Note 3 - Accounts Receivable - Summary of the Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Balance, beginning of period	$ 50	$ 59
Provision for (recoveries of) doubtful accounts	30	16
Write-offs	(16)	(25)
Balance, end of period	$ 64	$ 50