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The Company and Basis of Presentation (Details) $ / shares in Units, $ in Thousands |  |  |  |  |  |  |  |  | 3 Months Ended | 12 Months Ended | 121 Months Ended |  |  |  |
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Nov. 29, 2024 shares | Nov. 20, 2024 USD ($) $ / shares shares | May 14, 2024 shares | Apr. 23, 2024 shares | Mar. 20, 2024 USD ($) $ / shares shares | Mar. 18, 2024 shares | Dec. 11, 2023 $ / shares shares | Jun. 22, 2023 $ / shares | Mar. 31, 2025 USD ($) segment $ / shares shares | Mar. 31, 2024 shares | Dec. 31, 2024 USD ($) $ / shares shares | Mar. 31, 2025 USD ($) $ / shares shares | Sep. 06, 2024 USD ($) | Apr. 25, 2024 shares | Apr. 24, 2024 shares | Dec. 31, 2023 shares
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of operating segments | segment |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |
Proceeds from raising capital | $ |  |  |  |  |  |  |  |  |  |  |  | $ 1,300,000 |  |  |  |
Accumulated deficit | $ |  |  |  |  |  |  |  |  | $ (1,017,205) |  | $ (972,432) | (1,017,205) |  |  |  |
Marketable securities | $ |  |  |  |  |  |  |  |  | $ 564,800 |  |  | $ 564,800 |  |  |  |
Conversion Of Series B Non-Voting Convertible Preferred Stock | Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares converted (in shares) |  |  | 10,198,320 |  |  |  |  |  | 10,198,320 |  |  |  |  |  |  |
At-The-Market Offering |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of stock, authorized amount | $ |  |  |  |  |  |  |  |  |  |  |  |  | $ 500,000 |  |  |
Common Stock and Series B Non Voting Convertible Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Series B non-voting convertible 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 |  |  |  |  |  |  |  |  |  |  |
Issuance of non-voting convertible preferred stock (in shares) |  |  |  |  | 121,625 | 271,625 | 150,000 |  |  |  |  |  |  |  |  |
Preferred stock, par value (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  | $ 0.0001 |  | $ 0.0001 | $ 0.0001 |  |  |  |
Preferred stock, outstanding (in shares) |  |  |  |  |  |  |  |  | 16,667 |  | 16,667 | 16,667 |  |  |  |
Preferred stock, not automatically converted, outstanding (in shares) |  |  |  |  |  |  |  |  | 16,667 |  |  | 16,667 |  |  |  |
Series B Non Voting Convertible Preferred Stock | Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of non-voting convertible preferred stock (in shares) |  |  |  |  |  |  |  |  |  | 122,000 |  |  |  |  |  |
Preferred stock, outstanding (in shares) |  |  |  |  |  |  |  |  | 17,000 |  | 17,000 | 17,000 |  |  |  |
Series B Non Voting Convertible Preferred Stock | Conversion Of Series B Non-Voting Convertible Preferred Stock | Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares converted (in shares) |  |  | 254,958 |  |  |  |  |  | 254,958 |  |  |  |  |  |  |
Series B Non Voting Convertible Preferred Stock | Private Placement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of stock, price per share (in dollars per share) | $ / shares |  |  |  |  | $ 1,480 |  |  |  |  |  |  |  |  |  |  |
Sale of stock, proceeds received | $ |  |  |  |  | $ 168,900 |  |  |  |  |  |  |  |  |  |  |
Placement agent and other offering costs | $ |  |  |  |  | $ 11,200 |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |
Exchange of Series A non-voting convertible preferred stock into common stock (in shares) |  |  |  | 90,992 |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, outstanding (in shares) |  |  |  |  |  |  |  |  | 346,045 |  | 346,045 | 346,045 |  | 346,045 | 346,045 |
Series A Non Voting Convertible Preferred Stock | Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, outstanding (in shares) |  |  |  |  |  |  |  |  | 346,000 | 437,000 | 346,000 | 346,000 |  |  |  | 437,000
Series A Non Voting Convertible Preferred Stock | Conversion Of Series A Non-Voting Convertible Preferred Stock | Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares converted (in shares) |  |  |  | 90,992 |  |  |  |  |  |  |  |  |  |  |  |
Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exchange of Series A non-voting convertible preferred stock into common stock (in shares) |  |  |  | 3,639,680 |  |  |  |  |  |  |  |  |  |  |  |
Common Stock | At-The-Market Offering |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of stock, price per share (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 26.935 |  |  |  |  |
Sale of stock, proceeds received | $ |  |  |  |  |  |  |  |  |  |  | $ 20,500 |  |  |  |  |
Placement agent and other offering costs | $ |  |  |  |  |  |  |  |  |  |  | $ 400 |  |  |  |  |
Sale of stock, aggregate offering price | $ |  |  |  |  |  |  |  |  |  |  |  |  | 200,000 |  |  |
Number of shares of common stock sold (in shares) |  |  |  |  |  |  |  |  | 0 |  | 777,432 |  |  |  |  |
Sale of stock, remaining authorized amount | $ |  |  |  |  |  |  |  |  | $ 179,100 |  |  | $ 179,100 |  |  |  |
Common Stock | At-The-Market Offering | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of stock, aggregate offering price | $ |  |  |  |  |  |  |  |  |  |  |  |  | $ 179,100 |  |  |
Common Stock | Underwritten Offering |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of stock, price per share (in dollars per share) | $ / shares |  | $ 27.50 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of stock, proceeds received | $ |  | $ 215,900 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Placement agent and other offering costs | $ |  | $ 14,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares of common stock sold (in shares) |  | 8,366,250 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common Stock | Over-Allotment Option |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company and Basis of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares of common stock sold (in shares) | 1,091,250 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |
Asset Acquisition | 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 |  |  |  |  |  |  |  |

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