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available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false2Available amount under borrowing capacity13false 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5us-gaap_DebtWeightedAverageInterestRateus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsetruefalse00falsefalsefalse2falsetruefalse00falsefalsefalse3falsetruefalse00falsefalsefalse4truetruefalse0.0170.017falsefalsefalse5falsetruefalse00falsefalsefalse6falsetruefalse00falsefalsefalse7falsetruefalse00falsefalsefalse8falsetruefalse00falsefalsefalse9falsetruefalse00falsefalsefalse10falsetruefalse00falsefalsefalse11falsetruefalse00falsefalsefalse12falsetruefalse00falsefalsefalse13falsetruefalse00falsefalsefalse14falsetruefalse00falsefalsefalse15falsetruefalse00falsefalsefalse16falsetruefalse00falsefalsefalse17falsetruefalse00falsefalsefalse18falsetruefalse00falsefalsefalse19falsetruefalse00falsefalsefalse20falsetruefalse00falsefalsefalse21falsetruefalse00falsefalsefalse22falsetruefalse00falsefalsefalsenum:percentItemTypepureReflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of debt outstanding by type or by instrument at that time.No definition available.false0Weighted average interest rate15false 5gpi_MaximumPeriodForOutstandingBorrowinggpi_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse001 year 0 months 0 daysfalsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalse16falsefalsefalse00falsefalsefalse17falsefalsefalse00falsefalsefalse18falsefalsefalse00falsefalsefalse19falsefalsefalse00falsefalsefalse20falsefalsefalse00falsefalsefalse21falsefalsefalse00falsefalsefalse22falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaMaximum period for outstanding borrowing.No definition available.false0Maximum period for outstanding borrowing16false 5us-gaap_LettersOfCreditOutstandingAmountus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalse16truefalsefalse2930000029300000falsefalsefalse17falsefalsefalse00falsefalsefalse18falsefalsefalse00falsefalsefalse19falsefalsefalse00falsefalsefalse20falsefalsefalse00falsefalsefalse21falsefalsefalse00falsefalsefalse22falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe total amount of the contingent obligation under letters of credit outstanding as of the reporting date.No definition available.false2Letters of credit outstanding17false 5gpi_RestrictedPaymentgpi_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9truefalsefalse146300000146300000USD$falsetruefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalse16falsefalsefalse00falsefalsefalse17falsefalsefalse00falsefalsefalse18falsefalsefalse00falsefalsefalse19falsefalsefalse00falsefalsefalse20falsefalsefalse00falsefalsefalse21falsefalsefalse00falsefalsefalse22falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryRestricted payment.No definition available.false2Restricted payment18false 5gpi_MaximumLimitOfRestrictedPaymentgpi_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00$125.0 million plus (or minus if negative) (a) one-half of the aggregate consolidated net income of the Company for the period beginning on January 1, 2013 and ending on the date of determination and (b) the amount of net cash proceeds received from the sale of capital stock on or after January 1, 2013 and ending on the date of determination less (c) cash dividends and share repurchases (“Restricted Payment 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daysfalsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalse16falsefalsefalse00falsefalsefalse17falsefalsefalse00falsefalsefalse18falsefalsefalse00falsefalsefalse19falsefalsefalse00falsefalsefalse20falsefalsefalse00falsefalsefalse21falsefalsefalse00falsefalsefalse22falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaNumber of days related to cancellation of contract.No definition available.false0Cancellation of agreement20false 5gpi_PrimeInterestRateMinimumgpi_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsetruefalse00falsefalsefalse2falsetruefalse00falsefalsefalse3falsetruefalse00falsefalsefalse4falsetruefalse00falsefalsefalse5falsetruefalse00falsefalsefalse6falsetruefalse00falsefalsefalse7falsetruefalse00falsefalsefalse8truetruefalse0.0350.035falsefalsefalse9falsetruefalse00falsefalsefalse10falsetruefalse00falsefalsefalse11falsetruefalse00falsefalsefalse12falsetruefalse00falsefalsefalse13falsetruefalse00falsefalsefalse14falsetruefalse00falsefalsefalse15falsetruefalse00falsefalsefalse16falsetruefalse00falsefalsefalse17falsetruefalse00falsefalsefalse18falsetruefalse00falsefalsefalse19falsetruefalse00falsefalsefalse20falsetruefalse00falsefalsefalse21falsetruefalse00falsefalsefalse22falsetruefalse00falsefalsefalsenum:percentItemTypepurePrime interest rate, minimum.No definition available.false0Prime interest rate, minimum21false 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http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false0Debt interest rate22false 5gpi_DebtInstrumentMaturityDatePeriodgpi_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse0012 monthsfalsefalsefalse7falsefalsefalse001 monthfalsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalse16falsefalsefalse00falsefalsefalse17falsefalsefalse00falsefalsefalse18falsefalsefalse00falsefalsefalse19falsefalsefalse00falsefalsefalse20falsefalsefalse00falsefalsefalse21falsefalsefalse00falsefalsefalse22falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt Instrument Maturity Date PeriodNo definition available.false0Debt Instrument Maturity Date Period23false 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agreement as of the balance sheet date.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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 false0Interest rate, maximumfalseCredit Facilities (Details Textual) (USD $)NoRoundingUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.group1auto.com/role/CreditFacilitiesDetailsTextual2223