Note 11 - Stockholders' Equity - Outstanding and Exercisable Options (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Exercise Price Range 1 [Member]
Exercise price range, lower limit (in dollars per share)
Exercise price range, upper limit (in dollars per share)	$ 7
Number of options outstanding (in shares) | shares	15,930
Number of options outstanding, weighted average remaining contractual term (Year)	1 year
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 4.25
Number of options outstanding, intrinsic value | $	$ 0
Number of options exercisable (in shares) | shares	15,930
Number exercisable, weighted average exercise price (in dollars per share)	$ 4.25
Number of options exercisable, intrinsic value | $	$ 0
Exercise Price Range 2 [Member]
Exercise price range, lower limit (in dollars per share)
Exercise price range, upper limit (in dollars per share)	$ 10
Number of options outstanding (in shares) | shares	27,000
Number of options outstanding, weighted average remaining contractual term (Year)	2 years
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 8.03
Number of options outstanding, intrinsic value | $	$ 0
Number of options exercisable (in shares) | shares	7,000
Number exercisable, weighted average exercise price (in dollars per share)	$ 7.90
Number of options exercisable, intrinsic value | $	$ 0
Exercise Price Range 3 [Member]
Exercise price range, lower limit (in dollars per share)
Exercise price range, upper limit (in dollars per share)	$ 12
Number of options outstanding (in shares) | shares	240,000
Number of options outstanding, weighted average remaining contractual term (Year)	7 years 109 days
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 10.88
Number of options outstanding, intrinsic value | $	$ 0
Number of options exercisable (in shares) | shares	110,000
Number exercisable, weighted average exercise price (in dollars per share)	$ 11.05
Number of options exercisable, intrinsic value | $	$ 0
Exercise Price Range 4 [Member]
Exercise price range, lower limit (in dollars per share)
Exercise price range, upper limit (in dollars per share)	$ 15
Number of options outstanding (in shares) | shares	125,000
Number of options outstanding, weighted average remaining contractual term (Year)	3 years 182 days
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 15
Number of options outstanding, intrinsic value | $	$ 0
Number of options exercisable (in shares) | shares	125,000
Number exercisable, weighted average exercise price (in dollars per share)	$ 15
Number of options exercisable, intrinsic value | $	$ 0