| Document and Entity Information | Nov. 22, 2023 |
| Cover [Abstract] | |
| Security Exchange Name | NASDAQ |
| Entity Information, Former Legal or Registered Name | Aeglea BioTherapeutics,Inc. |
| Amendment Flag | false |
| Entity Central Index Key | 0001636282 |
| Current Fiscal Year End Date | --12-31 |
| Document Type | 8-K |
| Document Period End Date | Nov. 22, 2023 |
| Entity Registrant Name | SPYRE THERAPEUTICS, INC. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-37722 |
| Entity Tax Identification Number | 46-4312787 |
| Entity Address, Address Line One | 221 Crescent Street |
| Entity Address, Address Line Two | Building 23 |
| Entity Address, Address Line Three | Suite 105 |
| Entity Address, City or Town | Waltham |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02453 |
| City Area Code | 617 |
| Local Phone Number | 651-5940 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.0001 Par Value Per Share |
| Trading Symbol | SYRE |
| Entity Emerging Growth Company | false |
