Note 6 - Revenues - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Allowance for doubtful accounts, Balance	$ 265	$ 275
Provision for losses on accounts receivable	(5)	5
Write-offs less recoverieis		(3)
Allowance for doubtful accounts, Balance	$ 260	$ 277