v3.25.2
Cover - shares
 6 Months Ended
Jun. 30, 2025
Jul. 18, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2025  
Document Transition Report false  
Entity File Number 1-13461  
Entity Registrant Name Group 1 Automotive, Inc  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 76-0506313  
Entity Address, Address Line One 730 Town and Country Blvd.,  
Entity Address, Address Line Two Suite 500  
Entity Address, City or Town Houston,  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 77024  
City Area Code 713  
Local Phone Number 647-5700  
Title of each class Common stock, par value $0.01 per share  
Ticker symbol(s) GPI  
Name of exchange on which registered NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   12,939,665
Entity Central Index Key 0001031203  
Amendment Flag false  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Current Fiscal Year End Date --12-31