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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 |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Jan. 01, 2017
Disclosure of information about unconsolidated structured entities controlled by investment entity [line items] |  |  |
Book amount | ₩ 272,407 | ₩ 279,431 | ₩ 284,075
K Bank Inc. [member] |  |  |
Disclosure of information about unconsolidated structured entities controlled by investment entity [line items] |  |  |
Net assets | ₩ 280,083 | ₩ 233,775 |
Percentage of ownership | 10.00% | 10.00% |
Share in net assets | ₩ 52,655 | ₩ 42,108 |
Book amount | 52,655 | 42,108 |
Korea Information & Technology Fund [member] |  |  |
Disclosure of information about unconsolidated structured entities controlled by investment entity [line items] |  |  |
Net assets | ₩ 444,764 | ₩ 418,601 |
Percentage of ownership | 33.30% | 33.30% |
Share in net assets | ₩ 148,255 | ₩ 139,534 |
Book amount | 148,255 | 139,534 |
KT-SB Venture Investment Fund [member] |  |  |
Disclosure of information about unconsolidated structured entities controlled by investment entity [line items] |  |  |
Net assets | ₩ 8,940 | ₩ 5,884 |
Percentage of ownership | 50.00% | 50.00% |
Share in net assets | ₩ 4,470 | ₩ 2,942 |
Book amount | 4,470 | 2,942 |
KT-IBKC future investment fund [member] |  |  |
Disclosure of information about unconsolidated structured entities controlled by investment entity [line items] |  |  |
Net assets | ₩ 19,922 | ₩ 21,649 |
Percentage of ownership | 50.00% | 50.00% |
Share in net assets | ₩ 9,961 | ₩ 10,825 |
Book amount | 9,961 | 10,825 |
KT-CKP New Media Investment Fund [member] |  |  |
Disclosure of information about unconsolidated structured entities controlled by investment entity [line items] |  |  |
Net assets | ₩ 565 | ₩ 4,620 |
Percentage of ownership | 49.70% | 49.70% |
Share in net assets | ₩ 280 | ₩ 2,294 |
Book amount | ₩ 280 | ₩ 2,294 |

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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 2018-01-01 -Paragraph 24 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2018-03-01&anchor=para_24_a&doctype=Standard -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2018-01-01 -Paragraph B16 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_B16&doctype=Appendix&seq=2 -URIDate 2018-03-16 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 54 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_54_e&doctype=Standard -URIDate 2018-03-16 + Details
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