XML 46 R32.htm IDEA: XBRL DOCUMENT v3.21.2

INTERIM FINANCIAL INFORMATION - Business (Details)	Sep. 30, 2021 town dealership state
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	35
Number of dealerships	55
Brazil
Business And Organization
Number of states in which the entity operates | state	3
Number of dealerships	16

X

- Definition

Business And Organization [Line Items]

+ References

No definition available.

+ Details

Name:	gpi_BusinessAndOrganizationLineItems
Namespace Prefix:	gpi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of dealerships.

+ References

No definition available.

+ Details

Name:	gpi_NumberOfDealerships
Namespace Prefix:	gpi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Number of Towns in which Entity Operates

+ References

No definition available.

+ Details

Name:	gpi_NumberOfTownsInWhichEntityOperates
Namespace Prefix:	gpi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=gpi_UnitedStatesSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=gpi_UnitedKingdomSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=gpi_BrazilSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: