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v3.21.1

Retained Earnings - Summary of Retained Earnings (Parenthetical) (Detail) | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019
Miscellaneous equity [abstract] |  |
Minimum percentage of cash dividend declared appropriation to legal reserve | 10.00% | 10.00%
Percentage of legal reserve equal to capital stock issued | 50.00% | 50.00%

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- References No definition available. + Details
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Period Type: | duration

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- Definition Minimum percentage of cash dividend declared appropriation to legal reserve. + References No definition available. + Details
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Namespace Prefix: | kt_
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- Definition Percentage of legal reserves equal to capital stock. + References No definition available. + Details
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Namespace Prefix: | kt_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration