The Company and Basis of Presentation (Details) $ / shares in Units, $ in Thousands							1 Months Ended	3 Months Ended	109 Months Ended
	Mar. 20, 2024 USD ($) shares	Mar. 18, 2024 shares	Dec. 11, 2023 USD ($) $ / shares shares	Sep. 08, 2023	Jun. 26, 2023 USD ($) shares	Jun. 22, 2023 $ / shares shares	Apr. 30, 2023	Mar. 31, 2024 USD ($) segment $ / shares shares	Mar. 31, 2024 USD ($) $ / shares	Dec. 31, 2023 USD ($) $ / shares
Company and Basis of Presentation [Line Items]
Number of operating segments | segment								1
Employee workforce, termination percentage							83.00%
Common stock, par value (in dollars per share) | $ / shares								$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, par value (in dollars per share) | $ / shares								$ 0.0001	$ 0.0001	$ 0.0001
Series B non-voting convertible preferred stock, par value (in dollars per share) | $ / shares			$ 0.0001
Proceeds from raising capital									$ 1,100,000
Accumulated deficit								$ 808,271	808,271	$ 764,414
Cash, cash equivalents, and marketable securities								$ 485,000	$ 485,000
Asset Acquisition
Company and Basis of Presentation [Line Items]
Fixed exchange ratio						54.94488%
Spyre Therapeutics, Inc.
Company and Basis of Presentation [Line Items]
Asset acquisition, stockholder payment period						3 years
Asset acquisition, cash payment, threshold period						1 year
Spyre 2023 Equity Incentive Plan | Asset Acquisition
Company and Basis of Presentation [Line Items]
Number of outstanding and unexercised stock options to purchase (in shares) | shares						2,734
Series A Non Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares								$ 0.0001	$ 0.0001	$ 0.0001
Conversion basis						40
Issuance of Series B non-voting convertible preferred stock in connection with private placement, net of financing costs (in shares) | shares					721,452
Series A Non Voting Convertible Preferred Stock | Asset Acquisition
Company and Basis of Presentation [Line Items]
Number of shares transferred as equity interest in asset acquisition (in shares) | shares						364,887
Preferred stock, par value (in dollars per share) | $ / shares						$ 0.0001
Conversion basis						40
Series B Non Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Conversion basis			40
Series B non-voting convertible preferred stock, par value (in dollars per share) | $ / shares								$ 0.0001	$ 0.0001	$ 0.0001
Issuance of Series B non-voting convertible preferred stock in connection with private placement, net of financing costs (in shares) | shares	121,625	271,625	150,000					122,000
Private Placement
Company and Basis of Presentation [Line Items]
Gross proceeds received in private placement			$ 180,000
Placement agent and other offering costs	$ 11,200		10,900
Private Placement | Series A Non Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Number of shares sold in private placement | shares					721,452
Gross proceeds received in private placement					$ 210,000
Placement agent and other offering expenses in private placement					$ 12,700
Private Placement | Series B Non Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Gross proceeds received in private placement	$ 180,000		$ 90,000
Common Stock
Company and Basis of Presentation [Line Items]
Reverse stock split, conversion ratio				0.04
Common Stock | Asset Acquisition
Company and Basis of Presentation [Line Items]
Number of shares transferred as equity interest in asset acquisition (in shares) | shares						517,809
Common stock, par value (in dollars per share) | $ / shares						$ 0.0001
Common Stock | Private Placement
Company and Basis of Presentation [Line Items]
Number of shares of common stock sold (in shares) | shares			6,000,000