Fair Value - Summary of Fair Value Hierarchy Classifications of Financial Assets and Financial Liabilities That are Measured at Fair Value (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through profit or loss	₩ 5,813	₩ 6,277
Associates and joint ventures	279,431	284,075
Borrowings	6,683,662	8,120,791
Derivative financial assets for hedging purpose	7,389	227,318
Investment properties	1,189,531	1,148,044	₩ 1,102,070
Available-for-sale financial assets	380,953	404,774	₩ 360,037
Financial assets	10,237,369	10,216,182
Financial assets, at fair value	2,088,204	2,499,315
Financial liabilities at fair value through profit or loss	5,051	1,973
Derivative financial liabilities for hedging purpose	93,770	14,928
Financial liabilities	15,295,656	16,557,537
Financial liabilities, at fair value	6,837,147	8,201,096
Recurring fair value measurement [Member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through profit or loss	5,813	6,277
Derivative financial assets for hedging purpose	7,389	227,318
Available-for-sale financial assets	319,402	299,001
Financial assets	332,604	532,596
Financial liabilities at fair value through profit or loss	5,051	1,973
Derivative financial liabilities for hedging purpose	93,770	14,928
Financial liabilities	98,821	16,901
Not measured at fair value in statement of financial position but for which fair value is disclosed [Member]
Disclosure of detailed information about financial instruments [Line Items]
Associates and joint ventures		3,940
Borrowings	6,738,326	8,184,195
Investment properties	1,755,600	1,962,779
Financial assets	1,755,600	1,966,719
Financial liabilities	6,738,326	8,184,195
Level 1 [Member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets, at fair value	6,859	9,327
Level 1 [Member] \| Recurring fair value measurement [Member]
Disclosure of detailed information about financial instruments [Line Items]
Available-for-sale financial assets	6,859	5,387
Financial assets	6,859	5,387
Level 1 [Member] \| Not measured at fair value in statement of financial position but for which fair value is disclosed [Member]
Disclosure of detailed information about financial instruments [Line Items]
Associates and joint ventures		3,940
Financial assets		3,940
Level 2 [Member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets, at fair value	12,855	233,043
Financial liabilities, at fair value	76,045	14,928
Level 2 [Member] \| Recurring fair value measurement [Member]
Disclosure of detailed information about financial instruments [Line Items]
Derivative financial assets for hedging purpose	7,389	227,318
Available-for-sale financial assets	5,466	5,725
Financial assets	12,855	233,043
Derivative financial liabilities for hedging purpose	76,045	14,928
Financial liabilities	76,045	14,928
Level 3 [Member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets, at fair value	2,068,490	2,256,945
Financial liabilities, at fair value	6,761,102	8,186,168
Level 3 [Member] \| Recurring fair value measurement [Member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through profit or loss	5,813	6,277
Available-for-sale financial assets	307,077	287,889
Financial assets	312,890	294,166
Financial liabilities at fair value through profit or loss	5,051	1,973
Derivative financial liabilities for hedging purpose	17,725
Financial liabilities	22,776	1,973
Level 3 [Member] \| Not measured at fair value in statement of financial position but for which fair value is disclosed [Member]
Disclosure of detailed information about financial instruments [Line Items]
Borrowings	6,738,326	8,184,195
Investment properties	1,755,600	1,962,779
Financial assets	1,755,600	1,962,779
Financial liabilities	₩ 6,738,326	₩ 8,184,195

The amount of outstanding funds that the entity is obligated to repay.

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The amount of financial assets classified as derivative instruments. [Refer: Financial assets; Derivatives [member]]

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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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]

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The fair value of financial assets. [Refer: At fair value [member]; Financial assets]

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The amount of financial assets that are measured at fair value and for which gains (losses) are recognised in profit or loss. A financial asset shall be measured at fair value through profit or loss unless it is measured at amortised cost or at fair value through other comprehensive income. A gain (loss) on a financial asset measured at fair value shall be recognised in profit or loss unless it is part of a hedging relationship, it is an investment in an equity instrument for which the entity has elected to present gains and losses in other comprehensive income or it is a financial asset measured at fair value through other comprehensive income. [Refer: At fair value [member]; Financial assets]

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The amount of non-derivative financial assets that are designated as available for sale or are not classified as (a) loans and receivables; (b) held-to-maturity investments; or (c) financial assets at fair value through profit or loss. [Refer: Derivative financial assets; Financial assets at fair value through profit or loss; Held-to-maturity investments]

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The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) 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 deliver 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, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are 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. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Financial instruments, class [member]; Financial assets; Derivatives [member]]

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The fair value of financial liabilities. [Refer: At fair value [member]; Financial liabilities]

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The amount of financial liabilities that meet either of the following conditions: (a) they meet the definition of held for trading; or (b) upon initial recognition they are designated by the entity as at fair value through profit or loss. An entity may use this designation only when permitted by paragraph 4.3.5 of IFRS 9 (embedded derivatives) or when doing so results in more relevant information, because either: (a) it eliminates or significantly reduces a measurement or recognition inconsistency (sometimes referred to as ‘an accounting mismatch’) that would otherwise arise from measuring assets or liabilities or recognising the gains and losses on them on different bases; or (b) a group of financial liabilities or financial assets and financial liabilities is managed and its performance is evaluated on a fair value basis, in accordance with a documented risk management or investment strategy, and information about the group is provided internally on that basis to the entity’s key management personnel (as defined in IAS 24). [Refer: At fair value [member]; Key management personnel of entity or parent [member]; Derivatives [member]; Financial assets; Financial liabilities]

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The amount of investments accounted for using the equity method. The equity method is a method of accounting whereby the investment is initially recognised at cost and adjusted thereafter for the post-acquisition change in the investor's share of net assets of the investee. The investor's profit or loss includes its share of the profit or loss of the investee. The investor's other comprehensive income includes its share of the other comprehensive income of the investee. [Refer: At cost [member]]

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Expiry date 2019-01-01: The amount of property (land or a building - or part of a building - or both) held (by the owner or by the lessee under a finance lease) to earn rentals or for capital appreciation or both, rather than for: (a) use in the production or supply of goods or services or for administrative purposes; or (b) sale in the ordinary course of business. Effective 2019-01-01: The amount of property (land or a building - or part of a building - or both) held (by the owner or by the lessee as a right-of-use asset) to earn rentals or for capital appreciation or both, rather than for: (a) use in the production or supply of goods or services or for administrative purposes; or (b) sale in the ordinary course of business.

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