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v3.21.2

INTERIM FINANCIAL INFORMATION - Business (Details) | Jun. 30, 2021 town state dealership
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U.S. |
Business And Organization |
Number of states in which the entity operates | state | 15
Number of dealerships | 117
U.K. |
Business And Organization |
Number of towns in which the entity operates | town | 33
Number of dealerships | 48
Brazil |
Business And Organization |
Number of states in which the entity operates | state | 3
Number of dealerships | 16

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- Definition Business And Organization [Line Items] + References No definition available. + Details
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Namespace Prefix: | gpi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Number of dealerships. + References No definition available. + Details
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Namespace Prefix: | gpi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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- Definition Number of Towns in which Entity Operates + References No definition available. + Details
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Namespace Prefix: | gpi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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- Definition The number of states the entity operates in as of the balance sheet date. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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- Details
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Namespace Prefix: |
Data Type: | na
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Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |