Note 15 - Segment Information - Identifiable Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Identifiable Assets	$ 102,934	$ 103,905
Corporate, Non-Segment [Member]
Identifiable Assets	7,142	10,123
Electronic Test [Member]
Identifiable Assets	28,319	26,251
Environmental Technologies [Member]
Identifiable Assets	15,736	15,411
Process Technologies [Member]
Identifiable Assets	$ 51,737	$ 52,120