Note 11 - Summary of Outstanding Options by Exercise Price Ranges (Details)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Range 1 [Member]
Exercise price range, lower limit (in dollars per share)	$ 4.27
Exercise price range, upper limit (in dollars per share)	$ 4.41
Options outstanding, option shares (in shares) | shares	23,400
Options outstanding, weighted average exercise price (in dollars per share)	$ 4.39
Options outstanding, weighted average maturity	5 years 3 days
Options exercisable, option shares (in shares) | shares	23,400
Options exercisable, weighted average exercise price (in dollars per share)	$ 4.39
Options exercisable, weighted average maturity	5 years 3 days
Range 2 [Member]
Exercise price range, lower limit (in dollars per share)	$ 4.80
Exercise price range, upper limit (in dollars per share)	$ 4.96
Options outstanding, option shares (in shares) | shares	12,000
Options outstanding, weighted average exercise price (in dollars per share)	$ 4.80
Options outstanding, weighted average maturity	5 years 102 days
Options exercisable, option shares (in shares) | shares	12,000
Options exercisable, weighted average exercise price (in dollars per share)	$ 4.80
Options exercisable, weighted average maturity	5 years 102 days
Range 3 [Member]
Exercise price range, lower limit (in dollars per share)	$ 5.30
Exercise price range, upper limit (in dollars per share)	$ 6.87
Options outstanding, option shares (in shares) | shares	33,000
Options outstanding, weighted average exercise price (in dollars per share)	$ 5.86
Options outstanding, weighted average maturity	6 years 127 days
Options exercisable, option shares (in shares) | shares	33,000
Options exercisable, weighted average exercise price (in dollars per share)	$ 5.86
Options exercisable, weighted average maturity	6 years 127 days
Exercise price range, lower limit (in dollars per share)
Exercise price range, upper limit (in dollars per share)
Options outstanding, option shares (in shares) | shares	68,400
Options outstanding, weighted average exercise price (in dollars per share)	$ 5.17
Options outstanding, weighted average maturity	5 years 255 days
Options exercisable, option shares (in shares) | shares	68,400
Options exercisable, weighted average exercise price (in dollars per share)	$ 5.17
Options exercisable, weighted average maturity	5 years 255 days