Segment Information - Schedule of Reportable Business Segment (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues from Operations
Revenues from operations	$ 7,501,000	$ 8,071,000	$ 20,919,000	$ 23,748,000
Operating (Loss) Income
Total operating (loss) income	(746,000)	709,000	(190,000)	1,553,000
Interest expense, net	(3,000)	(3,000)	(9,000)	(7,000)
Gain (loss) on equity investment in unconsolidated subsidiary	60,205,000	(61,000)	59,453,000	(200,000)
Unrealized (loss) gain on marketable securities	(18,867,000)	122,000	(18,665,000)	15,000
Other income (expense), net	240,000	33,000	280,000	(12,000)
Total other income (expense)	41,575,000	91,000	41,059,000	(204,000)
INCOME BEFORE INCOME TAXES	40,829,000	800,000	40,869,000	1,349,000
Unallocated corporate expense [Member]
Operating (Loss) Income
Total operating (loss) income	(1,632,000)	(314,000)	(2,377,000)	(729,000)
Electronic components [Member]
Revenues from Operations
Revenues from operations	7,173,000	7,860,000	19,834,000	22,905,000
Electronic components [Member] | Reportable Segment [Member]
Operating (Loss) Income
Total operating (loss) income	854,000	1,064,000	2,037,000	2,249,000
Electronic instruments [Member]
Revenues from Operations
Revenues from operations	328,000	211,000	1,085,000	843,000
Electronic instruments [Member] | Reportable Segment [Member]
Operating (Loss) Income
Total operating (loss) income	$ 32,000	$ (41,000)	$ 150,000	$ 33,000