Note 1 - Summary of Significant Accounting Policies - Summary of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Beginning balance	$ 1,985	$ 1,456	$ 1,345
Provision for losses on accounts receivable	255	507	454
Write-offs and other adjustments	(296)	22	(343)
Ending balance	$ 1,944	$ 1,985	$ 1,456