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General Information - Additional Information (Detail) ₩ in Millions	12 Months Ended
	Dec. 31, 2025 KRW (₩) Entity	Dec. 31, 2024 KRW (₩)	Dec. 31, 2023 KRW (₩)
Disclosure of general information [Line Items]
Number of associates and joint ventures | Entity	115
Increase (decrease) in ownership interests in subsidiaries	₩ 772,803	₩ 462,168	₩ 262,746
Dividends paid by subsidiaries	946,248	1,403,415	₩ 441,113
POSCO INTERNATIONAL Corporation And Others [Member]
Disclosure of general information [Line Items]
Increase (decrease) in ownership interests in subsidiaries		₩ 15,440
POSCO HY Clean Metal Co., Ltd. and others [Member]
Disclosure of general information [Line Items]
Increase (decrease) in ownership interests in subsidiaries	₩ 35,662
Domestic [member]
Disclosure of general information [Line Items]
Number of subsidiaries | Entity	64
Foreign [member]
Disclosure of general information [Line Items]
Number of subsidiaries | Entity	134

X

- Definition

The amount of dividends received.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2025-01-01
-Paragraph B12
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2025-en-r&anchor=para_B12_a&doctype=Appendix&subtype=B
-URIDate 2025-03-27

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- Definition

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 106
-Subparagraph d
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_106_d_iii&doctype=Standard
-URIDate 2025-03-27

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- Definition

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