Note 7 - Stock-based Compensation (Details) - Summary of Stock Option Activity (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Common stock:
Options outstanding - beginning of period	274,746	1,316,068	1,002,350
Options outstanding - beginning of period	$ 1.99	$ 5.98	$ 7.50
Options granted	0	0	359,568
Options granted	$ 0	$ 0	$ 1.99
Options exercised	0	(119,822)
Options exercised	$ 0	$ 2.34
Options forfeited	0		(8,700)
Options forfeited	$ 0		$ 5.32
Options expired	0	(921,500)	(37,150)
Options expired	$ 0	$ 7.64	$ 8.72
Options outstanding - end of period	274,746	274,746	1,316,068
Options outstanding - end of period	$ 1.99	$ 1.99	$ 5.98
Options exercisable at end of period	137,376	68,688	956,500
Options exercisable at end of period	$ 1.99	$ 1.99	$ 7.48