v3.26.1
Cover Page - shares
 12 Months Ended
Dec. 31, 2025
Mar. 19, 2026
Document Information [Line Items]    
Document Type 20-F  
Amendment Flag false  
Document Period End Date Dec. 31, 2025  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus FY  
Entity Registrant Name SES S.A.  
Entity Central Index Key 0001347408  
Current Fiscal Year End Date --12-31  
Entity Well-known Seasoned Issuer No  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Voluntary Filers No  
Entity Interactive Data Current Yes  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity File Number 333-286828  
Entity Incorporation, State or Country Code N4  
Entity Address, Address Line One Château de Betzdorf  
Entity Address, Address Line Two L-6815 Betzdorf Grand Duchy  
Entity Address, Postal Zip Code L-6815  
Entity Address, City or Town Betzdorf  
Entity Address, Country LU  
Document Annual Report true  
Document Transition Report false  
Document Shell Company Report false  
Document Registration Statement false  
Document Accounting Standard International Financial Reporting Standards  
ICFR Auditor Attestation Flag false  
Auditor Name PricewaterhouseCoopers Assurance  
Auditor Firm ID 876  
Auditor Location Luxembourg  
Document Financial Statement Error Correction [Flag] false  
Business Contact [Member]    
Document Information [Line Items]    
Entity Address, Address Line One 7900 Tysons One Place  
Entity Address, Postal Zip Code 22102  
Entity Address, City or Town McLean  
Entity Address, Country VA  
Contact Personnel Name Aaron Shourie  
Contact Personnel Email Address aaron.shourie@ses.com  
Class A Ordinary Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   371,457,600
Class B Ordinary Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   185,728,800