Principal assumptions on actuarial valuation (Details) - ₩ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Disclosure - Principal assumptions on actuarial valuation [Abstract]
Discount rate	2.75% ~ 2.90%	2.45% ~ 2.64%
Future salary and benefit levels	4.88%	5.23%
Weighted average duration	13.40	13.34

The expected rate of salary increases used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2017-01-01
-Paragraph 144
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_144&doctype=Standard
-URIDate 2017-03-09

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Period Type:	instant