Note 1 - Significant Accounting Policies and Related Matters - Allowance for Doubtful Accounts and Sales Returns (Details) - Allowance for Doubtful Accounts and Sales Returns [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Balance	$ 623	$ 522	$ 399
Additions (recoveries) charged to income	263	293	388
Deductions from reserves	207	192	265
Balance	$ 679	$ 623	$ 522