Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
REVENUES:
New vehicle retail sales	$ 1,332,724gpi_NewVehicleRetailSales	$ 1,268,836gpi_NewVehicleRetailSales
Used vehicle retail sales	623,193gpi_UsedVehicleRetailSales	549,897gpi_UsedVehicleRetailSales
Used vehicle wholesale sales	100,192gpi_UsedVehicleWholesaleSales	89,173gpi_UsedVehicleWholesaleSales
Parts and service sales	282,189gpi_PartsAndServiceSales	269,317gpi_PartsAndServiceSales
Finance, insurance and other, net	94,556gpi_FinancialServicesRevenueNet	83,640gpi_FinancialServicesRevenueNet
Total revenues	2,432,854us-gaap_Revenues	2,260,863us-gaap_Revenues
COST OF SALES:
New vehicle retail sales	1,262,993gpi_NewVehicleRetailSalesCostOfSales	1,201,930gpi_NewVehicleRetailSalesCostOfSales
Used vehicle retail sales	577,072gpi_UsedVehicleRetailSalesCostOfSales	507,096gpi_UsedVehicleRetailSalesCostOfSales
Used vehicle wholesale sales	97,513	86,061
Parts and service sales	131,392gpi_PartsAndServiceSalesCostOfSales	127,654gpi_PartsAndServiceSalesCostOfSales
Total cost of sales	2,068,970us-gaap_CostOfGoodsAndServicesSold	1,922,741us-gaap_CostOfGoodsAndServicesSold
GROSS PROFIT	363,884us-gaap_GrossProfit	338,122us-gaap_GrossProfit
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	(271,469)	(257,558)
DEPRECIATION AND AMORTIZATION EXPENSE	(11,684)	(9,925)
INCOME FROM OPERATIONS	80,731us-gaap_OperatingIncomeLoss	70,639us-gaap_OperatingIncomeLoss
OTHER EXPENSE:
Floorplan interest expense	(9,348)gpi_FloorPlanInterestExpense	(10,913)gpi_FloorPlanInterestExpense
Other interest expense, net	(13,911)us-gaap_InterestExpenseOther	(10,513)us-gaap_InterestExpenseOther
INCOME BEFORE INCOME TAXES	57,472	49,213
PROVISION FOR INCOME TAXES	(21,657)us-gaap_IncomeTaxExpenseBenefit	(17,910)us-gaap_IncomeTaxExpenseBenefit
NET INCOME	$ 35,815us-gaap_NetIncomeLoss	$ 31,303us-gaap_NetIncomeLoss
BASIC EARNINGS PER SHARE	$ 1.47us-gaap_EarningsPerShareBasic	$ 1.29us-gaap_EarningsPerShareBasic
Weighted average common shares outstanding	23,443	23,339
DILUTED EARNINGS PER SHARE	$ 1.47us-gaap_EarningsPerShareDiluted	$ 1.19us-gaap_EarningsPerShareDiluted
Weighted average common shares outstanding	23,446	25,428
CASH DIVIDENDS PER COMMON SHARE	$ 0.20	$ 0.17

Aggregate revenue recognized during the period representing fees earned for the arrangement of financing for customers through various institutions, as well as from the sale of various insurance and vehicle service contracts to customers. In addition, revenue recognized includes amounts earned from certain vehicle service contract administrators for volume incentive rebates, interest income on reserves, as well as product underwriting profits. A reserve for future amounts that might be charged back is established based on the historical chargeback results and termination provisions of the applicable contracts.

No definition available.