Amount of expense for research and development. Includes, but is not limited to, cost for computer software product to be sold, leased, or otherwise marketed and writeoff of research and development assets acquired in transaction other than business combination or joint venture formation or both. Excludes write-down of intangible asset acquired in business combination or from joint venture formation or both, used in research and development activity.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

License and Collaboration Agreements - Foresight Diagnostics (Details) - USD ($) $ in Thousands			3 Months Ended		6 Months Ended
	Feb. 19, 2025	Jan. 03, 2024	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development			$ 30,721	$ 40,156	$ 62,724	$ 90,356
Accrued and other current liabilities			25,763		25,763		$ 28,244
Foresight Diagnostics Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Committed funding	$ 37,300	$ 26,200
Research and development			900	$ 1,700	3,400	$ 3,200
Foresight Diagnostics Collaboration Agreement \| Balance Sheet Location [Axis]: allo:AccruedAndOtherLiabilitiesCurrent
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Accrued and other current liabilities			$ 900		$ 900		$ 1,400