Business Segment, Geographic, and Concentration Risk Information - Summary of Revenue by Geographical Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Total revenue:
Total consolidated revenue	$ 18,428	$ 13,994	$ 67,829	$ 23,170
United States
Total revenue:
Total consolidated revenue	9,559	8,114	27,405	11,056
Spain
Total revenue:
Total consolidated revenue	5,000		30,000
India
Total revenue:
Total consolidated revenue	259	3,015	1,701	5,275
Austria
Total revenue:
Total consolidated revenue	2,227	964	5,102	2,682
China
Total revenue:
Total consolidated revenue	306	1,038	1,917	2,267
Other Foreign Countries
Total revenue:
Total consolidated revenue	$ 1,077	$ 863	$ 1,704	$ 1,890