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Consolidated subsidiaries (Details)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Korea Hydro & Nuclear Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Korea South-East Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Korea Midland Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Korea Western Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Korea Southern Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Korea East-West Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Engineering & Construction Company [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities [1] Architectural engineering for utility plant and others Architectural engineering for utility plant and others
Country of incorporation of subsidiary [1] KOREA KOREA
Proportion of ownership interest in subsidiary [1] 66.00% 66.00%
KEPCO Plant Service & Engineering [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 51.00% 51.00%
KEPCO Nuclear Fuel [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Nuclear fuel Nuclear fuel
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 96.00% 96.00%
KEPCO KDN [Member]    
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
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Garolim Tidal Power Plant [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities [2] Power generation Power generation
Country of incorporation of subsidiary [2] KOREA KOREA
Proportion of ownership interest in subsidiary [2] 49.00% 49.00%
KEPCO International HongKong [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary HONG KONG HONG KONG
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO International Philippines [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary PHILIPPINES PHILIPPINES
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Gansu International [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary HONG KONG HONG KONG
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Philippines Holdings [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary PHILIPPINES PHILIPPINES
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Philippines Corporation [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary PHILIPPINES PHILIPPINES
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Ilijan Corporation [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant rehabilitation and operation Utility plant rehabilitation and operation
Country of incorporation of subsidiary PHILIPPINES PHILIPPINES
Proportion of ownership interest in subsidiary 51.00% 51.00%
KEPCO Lebanon SARL [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary LEBANON LEBANON
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Neimenggu International [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary HONG KONG HONG KONG
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Shanxi International [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary HONG KONG HONG KONG
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOMIPO Global Pte [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary SINGAPORE SINGAPORE
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Canada Energy [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary CANADA CANADA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Netherlands B.V. [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary NETHERLANDS NETHERLANDS
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOREA Imouraren Uranium Investment Corp. [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary FRANCE FRANCE
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Australia [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOSEP Australia [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOMIPO Australia [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOWEPO Australia [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOSPO Australia [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Middle East Holding Company [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary BAHRAIN BAHRAIN
Proportion of ownership interest in subsidiary 100.00% 100.00%
Qatrana Electric Power Company [Member]    
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
Country of incorporation of subsidiary JORDAN JORDAN
Proportion of ownership interest in subsidiary 80.00% 80.00%
KHNP Canada Energy [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary CANADA CANADA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Bylong Australia [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Korea Waterbury Uranium Limited Partnership [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary CANADA CANADA
Proportion of ownership interest in subsidiary 80.00% 80.00%
Korea Electric Power Nigeria [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary NIGERIA NIGERIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Holdings de Mexico [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary MEXICO MEXICO
Proportion of ownership interest in subsidiary 100.00% 100.00%
KST Electric Power Company [Member]    
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
Country of incorporation of subsidiary MEXICO MEXICO
Proportion of ownership interest in subsidiary 56.00% 56.00%
KEPCO Energy Service Company [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary MEXICO MEXICO
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Netherlands S3 B.V. [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary NETHERLANDS NETHERLANDS
Proportion of ownership interest in subsidiary 100.00% 100.00%
PT. KOMIPO Pembangkitan Jawa Bali [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary INDONESIA INDONESIA
Proportion of ownership interest in subsidiary 51.00% 51.00%
PT. Cirebon Power Service [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities [2] Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary [2] INDONESIA INDONESIA
Proportion of ownership interest in subsidiary [2] 28.00% 28.00%
KOWEPO International Corporation [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary PHILIPPINES PHILIPPINES
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOSPO Jordan [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary JORDAN JORDAN
Proportion of ownership interest in subsidiary 100.00% 100.00%
EWP Philippines Corporation [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary PHILIPPINES PHILIPPINES
Proportion of ownership interest in subsidiary 100.00% 100.00%
EWP America [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary USA USA
Proportion of ownership interest in subsidiary 100.00% 100.00%
EWP Renewable [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary USA USA
Proportion of ownership interest in subsidiary 100.00% 100.00%
DG Fairhaven Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary USA USA
Proportion of ownership interest in subsidiary 100.00% 100.00%
DG Whitefield [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary USA USA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Springfield Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary USA USA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KNF Canada Energy Limited [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary CANADA CANADA
Proportion of ownership interest in subsidiary 96.00% 96.00%
PT KEPCO Resource Indonesia [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary INDONESIA INDONESIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
EWP Barbados 1 SRL [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary BARBADOS BARBADOS
Proportion of ownership interest in subsidiary 100.00% 100.00%
California Power Holdings [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary USA USA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Gyeonggi Green Energy [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 62.00% 62.00%
PT. Tanggamus Electric Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary INDONESIA INDONESIA
Proportion of ownership interest in subsidiary 53.00% 53.00%
Gyeongju Wind Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 70.00% 70.00%
KOMIPO America [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary USA USA
Proportion of ownership interest in subsidiary 100.00% 100.00%
EWPRC Biomass Holdings [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary USA USA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOSEP USA INC. [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary USA USA
Proportion of ownership interest in subsidiary 100.00% 100.00%
PT. EWP Indonesia [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary INDONESIA INDONESIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO Netherlands J3 B.V. [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary NETHERLANDS NETHERLANDS
Proportion of ownership interest in subsidiary 100.00% 100.00%
Korea Offshore Wind Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Global One Pioneer B.V. [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary NETHERLANDS NETHERLANDS
Proportion of ownership interest in subsidiary 100.00% 100.00%
Global Energy Pioneer B.V. [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary NETHERLANDS NETHERLANDS
Proportion of ownership interest in subsidiary 100.00% 100.00%
Mira Power Limited [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities [3] Power generation Power generation
Country of incorporation of subsidiary [3] PAKISTAN PAKISTAN
Proportion of ownership interest in subsidiary [3] 76.00% 76.00%
KOSEP Material [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities [4] Recycling fly ashes Recycling fly ashes
Country of incorporation of subsidiary [4] KOREA KOREA
Proportion of ownership interest in subsidiary [4] 86.00% 46.00%
Commerce and Industry Energy [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities [5] Power generation Power generation
Country of incorporation of subsidiary [5] KOREA KOREA
Proportion of ownership interest in subsidiary [5] 59.00% 59.00%
KEPCO Singapore Holdings Pte. [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary SINGAPORE SINGAPORE
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOWEPO India Private Limited [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary INDIA INDIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO KPS Philippines Corp. [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Country of incorporation of subsidiary PHILIPPINES PHILIPPINES
Proportion of ownership interest in subsidiary 51.00% 51.00%
KOSPO Chile SpA [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary CHILE CHILE
Proportion of ownership interest in subsidiary 100.00% 100.00%
PT. KOWEPO Sumsel Operation and Maintenance Services [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Country of incorporation of subsidiary INDONESIA INDONESIA
Proportion of ownership interest in subsidiary 95.00% 95.00%
HeeMang Sunlight Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Fujeij Wind Power Company [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary JORDAN JORDAN
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOSPO Youngnam Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant Operation of utility plant
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 50.00% 50.00%
HI Carbon Professional Private Special Asset Investment Trust 1 [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 97.00% 97.00%
Chitose Solar Power Plant [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary JAPAN JAPAN
Proportion of ownership interest in subsidiary 80.00% 80.00%
KEPCO Energy Solution [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Energy service Energy service
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
Solar School Plant [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation Power generation
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOSPO Power Services Limitada [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Country of incorporation of subsidiary CHILE CHILE
Proportion of ownership interest in subsidiary 65.00% 65.00%
Energy New Industry Specialized Investment Private Investment Trust [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company Holding company
Country of incorporation of subsidiary KOREA KOREA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOEN Bylong [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOMIPO Bylong [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOWEPO Bylong [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOSPO Bylong [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
EWP Bylong [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Resources development Resources development
Country of incorporation of subsidiary AUSTRALIA AUSTRALIA
Proportion of ownership interest in subsidiary 100.00% 100.00%
KOWEPO Lao International [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Utility plant maintenance and others Utility plant maintenance and others
Country of incorporation of subsidiary LAOS LAOS
Proportion of ownership interest in subsidiary 100.00% 100.00%
KEPCO US [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Country of incorporation of subsidiary USA  
Proportion of ownership interest in subsidiary 100.00%  
Reason Newly Established  
KEPCO Alamosa [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Country of incorporation of subsidiary USA  
Proportion of ownership interest in subsidiary 50.00%  
Reason Newly Established  
Cogentrix Solar Services [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Country of incorporation of subsidiary USA  
Proportion of ownership interest in subsidiary 50.00%  
Reason Newly Established  
Solar Investments I [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Country of incorporation of subsidiary USA  
Proportion of ownership interest in subsidiary 50.00%  
Reason Newly Established  
Cogentrix of Alamosa [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation  
Country of incorporation of subsidiary USA  
Proportion of ownership interest in subsidiary 50.00%  
Reason Newly Established  
KEPCO-LG CNS Mangilao Holdings [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Country of incorporation of subsidiary USA  
Proportion of ownership interest in subsidiary 70.00%  
Reason Newly Established  
Mangilao Investment [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Country of incorporation of subsidiary USA  
Proportion of ownership interest in subsidiary 70.00%  
Reason Newly Established  
KEPCO-LG CNS Mangilao Solar [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation  
Country of incorporation of subsidiary USA  
Proportion of ownership interest in subsidiary 70.00%  
Reason Newly Established  
Jeju Hanlim Offshore Wind Co [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Power generation  
Country of incorporation of subsidiary KOREA  
Proportion of ownership interest in subsidiary 70.00%  
Reason Newly Established  
PT. Siborpa Eco Power [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Operation of utility plant  
Country of incorporation of subsidiary INDONESIA  
Proportion of ownership interest in subsidiary 65.00%  
Reason Newly Established  
BSK E-New Industry Fund VII [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Country of incorporation of subsidiary KOREA  
Proportion of ownership interest in subsidiary 81.00%  
Reason Newly Established  
e-New Industry LB Fund 1 [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Country of incorporation of subsidiary KOREA  
Proportion of ownership interest in subsidiary 76.00%  
Reason Newly Established  
Songhyun e-New Industry Fund [Member]    
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]    
Key operation activities Holding company  
Country of incorporation of subsidiary KOREA  
Proportion of ownership interest in subsidiary 80.00%  
Reason Newly Established  
[1] Considering treasury stocks, the effective percentage of ownership is 66.08%.
[2] These subsidiaries are included in the consolidated financial statements as the Company obtained the majority of the voting power through the shareholders’ agreement.
[3] As of reporting date, the annual reporting period of all subsidiaries is December 31, except for Mira Power Limited which is November 30.
[4] The effective percentage of ownership has increased to 86.22% since Long Lasting Value exercised the put option to sell its investment to KOSEP during the year ended December 31, 2017.
[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.