COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Mar. 31, 2026 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Lessee rental payment obligations during remaining terms of leases under guarantee agreement	$ 26.6

Guarantor Obligations, Maximum Exposure Inestimable, Minimum Lease Payments Guaranteed

No definition available.

Name:	gpi_GuarantorObligationsMaximumExposureInestimableMinimumLeasePaymentsGuaranteed
Namespace Prefix:	gpi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant