Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
UK R&D tax credit	$ 6,664	$ 4,610
Prepaid insurance premium	4,469	3,154
Prepaid research and development	4,920	2,317
VAT recoverable	1,394	1,171
Deferred offering costs	228	0
Deferred offering costs	1,058	796
Prepaid expenses and other current assets	$ 18,733	$ 12,048

Prepaid Expense, Research And Development, Current

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- Definition

Research And Development Tax Credit, Current

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- References

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- Definition

Specific incremental costs directly attributable to a proposed or actual offering of securities which are deferred at the end of the reporting period.

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Amount of current assets classified as other.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer.

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Amount of asset related to consideration paid in advance for insurance that provides economic benefits within a future period of one year or the normal operating cycle, if longer.

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Carrying amount as of the balance sheet date of value added taxes due either from customers arising from sales on credit terms, or as previously overpaid to tax authorities. For classified balance sheets, represents the current amount receivable, that is amounts expected to be collected within one year or the normal operating cycle, if longer.

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