| Cover Page | Feb. 27, 2025 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 27, 2025 |
| Entity Registrant Name | Six Flags Entertainment Corporation/NEW |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-42157 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | FUN |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001999001 |
| Amendment Flag | false |
