Net Income - Other Income (Detail) $ in Millions, $ in Millions	12 Months Ended
Dec. 31, 2020 TWD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 TWD ($)	Dec. 31, 2018 TWD ($)
Analysis Of Income And Expense [Abstract]
Dividend income	$ 246	$ 9	$ 296	$ 396
Rental income	70		85	70
Others	154		150	234
Other income	$ 470	$ 17	$ 531	$ 700

The amount of dividends recognised as income. Dividends are distributions of profits to holders of equity investments in proportion to their holdings of a particular class of capital.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 112
-Subparagraph c
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-URIDate 2020-01-01

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