Note 1 - General and Basis of Presentation - Changes in the Allowance for Expected Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Beginning balance of the allowance for expected credit losses			$ 597
Ending balance of the allowance for expected credit losses	$ 253		253
Accounting Standards Update 2016-13 [Member]
Beginning balance of the allowance for expected credit losses	419	$ 779	597	$ 755
Change in the provision for expected credit losses for the period	(166)	0	(344)	24
Ending balance of the allowance for expected credit losses	$ 253	$ 779	$ 253	$ 779