v3.26.1
Cover Page - shares
 3 Months Ended
Mar. 31, 2026
May 01, 2026
Cover    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Document Transition Report false  
Entity File Number 001-39331  
Entity Registrant Name System1, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 92-3978051  
Entity Address, Address Line One 4235 Redwood Avenue  
Entity Address, City or Town Los Angeles  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 90066  
City Area Code 310  
Local Phone Number 924-6037  
Title of 12(b) Security Class A common stock, par value $0.0001 per share  
Trading Symbol SST  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Central Index Key 0001805833  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Class A Common Stock    
Cover    
Entity Common Stock, Shares Outstanding   8,150,474
Class C Common Stock    
Cover    
Entity Common Stock, Shares Outstanding   1,788,758