Other Balance Sheet Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued compensation	$ 6,372	$ 6,888	$ 2,044
Liability for early exercise of unvested stock options	808	1,133	1,658
Accrued purchase consideration for acquisition		0	975
Taxes payable	597	516	376
Deferred revenue	4,568	2,585	652
Other accrued and current liabilities	8,615	3,876	2,417
Accrued expenses and other current liabilities	$ 20,960	$ 14,998	$ 8,122

Deferred Compensation Share-Based Arrangements, Liability, Unvested Stock Options, Current

No definition available.

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- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled within one year or the normal operating cycle, if longer.

+ References

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-Publisher FASB
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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Total of the carrying values as of the balance sheet date of obligations incurred through that date and payable for obligations related to services received from employees, such as accrued salaries and bonuses, payroll taxes and fringe benefits. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.

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- Definition

Carrying value as of the balance sheet date of obligations incurred and payable for statutory income, sales, use, payroll, excise, real, property and other taxes. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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