Note 14 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Net revenues	$ 21,144			$ 14,443			$ 62,520	$ 38,948
Earnings (loss) before income tax expense (benefit)	2,532			433			8,166	(777)
Net earnings (loss)	2,175	$ 2,609	$ 2,212	458	$ 170	$ (1,143)	6,996	(515)
Corporate, Non-Segment [Member]
Earnings (loss) before income tax expense (benefit)	(611)			(214)			(1,592)	(242)
Net earnings (loss)	(525)			(139)			(1,364)	(161)
Thermal Testing Products [Member] | Operating Segments [Member]
Net revenues	13,042			10,724			36,863	29,534
Earnings (loss) before income tax expense (benefit)	865			478			1,991	39
Net earnings (loss)	743			379			1,706	26
EMS [Member] | Operating Segments [Member]
Net revenues	8,102			3,719			25,657	9,414
Earnings (loss) before income tax expense (benefit)	2,278			169			7,767	(574)
Net earnings (loss)	$ 1,957			$ 218			$ 6,654	$ (380)