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Supplementary Cash Flow Information - Partial Cash Paid for Investing Activities (Detail) $ in Thousands, $ in Thousands | 12 Months Ended
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Dec. 31, 2020 TWD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 TWD ($) | Dec. 31, 2018 TWD ($)
Statement of cash flows [abstract] |  |  |  |
Purchase of property, plant and equipment | $ 4,133,615 |  | $ 4,896,656 | $ 4,945,570
Add: Beginning balance of payable to contractors and equipment suppliers | 972,770 |  | 1,516,735 | 713,313
Add :Beginning balance of payable on lease |  |  |  | 29,842
Less: Ending balance of payable to contractors and equipment suppliers | (1,145,359) |  | (972,770) | (1,516,735)
Less:Ending balance of payable on lease |  |  |  | (17,792)
Cash paid during the year | $ 3,961,026 | $ 141,062 | $ 5,440,621 | $ 4,154,198

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- Definition The amount of additions to property, plant and equipment other than those acquired through business combinations. [Refer: Business combinations [member]; Property, plant and equipment] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 16 -IssueDate 2020-01-01 -Paragraph 73 -Subparagraph e -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=16&code=ifrs-tx-2020-en-r&anchor=para_73_e_i&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The cash outflow for the purchases of property, plant and equipment, classified as investing activities. [Refer: Property, plant and equipment] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 7 -IssueDate 2020-01-01 -Paragraph 16 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2020-en-r&anchor=para_16_a&doctype=Standard -URIDate 2020-01-01 + Details
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