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Consolidated subsidiaries (Details)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Korea Hydro & Nuclear Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
Korea South-East Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
Korea Midland Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
Korea Western Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
Korea Southern Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
Korea East-West Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KEPCO Engineering & Construction Company, Inc.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Engineering and construction for utility plant and others Engineering and construction for utility plant and others
Location KOREA KOREA
Proportion of ownership (%) [1] 65.77% 65.77%
KEPCO Plant Service & Engineering Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Location KOREA KOREA
Proportion of ownership (%) 51.00% 51.00%
KEPCO Nuclear Fuel Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Nuclear fuel Nuclear fuel
Location KOREA KOREA
Proportion of ownership (%) 96.36% 96.36%
KEPCO KDN Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Electric power information technology and others Electric power information technology and others
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KEPCO International HongKong Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location HONG KONG HONG KONG
Proportion of ownership (%) 100.00% 100.00%
KEPCO International Philippines Inc.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location PHILIPPINES PHILIPPINES
Proportion of ownership (%) 100.00% 100.00%
KEPCO Gansu International Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location HONG KONG HONG KONG
Proportion of ownership (%) 100.00% 100.00%
KEPCO Philippines Holdings Inc.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location PHILIPPINES PHILIPPINES
Proportion of ownership (%) 100.00% 100.00%
KEPCO Philippines Corporation    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location PHILIPPINES PHILIPPINES
Proportion of ownership (%) 100.00% 100.00%
KEPCO Ilijan Corporation    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Construction and operation of utility plant Construction and operation of utility plant
Location PHILIPPINES PHILIPPINES
Proportion of ownership (%) 51.00% 51.00%
KEPCO Lebanon SARL    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location LEBANON LEBANON
Proportion of ownership (%) 100.00% 100.00%
KEPCO Neimenggu International Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location HONG KONG HONG KONG
Proportion of ownership (%) 100.00% 100.00%
KEPCO Shanxi International Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location HONG KONG HONG KONG
Proportion of ownership (%) 100.00% 100.00%
KOMIPO Global Pte Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location SINGAPORE SINGAPORE
Proportion of ownership (%) 100.00% 100.00%
KEPCO Netherlands B.V.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location NETHERLANDS NETHERLANDS
Proportion of ownership (%) 100.00% 100.00%
KOREA Imouraren Uranium Investment Corp.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location FRANCE FRANCE
Proportion of ownership (%) 100.00% 100.00%
KEPCO Australia Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
KOSEP Australia Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
KOMIPO Australia Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
KOWEPO Australia Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
KOSPO Australia Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
KEPCO Middle East Holding Company    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location BAHRAIN BAHRAIN
Proportion of ownership (%) 100.00% 100.00%
Qatrana Electric Power Company    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Construction and operation of utility plant Construction and operation of utility plant
Location JORDAN JORDAN
Proportion of ownership (%) 80.00% 80.00%
KHNP Canada Energy, Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location CANADA CANADA
Proportion of ownership (%) 100.00% 100.00%
KEPCO Bylong Australia Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
Korea Waterbury Uranium Limited Partnership    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location CANADA CANADA
Proportion of ownership (%) 80.00% 80.00%
KEPCO Holdings de Mexico    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location MEXICO MEXICO
Proportion of ownership (%) 100.00% 100.00%
KST Electric Power Company, S.A.P.I. de C.V.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Construction and operation of utility plant Construction and operation of utility plant
Location MEXICO MEXICO
Proportion of ownership (%) 56.00% 56.00%
KEPCO Energy Service Company    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location MEXICO MEXICO
Proportion of ownership (%) 100.00% 100.00%
KEPCO Netherlands S3 B.V.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location NETHERLANDS NETHERLANDS
Proportion of ownership (%) 100.00% 100.00%
PT. KOMIPO Pembangkitan Jawa Bali    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location INDONESIA INDONESIA
Proportion of ownership (%) 51.00% 51.00%
PT. Cirebon Power Service    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location INDONESIA INDONESIA
Proportion of ownership (%) [2] 27.50% 27.50%
KOWEPO International Corporation    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location PHILIPPINES PHILIPPINES
Proportion of ownership (%) 99.99% 99.99%
KOSPO Jordan LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location JORDAN JORDAN
Proportion of ownership (%) 100.00% 100.00%
EWP Philippines Corporation    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location PHILIPPINES PHILIPPINES
Proportion of ownership (%) 0.00% 100.00%
Reason Liquidation  
EWP America Inc.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
EWP Renewable Corporation    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
DG Fairhaven Power, LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location USA USA
Proportion of ownership (%) [3] 100.00% 100.00%
DG Whitefield, LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location USA USA
Proportion of ownership (%) 0.00% 100.00%
Reason Sale of shares  
Springfield Power, LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location USA USA
Proportion of ownership (%) 0.00% 100.00%
Reason Sale of shares  
KNF Canada Energy Limited    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location CANADA CANADA
Proportion of ownership (%) 100.00% 100.00%
EWP Barbados 1 SRL    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location BARBADOS BARBADOS
Proportion of ownership (%) 100.00% 100.00%
California Power Holdings, LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
Gyeonggi Green Energy Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 62.01% 62.01%
PT. Tanggamus Electric Power    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location INDONESIA INDONESIA
Proportion of ownership (%) 52.50% 52.50%
Gyeongju Wind Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 70.00% 70.00%
KOMIPO America Inc.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
EWPRC Biomass Holdings, LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
KOSEP USA, Inc.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
PT. EWP Indonesia    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location INDONESIA INDONESIA
Proportion of ownership (%) 99.96% 99.96%
KEPCO Netherlands J3 B.V.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location NETHERLANDS NETHERLANDS
Proportion of ownership (%) 100.00% 100.00%
Korea Offshore Wind Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
Global One Pioneer B.V.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location NETHERLANDS NETHERLANDS
Proportion of ownership (%) 100.00% 100.00%
Global Energy Pioneer B.V.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location NETHERLANDS NETHERLANDS
Proportion of ownership (%) 100.00% 100.00%
Mira Power Limited    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location PAKISTAN PAKISTAN
Proportion of ownership (%) [4] 76.00% 76.00%
KOSEP Material Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Recycling fly ashes Recycling fly ashes
Location KOREA KOREA
Proportion of ownership (%) 86.22% 86.22%
Commerce and Industry Energy Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) [5] 85.03% 85.03%
KEPCO KPS Philippines Corp.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Location PHILIPPINES PHILIPPINES
Proportion of ownership (%) 99.99% 99.99%
KOSPO Chile SpA    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location CHILE CHILE
Proportion of ownership (%) 100.00% 100.00%
PT. KOWEPO Sumsel Operation and Maintenance Services    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Location INDONESIA INDONESIA
Proportion of ownership (%) 95.00% 95.00%
HeeMang Sunlight Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
Fujeij Wind Power Company    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location JORDAN JORDAN
Proportion of ownership (%) 100.00% 100.00%
KOSPO Youngnam Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Location KOREA KOREA
Proportion of ownership (%) 50.00% 50.00%
VI Carbon Professional Private Special Asset Investment Trust 1    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location KOREA KOREA
Proportion of ownership (%) 96.67% 96.67%
Chitose Solar Power Plant LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location JAPAN JAPAN
Proportion of ownership (%) 80.10% 80.10%
KEPCO Energy Solution Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Energy service Energy service
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KEPCO Solar Co., Ltd. (formerly, Solar School Plant Co., Ltd.)    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KOSPO Power Services Ltda.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Location CHILE CHILE
Proportion of ownership (%) 65.00% 65.00%
Energy New Industry Specialized Investment Private Investment Trust    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location KOREA KOREA
Proportion of ownership (%) 99.01% 99.01%
KOEN Bylong Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
KOMIPO Bylong Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
KOWEPO Bylong Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
KOSPO Bylong Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
EWP Bylong Pty., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Location AUSTRALIA AUSTRALIA
Proportion of ownership (%) 100.00% 100.00%
KOWEPO Lao International    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Location LAOS LAOS
Proportion of ownership (%) 100.00% 100.00%
KEPCO US Inc.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
KEPCO Alamosa LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 50.10% 50.10%
KEPCO Solar of Alamosa, LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
KEPCO Mangilao Holdings LLC (formerly, KEPCO-LG CNS Mangilao Holdings LLC)    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) [6] 100.00% 70.00%
Mangilao Investment LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
KEPCO Mangilao Solar, LLC (formerly, KEPCO-LG CNS Mangilao Solar, LLC)    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
Jeju Hanlim Offshore Wind Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 75.99% 75.99%
PT. Siborpa Eco Power    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Construction and operation of utility plant Construction and operation of utility plant
Location INDONESIA INDONESIA
Proportion of ownership (%) 55.00% 55.00%
BSK E-New Industry Fund VII    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location KOREA KOREA
Proportion of ownership (%) 81.67% 81.67%
e-New Industry LB Fund 1    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location KOREA KOREA
Proportion of ownership (%) 76.11% 76.11%
Songhyun e-New Industry Fund    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location KOREA KOREA
Proportion of ownership (%) 80.65% 80.65%
PT. Korea Energy Indonesia    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance
Location INDONESIA INDONESIA
Proportion of ownership (%) 95.00% 95.00%
KOLAT SpA    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Location CHILE CHILE
Proportion of ownership (%) 100.00% 100.00%
KEPCO California, LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
KEPCO Mojave Holdings, LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
Incheon Fuel Cell Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 60.00% 60.00%
KOEN Service Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance and service Facility maintenance and service
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KOMIPO Service Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance and service Facility maintenance and service
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KOWEPO Service Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance and service Facility maintenance and service
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KOSPO Service Co., Ltd    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance and service Facility maintenance and service
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
EWP Service Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance and service Facility maintenance and service
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
PT. KOMIPO Energy Indonesia    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Location INDONESIA INDONESIA
Proportion of ownership (%) 95.00% 95.00%
KNF Partners Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance Facility maintenance
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KOSPO USA Inc.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
Nambu USA LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
Tamra Offshore Wind Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 63.00% 63.00%
KEPCO MCS Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Electric meter reading and others Electric meter reading and others
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KEPCO FMS Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Security service and others Security service and others
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
Firstkeepers Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance Facility maintenance
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
Secutec Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Security service Security service
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
SE Green Energy Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 84.80% 84.80%
KEPCO Mangilao America LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) [7] 100.00% 100.00%
Mangilao Intermediate Holdings LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location USA USA
Proportion of ownership (%) 100.00% 100.00%
KEPCO CSC Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance and service Facility maintenance and service
Location KOREA KOREA
Proportion of ownership (%) 100.00% 100.00%
KOAK Power Limited    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance Facility maintenance
Location PARKISTAN PARKISTAN
Proportion of ownership (%) 100.00% 100.00%
KOMIPO Europe B.V.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location NETHERLANDS NETHERLANDS
Proportion of ownership (%) 100.00% 100.00%
Haenanum Energy Fund    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Location KOREA KOREA
Proportion of ownership (%) 99.64% 99.64%
Paju Ecoenergy Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Location KOREA KOREA
Proportion of ownership (%) 89.00% 89.00%
BSK E-New Industry Fund X    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Location KOREA  
Proportion of ownership (%) 66.80%  
Reason Newly established  
Guam Ukudu Power LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation  
Location USA  
Proportion of ownership (%) 100.00%  
Reason Newly established  
TS Energy No. 25 Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation  
Location KOREA  
Proportion of ownership (%) 90.00%  
Reason New investment  
KPS Partners Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance and service  
Location KOREA  
Proportion of ownership (%) 100.00%  
Reason Newly established  
KEPCO E&C Service Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Facility maintenance and service  
Location KOREA  
Proportion of ownership (%) 100.00%  
Reason Newly established  
Moha Solar Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation  
Location KOREA  
Proportion of ownership (%) 100.00%  
Reason New investment  
Ogiri Solar Power Co., Ltd.    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation  
Location KOREA  
Proportion of ownership (%) 70.00%  
Reason Newly established  
KHNP USA LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Location USA  
Proportion of ownership (%) 100.00%  
Reason Newly established  
KOMIPO Vanphong Power Service LLC    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others  
Location VIETNAM  
Proportion of ownership (%) 100.00%  
Reason Newly established  
Energy Innovation Fund I    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Location KOREA  
Proportion of ownership (%) 71.91%  
Reason Additional acquisition  
[1] Considering treasury stocks, the effective percentage of ownership is 66.08%.
[2] The effective percentage of ownership is less than 50%. However, this subsidiary is included in the consolidated financial statements as the Company obtained the majority of the voting power through the shareholders' agreement.
[3] As 100% of the shares held were sold after the end of the reporting period, the assets of DG Fairhaven Power, LLC were classified as assets held-for-sale.
[4] As of the reporting date, the annual reporting period of all subsidiaries is December 31, except for Mira Power Limited which is November 30.
[5] The Company guarantees a certain return on investment related to Commerce and Industry Energy Co., Ltd. for the financial investors. The financial investors have a right to sell their shares to the Company which can be exercised 84 months after the date of investment. Accordingly, the purchase price including the return on investment is classified as a liability.
[6] As of the end of the reporting period, the Company does not have a shareholding; however, this subsidiary is included in the consolidated financial statements as the Company has control over the entity by virtue of the right to nominate all 4 members of the board of directors.
[7] As of the end of the reporting period, the Company does not have a shareholding; however, this subsidiary is included in the consolidated financial statements as the Company has control over the entity by virtue of the right to nominate the CEO and key management members.