Lease Arrangements - Lease Liabilities (Detail) $ in Millions, $ in Millions	Dec. 31, 2020 TWD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 TWD ($)
Lease liabilities [abstract]
Current portion (classified under accrued expenses and other current liabilities)	$ 1,828.0		$ 2,275.1
Noncurrent portion	20,560.6	$ 732.2	15,041.8
Lease liabilities	$ 22,388.6		$ 17,316.9

The amount of current lease liabilities. [Refer: Lease liabilities]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2020-01-01
-Paragraph 47
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2020-en-r&anchor=para_47_b&doctype=Standard
-URIDate 2020-01-01

+ Details

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Period Type:	instant

- 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

+ Details

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- References

No definition available.

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Balance Type:	na
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- Definition

The amount of non-current lease liabilities. [Refer: Lease liabilities]

+ References

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant