Segment Reporting - Long-Lived Assets Consisting of Property and Equipment, Net by Geographic Regions (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Long-lived assets	$ 18,719	$ 10,704
United States
Segment Reporting Information [Line Items]
Long-lived assets	17,925	9,888
Europe
Segment Reporting Information [Line Items]
Long-lived assets	525	351
Rest of World
Segment Reporting Information [Line Items]
Long-lived assets	$ 269	$ 465

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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