Note 15 - Stock Options and Stock-based Employee Compensation - Summary of Stock Option Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Shares Outstanding, Beginning Balance (in shares) | shares	4,417
Weighted Average Exercise Price, Outstanding, at Beginning Period (in dollars per share) | $ / shares	$ 6.73
Shares Granted (in shares) | shares	1,146
Weighted Average Exercise Price, Granted (in dollars per share) | $ / shares	$ 3.33
Shares Forfeited or Expired (in shares) | shares	(246)
Weighted Average Exercise Price, Forfeited or Expired (in dollars per share) | $ / shares	$ 13.58
Shares Outstanding, Ending Balance (in shares) | shares	5,317
Weighted Average Exercise Price, Outstanding, at Ending Period (in dollars per share) | $ / shares	$ 5.87
Weighted Average Remaining Contractual Life, Outstanding (Year)	9 years
Shares Vested and Exercisable (in shares) | shares	1,564
Weighted Average Exercise Price, Vested and Exercisable (in dollars per share) | $ / shares	$ 9.78
Weighted Average Remaining Contractual Life, Vested and Exercisable (Year)	8 years 328 days
Vested and expected to vest (in shares) | shares	5,075
Weighted Average Exercise Price, Vested and Expected to Vest (in dollars per share) | $ / shares	$ 5.85
Weighted Average Remaining Contractual Life, Vested and Expected to Vest (Year)	9 years