v3.25.1
Document and Entity Information - shares
3 Months Ended
Mar. 31, 2025
May 06, 2025
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Mar. 31, 2025  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q1  
Entity Registrant Name GTJ REIT, INC.  
Entity Central Index Key 0001368757  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Document Quarterly Report true  
Document Transition Report false  
Entity Common Stock, Shares Outstanding   13,345,980
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Tax Identification Number 20-5188065  
Entity File Number 333-136110  
Entity Incorporation, State or Country Code MD  
Entity Address, Address Line One 1399 Franklin Avenue  
Entity Address, Address Line Two Suite 100  
Entity Address, City or Town Garden City  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 11530  
City Area Code 516  
Local Phone Number 693-5500