Note 12 - Stock Based Compensation - Stock Option Activity (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Expired (in shares)
Expired, weighted average exercise price per share (in dollars per share)
The 2010 Stock Option and Incentive Plan [Member]
Outstanding, shares (in shares)			783,383
Outstanding, weighted average exercise price per share (in dollars per share)			$ 12.14
Granted, shares (in shares)	3,565,000	611,688	3,565,000	611,688
Granted, weighted average exercise price per share (in dollars per share)			$ 1.51
Granted			$ 3,667,300
Forfeited, shares (in shares)
Forfeited, weighted average exercise price per share (in dollars per share)
Outstanding, shares (in shares)	4,348,383		4,348,383
Outstanding, Weighted average exercise price per share (in dollars per share)	$ 3.43		$ 3.43
Outstanding, weighted average contractual life remaining in years (Year)			9 years 197 days
Outstanding, aggreate instrinsic value	$ 3,806,650		$ 3,806,650
Exercisable, shares (in shares)	2,876,409		2,876,409
Exercisable, Weighted average exercise price per share (in dollars per share)	$ 4.14		$ 4.14
Exercisable, weighted average contractual life remaining in years (Year)			9 years 204 days
Exercisable, aggreate instrinsic value	$ 2,841,125		$ 2,841,125
Vested and expected to vest, shares (in shares)	4,348,383		4,348,383
Vested and expected to vest, Weighted average exercise price per share (in dollars per share)	$ 3.43		$ 3.43
Vested and expected to vest, weighted average contractual life remaining in years (Year)			9 years 197 days
Vested and expected to vest, aggreate instrinsic value	$ 3,806,650		$ 3,806,650