Financial Instruments - Remaining Contractual Maturity for Non-derivative Financial Liabilities (Detail) - TWD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Non-derivative financial liabilities	$ 73,719	$ 45,357
Less Than 1 Month [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Non-derivative financial liabilities	44,749	36,437
1-3 Months [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Non-derivative financial liabilities	7	10
3 Months to 1 Year [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Non-derivative financial liabilities	4,136	2,562
1-5 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Non-derivative financial liabilities	13,627	6,348
More Than 5 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Non-derivative financial liabilities	11,200	0
Non-interest bearing [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	45,052	43,667
Non-interest bearing [Member] \| Less Than 1 Month [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	37,749	36,387
Non-interest bearing [Member] \| 1-3 Months [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	0	0
Non-interest bearing [Member] \| 3 Months to 1 Year [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	2,476	2,532
Non-interest bearing [Member] \| 1-5 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	4,827	4,748
Non-interest bearing [Member] \| More Than 5 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	0	0
Floating interest rate instruments [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	$ 1,667	$ 1,690
Floating interest rate instruments [Member] \| Weighted average [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Interest rates of bank loans	0.78%	0.98%
Floating interest rate instruments [Member] \| Less Than 1 Month [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	$ 0	$ 50
Floating interest rate instruments [Member] \| 1-3 Months [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	7	10
Floating interest rate instruments [Member] \| 3 Months to 1 Year [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	1,660	30
Floating interest rate instruments [Member] \| 1-5 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	0	1,600
Floating interest rate instruments [Member] \| More Than 5 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	0	0
Fixed interest rate instruments [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	$ 27,000
Fixed interest rate instruments [Member] \| Weighted average [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Interest rates of bank loans	0.50%
Fixed interest rate instruments [Member] \| Less Than 1 Month [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	$ 7,000
Fixed interest rate instruments [Member] \| 1-3 Months [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	0
Fixed interest rate instruments [Member] \| 3 Months to 1 Year [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	0
Fixed interest rate instruments [Member] \| 1-5 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	8,800
Fixed interest rate instruments [Member] \| More Than 5 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans	11,200
Fair value interest rate risk [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Financial assets	24,218	30,947
Financial liabilities	36,576	9,758
Cash flow interest rate risk [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Financial assets	9,306	7,681
Financial liabilities	$ 1,667	$ 1,690

The amount of contractual undiscounted cash flows in relation to bank borrowings. [Refer: Borrowings]

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- Definition

The amount of contractual undiscounted cash flows in relation to bonds issued. [Refer: Bonds issued]

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- Definition

The interest rate on borrowings. [Refer: Borrowings]

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- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

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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

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- Definition

The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) 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 deliver 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, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are 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. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Financial instruments, class [member]; Financial assets; Derivatives [member]]

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- Definition

The amount of contractual undiscounted cash flows in relation to non-derivative financial liabilities.

+ References

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-Name IFRS
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- Definition

The amount of contractual undiscounted cash flows in relation to trade and other payables. [Refer: Trade and other payables]

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