Details of expense relating to defined benefit plans (Details) - KRW (₩) ₩ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure - Details of expense relating to defined benefit plans [Abstract]
Current service cost	₩ 392,820	₩ 378,930	₩ 315,811
Interest cost	79,524	67,104	63,808
Expected return on plan assets	(31,307)	(23,612)	(22,557)
Loss from settlement	(1,055)	(706)	(641)
Defined benefit	₩ 439,982	₩ 421,716	₩ 356,421

The decrease (increase) in the net defined benefit liability (asset) resulting from settlements. Settlements are transactions that eliminate all further legal or constructive obligations for part or all of the benefits provided under a defined benefit plan, other than a payment of benefits to, or on behalf of, employees that is set out in the terms of the plan and included in the actuarial assumptions. [Refer: Net defined benefit liability (asset); Defined benefit plans [member]; Actuarial assumptions [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2017-01-01
-Paragraph 141
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_141_d&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_GainsLossesArisingFromSettlementsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration