Note 3 - Segment Information - Schedule of Other Segment Disclosures (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024
Interest revenue (a)	[1]	$ 417	$ 499
Amortization (b)	[2]	6	5
Stock-based compensation (c)	[3]	9	9
Capital expenditures		0	0
Corporate Segment [Member]
Interest revenue (a)	[1]	170	210
Amortization (b)	[2]	0	0
Stock-based compensation (c)	[3]	9	9
Capital expenditures		0	0
Operating Segments [Member]
Interest revenue (a)	[1]	417	499
Amortization (b)	[2]	6	5
Stock-based compensation (c)	[3]	9	9
Capital expenditures		0	0
Operating Segments [Member] | Electronic Instruments [Member]
Interest revenue (a)	[1]	0	0
Amortization (b)	[2]	6	5
Stock-based compensation (c)	[3]	0	0
Capital expenditures		0	0
Operating Segments [Member] | Merchant Investment [Member]
Interest revenue (a)	[1]	247	289
Amortization (b)	[2]	0	0
Stock-based compensation (c)	[3]	0	0
Capital expenditures		0	0
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment [Member]
Interest revenue (a)	[1]	0	0
Amortization (b)	[2]	0	0
Stock-based compensation (c)	[3]	0	0
Capital expenditures		$ 0	$ 0

[1] Interest revenue is included in Net investment income on the Consolidated Statements of Operations.

[2] Depreciation and Amortization are included within the other segment expense captions, such as Manufacturing cost of sales, Engineering, or Other segment items.

[3] Stock-based compensation is included within the Compensation expense caption.