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Basis of preparation of financial statements and principal accounting policies - Information About Differences Between Operating Lease Commitments And Lease Liabilities (Detail) - TWD ($) $ in Thousands | Dec. 31, 2019 | Jan. 01, 2019
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Statement [line items] |  |
Operating lease commitments disclosed by applying IAS 17 as of December 31, 2018 |  | $ 320,214
Add: Lease payable recognized under finance lease by applying IAS 17 as of December 31, 2018 |  | 17,792
Less: Short-term leases |  | (28,121)
Add: Adjustments as a result of a different treatment of extension and termination options |  | 874,298
Total lease contracts amount recognized as lease liabilities by applying IFRS 16 on January 1, 2019 | $ 917,452 | 1,184,183
Lease liabilities recognized as of January 1, 2019 by applying IFRS 16 | $ 692,951 |
Effects Of Adopting New Standards [member] |  |
Statement [line items] |  |
Lease liabilities recognized as of January 1, 2019 by applying IFRS 16 |  | $ 884,275
Bottom of range [member] |  |
Statement [line items] |  |
Incremental borrowing interest rate at the date of initial application |  | 1.7895%
Top of range [member] |  |
Statement [line items] |  |
Incremental borrowing interest rate at the date of initial application |  | 3.9474%

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- Definition The amount of contractual undiscounted cash flows in relation to lease liabilities before deducting finance charges. [Refer: Lease liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2019-01-01 -Paragraph 58 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2019-en-r&anchor=para_58&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 7 -IssueDate 2019-01-01 -Paragraph B11D -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2019-en-r&anchor=para_B11D_a&doctype=Appendix&subtype=B -URIDate 2019-03-27 + Details
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- Definition The amount of the lease commitments for short-term leases accounted for applying paragraph 6 of IFRS 16. Short-term lease is a lease that, at the commencement date, has a lease term of 12 months or less. A lease that contains a purchase option is not a short-term lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2019-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2019-en-r&anchor=para_55&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of liabilities related to the entity's leases. Lease is a contract, or part of a contract, that conveys the right to use an underlying asset for a period of time in exchange for consideration. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2019-01-01 -Paragraph 47 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2019-en-r&anchor=para_47_b&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The weighted average lessee's incremental borrowing rate applied to lease liabilities recognised in the statement of financial position at the date of initial application of IFRS 16. The incremental borrowing rate is the rate of interest that a lessee would have to pay to borrow over a similar term, and with a similar security, the funds necessary to obtain an asset of a similar value to the right-of-use asset in a similar economic environment. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2019-01-01 -Paragraph C12 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2019-en-r&anchor=para_C12_a&doctype=Appendix&subtype=C -URIDate 2019-03-27 + Details
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- Definition Changes arising from extension options and termination options. + References No definition available. + Details
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- Definition Finance Lease Commitments Under IAS 17. + References No definition available. + Details
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- Definition Operating lease commitments under IAS 17. + References No definition available. + Details
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- Details
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