Note 10 - Stockholders' Equity - Outstanding and Exercisable Options (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Exercise Price Range 1 [Member]
Exercise price range, lower limit (in dollars per share)	$ 4
Exercise price range, upper limit (in dollars per share)	$ 7
Number of options outstanding (in shares) | shares	45,000
Number of options outstanding, weighted average remaining contractual term (Year)	0 years
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 5
Number of options outstanding, intrinsic value | $	$ 0
Number of options exercisable (in shares) | shares	45,000
Number of options exercisable, weighted average exercise price (in dollars per share)	$ 5
Number of options exercisable, intrinsic value | $	$ 0
Exercise Price Range 2 [Member]
Exercise price range, lower limit (in dollars per share)	$ 7.01
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)	0 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	27,000
Number of options exercisable, weighted average exercise price (in dollars per share)	$ 8.03
Number of options exercisable, intrinsic value | $	$ 0
Exercise Price Range 3 [Member]
Exercise price range, lower limit (in dollars per share)	$ 10.01
Exercise price range, upper limit (in dollars per share)	$ 12
Number of options outstanding (in shares) | shares	220,000
Number of options outstanding, weighted average remaining contractual term (Year)	109 days
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 10.81
Number of options outstanding, intrinsic value | $	$ 0
Number of options exercisable (in shares) | shares	180,000
Number of options 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)	$ 12.01
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)	1 year 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 of options exercisable, weighted average exercise price (in dollars per share)	$ 15
Number of options exercisable, intrinsic value | $	$ 0