Segment and Geographic Information - Summary of Revenue by Geographic Area Based on the Customers' Location (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Entity Wide Revenue Major Customer [Line Items]
Total revenue	$ 87,782	$ 80,962	$ 34,042
United States
Entity Wide Revenue Major Customer [Line Items]
Total revenue	46,236	34,231	11,506
Reportable Geographical Components | United States
Entity Wide Revenue Major Customer [Line Items]
Total revenue	46,236	34,231	11,506
Reportable Geographical Components | France
Entity Wide Revenue Major Customer [Line Items]
Total revenue	12,235	5,812	0
Reportable Geographical Components | Germany
Entity Wide Revenue Major Customer [Line Items]
Total revenue	7,393	13,727	0
Reportable Geographical Components | Rest of World
Entity Wide Revenue Major Customer [Line Items]
Total revenue	$ 21,918	$ 27,192	$ 22,536