Note 16 - Stock Based Compensation - Roll-forward of Non-vested Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Nonvested, beginning year, number of shares (in shares)	1,962,163	1,659,102
Nonvested, beginning of year, Weighted-Average Grant Date Fair Value (in dollars per share)	$ 2.83
Granted, number of shares (in shares)	1,356,500	1,106,800	916,000
Granted, Weighted-Average Grant Date Fair Value (in dollars per share)	$ 2.15	$ 2.85	$ 3.75
Vested, number of shares (in shares)	(842,898)
Vested, Weighted-Average Grant Date Fair Value (in dollars per share)	$ 2.83
Forfeited, number of shares (in shares)	(108,250)
Forfeited, Weighted-Average Grant Date Fair Value (in dollars per share)	$ 2.83
Nonvested, end of year, number of shares (in shares)	2,367,515	1,962,163	1,659,102
Nonvested, end of year, Weighted-Average Grant Date Fair Value (in dollars per share)	$ 2.58	$ 2.83