Domestic and Foreign Revenues - Significant Foreign Revenues from Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Entity Wide Revenue Major Customer [Line Items]
Revenues from operations	$ 6,882	$ 7,059	$ 13,418	$ 15,677
Malaysia [Member]
Entity Wide Revenue Major Customer [Line Items]
Revenues from operations	433	563	1,042	1,581
Hong Kong [Member]
Entity Wide Revenue Major Customer [Line Items]
Revenues from operations	166	365	355	611
Germany [Member]
Entity Wide Revenue Major Customer [Line Items]
Revenues from operations	204	103	286	293
Australia [Member]
Entity Wide Revenue Major Customer [Line Items]
Revenues from operations	189	332	189	493
All other foreign countries [Member]
Entity Wide Revenue Major Customer [Line Items]
Revenues from operations	405	644	873	1,115
Foreign [Member]
Entity Wide Revenue Major Customer [Line Items]
Revenues from operations	1,397	2,007	2,745	4,093
Domestic [Member]
Entity Wide Revenue Major Customer [Line Items]
Revenues from operations	$ 5,485	$ 5,052	$ 10,673	$ 11,584