Note 5 - Revenues - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Allowance for doubtful accounts, Balance	$ 277	$ 262	$ 275	$ 255
Provision for losses on accounts receivable	9	9	14	18
Write-offs less recoverieis	(15)	(4)	(18)	(6)
Allowance for doubtful accounts, Balance	$ 271	$ 267	$ 271	$ 267