Inventories (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2018	Dec. 31, 2017
Inventory [Line Items]
Raw materials	₩ 3,884,130	₩ 3,526,006
Merchandise		107
Work-in-progress	188,879	137,681
Finished goods	50,526	71,406
Supplies	1,854,844	1,577,721
Inventories in transit	1,196,113	679,358
Other inventories	13,761	9,807
Total Inventories	7,188,253	6,002,086
Acquisition cost
Inventory [Line Items]
Raw materials	3,886,739	3,528,835
Merchandise		107
Work-in-progress	189,907	138,709
Finished goods	50,526	72,923
Supplies	1,858,751	1,581,661
Inventories in transit	1,196,113	679,358
Other inventories	13,761	9,807
Total Inventories	7,195,797	6,011,400
Valuation allowance
Inventory [Line Items]
Raw materials	(2,609)	(2,829)
Merchandise		0
Work-in-progress	(1,028)	(1,028)
Finished goods	0	(1,517)
Supplies	(3,907)	(3,940)
Inventories in transit	0	0
Other inventories	0	0
Total Inventories	₩ (7,544)	₩ (9,314)

A classification of current inventory representing the amount of inventories in transit. [Refer: Inventories]

Name:	ifrs-full_CurrentInventoriesInTransit
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of current inventories. [Refer: Inventories]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 2
-IssueDate 2018-01-01
-Paragraph 36
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=2&date=2018-03-01&anchor=para_36_b&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 54
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_54_g&doctype=Standard
-URIDate 2018-03-16

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 68
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_68&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_Inventories
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

A classification of current inventory representing the amount of goods acquired for resale. [Refer: Inventories]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 2
-IssueDate 2018-01-01
-Paragraph 37
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=2&date=2018-03-01&anchor=para_37&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 78
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_78_c&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_Merchandise
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of inventory that the entity does not separately disclose in the same statement or note. [Refer: Inventories]

+ References

+ Details

Name:	ifrs-full_OtherInventories
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

A classification of current inventory representing the amount of supplies to be used for the production process. [Refer: Inventories]

+ References

+ Details

Name:	ifrs-full_ProductionSupplies
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

A classification of current inventory representing the amount of assets to be consumed in the production process or in the rendering of services. [Refer: Inventories]

+ References

+ Details

Name:	ifrs-full_RawMaterials
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_InventoryFinishedGoods
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_InventoryLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_InventoryWorkInProcess
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_PublicUtilitiesInventoryAxis=ifrs-full_GrossCarryingAmountMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesInventoryAxis=us-gaap_FairValueAdjustmentToInventoryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: