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Related Party Transactions - Summary of Transactions Prior Liquidation (Detail) - KRW (₩) ₩ in Millions | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | --- | ---
Statement [Line Items] |  |  |
Dividend Income |  |  | ₩ 11,146
Payables | ₩ 20,857 | ₩ 57,907 |
K-Realty CR-REITs No.1 [member] |  |  |
Statement [Line Items] |  |  |
Dividend Income |  |  | 8,932
Others [member] |  |  |
Statement [Line Items] |  |  |
Dividend Income |  |  | ₩ 2,148
Acquisition of right of use assets [member] |  |  |
Statement [Line Items] |  |  |
Dividend Income |  | 776 |
Acquisition of right of use assets [member] | K-Realty CR-REITs No.1 [member] |  |  |
Statement [Line Items] |  |  |
Dividend Income |  | 776 |
Finance costs [member] | K-Realty CR-REITs No.1 [member] |  |  |
Statement [Line Items] |  |  |
Payables |  | 2,225 |
Interest Expense [member] |  |  |
Statement [Line Items] |  |  |
Payables | 917 | 2,225 |
Interest Expense [member] | K-Realty CR-REITs No.1 [member] |  |  |
Statement [Line Items] |  |  |
Payables | 917 |  |
Dividend Income [member] |  |  |
Statement [Line Items] |  |  |
Payables | 17,345 | 15,354 |
Dividend Income [member] | K-Realty CR-REITs No.1 [member] |  |  |
Statement [Line Items] |  |  |
Payables | 8,061 | 10,928 |
Dividend Income [member] | Others [member] |  |  |
Statement [Line Items] |  |  |
Payables | 43 | 146 |
Dividend Income [member] | Korea Information & Technology Investment Fund (KIF Investment Fund) [member] |  |  |
Statement [Line Items] |  |  |
Payables | 9,241 | ₩ 4,280 |
Interest income [member] |  |  |
Statement [Line Items] |  |  |
Dividend Income | 14 |  |
Interest income [member] | K Bank Inc. [member] |  |  |
Statement [Line Items] |  |  |
Dividend Income | ₩ 14 |  |

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