XML 128 R164.htm IDEA: XBRL DOCUMENT
v3.20.1

Accumulated Other Comprehensive Income and Other Components of Equity - Summary of Changes in Accumulated Other Comprehensive Income (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
Beginning | ₩ 50,158 | ₩ 30,985
Changes in accounting policy |  | 17,741
Increase /decrease | 189,460 | 45,711
Reclassified to gain or loss | (44,684) | (44,279)
Ending | 194,934 | 50,158
Changes in investments in associates and joint ventures [member] |  |
Beginning | (871) | (735)
Increase /decrease | 2,427 | (136)
Ending | 1,556 | (871)
Gain or Loss on derivatives valuation [member] |  |
Beginning | (30,474) | (3,463)
Increase /decrease | 67,534 | 17,268
Reclassified to gain or loss | (44,684) | (44,279)
Ending | (7,624) | (30,474)
Gain on valuation of financial assets at fair value through other comprehensive income [member] |  |
Beginning | 96,704 | 52,673
Changes in accounting policy |  | 17,741
Increase /decrease | 114,869 | 26,290
Ending | 211,573 | 96,704
Exchange differences on translation for foreign operations [member] |  |
Beginning | (15,201) | (17,490)
Increase /decrease | 4,630 | 2,289
Ending | ₩ (10,571) | ₩ (15,201)

X
- Definition The amount of accumulated items of income and expense (including reclassification adjustments) that are not recognised in profit or loss as required or permitted by other IFRSs. [Refer: IFRSs [member]; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_55&doctype=Standard -URIDate 2019-03-27 + Details
Name: | ifrs-full_AccumulatedOtherComprehensiveIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of other comprehensive income that will be reclassified to profit or loss, before tax. [Refer: Other comprehensive income] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph IG6 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_IG6&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 82A -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_82A&doctype=Standard -URIDate 2019-03-27 + Details
Name: | ifrs-full_OtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossBeforeTax
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Changes in accounting policies adjustments. + References No definition available. + Details
Name: | kt_ChangesInAccountingPoliciesAdjustments
Namespace Prefix: | kt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Increase (decrease) in other comprehensive income + References No definition available. + Details
Name: | kt_IncreaseDecreaseInOtherComprehensiveIncome
Namespace Prefix: | kt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | ifrs-full_ComponentsOfEquityAxis=kt_ChangesinInvestmentsInAssociatesandJointVenturesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ComponentsOfEquityAxis=kt_GainOrLossOnDerivativesValuationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ComponentsOfEquityAxis=kt_GainOnValuationOfFinancialAssetsAtFairValueThroughOtherComprehensiveIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ComponentsOfEquityAxis=kt_ExchangeDifferencesOnTranslationForForeignOperationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |