Note 2 - Summary of Significant Accounting Policies - Accounts Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Balance, beginning of year	$ 260	$ 146
Provision	(56)	120
Recoveries/write-offs	(185)	(6)
Balance, end of year	$ 19	$ 260