Note 9 - Stock Options - Outstanding (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Number of outstanding options (in thousands) (in shares)	[1]	1,738
Number of outstanding options (in thousands) (in shares)		1,662	2,079
Weighted average remaining contractual life (Year)	[1]	3 years 3 days
Weighted average remaining contractual life (Year)		2 years 273 days
Weighted average exercise price per share (in dollars per share)	[1]	$ 0.68
Weighted average exercise price per share (in dollars per share)		$ 0.68	$ 0.59
Intrinsic value (in thousands)	[1]	$ 1,178
Intrinsic value (in thousands)		$ 1,123

[1] Includes effects of expected forfeitures