Net Revenue - Summary of Disaggregation of Revenue from Contracts with Customers by Product (Detail) - TWD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from contracts with customers	$ 1,339,254.8	$ 1,069,985.4	$ 1,031,473.6
Wafer [member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from contracts with customers	1,178,456.3	927,317.3	911,296.4
Other Products [member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from contracts with customers	$ 160,798.5	$ 142,668.1	$ 120,177.2

The amount of revenue from contracts with customers. A customer is a party that has contracted with an entity to obtain goods or services that are an output of the entity’s ordinary activities in exchange for consideration.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2020-01-01
-Paragraph 113
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2020-en-r&anchor=para_113_a&doctype=Standard
-URIDate 2020-01-01

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2020-01-01
-Paragraph 114
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2020-en-r&anchor=para_114&doctype=Standard
-URIDate 2020-01-01

Name:	ifrs-full_RevenueFromContractsWithCustomers
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration