Note 1 - Organization and Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Balance at January 1	$ 1,816	$ 1,411
Provision charged to expense	(498)	573
Write-offs / Recoveries	(483)	(168)
Balance at December 31	$ 835	$ 1,816