| Schedule of Calculation of Numerator and Denominator in Earnings Per Share [Table Text Block] |
Earnings per share is computed as follows: | | | | | | | | | | | | | | Year Ended December 31, | | 2014 | | 2013 | | 2012 | Income available to common shareholders: | | | | | | Net income | $ | 23,169 |
| | $ | 22,853 |
| | $ | 24,595 |
| Weighted-average shares: | |
| | |
| | |
| Basic: | |
| | |
| | |
| Outstanding | 13,337,198 |
| | 13,639,356 |
| | 13,867,771 |
| Partially-paid share subscriptions | 484,025 |
| | 531,325 |
| | 234,595 |
| Basic weighted-average shares | 13,821,223 |
| | 14,170,681 |
| | 14,102,366 |
| Diluted: | |
| | |
| | |
| Basic from above | 13,821,223 |
| | 14,170,681 |
| | 14,102,366 |
| Incremental shares from assumed: | |
| | |
| | |
| Exercise of stock subscription purchase rights | 54,824 |
| | 34,273 |
| | 5,750 |
| Exercise of stock options and awards | 362,229 |
| | 397,478 |
| | 500,741 |
| Diluted weighted-average shares | 14,238,276 |
| | 14,602,432 |
| | 14,608,857 |
| Share data: | |
| | |
| | |
| Earnings per share--basic | $ | 1.68 |
| | $ | 1.61 |
| | $ | 1.74 |
| Earnings per share--diluted | $ | 1.63 |
| | $ | 1.57 |
| | $ | 1.68 |
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