Segment, Customer Concentration and Geographical Information - Company Revenue in Different Geographic Locations (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Revenue from External Customer [Line Items]
Total revenues	$ 12,416	$ 12,629	$ 12,933	$ 13,322	$ 12,278	$ 11,782	$ 10,854	$ 8,432	$ 51,300	$ 43,346
Americas [Member] | Reportable Geographical Components [Member]
Revenue from External Customer [Line Items]
Total revenues									49,349	43,236
EMEA [Member] | Reportable Geographical Components [Member]
Revenue from External Customer [Line Items]
Total revenues									1,930	67
Asia Pacific [Member] | Reportable Geographical Components [Member]
Revenue from External Customer [Line Items]
Total revenues									$ 21	$ 43