| 14. | Earnings per share |
| | | December 31, 2017 | | December 31, 2016 | | December 31, 2015 | | |||
| (Thousands of U.S. dollars) | | | | | | | | | | |
| Profit for the year | | | 81,999 | | | 87,045 | | | 103,984 | |
| | | | | | | | | | | |
| (U.S. dollars) | | | | | | | | | | |
| Basic earnings per share | | | 2.09 | | | 2.23 | | | 2.67 | |
| Diluted earnings per share | | | 2.08 | | | 2.22 | | | 2.66 | |
| | | | | | | | | | | |
| (Share units) | | | | | | | | | | |
| Weighted average common shares outstanding - applicable to basic | | | 39,311 | | | 39,085 | | | 38,925 | |
| | | | | | | | | | | |
| Effect of diluted securities: | | | | | | | | | | |
| Stock options and restricted stock units plans | | | 18 | | | 125 | | | 188 | |
| Adjusted weighted average common shares outstanding applicable to diluted EPS | | | 39,329 | | | 39,210 | | | 39,113 | |