v3.26.1
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2026
Aug. 03, 2026
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 001-42113  
Entity Registrant Name Seaport Entertainment Group Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 99-0947924  
Entity Address, Address Line One 199 Water Street  
Entity Address, City or Town New York  
Entity Address State Or Province NY  
Entity Address, Postal Zip Code 10038  
City Area Code 212  
Local Phone Number 732-8257  
Title of 12(b) Security Common Stock, par value $0.01 per share  
Trading Symbol SEG  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Ex Transition Period true  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   12,809,536
Entity Central Index Key 0002009684  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Amendment Flag false