Finance Income and Costs - Details of Finance Income and Costs (Parenthetical) (Detail) ₩ in Millions	12 Months Ended
Dec. 31, 2018 KRW (₩) shares
Analysis of income and expense [abstract]
Gain on disposal of shares of convertible redeemable bonds \| ₩	₩ 58,000
Disposal of shares of convertible redeemable bonds \| shares	200,000

Gain on disposal of shares of convertible redeemable bonds.

No definition available.

Name:	skm_GainOnDisposalOfSharesOfConvertibleRedeemableBonds
Namespace Prefix:	skm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration