Note 6 - Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Net Carrying Amount	$ 20,905	$ 21,634
Finite-lived, Gross Carrying Amount	21,044	21,015
Finite-lived, Accumulated Amortization	8,589	7,809
Net Carrying Amount, finite-lived	12,455	13,206
Indefinite-lived, Gross Carrying Amount	8,450	8,428
Net Carrying Amount, indefinite-lived	8,450	8,428
Intangible Assets, Gross Carrying Amount	29,494	29,443
Net Carrying Amount	20,905	21,634
Trademarks [Member]
Indefinite-lived, Gross Carrying Amount	8,450	8,428
Net Carrying Amount, indefinite-lived	8,450	8,428
Customer Relationships [Member]
Finite-lived, Gross Carrying Amount	16,566	16,544
Finite-lived, Accumulated Amortization	6,634	6,160
Net Carrying Amount, finite-lived	9,932	10,384
Patented Technology [Member]
Finite-lived, Gross Carrying Amount	2,971	2,950
Finite-lived, Accumulated Amortization	682	569
Net Carrying Amount, finite-lived	2,289	2,381
Patents [Member]
Finite-lived, Gross Carrying Amount	590	590
Finite-lived, Accumulated Amortization	587	585
Net Carrying Amount, finite-lived	3	5
Customer Backlog [Member]
Finite-lived, Gross Carrying Amount	507	521
Finite-lived, Accumulated Amortization	276	85
Net Carrying Amount, finite-lived	231	436
Computer Software, Intangible Asset [Member]
Finite-lived, Gross Carrying Amount	270	270
Finite-lived, Accumulated Amortization	270	270
Net Carrying Amount, finite-lived	0	0
Trade Names [Member]
Finite-lived, Gross Carrying Amount	140	140
Finite-lived, Accumulated Amortization	140	140
Net Carrying Amount, finite-lived	0	0
Environmental Technologies [Member]
Net Carrying Amount	878	893
Net Carrying Amount	878	893
Process Technologies [Member]
Net Carrying Amount	15,054	15,667
Net Carrying Amount	15,054	15,667
Acculogic [Member] | Electronic Test [Member]
Net Carrying Amount	4,973	5,074
Net Carrying Amount	4,973	5,074
Sigma [Member] | Environmental Technologies [Member]
Net Carrying Amount	510	510
Net Carrying Amount	510	510
Thermonics [Member] | Environmental Technologies [Member]
Net Carrying Amount	3	5
Net Carrying Amount	3	5
Z-Sciences [Member] | Environmental Technologies [Member]
Net Carrying Amount	365	378
Net Carrying Amount	365	378
Ambrell [Member] | Process Technologies [Member]
Net Carrying Amount	10,375	10,680
Net Carrying Amount	10,375	10,680
Videology [Member] | Process Technologies [Member]
Net Carrying Amount	4,679	4,987
Net Carrying Amount	$ 4,679	$ 4,987