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Effects on Initial Application of IFRS 15 and Information for the Year Ended December 31, 2017 in Conformity With IAS 18 - Additional Information (Detail) $ in Thousands, $ in Thousands | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2019 TWD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 TWD ($) | Dec. 31, 2017 TWD ($) | Dec. 31, 2019 USD ($) | Jan. 01, 2018 TWD ($)
Disclosure of initial application of standards or interpretations [line items] |  |  |  |  |  |
Retained earnings | $ 4,651,215 |  | $ 3,602,663 |  | $ 155,507 |
Inventories | 1,767,642 |  | 1,778,835 |  | 59,099 |
Contract assets | 377,869 |  | 299,835 |  |  | $ 254,997
Provision for sales allowance | 1,998 |  | 29,352 |  | 67 |
Deferred tax assets | 194,552 |  | 226,716 | $ 212,372 | 6,505 |
Deferred tax liabilities | 309,129 |  | 308,759 | 174,293 | $ 10,335 |
Revenue | 20,337,881 | $ 679,969 | 18,480,027 | 17,940,855 |  |
Cost of revenue | 16,411,742 | 548,704 | 15,050,032 | 14,703,729 |  |
Income tax expense | 513,679 | $ 17,174 | 456,618 | $ 550,487 |  |
Contract liabilities | $ 1,231 |  | 1,432 |  |  | 1,152
Increase (decrease) due to application of IFRS 15 [member] |  |  |  |  |  |
Disclosure of initial application of standards or interpretations [line items] |  |  |  |  |  |
Retained earnings |  |  |  |  |  | (8,693)
Inventories |  |  | (237,271) |  |  |
Contract assets |  |  | 300,376 |  |  |
Provision for sales allowance |  |  | 32,627 |  |  | 70,156
Deferred tax assets |  |  | 81 |  |  | (626)
Deferred tax liabilities |  |  |  |  |  | 8,067
Revenue |  |  | 300,376 |  |  |
Cost of revenue |  |  | 237,271 |  |  |
Expected credit loss |  |  | 135 |  |  |
Foreign exchange loss |  |  | 406 |  |  |
Income tax expense |  |  | (81) |  |  |
Contract liabilities |  |  | $ 1,432 |  |  |
Increase (decrease) due to application of IFRS 15 [member] | Customized products [member] |  |  |  |  |  |
Disclosure of initial application of standards or interpretations [line items] |  |  |  |  |  |
Retained earnings |  |  |  |  |  | 46,607
Inventories |  |  |  |  |  | (208,505)
Contract assets |  |  |  |  |  | $ 255,112

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