Note 8 - Stock Options - Outstanding (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Number of outstanding options (in thousands) (in shares)	[1]	1,229
Number of outstanding options (in thousands) (in shares)		1,172	1,662
Weighted average remaining contractual life (Year)	[1]	3 years 25 days
Weighted average remaining contractual life (Year)		2 years 292 days
Weighted average exercise price per share (in dollars per share)	[1]	$ 0.83
Weighted average exercise price per share (in dollars per share)		$ 0.84	$ 0.68
Intrinsic value (in thousands)	[1]	$ 3,092
Intrinsic value (in thousands)		$ 2,940

[1] Includes effects of expected forfeitures