Subsequent Events (Details) $ in Thousands, ₩ in Millions	12 Months Ended
Dec. 31, 2019 KRW (₩)	Dec. 31, 2019 USD ($)
Foreign bond
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea South-East Power Co., Ltd.
Issue date	Feb. 03, 2020
Maturity	Feb. 03, 2025
Interest rate (%)	2.13%	2.13%
Amounts issued for the subsequent period \| $		$ 300,000
#54-1 non-guaranteed corporate bond
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Midland Power Co., Ltd.
Issue date	Feb. 25, 2020
Maturity	Feb. 25, 2040
Interest rate (%)	1.53%	1.53%
Amounts issued for the subsequent period	₩ 50,000
#54-2 non-guaranteed corporate bond
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Midland Power Co., Ltd.
Issue date	Feb. 25, 2020
Maturity	Feb. 25, 2050
Interest rate (%)	1.53%	1.53%
Amounts issued for the subsequent period	₩ 120,000
#55 non-guaranteed corporate bond
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Hydro & Nuclear Power Co., Ltd.
Issue date	Mar. 18, 2020
Maturity	Mar. 18, 2040
Interest rate (%)	1.59%	1.59%
Amounts issued for the subsequent period	₩ 80,000
#55-1 non-guaranteed corporate bond
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Hydro & Nuclear Power Co., Ltd.
Issue date	Apr. 02, 2020
Maturity	Apr. 02, 2040
Interest rate (%)	1.80%	1.80%
Amounts issued for the subsequent period	₩ 50,000
#55-2 non-guaranteed corporate bond
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Hydro & Nuclear Power Co., Ltd.
Issue date	Apr. 02, 2020
Maturity	Apr. 02, 2050
Interest rate (%)	1.80%	1.80%
Amounts issued for the subsequent period	₩ 50,000
Foreign short-term borrowing 1
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Western Power Co., Ltd.
Issue date	Feb. 06, 2020
Maturity	May 06, 2020
Interest rate (%)	1.97%	1.97%
Amounts issued for the subsequent period \| $		$ 24,658
Foreign short-term borrowing 2
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Western Power Co., Ltd.
Issue date	Feb. 06, 2020
Maturity	May 26, 2020
Interest rate (%)	1.86%	1.86%
Amounts issued for the subsequent period \| $		$ 7,329

No definition available.

Name:	kep_BondsIssuedForSubsequentPeriod
Namespace Prefix:	kep_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date the debt instrument was issued, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_DebtInstrumentIssuanceDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Identification of the contractual issuer of the debt instrument (for example, a subsidiary of the reporting entity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Name:	us-gaap_DebtInstrumentIssuer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentAxis=kep_ForeignBondMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kep_NonGuaranteedCorporateBond541Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kep_NonGuaranteedCorporateBond542Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kep_Non-guaranteedCorporateBond55Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kep_Non-guaranteedCorporateBond551Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kep_Non-guaranteedCorporateBond552Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kep_ForeignShortTermBorrowing1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kep_ForeignShortTermBorrowing2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: