Note 3 - Segment Information - Schedule of Other Segment Disclosures (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2024		Dec. 31, 2023
Interest revenue (a)		$ 503	$ 531	$ 538	$ 499	$ 549	$ 544	$ 275	$ 198	$ 2,070	[1]	$ 1,566	[1]
Depreciation	[2]									0		1
Amortization (b)	[2]									21		21
Stock-based compensation (c)	[3]									36		3
Total assets		43,145				41,850				43,145		41,850
Capital expenditures										0		0
Corporate Segment [Member]
Interest revenue (a)	[1]									843		697
Depreciation	[2]									0		0
Amortization (b)	[2]									0		0
Stock-based compensation (c)	[3]									36		3
Total assets		17,148				17,477				17,148		17,477
Capital expenditures										0		0
Operating Segments [Member]
Interest revenue (a)	[1]									2,070		1,566
Depreciation	[2]									0		1
Amortization (b)	[2]									21		21
Stock-based compensation (c)	[3]									36		3
Total assets		43,145				41,850				43,145		41,850
Capital expenditures										0		0
Operating Segments [Member] | Electronic Instruments [Member]
Interest revenue (a)	[1]									0		0
Depreciation	[2]									0		1
Amortization (b)	[2]									21		21
Stock-based compensation (c)	[3]									0		0
Total assets		1,249				843				1,249		843
Capital expenditures										0		0
Operating Segments [Member] | Merchant Investment [Member]
Interest revenue (a)	[1]									1,227		869
Depreciation	[2]									0		0
Amortization (b)	[2]									0		0
Stock-based compensation (c)	[3]									0		0
Total assets		24,748				23,530				24,748		23,530
Capital expenditures										0		0
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment [Member]
Interest revenue (a)	[1]									0		0
Depreciation	[2]									0		0
Amortization (b)	[2]									0		0
Stock-based compensation (c)	[3]									0		0
Total assets		$ 0				$ 0				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.