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Application of New and Amended International Financial Reporting Standards - Schedule of Original And New Measurement Categories and Carrying Amounts under IAS 39 and IFRS 9 (Details) - TWD ($) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2018 | Jan. 01, 2018 | Dec. 31, 2017
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Financial assets measured at FVTPL | $ 517 |  | $ 0
Add: reclassification from available for sale (IAS 39) - mandatory reclassification |  |  | 5,751
Financial assets at fair value through other comprehensive income - equity investments - subtotal | 6,933 |  |
Financial assets measured at Amortized cost | 70,241 |  |
Add: reclassification from loans and receivables (IAS 39) |  |  | 68,983
Financial liabilities measured at amortized cost | $ 40,334 |  | $ 39,725
Total retained earnings [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Add: reclassification from available for sale (IAS 39) - mandatory reclassification |  | $ 6 |
Financial assets at fair value through profit or loss - subtotal |  | 6 |
Add: reclassification from available for sale (IAS 39) - designated at January 1, 2018 |  | 1,516 |
Financial assets at fair value through other comprehensive income - equity investments - subtotal |  | 1,516 |
Total |  | 1,522 |
Noncontrolling interests [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Add: reclassification from available for sale (IAS 39) - designated at January 1, 2018 |  | (1) |
Financial assets at fair value through other comprehensive income - equity investments - subtotal |  | (1) |
Total |  | (1) |
IAS 39 [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Financial liabilities measured at FVTPL |  | (1) |
Total |  | (1) |
IFRS 9 [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Add: reclassification from available for sale (IAS 39) - mandatory reclassification |  | 596 |
Financial assets at fair value through profit or loss - subtotal |  | 596 |
Financial liabilities measured at FVTPL |  | (1) |
Add: reclassification from available for sale (IAS 39) - designated at January 1, 2018 |  | 6,997 |
Financial assets at fair value through other comprehensive income - equity investments - subtotal |  | 6,997 |
Add: reclassification from loans and receivables (IAS 39) |  | 68,983 |
Financial Assets measured at amortized cost - subtotal |  | 68,983 |
Add: reclassification from amortized cost (IAS 39) |  | (39,725) |
Financial Liabilities measured at amortized cost - subtotal |  | (39,725) |
Add: reclassification from Hedging derivative instrument (IAS 39) |  | (1) |
Hedging financial liabilities - subtotal |  | (1) |
Total |  | 36,849 |
Reclassifications [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Add: reclassification from available for sale (IAS 39) - mandatory reclassification |  | 596 |
Financial assets at fair value through profit or loss - subtotal |  | 596 |
Add: reclassification from available for sale (IAS 39) - designated at January 1, 2018 |  | 5,155 |
Financial assets at fair value through other comprehensive income - equity investments - subtotal |  | 5,155 |
Add: reclassification from loans and receivables (IAS 39) |  | 68,983 |
Financial Assets measured at amortized cost - subtotal |  | 68,983 |
Add: reclassification from amortized cost (IAS 39) |  | (39,725) |
Financial Liabilities measured at amortized cost - subtotal |  | (39,725) |
Add: reclassification from Hedging derivative instrument (IAS 39) |  | (1) |
Hedging financial liabilities - subtotal |  | (1) |
Total |  | 35,008 |
Remeasurements [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Add: reclassification from available for sale (IAS 39) - designated at January 1, 2018 |  | 1,842 |
Financial assets at fair value through other comprehensive income - equity investments - subtotal |  | 1,842 |
Total |  | 1,842 |
Other Adjustment [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Add: reclassification from available for sale (IAS 39) - mandatory reclassification |  | (6) |
Financial assets at fair value through profit or loss - subtotal |  | (6) |
Add: reclassification from available for sale (IAS 39) - designated at January 1, 2018 |  | 327 |
Financial assets at fair value through other comprehensive income - equity investments - subtotal |  | 327 |
Total |  | 321 |
Cash and Cash Equivalents [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Financial Assets, Measurement Category, IAS 39 | Loans and receivables |  |
Financial Assets, Measurement Category, IFRS 9 | Amortized cost |  |
Financial Assets, Carrying Amount, IAS 39 |  | 28,825 |
Financial Assets, Carrying Amount, IFRS 9 |  | 28,825 |
Equity Securities I [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Financial Assets, Measurement Category, IAS 39 | Available-for-sale |  |
Financial Assets, Measurement Category, IFRS 9 | FVTPL |  |
Financial Assets, Carrying Amount, IAS 39 |  | 596 |
Financial Assets, Carrying Amount, IFRS 9 |  | 596 |
Equity Securities II [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Financial Assets, Measurement Category, IAS 39 | Available-for-sale |  |
Financial Assets, Measurement Category, IFRS 9 | FVOCI- equity investments |  |
Financial Assets, Carrying Amount, IAS 39 |  | 5,155 |
Financial Assets, Carrying Amount, IFRS 9 |  | 6,997 |
Trade Notes and Accounts Receivable, Receivables from Related Parties, Other Current Monetary Assets and Refundable Deposits [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Financial Assets, Measurement Category, IAS 39 | Loans and receivables |  |
Financial Assets, Measurement Category, IFRS 9 | Amortized cost |  |
Financial Assets, Carrying Amount, IAS 39 |  | 40,158 |
Financial Assets, Carrying Amount, IFRS 9 |  | 40,158 |
Short-term loans, trade notes and accounts payable, payables to related parties, partial other payables, customers’ deposit and loan-term loans |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Financial Liabilities, Measurement Category, IAS 39 | Amortized cost |  |
Financial Liabilities, Measurement Category, IFRS 9 | Amortized cost |  |
Financial Liabilities, Carrying Amount, IAS 39 |  | 39,725 |
Financial Liabilities, Carrying Amount, IFRS 9 |  | 39,725 |
Derivatives [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Financial Liabilities, Measurement Category, IAS 39 | Held-for-trading |  |
Financial Liabilities, Measurement Category, IFRS 9 | FVTPL |  |
Financial Liabilities, Carrying Amount, IAS 39 |  | 1 |
Financial Liabilities, Carrying Amount, IFRS 9 |  | 1 |
Hedging Derivative Financial Liabilities [Member] |  |  |
Disclosure Of Initial Application Of Standards Or Interpretations [Line Items] |  |  |
Financial Liabilities, Measurement Category, IAS 39 | Hedging derivative financial liabilities |  |
Financial Liabilities, Measurement Category, IFRS 9 | Hedging financial liabilities |  |
Financial Liabilities, Carrying Amount, IAS 39 |  | 1 |
Financial Liabilities, Carrying Amount, IFRS 9 |  | $ 1 |

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- Definition The amount of investments in equity instruments that the entity has designated at fair value through other comprehensive income. [Refer: At fair value [member]; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 11A -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_11A_c&doctype=Standard -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 8 -Subparagraph h -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_8_h&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 25 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_25&doctype=Standard -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 35H -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35H&doctype=Standard -URIDate 2018-03-16 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 35I -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35I&doctype=Standard -URIDate 2018-03-16 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 35M -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35M&doctype=Standard -URIDate 2018-03-16 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 35N -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35N&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition The amount of financial assets that are measured at fair value and for which gains (losses) are recognised in profit or loss. A financial asset shall be measured at fair value through profit or loss unless it is measured at amortised cost or at fair value through other comprehensive income. A gain (loss) on a financial asset measured at fair value shall be recognised in profit or loss unless it is part of a hedging relationship, it is an investment in an equity instrument for which the entity has elected to present gains and losses in other comprehensive income or it is a financial asset measured at fair value through other comprehensive income. [Refer: At fair value [member]; Financial assets] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 8 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_8_a&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition The amount of financial liabilities at amortised cost. The amortised cost is the amount at which financial liabilities are measured at initial recognition minus principal repayments, plus or minus the cumulative amortisation using the effective interest method of any difference between that initial amount and the maturity amount. [Refer: Financial liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 8 -Subparagraph g -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_8_g&doctype=Standard -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2021-01-01 -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 8 -Subparagraph f -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-02&anchor=para_8_f&doctype=Standard&book=b -URIDate 2018-03-16 + Details
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- Definition The amount of financial liabilities that meet either of the following conditions: (a) they meet the definition of held for trading; or (b) upon initial recognition they are designated by the entity as at fair value through profit or loss. An entity may use this designation only when permitted by paragraph 4.3.5 of IFRS 9 (embedded derivatives) or when doing so results in more relevant information, because either: (a) it eliminates or significantly reduces a measurement or recognition inconsistency (sometimes referred to as ‘an accounting mismatch’) that would otherwise arise from measuring assets or liabilities or recognising the gains and losses on them on different bases; or (b) a group of financial liabilities or financial assets and financial liabilities is managed and its performance is evaluated on a fair value basis, in accordance with a documented risk management or investment strategy, and information about the group is provided internally on that basis to the entity’s key management personnel (as defined in IAS 24). [Refer: At fair value [member]; Key management personnel of entity or parent [member]; Derivatives [member]; Financial assets; Financial liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 8 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_8_e&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition The amount of non-derivative financial assets with fixed or determinable payments that are not quoted in an active market, other than: (a) those that the entity intends to sell immediately or in the near term, which shall be classified as held for trading, and those that the entity, upon initial recognition, designates as at fair value through profit or loss; (b) those that the entity, upon initial recognition, designates as available for sale; or (c) those for which the holder may not recover substantially all of its initial investment, other than because of credit deterioration, which shall be classified as available for sale. An interest acquired in a pool of assets that are not loans or receivables (for example, an interest in a mutual fund or a similar fund) is not a loan or receivable. [Refer: Derivative financial assets] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2021-01-01 -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 8 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-02&anchor=para_8_c&doctype=Standard&book=b -URIDate 2018-03-16 + Details
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- Definition The amount of assets less the amount of liabilities. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 1 -IssueDate 2018-01-01 -Paragraph IG63 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=1&date=2018-03-01&anchor=para_IG63&doctype=Implementation%20Guidance -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_112_c&doctype=Standard -URIDate 2018-03-16 + Details
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