Note 11 - Stock Options - Summary of the Status of Non-vested Shares (Details) - $ / shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Balance, non-vested (in shares)	1,659,834
Balance, non-vested, weighted average grant date fair value (in dollars per share)	$ 0.58
Granted, non-vested (in shares)	2,171,600	1,565,000
Granted, weighted average grant date fair value (in dollars per share)	$ 0.18	$ 0.33
Vested, non-vested (in shares)	(1,651,333)
Vested, weighted average grant date fair value (in dollars per share)	$ 0.45
Forfeited, non-vested (in shares)	(70,001)
Forfeited, weighted average grant date fair value (in dollars per share)	$ 0.35
Balance, non-vested (in shares)	2,110,100
Balance, non-vested, weighted average grant date fair value (in dollars per share)	$ 0.26