XML 56 R42.htm IDEA: XBRL DOCUMENT
v3.20.2

Financial Instruments and Fair Value Measurements - Schedule of Long-term Debt Carrying Value and Fair Value (Details) - USD ($) $ in Millions | Jun. 30, 2020 | Dec. 31, 2019
--- | --- | ---
5.00% Senior Notes |  |
Debt Instrument [Line Items] |  |
Interest rate (as a percentage) | 5.00% |
Carrying Value |  |
Debt Instrument [Line Items] |  |
Debt, fair value | $ 636.9 | $ 587.1
Carrying Value | 5.00% Senior Notes |  |
Debt Instrument [Line Items] |  |
Debt, fair value | 547.1 | 546.4
Carrying Value | Real estate related |  |
Debt Instrument [Line Items] |  |
Debt, fair value | 89.8 | 40.7
Fair Value |  |
Debt Instrument [Line Items] |  |
Debt, fair value | 631.1 | 600.6
Fair Value | 5.00% Senior Notes |  |
Debt Instrument [Line Items] |  |
Debt, fair value | 549.9 | 559.5
Fair Value | Real estate related |  |
Debt Instrument [Line Items] |  |
Debt, fair value | $ 81.2 | $ 41.1

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
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_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
Name: | us-gaap_LongTermDebtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gpi_A5.00SeniorNoteMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gpi_RealEstateRelatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |