Income tax expense - Summary of the amount of temporary difference regarding investment in subsidiaries that are not recognized as deferred tax liabilities (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2025	Dec. 31, 2024
The amount of temporary difference regarding investment in subsidiaries that are not recognized as deferred tax liabilities [Abstract]
Investment in subsidiaries, etc.	₩ (10,643,726)	₩ (10,203,270)

The aggregate amount of temporary differences associated with investments in subsidiaries, branches and associates and interests in joint arrangements, for which deferred tax liabilities have not been recognised as a result of satisfying both of the following conditions: (a) the parent, investor, joint venturer or joint operator is able to control the timing of the reversal of the temporary difference; and (b) it is probable that the temporary difference will not reverse in the foreseeable future. [Refer: Total for all associates [member]; Total for all subsidiaries [member]; Temporary differences [member]; Investments in subsidiaries reported in separate financial statements]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2025-01-01
-Paragraph 81
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=12&code=ifrs-tx-2025-en-r&anchor=para_81_f&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_TemporaryDifferencesAssociatedWithInvestmentsInSubsidiariesBranchesAndAssociatesAndInterestsInJointVentures
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant