Commitments and Contingencies - Additional Information (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2018	Dec. 31, 2017
Commitments and contingencies [Line Items]
Short-term financial instruments as collateral for guarantees	₩ 1,045,676	₩ 616,780
Sales of handsets [member]
Commitments and contingencies [Line Items]
Accounts receivables - other	612,779
Legal proceedings provision [member]
Commitments and contingencies [Line Items]
Provisions for legal claims and litigation	0
Current provisions for legal claims and litigation	36,844
Non-current provisions for legal claims and litigation	57,310
SK Broadband Co., Ltd. [member]
Commitments and contingencies [Line Items]
Properties pledged as collateral for leases on buildings	3,868
Short-term financial instruments as collateral for guarantees	11
Life and Security Holdings Co., Ltd. [member]
Commitments and contingencies [Line Items]
Shares pledged for long-term borrowings	₩ 1,900,000

The amount of outstanding funds that the entity is obligated to repay.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_55&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_Borrowings
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of current provisions. [Refer: Provisions]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 54
-Subparagraph l
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_54_l&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_CurrentProvisions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of non-current provisions. [Refer: Provisions]

+ References

+ Details

Name:	ifrs-full_NoncurrentProvisions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of current financial assets that the entity does not separately disclose in the same statement or note. [Refer: Other financial assets; Current financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 54
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_54_d&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_OtherCurrentFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of provisions other than provisions for employee benefits. [Refer: Provisions]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 37
-IssueDate 2018-01-01
-Paragraph 84
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2018-03-01&anchor=para_84_a&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 78
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_78_d&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_OtherProvisions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount receivable by the entity that it does not separately disclose in the same statement or note.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 78
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_78_b&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_OtherReceivables
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of property, plant and equipment pledged as security for liabilities. [Refer: Property, plant and equipment]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 16
-IssueDate 2018-01-01
-Paragraph 74
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=16&date=2018-03-01&anchor=para_74_a&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_PropertyPlantAndEquipmentPledgedAsSecurity
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Commitments and contingencies.

+ References

No definition available.

+ Details

Name:	skm_CommitmentsAndContingenciesLineItems
Namespace Prefix:	skm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ifrs-full_ProductsAndServicesAxis=skm_SalesOfHandsetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfProvisionsAxis=ifrs-full_LegalProceedingsProvisionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=skm_SKBroadbandCoLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=skm_LifeAndSecurityHoldingsCoLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: