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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, 2018 | Dec. 31, 2017
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | ₩ 10,387,651 |
Ending balance | 10,844,722 | ₩ 10,387,651
Beginning balance | 15,297,610 |
Ending balance | 15,334,068 | 15,297,610
Financial assets at fair value through profit or loss [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | 5,913 |
Ending balance | 777,685 | 5,913
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 | 5,813 | 6,277
Amount recognized in profit or loss |  | (464)
Ending balance |  | 5,813
Recurring fair value measurement [Member] | Level 3 [Member] | Available-for-sale [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | 307,077 | 287,889
Purchases |  | 85,287
Reclassification |  | (277)
Sales |  | (124,159)
Amount recognized in profit or loss |  | (113)
Amount recognized in other comprehensive income |  | 58,450
Ending balance |  | 307,077
Recurring fair value measurement [Member] | Level 3 [Member] | Other derivative liabilities [Member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | 5,051 | 1,973
Purchases |  | 0
Reclassification |  | 0
Sales |  | 0
Amount recognized in profit or loss |  | 3,078
Ending balance |  | 5,051
Recurring fair value measurement [Member] | Level 3 [Member] | Derivative financial liabilities [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Beginning balance | 17,725 |
Changes in accounting policy | 0 |
Purchases | 0 | 0
Reclassification | 0 | 0
Changes in scope of consolidation | 0 |
Sales | 0 | 0
Amount recognized in profit or loss | (17,255) | 19,634
Amount recognized in other comprehensive income | 9,713 | (1,909)
Ending balance | 10,183 | 17,725
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 | 5,051 |
Changes in accounting policy | 0 |
Purchases | 0 |
Reclassification | 0 |
Changes in scope of consolidation | 0 |
Sales | 0 |
Amount recognized in profit or loss | 2,707 |
Ending balance | 7,758 | 5,051
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 | 97,547 |
Changes in accounting policy | 32,745 |
Purchases | 21,365 |
Reclassification | 1,581 |
Sales | (1,852) |
Amount recognized in profit or loss | 12,214 |
Ending balance | 163,600 | 97,547
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 | 238,517 |
Changes in accounting policy | 2,085 |
Purchases | 8,802 |
Reclassification | (296) |
Changes in scope of consolidation | 364 |
Sales | (1,099) |
Amount recognized in profit or loss | 89 |
Amount recognized in other comprehensive income | 63,074 |
Ending balance | ₩ 311,536 | ₩ 238,517

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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 2018-01-01 -Paragraph 25 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_25&doctype=Standard -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 35H -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35H&doctype=Standard -URIDate 2018-03-16 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 35I -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35I&doctype=Standard -URIDate 2018-03-16 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 35M -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35M&doctype=Standard -URIDate 2018-03-16 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 35N -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35N&doctype=Standard -URIDate 2018-03-16 + Details
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