The Company and Basis of Presentation (Details) $ / shares in Units, $ in Thousands												1 Months Ended		3 Months Ended			12 Months Ended			130 Months Ended
	Oct. 15, 2025 USD ($) $ / shares shares	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 USD ($) $ / shares shares	Sep. 08, 2023	Jun. 26, 2023 USD ($) $ / shares shares	Jun. 22, 2023 $ / shares shares	Feb. 12, 2026 USD ($) $ / shares shares	Jun. 30, 2023 shares	Dec. 31, 2025 USD ($) $ / shares shares	Dec. 31, 2023 shares	Jun. 30, 2023	Dec. 31, 2025 USD ($) segment $ / shares shares	Dec. 31, 2024 USD ($) $ / shares shares	Dec. 31, 2023 shares	Dec. 31, 2025 USD ($) $ / shares shares	Feb. 28, 2025 USD ($)	Sep. 06, 2024 USD ($)	Apr. 25, 2024 shares	Dec. 08, 2023	Dec. 31, 2022 shares
Company and Basis of Presentation [Line Items]
Number of operating segments | segment																	1
Employee workforce, termination percentage																83.00%
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)								150,000
Proceeds from raising capital | $																				$ 1,600,000
Accumulated deficit | $														$ 1,127,635			$ 1,127,635	$ 972,432		1,127,635
Cash, cash equivalents, and marketable securities | $														$ 756,500			$ 756,500			$ 756,500
Private Placement
Company and Basis of Presentation [Line Items]
Sale of stock (in shares)										721,452			721,452
Public offering price (in dollars per share) | $ / shares										$ 291.08
Aggregate purchase price for stock sold | $								$ 84,600		$ 197,300
Offering costs | $						$ 11,200		$ 5,400		$ 12,700
At-The-Market Offering
Company and Basis of Presentation [Line Items]
Sale of stock, authorized amount | $																						$ 500,000
Series A Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Convertible preferred stock, par value (in dollars per share) | $ / shares														$ 0.0001			$ 0.0001	$ 0.0001		$ 0.0001
Conversion basis											40
Preferred stock, outstanding (in shares)														346,045	437,037		346,045	346,045	437,037	346,045			346,045
Series B Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Convertible preferred stock, par value (in dollars per share) | $ / shares														$ 0.0001			$ 0.0001	$ 0.0001		$ 0.0001
Conversion basis						40		40																40
Series B non-voting convertible preferred stock, par value (in dollars per share) | $ / shares								$ 0.0001
Issuance of Series B non-voting convertible preferred stock in connection with private placement, net of financing costs (in shares)						121,625	271,625	150,000
Preferred stock, outstanding (in shares)														16,667			16,667	16,667		16,667
Preferred stock, not automatically converted, outstanding (in shares)														16,667			16,667			16,667
Series B Non-Voting Convertible Preferred Stock | Private Placement
Company and Basis of Presentation [Line Items]
Public offering price (in dollars per share) | $ / shares						$ 1,480		$ 600
Aggregate purchase price for stock sold | $						$ 168,900		$ 169,100
Offering costs | $						$ 11,200		$ 10,900
Issuance of Series B non-voting convertible preferred stock in connection with private placement, net of financing costs (in shares)						121,625	271,625	150,000
Common Stock
Company and Basis of Presentation [Line Items]
Exchange of Series A non-voting convertible preferred stock for common stock (in shares)					3,639,680
Common Stock | At-The-Market Offering
Company and Basis of Presentation [Line Items]
Sale of stock (in shares)														445,668			445,668	777,432
Public offering price (in dollars per share) | $ / shares														$ 33.772			$ 33.772	$ 26.935		$ 33.772
Aggregate purchase price for stock sold | $														$ 14,800			$ 14,800	$ 20,500
Offering costs | $														300			300	$ 400
Sale of stock, authorized amount | $																					$ 500,000
Sale of stock, aggregate offering price | $																					$ 179,100	$ 200,000
Sale of stock, remaining authorized amount available for sale | $														$ 164,100			$ 164,100			$ 164,100
Common Stock | At-The-Market Offering | Subsequent Event
Company and Basis of Presentation [Line Items]
Sale of stock (in shares)												296,396
Public offering price (in dollars per share) | $ / shares												$ 33.566
Aggregate purchase price for stock sold | $												$ 9,700
Offering costs | $												200
Sale of stock, remaining authorized amount available for sale | $												$ 154,100
Common Stock | November 2024 Underwritten Offering
Company and Basis of Presentation [Line Items]
Sale of stock (in shares)			8,366,250
Public offering price (in dollars per share) | $ / shares			$ 27.50
Aggregate purchase price for stock sold | $			$ 215,900
Offering costs | $			$ 14,200
Common Stock | Over-Allotment Option
Company and Basis of Presentation [Line Items]
Sale of stock (in shares)	2,229,729	1,091,250
Common Stock | October 2025 Underwritten Offering
Company and Basis of Presentation [Line Items]
Sale of stock (in shares)	17,094,594
Public offering price (in dollars per share) | $ / shares	$ 18.50
Aggregate purchase price for stock sold | $	$ 296,400
Offering costs | $	$ 19,900
Common Stock
Company and Basis of Presentation [Line Items]
Reverse stock split, conversion ratio									0.04
Conversion of non-voting convertible preferred stock into common stock (in shares)																		10,198,000
Exchange of Series A non-voting convertible preferred stock for common stock (in shares)																		3,640,000
Common Stock | Conversion of Series A Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Conversion of non-voting convertible preferred stock into common stock (in shares)															25,972,080
Common Stock | Conversion of Series B Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Conversion of non-voting convertible preferred stock into common stock (in shares)				10,198,320														10,198,320
Common Stock | Series A Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Conversion of non-voting convertible preferred stock into common stock (in shares)																			25,972,000
Common Stock | Series B Non-Voting Convertible Preferred Stock | Private Placement
Company and Basis of Presentation [Line Items]
Sale of stock (in shares)								6,000,000
Public offering price (in dollars per share) | $ / shares								$ 15.00
Preferred Stock | Series A Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Conversion of non-voting convertible preferred stock into common stock (in shares)																			(649,000)
Exchange of Series A non-voting convertible preferred stock for common stock (in shares)																		(91,000)
Preferred stock, outstanding (in shares)														346,000	437,000		346,000	346,000	437,000	346,000					0
Preferred Stock | Series A Non-Voting Convertible Preferred Stock | Conversion of Series A Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Conversion of non-voting convertible preferred stock into common stock (in shares)					90,992										649,302
Preferred Stock | Series B Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Issuance of Series B non-voting convertible preferred stock in connection with private placement, net of financing costs (in shares)																		122,000	150,000
Conversion of non-voting convertible preferred stock into common stock (in shares)																		(255,000)
Preferred stock, outstanding (in shares)														17,000	0		17,000	17,000	0	17,000					0
Preferred Stock | Series B Non-Voting Convertible Preferred Stock | Conversion of Series B Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Conversion of non-voting convertible preferred stock into common stock (in shares)				254,958														254,958
Spyre Therapeutics, Inc.
Company and Basis of Presentation [Line Items]
Fixed exchange ratio											0.5494488
Asset acquisition, cash payment, threshold period											1 year
Spyre Therapeutics, Inc. | Spyre 2023 Equity Incentive Plan
Company and Basis of Presentation [Line Items]
Number of outstanding and unexercised stock options to purchase (in shares)											2,734
Spyre Therapeutics, Inc. | Series A Non-Voting Convertible Preferred Stock
Company and Basis of Presentation [Line Items]
Shares transferred as equity interest in asset acquisition (in shares)											364,887
Convertible preferred stock, par value (in dollars per share) | $ / shares											$ 0.0001
Conversion basis											40
Spyre Therapeutics, Inc. | Common Stock
Company and Basis of Presentation [Line Items]
Shares transferred as equity interest in asset acquisition (in shares)											517,809