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Investments in Associates and Joint Ventures - Summary of Reconciliation of Carrying Amount of Interests in the Associates and Joint Ventures (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Book amount | ₩ 1,288,429 | ₩ 557,881
K Bank [member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets | ₩ 1,737,237 | ₩ 488,819
Percentage of ownership | 33.72% | 34.00%
Share in net assets | ₩ 585,837 | ₩ 166,198
Intercompany transaction and others | 245,900 | 42,074
Book amount | 831,737 | 208,272
Korea Information & Technology Fund [member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets | ₩ 536,804 | ₩ 510,464
Percentage of ownership | 33.33% | 33.30%
Share in net assets | ₩ 178,935 | ₩ 170,155
Book amount | 178,935 | 170,155
KT-IBKC future investment fund [member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets | ₩ 24,163 | ₩ 32,379
Percentage of ownership | 50.00% | 50.00%
Share in net assets | ₩ 12,081 | ₩ 16,190
Book amount | 12,081 | 16,190
Hyundai Robotics Co., Ltd. [member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets | ₩ 279,461 | ₩ 301,566
Percentage of ownership | 10.00% | 10.00%
Share in net assets | ₩ 27,946 | ₩ 30,157
Intercompany transaction and others | 20,779 | 20,779
Book amount | 48,725 | ₩ 50,936
KREALTYCR REITs No One Member [Member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets | ₩ 208,825 |
Percentage of ownership | 30.05% |
Share in net assets | ₩ 62,752 |
Intercompany transaction and others | 4,906 |
Book amount | ₩ 67,658 |

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- Definition The amount of investments accounted for using the equity method. The equity method is a method of accounting whereby the investment is initially recognised at cost and adjusted thereafter for the post-acquisition change in the investor's share of net assets of the investee. The investor's profit or loss includes its share of the profit or loss of the investee. The investor's other comprehensive income includes its share of the other comprehensive income of the investee. [Refer: At cost [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2021-01-01 -Paragraph 24 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2021-en-r&anchor=para_24_a&doctype=Standard -URIDate 2021-03-24 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2021-01-01 -Paragraph B16 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2021-en-r&anchor=para_B16&doctype=Appendix&subtype=B -URIDate 2021-03-24 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2021-01-01 -Paragraph 54 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2021-en-r&anchor=para_54_e&doctype=Standard -URIDate 2021-03-24 + Details
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- Definition The proportion of ownership interest in an associate attributable to the entity. [Refer: Associates [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 27 -IssueDate 2021-01-01 -Paragraph 17 -Subparagraph b -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2021-en-r&anchor=para_17_b_iii&doctype=Standard -URIDate 2021-03-24 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 27 -IssueDate 2021-01-01 -Paragraph 16 -Subparagraph b -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2021-en-r&anchor=para_16_b_iii&doctype=Standard -URIDate 2021-03-24 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2021-01-01 -Paragraph 21 -Subparagraph a -Clause iv -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2021-en-r&anchor=para_21_a_iv&doctype=Standard -URIDate 2021-03-24 + Details
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