Note 11 - Outstanding and Exercisable Options (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Exercise Price Range 1 [Member]
Exercise price range, lower limit (in dollars per share)	$ 3
Exercise price range, upper limit (in dollars per share)	$ 3.99
Number of options outstanding (in shares) | shares	34,000
Number of options outstanding, weighted average remaining contractual term (Year)	1 year 346 days
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 3.65
Number of options outstanding, intrinsic value | $	$ 171,020
Number of options exercisable (in shares) | shares	34,000
Number exercisable, weighted average exercise price (in dollars per share)	$ 3.65
Number of options exercisable, intrinsic value | $	$ 171,020
Exercise Price Range 2 [Member]
Exercise price range, lower limit (in dollars per share)	$ 4
Exercise price range, upper limit (in dollars per share)	$ 4.49
Number of options outstanding (in shares) | shares	15,930
Number of options outstanding, weighted average remaining contractual term (Year)	4 years 14 days
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 4.25
Number of options outstanding, intrinsic value | $	$ 70,570
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 | $	$ 70,570
Exercise Price Range 3 [Member]
Exercise price range, lower limit (in dollars per share)	$ 5
Exercise price range, upper limit (in dollars per share)	$ 7.99
Number of options outstanding (in shares) | shares	9,800
Number of options outstanding, weighted average remaining contractual term (Year)	5 years 14 days
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 7.90
Number of options outstanding, intrinsic value | $	$ 7,644
Number of options exercisable (in shares) | shares	9,800
Number exercisable, weighted average exercise price (in dollars per share)	$ 7.90
Number of options exercisable, intrinsic value | $	$ 7,644
Exercise Price Range 4 [Member]
Exercise price range, lower limit (in dollars per share)	$ 8
Exercise price range, upper limit (in dollars per share)	$ 12
Number of options outstanding (in shares) | shares	225,000
Number of options outstanding, weighted average remaining contractual term (Year)	6 years 233 days
Number of options outstanding, weighted average exercise price (in dollars per share)	$ 9.43
Number of options outstanding, intrinsic value | $	$ 0
Number of options exercisable (in shares) | shares	65,000
Number exercisable, weighted average exercise price (in dollars per share)	$ 9.43
Number of options exercisable, intrinsic value | $	$ 0