v3.25.2
Cover Page - shares
6 Months Ended
Jun. 29, 2025
Aug. 01, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 29, 2025  
Document Transition Report false  
Entity File Number 001-42157  
Entity Registrant Name Six Flags Entertainment Corporation/NEW  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 93-4097909  
Entity Address, Address Line One 8701 Red Oak Blvd.  
Entity Address, City or Town Charlotte  
Entity Address, State or Province NC  
Entity Address, Postal Zip Code 28217  
City Area Code 704  
Local Phone Number 414-4700  
Title of 12(b) Security Common Stock, par value $0.01 per share  
Trading Symbol FUN  
Security Exchange Name 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   101,279,362
Amendment Flag false  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0001999001  
Current Fiscal Year End Date --12-31