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Termination fee required to pay.

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Termination fee required to receive.

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Face amount or stated value per share of common stock.

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Amount of increase (decrease) in obligation for operating lease.

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Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The number of positions eliminated during the period as a percentage of total positions eliminated during the period in connection with the restructuring plan(s).

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Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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Subsequent Events - Additional Information (Details) - USD ($)		1 Months Ended		3 Months Ended			9 Months Ended		12 Months Ended
	Nov. 07, 2024	Feb. 29, 2024	Jan. 31, 2024	Sep. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	May 15, 2023
Subsequent Event [Line Items]
Percentage of workforce reduction			95.00%
Lease obligations remaining				$ 0		$ 2,600,000	$ 600,000	$ 7,700,000	$ 9,700,000	$ 6,600,000
Common stock, par value				$ 0.0001			$ 0.0001		$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, par value				$ 0.0001			$ 0.0001		$ 0.0001	$ 0.0001	$ 0.0001
2024 SOW under the DMS Agreement \| Forecast
Subsequent Event [Line Items]
Lease obligations remaining					$ 2,900,000
Subsequent Event
Subsequent Event [Line Items]
Percentage of workforce reduction			95.00%
Personnel-related restructuring charges			$ 10,000,000
Decrease in lease payments		$ 5,700,000
Subsequent Event \| Merger Agreement
Subsequent Event [Line Items]
Merger agreement date	Nov. 07, 2024
Common stock, par value	$ 0.0001
Stock option exercise price per share	92
Subsequent Event \| Kalaris Therapeutics, Inc. \| Merger Agreement
Subsequent Event [Line Items]
Common stock, par value	0.00001
Preferred stock, par value	$ 0.00001
Termination fee required to pay	$ 3,480,000
Termination fee required to receive	$ 10,410,000
Subsequent Event \| Restricted Stock Units
Subsequent Event [Line Items]
Awards vesting period			4 years