Note 16 - Employee Benefit Plans - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance outstanding, weighted average exercise price (in dollars per share)	$ 15.74	$ 19.95	$ 19.58
Granted, weighted average exercise price (in dollars per share)
Exercised, weighted average exercise price (in dollars per share)	7.07	5.19	5.20
Forfeited, weighted average exercise price (in dollars per share)	$ 28.71	29.48	28.34
Balance outstanding (in shares)	17,500
Balance outstanding, weighted average exercise price (in dollars per share)	$ 5.14	$ 15.74	$ 19.95
Options exercisable, weighted average exercise price (in dollars per share)	$ 5.14
Incentive Stock Options [Member]
Balance outstanding (in shares)	46,000	60,000	91,500
Granted (in shares)
Exercised (in shares)	(13,500)	(3,000)	(11,500)
Forfeited (in shares)	(20,000)	(11,000)	(20,000)
Balance outstanding (in shares)	12,500	46,000	60,000
Options exercisable (in shares)	12,500
Non-Incentive Stock Options [Member]
Balance outstanding (in shares)	25,000	50,000	57,500
Granted (in shares)
Exercised (in shares)	(10,000)		(5,000)
Forfeited (in shares)	(10,000)	(25,000)	(2,500)
Balance outstanding (in shares)	5,000	25,000	50,000
Options exercisable (in shares)	5,000