Note 3 - Segment Information - Schedule of Other Segment Disclosures (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2025		Dec. 31, 2024
Interest revenue (a)		$ 410	$ 442	$ 428	$ 417	$ 503	$ 531	$ 538	$ 499	$ 1,697	[1]	$ 2,071	[1]
Amortization (b)	[2]									21		21
Stock-based compensation (c)	[3]									61		36
Total assets		46,776				43,145				46,776		43,145
Capital expenditures										0		0
Corporate Segment [Member]
Interest revenue (a)	[1]									655		843
Amortization (b)	[2]									0		0
Stock-based compensation (c)	[3]									61		36
Total assets		19,771				17,148				19,771		17,148
Capital expenditures										0		0
Operating Segments [Member]
Interest revenue (a)	[1]									1,697		2,071
Amortization (b)	[2]									21		21
Stock-based compensation (c)	[3]									61		36
Total assets		46,776				43,145				46,776		43,145
Capital expenditures										0		0
Operating Segments [Member] | Electronic Instruments [Member]
Interest revenue (a)	[1]									0		0
Amortization (b)	[2]									21		21
Stock-based compensation (c)	[3]									0		0
Total assets		1,237				1,249				1,237		1,249
Capital expenditures										0		0
Operating Segments [Member] | Merchant Investment [Member]
Interest revenue (a)	[1]									1,042		1,228
Amortization (b)	[2]									0		0
Stock-based compensation (c)	[3]									0		0
Total assets		25,768				24,748				25,768		24,748
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
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] Amortization is 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.