| Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Earnings per share – basic:
| | | | | | | | | | | | | | | | | | Net income | | $ | 48,847 | | | $ | 7,467 | | | $ | 64,710 | | | $ | 26,309 | | | Income allocated to participating securities | | | (41 | ) | | | (7 | ) | | | (50 | ) | | | (22 | ) | | Income available to common shareholders | | $ | 48,806 | | | $ | 7,460 | | | $ | 64,660 | | | $ | 26,287 | | Weighted-average shares outstanding – basic
| | | 37,449 | | | | 37,308 | | | | 37,412 | | | | 37,294 | | Earnings per share – basic
| | $ | 1.30 | | | $ | 0.20 | | | $ | 1.73 | | | $ | 0.70 | | | | | | | | | | | | | | | | | | | | Earnings per share – diluted:
| | | | | | | | | | | | | | | | | | Net income | | $ | 48,847 | | | $ | 7,467 | | | $ | 64,710 | | | $ | 26,309 | | Income all ocated to participating securities
| | | (41 | ) | | | (7 | ) | | | (50 | ) | | | (22 | ) | | Income available to common shareholders | | $ | 48,806 | | | $ | 7,460 | | | $ | 64,660 | | | $ | 26,287 | | Weighted-average shares outstanding – basic
| | | 37,449 | | | | 37,308 | | | | 37,412 | | | | 37,294 | | | Dilutive effect of stock options and restricted stock units | | | 477 | | | | 170 | | | | 404 | | | | 181 | | Weighted-average common shares outstanding – diluted
| | | 37,926 | | | | 37,478 | | | | 37,816 | | | | 37,475 | | Earnings per share – diluted
| | $ | 1.29 | | | $ | 0.20 | | | $ | 1.71 | | | $ | 0.70 | | |