Note 9 - Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Beginning of year	$ 421	$ 447	$ 473
Current year positions			(26)
Prior year positions	(123)	(26)
End of year	$ 298	$ 421	$ 447