 9,496.4	$ 18,361.9	$ 17,753.0
Net income attributable to Lithia Motors, Inc.	$ 218.4	$ 324.6	$ 391.1	$ 572.2
Basic earnings per share attributable to Lithia Motors, Inc. (in dollars per share)	$ 8.03	$ 11.79	$ 14.29	$ 20.80
Diluted earnings per share attributable to Lithia Motors, Inc. (in dollars per share)	$ 8.02	$ 11.77	$ 14.27	$ 20.76

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-SubTopic 10
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(3)
-SubTopic 10
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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