Note 12 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Net revenues	$ 14,632			$ 20,160			$ 47,046	$ 60,128
Earnings (loss) before income tax expense (benefit)	794			162			1,956	5,540
Net earnings	647	$ (187)	$ 1,138	(566)	$ 4,014	$ 381	1,598	3,829
Corporate, Non-Segment [Member]
Earnings (loss) before income tax expense (benefit)	(177)			(447)			(1,617)	(1,055)
Net earnings	(143)			(352)			(1,321)	(867)
Thermal Testing Products [Member] | Operating Segments [Member]
Net revenues	10,622			14,616			33,775	41,849
Earnings (loss) before income tax expense (benefit)	496			(684)			1,949	1,816
Net earnings	403			(1,192)			1,592	768
EMS [Member] | Operating Segments [Member]
Net revenues	4,010			5,544			13,271	18,279
Earnings (loss) before income tax expense (benefit)	475			1,293			1,624	4,779
Net earnings	$ 387			$ 978			$ 1,327	$ 3,928