Note 11 - Stock-based Compensation - Non-Vested Restricted Stock (Details) - Restricted Stock [Member]	3 Months Ended
	Mar. 31, 2020 $ / shares shares
Non-vested (in shares) | shares	1,308,613
Non-vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.91
Granted (in shares) | shares	110,595
Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.51
Vested (in shares) | shares	(19,153)
Vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.87
Canceled or forfeited (in shares) | shares	(6,974)
Canceled or forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.90
Non-vested (in shares) | shares	1,393,081
Non-vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.83