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Goodwill and Acquired Intangible Assets (Tables) | 12 Months Ended
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Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract] |
Cumulative Value of Intangible Assets Related to Acquisition |
|  | December 31 |
|  | 2019 |
|  | US$ |
|  | Cost |  |  | Accumulated Impairment |  |  | Accumulated Amortization |  |  | Net Carrying Amount |
Acquisition-related intangible assets |  |  | 13,117 |  |  |  | (3,699 | ) |  |  | (9,418 | ) |  |  | — |
Schedule of Goodwill |
|  | December 31 |
|  | 2019 |  |  | 2020 |
|  | US$ |  |  | US$ |
|  | Cost |  |  | Disposal of FCI |  |  | Accumulated Impairment |  |  | Foreign Currency Adjustment |  |  | Net Carrying Amount |  |  | Cost |  |  | Disposal of FCI |  |  | Accumulated Impairment |  |  | Foreign Currency Adjustment |  |  | Net Carrying Amount |
Goodwill |  |  | 100,129 |  |  |  | (25,117 | ) |  |  | (57,485 | ) |  |  | (38 | ) |  |  | 17,489 |  |  |  | 100,129 |  |  |  | (25,117 | ) |  |  | (74,974 | ) |  |  | (38 | ) |  |  | — |

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