Note 13 - Employee Benefit Plans - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Balance outstanding (in dollars per share)	$ 19.58	$ 18.23	$ 16.54
Granted (in dollars per share)
Exercised (in dollars per share)	5.20	5.22	5.33
Forfeited (in dollars per share)	$ 28.28	25.19	19.03
Balance outstanding (in shares)	112,500
Balance outstanding (in dollars per share)	$ 20.15	$ 19.58	$ 18.23
Options exercisable as of December 31, 2016 (in dollars per share)	$ 20.15
Incentive Stock Options [Member]
Balance outstanding (in shares)	91,500	140,300	168,100
Granted (in shares)
Exercised (in shares)	(11,500)	(10,800)	(25,100)
Forfeited (in shares)	(20,000)	(38,000)	(2,700)
Balance outstanding (in shares)	60,000	91,500	140,300
Options exercisable as of December 31, 2016 (in shares)	60,000
Non Incentive Stock Options [Member]
Balance outstanding (in shares)	57,500	82,500	121,000
Granted (in shares)
Exercised (in shares)	(5,000)	(25,000)	(14,500)
Forfeited (in shares)			(24,000)
Balance outstanding (in shares)	52,500	57,500	82,500
Options exercisable as of December 31, 2016 (in shares)	52,500