Financial Assets and Liabilities at Fair Value through Profit or Loss - Summary of Financial Assets and Liabilities at Fair Value through Profit or Loss (Detail) - TWD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Disclosure of detailed information about financial instruments [line items]
Financial assets, Mandatorily measured at FVTPL	$ 58.3	$ 2,259.4
Forward exchange contracts [member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, Held for trading	1,828.3	94.1
Financial assets, Mandatorily measured at FVTPL	$ 58.3	$ 2,259.4

The amount of financial liabilities at fair value through profit or loss that meet the definition of held for trading. A financial liability is classified as held for trading if: (a) it is acquired or incurred principally for the purpose of selling or repurchasing it in the near term; (b) on initial recognition it is part of a portfolio of identified financial instruments that are managed together and for which there is evidence of a recent actual pattern of short-term profit-taking; or (c) it is a derivative (except for a derivative that is a financial guarantee contract or a designated and effective hedging instrument). [Refer: Financial liabilities at fair value through profit or loss]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2020-01-01
-Paragraph 8
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_8_e&doctype=Standard
-URIDate 2020-01-01

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Period Type:	instant