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Other Financial Assets and Liabilities - Summary of Hedging instruments (Detail) - Derivatives [member] - KRW (₩) ₩ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019
Disclosure of detailed information about hedging instruments [line items] |  |
Contract amount | ₩ 2,771,700 | ₩ 2,616,123
Assets | 7,684 | 58,576
Liabilities | 127,929 | 20,096
Changes in fair value to calculate the ineffective portion of hedges | (154,528) | 64,876
USD |  |
Disclosure of detailed information about hedging instruments [line items] |  |
Foreign currency | 1,768,912 | 1,574,068
Contract amount | 2,037,568 | 1,788,831
Assets | 2,111 | 30,175
Liabilities | 100,623 | 10,692
Changes in fair value to calculate the ineffective portion of hedges | (136,852) | 49,480
JPY |  |
Disclosure of detailed information about hedging instruments [line items] |  |
Foreign currency | 46,000,000 | 80,000,000
Contract amount | 488,924 | 827,292
Assets | 5,573 | 28,401
Liabilities | 13,839 | 9,404
Changes in fair value to calculate the ineffective portion of hedges | (4,065) | ₩ 15,396
SGD |  |
Disclosure of detailed information about hedging instruments [line items] |  |
Foreign currency | 284,000 |
Contract amount | 245,208 |
Liabilities | 13,467 |
Changes in fair value to calculate the ineffective portion of hedges | ₩ (13,611) |

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- Definition The gain (loss) on the change in fair value of the hedging instrument used as a basis for recognising hedge ineffectiveness. Hedge ineffectiveness is the extent to which the changes in the fair value or the cash flows of the hedging instrument are greater or less than those on the hedged item. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 24A -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_24A_c&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of a hedging instrument, recognised as an asset. [Refer: Hedging instruments [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 24A -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_24A_a&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of a hedging instrument, recognised as a liability. [Refer: Hedging instruments [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 24A -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_24A_a&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The nominal amount of the hedging instruments in hedging relationships to which the entity is applying the exceptions in the scope of the amendments for interest rate benchmark reform. [Refer: Nominal amount of hedging instrument] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 24H -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_24H_e&doctype=Standard -URIDate 2020-01-01 + Details
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