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BASIS OF PRESENTATION, CONSOLIDATION AND SUMMARY OF ACCOUNTING POLICIES - Statements of Cash Flows (Details) | 12 Months Ended
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Dec. 31, 2021
Accounting Policies [Abstract] |
Percent of value of the vehicle financed by the company (up to) | 85.00%

X
- Definition Value of used vehicle inventory financed + References No definition available. + Details
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Namespace Prefix: | gpi_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration