Note 12 - Segment and Enterprise-wide Disclosures - Net Sales to Unaffiliated Customers by Geography (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net sales	$ 39,503	$ 38,368	$ 40,670	$ 35,883	$ 37,548	$ 36,416	$ 24,851	$ 30,551	$ 154,424	$ 129,366	$ 117,232
UNITED STATES
Net sales									93,866	75,222	63,130
GERMANY
Net sales									12,968	12,365	12,400
Other Countries [Member]
Net sales									$ 47,590	$ 41,779	$ 41,702