Note 10 - Business Segments - Financial Information by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue	$ 15,496	$ 14,730
Gross profit	8,664	8,104
Package Testing Segment [Member] | Operating Segments [Member]
Revenue	7,436	7,002
Gross profit	4,382	4,031
Permeation Segment [Member] | Operating Segments [Member]
Revenue	5,583	5,283
Gross profit	3,219	2,995
Industrial Analyzers and Other Segment [Member] | Operating Segments [Member]
Revenue	2,477	2,445
Gross profit	$ 1,063	$ 1,078