| December 31, | |||||||||
| 2016 | 2017 | ||||||||
| Cost: | |||||||||
| Computers, equipment and software | $ | 60,074 | $ | 80,888 | |||||
| Motor vehicles | 1,552 | 1,659 | |||||||
| Buildings | 1,833 | 1,833 | |||||||
| Leasehold improvements | 20,991 | 22,080 | |||||||
| 84,450 | 106,460 | ||||||||
| Accumulated depreciation: | |||||||||
| Computers, equipment and software | $ | 46,659 | $ | 64,604 | |||||
| Motor vehicles | 531 | 636 | |||||||
| Buildings | 23 | 70 | |||||||
| Leasehold improvements | 11,107 | 11,343 | |||||||
| 58,320 | 76,653 | ||||||||
| Depreciated cost | $ | 26,130 | $ | 29,807 | |||||