Fair value measurement and financial instruments - Schedule of Financial Liabilities Measured on Recurring Basis (Details) - Level 3 - Fair Value, Recurring - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Other non-current liabilities:
Preferred stock warrant liabilities	$ 2,535	$ 1,140	$ 822
Total financial liabilities measured and recorded at fair value	$ 39,863	$ 1,140	$ 822

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant