Note 5 - Accounts Receivable - Summary of Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Gross accounts receivable	$ 89,565	$ 86,625
Unearned income	(4,103)	(4,033)
Allowance for doubtful accounts	(12,742)	(11,997)	$ (18,490)
Accounts Receivable, after Allowance for Credit Loss, Total	72,720	70,595
Current trade receivables	49,076	46,918
Current unearned interest income	(2,727)	(2,678)
Long-term trade receivables	27,747	27,710
Long-term unearned interest income	$ (1,376)	$ (1,355)