Note 10 - Shareholders' Equity - Information about Stock Options (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 1.51
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 3.45
Options Outstanding Options (in shares) | shares	1,065,000
Options Outstanding Weighted Average Exercise Price (in dollars per share)	$ 2.06
Options Outstanding Weighted Average Remaining Contract Life (Year)	4 years 73 days
Options Outstanding Aggregate Intrinsic Value | $	$ 1,530,000
Options Exercisable Options (in shares) | shares	130,000
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 1.53
Options Exercisable Weighted Average Remaining Contract Life (Year)	2 years 146 days
Options Exercisable Aggregate Intrinsic Value | $	$ 256,000