Note 3 - Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024
Net sales		$ (498)	$ (392)
Net investment income		(417)	(499)
Net gains (losses)		3	(3)
Total revenues		918	888
Manufacturing cost of sales		237	204
Engineering		57	39
Commissions		19	19
Sales and marketing		57	33
Accounting		75	156
Compensation		248	188
Corporate allocations (a)	[1]	0	0
Other segment items (b)	[2]	184	170
Engineering, selling and administrative		640	605
Total expenses		877	809
Segment profit (loss)		41	79
Income from operations before income taxes		41	79
Operating Segments [Member] | Electronic Instruments [Member]
Net sales		(498)	(392)
Net investment income		0	0
Net gains (losses)		0	0
Total revenues		498	392
Manufacturing cost of sales		237	204
Engineering		57	39
Commissions		19	19
Sales and marketing		57	33
Accounting		0	0
Compensation		56	58
Corporate allocations (a)	[1]	11	9
Other segment items (b)	[2]	42	28
Engineering, selling and administrative		242	186
Total expenses		479	390
Segment profit (loss)		19	2
Operating Segments [Member] | Merchant Investment [Member]
Net sales		0	0
Net investment income		(247)	(289)
Net gains (losses)		0	0
Total revenues		247	289
Manufacturing cost of sales		0	0
Engineering		0	0
Commissions		0	0
Sales and marketing		0	0
Accounting		0	0
Compensation		0	0
Corporate allocations (a)	[1]	93	49
Other segment items (b)	[2]	1	0
Engineering, selling and administrative		94	49
Total expenses		94	49
Segment profit (loss)		153	240
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Net sales		0	0
Net investment income		(170)	(210)
Net gains (losses)		3	(3)
Total revenues		173	207
Manufacturing cost of sales		0	0
Engineering		0	0
Commissions		0	0
Sales and marketing		0	0
Accounting		75	156
Compensation		192	130
Corporate allocations (a)	[1]	(104)	(58)
Other segment items (b)	[2]	141	142
Engineering, selling and administrative		304	370
Total expenses		304	370
Segment profit (loss)		$ (131)	$ (163)

[1] The Electronic Instruments and Merchant Investment segments are allocated overhead expenses from the Corporate segment based on each segment's assets as a percentage of Total assets.

[2] Other segment items for each reportable segment includes the following: Electronic Instruments - rent, amortization, professional service fees, and certain other overhead expenses. Merchant Investment - legal expense and certain other overhead expenses. Corporate - legal expense, insurance expense, filing fees, fees paid to MtronPTI under Amended and Restated Transitional Administrative and Management Services Agreement, and certain other overhead expenses.