Consolidated Balance Sheet Components - Prepaid expenses and other current assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Consolidated Balance Sheet Components
Prepaid expenses	$ 3,162	$ 2,707
Loans receivable from equity method investment, current		62
Other current assets	1,986	1,377
Prepaid expenses and other current assets	$ 5,148	$ 4,146

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

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Name:	us-gaap_PrepaidExpenseCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant