Note 3 - Stock-based Compensation - Stock Option Activity (Details) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Options outstanding (in shares)	1,065,000
Options outstanding, weighted average exercise price (in dollars per share)	$ 2.06
Granted to employees and non-employee directors (in shares)	0	0
Granted to employees and non-employee directors, weighted average exercise price (in dollars per share)
Exercised (in shares)
Exercised, weighted average exercise price (in dollars per share)
Canceled/expired/forfeited (in shares)
Canceled/expired/forfeited, weighted average exercise price (in dollars per share)
Options outstanding (in shares)	1,065,000
Options outstanding, weighted average exercise price (in dollars per share)	$ 2.06
Options exercisable (in shares)	130,000
Options exercisable, weighted average exercise price (in dollars per share)	$ 1.53