Note 12 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net revenues	$ 15,888	$ 10,485	$ 30,068	$ 19,132
Earnings before income tax expense	2,336	749	5,508	873
Net earnings	1,445	486	3,523	567
Corporate, Non-Segment [Member]
Earnings before income tax expense	(1,177)	(693)	(1,549)	(793)
Net earnings	(728)	(450)	(972)	(515)
Thermal Products [Member] | Operating Segments [Member]
Net revenues	9,194	5,594	16,970	10,788
Earnings before income tax expense	1,350	734	3,196	1,307
Net earnings	835	476	2,045	849
EMS [Member] | Operating Segments [Member]
Net revenues	6,694	4,891	13,098	8,344
Earnings before income tax expense	2,163	708	3,861	359
Net earnings	$ 1,338	$ 460	$ 2,450	$ 233