Note 5 - Supplemental Balance Sheet Information - Composition of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cost	$ 20,039	$ 19,892
Accumulated Amortization	10,830	10,171
Net	9,209	9,721
Trademarks [Member]
Cost	3,410	3,403
Accumulated Amortization	0	0
Net	3,410	3,403
Customer Relationships [Member]
Cost	9,171	9,080
Accumulated Amortization	5,115	4,721
Net	4,056	4,359
Patented Technology [Member]
Cost	5,557	5,521
Accumulated Amortization	5,014	4,869
Net	543	652
Distributor Relationships [Member]
Cost	377	377
Accumulated Amortization	377	377
Net	0	0
Trade Names [Member]
Cost	1,524	1,511
Accumulated Amortization	324	204
Net	$ 1,200	$ 1,307