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Profit Before Income Tax - Summary of Employee Benefits Expense (Detail) $ in Thousands, $ in Thousands | 12 Months Ended
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Dec. 31, 2017 TWD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 TWD ($) | Dec. 31, 2015 TWD ($)
Post-employment benefits |  |  |  |
Defined contribution plans | $ 2,340,826 | $ 78,975 | $ 2,356,416 | $ 2,324,737
Defined benefit plans | 266,267 | 8,983 | 394,741 | 413,490
Post-employment benefits | 2,607,093 | 87,958 | 2,751,157 | 2,738,227
Equity-settled share-based payments | 438,765 | 14,803 | 470,788 | 133,496
Other employee benefits | 51,043,198 | 1,722,105 | 49,525,940 | 47,883,464
Employee benefits expense | 54,089,056 | 1,824,866 | 52,747,885 | 50,755,187
Operating costs [member] |  |  |  |
Post-employment benefits |  |  |  |
Employee benefits expense | 35,978,403 | 1,213,846 | 35,588,529 | 34,720,359
Operating expenses [member] |  |  |  |
Post-employment benefits |  |  |  |
Employee benefits expense | $ 18,110,653 | $ 611,020 | $ 17,159,356 | $ 16,034,828

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- Definition The expense of all forms of consideration given by an entity in exchange for a service rendered by employees or for the termination of employment. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 102 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_102&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 99 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_99&doctype=Standard -URIDate 2017-03-09 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 104 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_104&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The amount of expense from share-based payment transactions with employees. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The amount of expense from employee benefits (other than termination benefits), which are expected to be settled wholly within twelve months after the end of the annual reporting period in which the employees render the related services, that the entity does not separately disclose in the same statement or note. [Refer: Employee benefits expense] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 9 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_9&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The amount of post-employment benefit expense relating to defined benefit plans. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 5 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_5&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The amount of post-employment benefit expense relating to defined contribution plans. Defined contribution plans are post-employment benefit plans under which an entity pays fixed contributions into a separate entity (a fund) and will have no legal or constructive obligation to pay further contributions if the fund does not hold sufficient assets to pay all employee benefits relating to employee service in the current and prior periods. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 53 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_53&doctype=Standard -URIDate 2017-03-09 + Details
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