Note 19 - Stock-based Compensation - Options Outstanding and Exercisable (Details) - USD ($) |
12 Months Ended | |||
|---|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Number, Options outstanding (in shares) | 185,023 | 290,853 | 447,966 | 591,086 |
| Number, Exercisable options (in shares) | 185,023 | 290,853 | 447,966 | |
| Weighted average exercise price, Options outstanding (in dollars per share) | $ 21.04 | $ 20.88 | $ 20.94 | $ 20.73 |
| Weighted average exercise price, Exercisable options (in dollars per share) | $ 21.03 | $ 20.88 | $ 20.94 | |
| Aggregate intrinsic value, Options outstanding | $ 3,907,758 | $ 2,280,288 | $ 4,640,917 | |
| Aggregate intrinsic value, Exercisable options | $ 3,907,758 | $ 2,280,288 | $ 4,640,917 | |
| Weighted average contractual term, Options outstanding (Year) | 2 years | 2 years 328 days | 2 years 255 days | |
| Weighted average contractual term, Exercisable options (Year) | 2 years | 2 years 328 days | 2 years 255 days | |