XML 30 R57.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Business and Summary of Significant Accounting Policies and Estimates - Business and Credit Risk Concentrations (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018
Concentration Risk [Line Items] |  |
Amounts due | $ 227.9 | $ 197.2
Due from Manufacturers |  |
Concentration Risk [Line Items] |  |
Amounts due | $ 124.0 | $ 105.1
Toyota | Due from Manufacturers |  |
Concentration Risk [Line Items] |  |
Percentage of Company's new vehicle sales volume more than which no other manufacturer accounted for | 24.70% |
Volkswagen | Due from Manufacturers |  |
Concentration Risk [Line Items] |  |
Percentage of Company's new vehicle sales volume more than which no other manufacturer accounted for | 14.10% |
BMW | Due from Manufacturers |  |
Concentration Risk [Line Items] |  |
Percentage of Company's new vehicle sales volume more than which no other manufacturer accounted for | 12.00% |
Honda | Due from Manufacturers |  |
Concentration Risk [Line Items] |  |
Percentage of Company's new vehicle sales volume more than which no other manufacturer accounted for | 10.70% |
Ford | Due from Manufacturers |  |
Concentration Risk [Line Items] |  |
Percentage of Company's new vehicle sales volume more than which no other manufacturer accounted for | 10.40% |

X
- Definition Percentage of Company's new vehicle sales volume more then which no other manufacturer accounted for. + References No definition available. + Details
Name: | gpi_PercentageofCompanysNewVehicleSalesVolumeMoreThanWhichNoOtherManufacturerAccountedfor
Namespace Prefix: | gpi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4531-111522 + Details
Name: | us-gaap_AccountsReceivableGrossCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ConcentrationRiskLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=gpi_AmountsDueFromManufacturersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=gpi_ToyotaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=gpi_VolkswagenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=gpi_BmwMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=gpi_HondaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=gpi_FordMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |