Fair Value - Summary of Valuation Techniques and Inputs (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other financial assets
Derivative financial assets for hedging purpose	₩ 7,389	₩ 227,318
Available-for-sale financial assets	380,953	404,774	₩ 360,037
Investment properties	1,189,531	1,148,044	₩ 1,102,070
Other financial liabilities
Derivative financial liabilities for hedging purpose	93,770	14,928
Borrowings	6,683,662	8,120,791
Recurring fair value measurement [Member]
Other financial assets
Derivative financial assets for hedging purpose	7,389	227,318
Available-for-sale financial assets	319,402	299,001
Other financial liabilities
Derivative financial liabilities for hedging purpose	93,770	14,928
Recurring fair value measurement [Member] \| Level 3 [Member]
Other financial assets
Available-for-sale financial assets	307,077	287,889
Other financial liabilities
Derivative financial liabilities for hedging purpose	17,725
Recurring fair value measurement [Member] \| Level 3 [Member] \| Financial assets at fair value through profit or loss [member]
Other financial assets
Others	5,813	6,277
Other financial liabilities
Other derivative financial liabilities	₩ 5,051	₩ 1,973
Valuation techniques	Discounted cash flow model	Discounted cash flow model
Valuation techniques	Discounted cash flow model Comparable Company Analysis	Discounted cash flow model Comparable Company Analysis
Valuation techniques	Discounted cash flow model	Discounted cash flow model
Valuation techniques	Discounted cash flow model Comparable Company Analysis	Discounted cash flow model Comparable Company Analysis
Recurring fair value measurement [Member] \| Level 2 [Member]
Other financial assets
Derivative financial assets for hedging purpose	₩ 7,389	₩ 227,318
Available-for-sale financial assets	5,466	5,725
Other financial liabilities
Derivative financial liabilities for hedging purpose	₩ 76,045	₩ 14,928
Valuation techniques	Discounted cash flow model	Discounted cash flow model
Valuation techniques		Discounted cash flow model
Valuation techniques	Discounted cash flow model	Discounted cash flow model
Valuation techniques		Discounted cash flow model
Recurring fair value measurement [Member] \| Level 2, 3 [Member]
Other financial assets
Available-for-sale financial assets	₩ 312,543	₩ 293,614
Other financial liabilities
Derivative financial liabilities for hedging purpose	₩ 93,770
Valuation techniques	Discounted cash flow model	Discounted cash flow model
Valuation techniques	Hull-White Model, Discounted cash flow model
Valuation techniques	Discounted cash flow model	Discounted cash flow model
Valuation techniques	Hull-White Model, Discounted cash flow model
Not measured at fair value in statement of financial position but for which fair value is disclosed [Member]
Other financial assets
Investment properties	₩ 1,755,600	₩ 1,962,779
Other financial liabilities
Borrowings	6,738,326	8,184,195
Not measured at fair value in statement of financial position but for which fair value is disclosed [Member] \| Level 3 [Member]
Other financial assets
Investment properties	1,755,600	1,962,779
Other financial liabilities
Borrowings	₩ 6,738,326	₩ 8,184,195
Valuation techniques	Discounted cash flow model	Discounted cash flow model
Valuation techniques	Discounted cash flow model	Discounted cash flow model
Valuation techniques	Discounted cash flow model	Discounted cash flow model
Valuation techniques	Discounted cash flow model	Discounted cash flow model

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

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The description of the valuation techniques (for example, the market approach, cost approach and income approach) used for the fair value measurement of assets. [Refer: Valuation techniques [member]; Cost approach [member]; Income approach [member]; Market approach [member]]

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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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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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