Principal assumptions on actuarial valuation (Details) - ₩ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Disclosure - Principal assumptions on actuarial valuation [Abstract]
Discount rate	1.87%~2.12%	1.92%~2.05%
Future salary and benefit levels	4.28%	4.39%
Weighted average duration	10.77	10.95

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 2020-01-01
-Paragraph 144
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_144&doctype=Standard
-URIDate 2020-01-01

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant