Note 17 - Employee Benefit Plans - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance outstanding, weighted average exercise price (in dollars per share)	$ 5.14	$ 15.74	$ 19.95
Granted, weighted average exercise price (in dollars per share)
Exercised, weighted average exercise price (in dollars per share)	5.12	7.07	5.19
Forfeited, weighted average exercise price (in dollars per share)		28.71	29.48
Balance outstanding, weighted average exercise price (in dollars per share)		$ 5.14	$ 15.74
Options exercisable, weighted average exercise price (in dollars per share)
Incentive Stock Options [Member]
Balance outstanding (in shares)	12,500	46,000	60,000
Granted (in shares)
Exercised (in shares)	(12,500)	(13,500)	(3,000)
Forfeited (in shares)		(20,000)	(11,000)
Balance outstanding (in shares)		12,500	46,000
Options exercisable (in shares)
Non-Incentive Stock Options [Member]
Balance outstanding (in shares)	5,000	25,000	50,000
Granted (in shares)
Exercised (in shares)	(5,000)	(10,000)
Forfeited (in shares)		(10,000)	(25,000)
Balance outstanding (in shares)		5,000	25,000
Options exercisable (in shares)