XML 93 R109.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Condensed Consolidated Financial Information - Condensed Consolidated Balance Sheets Parenthetical (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Condensed Financial Information Disclosure [Abstract] |  |
Offset account related to floorplan notes payable | $ 106.8 | $ 33.6
FMCC offset | $ 4.1 | $ 0.1

X
- Definition FMCC Offset + References No definition available. + Details
Name: | gpi_FMCCOffset
Namespace Prefix: | gpi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Floorplan offset. + References No definition available. + Details
Name: | gpi_FloorplanOffset
Namespace Prefix: | gpi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | srt_CondensedFinancialInformationOfParentCompanyOnlyDisclosureAbstract
Namespace Prefix: | srt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration