Pension Plans - Schedule of Components of Benefit Expense (Details) - KRW (₩) ₩ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Retirement Benefits [Abstract]
Service cost	₩ 154,307		₩ 226,787
Interest cost	8,381		10,991
Prior service cost
Total	₩ 162,687	₩ 165,654	₩ 237,778