ACQUISITIONS - Schedule of Pro Forma Summary of All Acquisitions (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Business Combination and Asset Acquisition [Abstract]
Revenue	$ 9,024.4	$ 8,197.2
Net income attributable to Lithia Motors, Inc.	$ 170.8	$ 245.7
Basic earnings per share attributable to Lithia Motors, Inc. (in dollars per share)	$ 6.20	$ 8.94
Diluted earnings per share attributable to Lithia Motors, Inc. (in dollars per share)	$ 6.19	$ 8.92

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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- Definition

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.

+ References

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- Definition

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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- Definition

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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