Note 11 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Net revenues	$ 14,352		$ 21,097		$ 32,414	$ 39,968
Earnings (loss) before income tax expense (benefit)	(300)		4,396		1,162	5,378
Net earnings	(187)	$ 1,138	4,014	$ 381	951	4,395
Corporate, Non-Segment [Member]
Earnings (loss) before income tax expense (benefit)	(711)		(390)		(1,440)	(608)
Net earnings	(610)		(346)		(1,178)	(515)
Thermal Testing Products [Member] | Operating Segments [Member]
Net revenues	10,519		13,999		23,153	27,233
Earnings (loss) before income tax expense (benefit)	309		2,592		1,453	2,500
Net earnings	298		2,415		1,189	1,960
EMS [Member] | Operating Segments [Member]
Net revenues	3,833		7,098		9,261	12,735
Earnings (loss) before income tax expense (benefit)	102		2,194		1,149	3,486
Net earnings	$ 125		$ 1,945		$ 940	$ 2,950