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Fair Value - Summary of Changes in Level 3 of Fair Value Hierarchy for Recurring Fair Value Measurements (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | ₩ 11,000,665 |
Ending balance | 10,476,853 | ₩ 11,000,665
Beginning balance | 16,128,644 |
Ending balance | 14,597,106 | 16,128,644
Financial assets at fair value through profit or loss [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | 632,324 |
Ending balance | 809,919 | 632,324
Level 3 [Member] | Financial assets at fair value through profit or loss [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Disposal |  | (9,734)
Recurring fair value measurement [Member] | Level 3 [Member] | Financial assets at fair value through profit or loss [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | 495,141 |
Purchases | 374,259 |
Reclassification | 208 |
Disposal | (451,663) | (485,419)
Amount recognized in profit or loss | 14,564 |
Ending balance | 432,509 | 495,141
Recurring fair value measurement [Member] | Level 3 [Member] | Derivative financial liabilities [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | 17,788 | (10,183)
Amount recognized in profit or loss |  | 14,462
Amount recognized in other comprehensive income |  | 13,509
Ending balance |  | 17,788
Beginning balance | (17,788) |
Amount recognized in profit or loss | 29,345 |
Amount recognized in other comprehensive income | (7,363) |
Ending balance | 4,194 | (17,788)
Recurring fair value measurement [Member] | Level 3 [Member] | Financial liabilities designated as at fair value through profit or loss [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance |  | 7,758
Amount recognized in profit or loss | (161) | 1,976
Recurring fair value measurement [Member] | Level 3 [Member] | Financial assets at fair value through profit or loss [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | 495,141 | 163,600
Purchases |  | 584,671
Reclassification |  | 225,873
Amount recognized in profit or loss |  | 6,416
Ending balance |  | 495,141
Purchases | 2,798 |
Ending balance | 2,637 |
Recurring fair value measurement [Member] | Level 3 [Member] | Financial assets at fair value through other comprehensive income [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | 42,054 | 311,536
Purchases | 13,142 | 6,081
Reclassification |  | (444,782)
Disposal | (571) | (941)
Amount recognized in profit or loss | (428) |
Amount recognized in other comprehensive income | (3,408) | 170,160
Ending balance | ₩ 50,789 | ₩ 42,054

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- Definition The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 25 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_25&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 35H -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_35H&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 35I -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_35I&doctype=Standard -URIDate 2020-01-01 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 35M -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_35M&doctype=Standard -URIDate 2020-01-01 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 35N -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_35N&doctype=Standard -URIDate 2020-01-01 + Details
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