Note 13 - Segment Reporting - Summary of Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Balance at beginning of period	$ 222	$ 131
Charged to costs and expenses	0	91
Write-offs during period	12	0
Balance at end of period	$ 210	$ 222