Note 5 - Allowance for Doubtful Accounts - Activity in Accounts Receivable Allowance from Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Balance at beginning of period	$ 127	$ 190
Allowance for doubtful accounts	346	(63)
Write-offs	(77)	(36)
Other adjustments	196
Balance at end of period	$ 473	$ 127