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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, 2019 | Dec. 31, 2018
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Book amount | ₩ 267,660 | ₩ 272,407
K Bank Inc. [member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets | ₩ 204,472 | ₩ 280,083
Percentage of ownership | 10.00% | 10.00%
Share in net assets | ₩ 45,158 | ₩ 52,655
Book amount | 45,158 | 52,655
Korea Information & Technology Fund [member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets | ₩ 491,924 | ₩ 444,764
Percentage of ownership | 33.30% | 33.30%
Share in net assets | ₩ 163,975 | ₩ 148,255
Book amount | 163,975 | 148,255
KT-SB Venture Investment Fund [member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets |  | ₩ 8,940
Percentage of ownership |  | 50.00%
Share in net assets |  | ₩ 4,470
Book amount |  | 4,470
KT-IBKC future investment fund [member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets | ₩ 28,200 | ₩ 19,922
Percentage of ownership | 50.00% | 50.00%
Share in net assets | ₩ 14,100 | ₩ 9,961
Book amount | 14,100 | 9,961
KT-CKP New Media Investment Fund [member] |  |
Disclosure Of Associates And Joint Ventures [Line Items] |  |
Net assets | ₩ 270 | ₩ 565
Percentage of ownership | 49.70% | 49.70%
Share in net assets | ₩ 134 | ₩ 280
Book amount | ₩ 134 | ₩ 280

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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 2019-01-01 -Paragraph 24 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2019-en-r&anchor=para_24_a&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2019-01-01 -Paragraph B16 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2019-en-r&anchor=para_B16&doctype=Appendix&subtype=B -URIDate 2019-03-27 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 54 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_54_e&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of assets less the amount of liabilities. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 1 -IssueDate 2019-01-01 -Paragraph IG63 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=1&code=ifrs-tx-2019-en-r&anchor=para_IG63&doctype=Implementation%20Guidance -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_112_c&doctype=Standard -URIDate 2019-03-27 + 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 2019-01-01 -Paragraph 17 -Subparagraph b -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2019-en-r&anchor=para_17_b_iii&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 27 -IssueDate 2019-01-01 -Paragraph 16 -Subparagraph b -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2019-en-r&anchor=para_16_b_iii&doctype=Standard -URIDate 2019-03-27 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2019-01-01 -Paragraph 21 -Subparagraph a -Clause iv -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2019-en-r&anchor=para_21_a_iv&doctype=Standard -URIDate 2019-03-27 + Details
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