| | 12-31-2017 | | 12-31-2016 | |
Goodwill | | ThU.S.$ | | ThU.S.$ | |
Opening balance at January 1 | | 74,893 | | 69,475 | |
Impairment | | (4,640) | | - | |
Increase (decrease) in foreign currency exchange | | (331) | | 5,418 | |
Closing balance at December 31, 2017 | | 69,922 | | 74,893 | |