Lease - Additional Information (Details) - KRW (₩) ₩ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Statements [Line Items]
Expense relating to short-term leases for which recognition exemption has been used	₩ 199,490	₩ 45,787
Expense relating to leases of low-value assets for which recognition exemption has been used	2,349	2,796
Cash outflow related to leases	922,200	807,609
Discounted unguaranteed residual value of assets	₩ 19,574	₩ 16,407
Maximum
Statements [Line Items]
Implicit interest rate on finance lease	16.83%	16.60%
Minimum
Statements [Line Items]
Implicit interest rate on finance lease	0.00%	1.39%
Power Purchase Agreement \| Maximum
Statements [Line Items]
Lease term of finance lease	11 years
Power Purchase Agreement \| Minimum
Statements [Line Items]
Lease term of finance lease	2 years
Jordan Electric Power Company \| Power Purchase Agreement
Statements [Line Items]
Lease term of finance lease	25 years
Fujeij Wind Power Plant \| Power Purchase Agreement
Statements [Line Items]
Lease term of finance lease	20 years
Fly Ash Pipe Conduit \| Power Purchase Agreement
Statements [Line Items]
Average Lease Term	7 years
Commission Federal De Elecrticidad \| Power Purchase Agreement
Statements [Line Items]
Lease term of finance lease	25 years

The cash outflow for leases.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2021-01-01
-Paragraph 53
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2021-en-r&anchor=para_53_g&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_CashOutflowForLeases
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of the discounted unguaranteed residual value of assets subject to finance leases. Unguaranteed residual value is the portion of the residual value of the underlying asset, the realisation of which by a lessor is not assured or is guaranteed solely by a party related to the lessor. Finance lease is a lease that transfers substantially all the risks and rewards incidental to ownership of an underlying asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2021-01-01
-Paragraph 94
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2021-en-r&anchor=para_94&doctype=Standard
-URIDate 2021-03-24

+ Details

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

- Definition

The amount of the expense relating to leases of low-value assets accounted for applying paragraph 6 of IFRS 16. This expense shall not include the expense relating to short-term leases of low-value assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2021-01-01
-Paragraph 53
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2021-en-r&anchor=para_53_d&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_ExpenseRelatingToLeasesOfLowvalueAssetsForWhichRecognitionExemptionHasBeenUsed
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of the expense relating to short-term leases accounted for applying paragraph 6 of IFRS 16. This expense need not include the expense relating to leases with a lease term of one month or less. Short-term lease is a lease that, at the commencement date, has a lease term of 12 months or less. A lease that contains a purchase option is not a short-term lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2021-01-01
-Paragraph 53
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2021-en-r&anchor=para_53_c&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_ExpenseRelatingToShorttermLeasesForWhichRecognitionExemptionHasBeenUsed
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Average lease term

+ References

No definition available.

+ Details

Name:	kep_AverageLeaseTerm
Namespace Prefix:	kep_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

implicit interest rate on finance lease.

+ References

No definition available.

+ Details

Name:	kep_ImplicitInterestRateOnFinanceLease
Namespace Prefix:	kep_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Lease term of finance lease.

+ References

No definition available.

+ Details

Name:	kep_LeaseTermOfFinanceLease
Namespace Prefix:	kep_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Statements.

+ References

No definition available.

+ Details

Name:	kep_StatementsLineItems
Namespace Prefix:	kep_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	kep_AgreementNameAxis=kep_PowerPurchaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	kep_CounterpartiesNamesAxis=kep_JordanElectricPowerCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	kep_CounterpartiesNamesAxis=kep_FujeijWindPowerPlantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	kep_CounterpartiesNamesAxis=kep_FlyAshPipeConduitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	kep_CounterpartiesNamesAxis=kep_CommissionFederalDeElecrticidadMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: