Segment and Geographic Information - Summary of Revenue by Geographic Area on the Customers' Location (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Entity Wide Revenue Major Customer [Line Items]
Total revenue	$ 22,237	$ 10,390	$ 6,399
Reportable Geographical Components | United States
Entity Wide Revenue Major Customer [Line Items]
Total revenue	1,106	5,332	$ 6,399
Reportable Geographical Components | Japan
Entity Wide Revenue Major Customer [Line Items]
Total revenue	10,375
Reportable Geographical Components | Netherlands
Entity Wide Revenue Major Customer [Line Items]
Total revenue	5,486
Reportable Geographical Components | Italy
Entity Wide Revenue Major Customer [Line Items]
Total revenue	5,088
Reportable Geographical Components | Korea
Entity Wide Revenue Major Customer [Line Items]
Total revenue	$ 182	4,988
Reportable Geographical Components | Rest of World
Entity Wide Revenue Major Customer [Line Items]
Total revenue		$ 70