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Segment Information - Financial Segment Information for Operating Segments (Detail) $ in Thousands, $ in Thousands | 12 Months Ended
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Dec. 31, 2023 TWD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2022 TWD ($) | Dec. 31, 2021 TWD ($)
Revenue |  |  |  |
Revenue | $ 21,356,228 | $ 697,460 | $ 23,517,064 | $ 27,400,035
Operating profit (loss) | 1,908,452 | 62,327 | 3,216,679 | 5,562,389
Depreciation expenses | (4,779,333) |  | (4,751,902) | (4,634,112)
Share of profit of associates | 219,891 | 7,182 | 453,715 | 625,733
Interest income | 193,189 | $ 6,309 | 57,199 | 9,980
Interest expense | (265,957) |  | (142,439) | (120,998)
Purchase of property, plant and equipment | 3,228,471 |  | 4,918,482 | 6,552,702
External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 21,356,228 |  | 23,517,064 | 27,400,035
Operating segments [member] | Testing [member] |  |  |  |
Revenue |  |  |  |
Revenue | 4,394,726 |  | 5,243,997 | 5,899,600
Operating profit (loss) | 514,707 |  | 1,253,477 | 1,814,021
Depreciation expenses | (1,065,689) |  | (1,042,455) | (921,999)
Purchase of property, plant and equipment | 749,158 |  | 1,086,682 | 1,841,359
Operating segments [member] | Testing [member] | External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 4,394,726 |  | 5,243,997 | 5,899,600
Operating segments [member] | Assembly [member] |  |  |  |
Revenue |  |  |  |
Revenue | 4,629,430 |  | 6,705,898 | 7,963,714
Operating profit (loss) | (1,180,481) |  | (93,585) | 857,304
Depreciation expenses | (722,462) |  | (694,835) | (576,138)
Purchase of property, plant and equipment | 568,289 |  | 957,790 | 1,553,475
Operating segments [member] | Assembly [member] | External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 4,629,430 |  | 6,705,898 | 7,963,714
Operating segments [member] | LCDD [member] |  |  |  |
Revenue |  |  |  |
Revenue | 7,821,640 |  | 7,288,642 | 8,211,099
Operating profit (loss) | 2,058,285 |  | 1,795,741 | 2,336,394
Depreciation expenses | (2,547,253) |  | (2,505,297) | (2,579,150)
Purchase of property, plant and equipment | 1,756,590 |  | 2,677,489 | 2,748,697
Operating segments [member] | LCDD [member] | External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 7,821,640 |  | 7,288,642 | 8,211,099
Operating segments [member] | Bumping [member] |  |  |  |
Revenue |  |  |  |
Revenue | 4,510,432 |  | 4,278,527 | 5,325,622
Operating profit (loss) | 522,386 |  | 268,159 | 561,642
Depreciation expenses | (435,709) |  | (500,863) | (549,020)
Purchase of property, plant and equipment | 152,908 |  | 196,521 | 408,751
Operating segments [member] | Bumping [member] | External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 4,510,432 |  | 4,278,527 | 5,325,622
Operating segments [member] | Others [member] |  |  |  |
Revenue |  |  |  |
Revenue | 59,481 |  | 50,600 | 43,808
Operating profit (loss) | (6,194) |  | (6,821) | (6,987)
Depreciation expenses | (8,220) |  | (8,452) | (7,805)
Share of profit of associates | 420,393 |  | 884,555 | 1,211,177
Interest income | 193,189 |  | 57,199 | 9,980
Interest expense | (265,957) |  | (142,439) | (120,998)
Purchase of property, plant and equipment | 1,526 |  |  | 420
Operating segments [member] | Others [member] | Intersegment [member] |  |  |  |
Revenue |  |  |  |
Revenue | 59,481 |  | 50,600 | 43,808
Elimination [member] |  |  |  |
Revenue |  |  |  |
Revenue | (59,481) |  | (50,600) | (43,808)
Operating profit (loss) | (251) |  | (292) | 15
Share of profit of associates | (200,502) |  | (430,840) | 585,444
Elimination [member] | Intersegment [member] |  |  |  |
Revenue |  |  |  |
Revenue | $ (59,481) |  | $ (50,600) | $ (43,808)

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