Business Segment, Geographic and Major Customer Information - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues from External Customers and Long-Lived Assets
Total revenues	$ 10,179	$ 12,739	$ 31,114	$ 41,035
U.S.
Revenues from External Customers and Long-Lived Assets
Total revenues	8,094	9,928	24,624	32,639
UAE
Revenues from External Customers and Long-Lived Assets
Total revenues	1,319	1,473	3,741	3,781
Other countries
Revenues from External Customers and Long-Lived Assets
Total revenues	$ 766	$ 1,338	$ 2,749	$ 4,615