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Investments in Joint Ventures 1 (Details) - KRW (₩)
₩ in Millions
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Disclosure of joint ventures [line items]      
Acquisition cost ₩ 2,069,491 ₩ 1,943,392  
Total acquisition cost 5,129,326 4,425,153  
Book value [Abstract]      
Total book value 7,471,384 6,170,533  
Book value ₩ 2,239,011 ₩ 1,919,746 ₩ 1,663,029
KEPCO-Uhde Inc.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 52.80% [1] 52.80%  
Acquisition cost ₩ 11,355 [1] ₩ 11,355  
Book value [Abstract]      
Book value ₩ 58 [1] ₩ 100  
Shuweihat Asia Power Investment B.V.      
Disclosure of joint ventures [line items]      
Key operation activities Holding company Holding company  
Location Netherlands Netherlands  
Percentage of ownership 49.00% 49.00%  
Acquisition cost ₩ 44,405 ₩ 44,405  
Book value [Abstract]      
Book value ₩ 37,069 ₩ 13,264 18,318
Shuweihat Asia Operation & Maintenance Company      
Disclosure of joint ventures [line items]      
Key operation activities Maintenance of utility plant [1] Maintenance of utility plant  
Location Cayman [1] Cayman  
Percentage of ownership 55.00% [1] 55.00%  
Acquisition cost ₩ 30 [1] ₩ 30  
Book value [Abstract]      
Book value ₩ 1,380 [1] ₩ 1,057 1,408
Waterbury Lake Uranium L.P.      
Disclosure of joint ventures [line items]      
Key operation activities Resources development Resources development  
Location Canada Canada  
Percentage of ownership 33.10% 33.10%  
Acquisition cost ₩ 26,602 ₩ 26,602  
Book value [Abstract]      
Book value ₩ 21,590 ₩ 19,797 20,562
ASM-BG Investicii AD      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Bulgaria Bulgaria  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 16,101 ₩ 16,101  
Book value [Abstract]      
Book value ₩ 18,692 ₩ 18,200 19,376
RES Technology AD      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Bulgaria Bulgaria  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 15,595 ₩ 15,595  
Book value [Abstract]      
Book value ₩ 16,703 ₩ 15,930 16,248
KV Holdings, Inc.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Philippines Philippines  
Percentage of ownership 40.00% 40.00%  
Acquisition cost ₩ 2,103 ₩ 2,103  
Book value [Abstract]      
Book value ₩ 2,527 ₩ 2,405 2,441
KEPCO SPC Power Corporation      
Disclosure of joint ventures [line items]      
Key operation activities Construction and operation of utility plant [1] Construction and operation of utility plant  
Location Philippines [1] Philippines  
Percentage of ownership 75.20% [1] 75.20%  
Acquisition cost ₩ 94,579 [1] ₩ 94,579  
Book value [Abstract]      
Book value ₩ 198,979 [1] ₩ 201,663 214,794
Gansu Datang Yumen Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location China China  
Percentage of ownership 40.00% 40.00%  
Acquisition cost ₩ 16,621 ₩ 16,621  
Book value [Abstract]      
Book value ₩ 6,635 ₩ 6,530 8,149
Datang Chifeng Renewable Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location China China  
Percentage of ownership 40.00% 40.00%  
Acquisition cost ₩ 121,928 ₩ 121,928  
Book value [Abstract]      
Book value ₩ 204,587 ₩ 188,478 185,307
Datang KEPCO Chaoyang Renewable Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location China China  
Percentage of ownership 40.00% 40.00%  
Acquisition cost ₩ 39,872 ₩ 39,872  
Book value [Abstract]      
Book value ₩ 44,217 ₩ 42,530 41,024
Rabigh Electricity Company      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Saudi Arabia Saudi Arabia  
Percentage of ownership 40.00% 40.00%  
Acquisition cost ₩ 109,743 ₩ 109,743  
Book value [Abstract]      
Book value ₩ 143,678 ₩ 97,157 109,096
Rabigh Operation & Maintenance Company Limited      
Disclosure of joint ventures [line items]      
Key operation activities Maintenance of utility plant Maintenance of utility plant  
Location Saudi Arabia Saudi Arabia  
Percentage of ownership 40.00% 40.00%  
Acquisition cost ₩ 70 ₩ 70  
Book value [Abstract]      
Book value ₩ 4,071 ₩ 3,813 6,879
Jamaica Public Service Company Limited      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Jamaica Jamaica  
Percentage of ownership 40.00% 40.00%  
Acquisition cost ₩ 301,910 ₩ 301,910  
Book value [Abstract]      
Book value ₩ 294,649 ₩ 266,221 253,607
KW Nuclear Components Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Manufacturing Manufacturing  
Location Korea Korea  
Percentage of ownership 45.00% 45.00%  
Acquisition cost ₩ 833 ₩ 833  
Book value [Abstract]      
Book value ₩ 15,734 ₩ 11,171 9,052
Busan Shinho Solar Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 25.00% 25.00%  
Acquisition cost ₩ 2,100 ₩ 2,100  
Book value [Abstract]      
Book value ₩ 5,841 ₩ 5,378 5,045
Global Trade Of Power System Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Exporting products and technology of small or medium business by proxy Exporting products and technology of small or medium business by proxy  
Location Korea Korea  
Percentage of ownership 29.00% 29.00%  
Acquisition cost ₩ 290 ₩ 290  
Book value [Abstract]      
Book value ₩ 597 ₩ 546 571
Expressway Solar-light Power Generation Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.00% 29.00%  
Acquisition cost ₩ 1,856 ₩ 1,856  
Book value [Abstract]      
Book value ₩ 3,084 ₩ 2,896 2,883
Amman Asia Electric Power Company      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Jordan Jordan  
Percentage of ownership 60.00% 60.00%  
Acquisition cost ₩ 111,476 ₩ 111,476  
Book value [Abstract]      
Book value ₩ 178,679 ₩ 161,253 192,164
KAPES, Inc.      
Disclosure of joint ventures [line items]      
Key operation activities R & D R & D  
Location Korea Korea  
Percentage of ownership 51.00% 51.00%  
Acquisition cost ₩ 5,629 ₩ 5,629  
Book value [Abstract]      
Book value ₩ 0 ₩ 0 10,832
Honam Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.00% 29.00%  
Acquisition cost ₩ 3,480 ₩ 3,480  
Book value [Abstract]      
Book value 4,041 ₩ 3,887 4,375
Jeongam Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities   Power generation  
Location   Korea  
Percentage of ownership   40.00%  
Acquisition cost   ₩ 5,580  
Book value [Abstract]      
Book value ₩ 0 ₩ 4,620 4,437
Korea Power Engineering Service Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Construction and service Construction and service  
Location Korea Korea  
Percentage of ownership 29.00% 29.00%  
Acquisition cost ₩ 290 ₩ 290  
Book value [Abstract]      
Book value ₩ 5,415 ₩ 5,362 4,902
Chun-cheon Energy Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.90% 29.90%  
Acquisition cost ₩ 52,700 ₩ 52,700  
Book value [Abstract]      
Book value ₩ 25,896 ₩ 27,518 34,872
Yeonggwangbaeksu Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 15.00% 15.00%  
Acquisition cost ₩ 3,000 ₩ 3,000  
Book value [Abstract]      
Book value ₩ 2,728 ₩ 3,124 3,040
Nghi Son 2 Power LLC      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Vietnam Vietnam  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 2,781 ₩ 2,781  
Book value [Abstract]      
Book value ₩ 0 ₩ 0 0
Kelar S.A      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Chile Chile  
Percentage of ownership 65.00% 65.00%  
Acquisition cost ₩ 78,060 ₩ 78,060  
Book value [Abstract]      
Book value ₩ 86,695 ₩ 71,449 70,462
PT. Tanjung Power Indonesia      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Indonesia Indonesia  
Percentage of ownership 35.00% 35.00%  
Acquisition cost ₩ 26,892 ₩ 26,892  
Book value [Abstract]      
Book value ₩ 46,546 ₩ 33,063 34,327
Incheon New Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.00% 29.00%  
Acquisition cost ₩ 461 ₩ 461  
Book value [Abstract]      
Book value ₩ 0 ₩ 0 0
Seokmun Energy Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.00% 29.00%  
Acquisition cost ₩ 15,370 ₩ 15,370  
Book value [Abstract]      
Book value ₩ 13,842 ₩ 14,814 17,342
Daehan Wind Power PSC      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Jordan Jordan  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 7,493 ₩ 7,493  
Book value [Abstract]      
Book value ₩ 5,154 ₩ 0 1,757
Barakah One Company      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location UAE UAE  
Percentage of ownership 18.00% 18.00%  
Acquisition cost ₩ 118 ₩ 118  
Book value [Abstract]      
Book value ₩ 0 ₩ 0 0
Nawah Energy Company      
Disclosure of joint ventures [line items]      
Key operation activities Operation of utility plant Operation of utility plant  
Location UAE UAE  
Percentage of ownership 18.00% 18.00%  
Acquisition cost ₩ 296 ₩ 296  
Book value [Abstract]      
Book value ₩ 294 ₩ 270 285
Momentum      
Disclosure of joint ventures [line items]      
Key operation activities International thermonuclear experimental reactor construction management International thermonuclear experimental reactor construction management  
Location France France  
Percentage of ownership 33.33% 33.33%  
Acquisition cost ₩ 1 ₩ 1  
Book value [Abstract]      
Book value ₩ 368 ₩ 565 553
Daegu Green Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.00% 29.00%  
Acquisition cost ₩ 46,225 ₩ 46,225  
Book value [Abstract]      
Book value ₩ 24,054 ₩ 23,045 22,824
Yeonggwang Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 46.00% 46.00%  
Acquisition cost ₩ 17,475 ₩ 17,475  
Book value [Abstract]      
Book value ₩ 17,646 ₩ 17,256 17,627
Chester Solar IV SpA      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Chile Chile  
Percentage of ownership 45.00% 45.00%  
Acquisition cost ₩ 1,700 ₩ 1,700  
Book value [Abstract]      
Book value ₩ 0 ₩ 1,064 672
Chester Solar V SpA      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Chile Chile  
Percentage of ownership 45.00% 45.00%  
Acquisition cost ₩ 525 ₩ 525  
Book value [Abstract]      
Book value ₩ 25 ₩ 277 146
Diego de Almagro Solar SpA      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Chile Chile  
Percentage of ownership 45.00% 45.00%  
Acquisition cost ₩ 2,091 ₩ 2,091  
Book value [Abstract]      
Book value ₩ 362 ₩ 1,490 1,035
South Jamaica Power Company Limited      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Jamaica Jamaica  
Percentage of ownership 20.00% 20.00%  
Acquisition cost ₩ 20,430 ₩ 20,521  
Book value [Abstract]      
Book value ₩ 37,360 ₩ 31,897 13,863
Daesan Green Energy Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 35.00% 35.00%  
Acquisition cost ₩ 17,850 ₩ 17,850  
Book value [Abstract]      
Book value ₩ 21,244 ₩ 22,552 17,182
RE Holiday Holdings LLC      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location USA USA  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 42,948 ₩ 42,948  
Book value [Abstract]      
Book value ₩ 73,167 ₩ 68,809 42,070
RE Pioneer Holdings LLC      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location USA USA  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 27,891 ₩ 27,891  
Book value [Abstract]      
Book value ₩ 47,015 ₩ 49,639 31,156
RE Barren Ridge 1 Holdings LLC      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location USA USA  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 28,021 ₩ 28,021  
Book value [Abstract]      
Book value ₩ 1,883 ₩ 4,466 42,916
RE Astoria 2 LandCo LLC      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location USA USA  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 5,188 ₩ 5,188  
Book value [Abstract]      
Book value ₩ 5,998 ₩ 5,230 5,602
RE Barren Ridge LandCo LLC      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location USA USA  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 2,187 ₩ 2,187  
Book value [Abstract]      
Book value ₩ 2,120 ₩ 1,847 1,966
Laurel SpA      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Chile Chile  
Percentage of ownership 45.00% 45.00%  
Acquisition cost ₩ 1,222 ₩ 1,222  
Book value [Abstract]      
Book value ₩ 290 ₩ 1,092 595
KIAMCO KOWEPO Bannerton Hold Co Pty Ltd      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Australia Australia  
Percentage of ownership 12.37% 12.37%  
Acquisition cost ₩ 4,095 ₩ 4,095  
Book value [Abstract]      
Book value ₩ 3,625 ₩ 4,129 4,024
Chile Solar JV SpA      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Chile Chile  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 37,689 ₩ 37,689  
Book value [Abstract]      
Book value 32,457 ₩ 34,883 34,859
Taebaek Gadeoksan Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities   Power generation  
Location   Korea  
Percentage of ownership   47.31%  
Acquisition cost   ₩ 12,570  
Book value [Abstract]      
Book value ₩ 0 ₩ 13,362 7,846
Cheong-Song Noraesan Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.01% 29.01%  
Acquisition cost ₩ 3,200 ₩ 3,200  
Book value [Abstract]      
Book value ₩ 4,106 ₩ 3,453 3,043
Chester Solar I SpA      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Chile Chile  
Percentage of ownership 45.00% 45.00%  
Acquisition cost ₩ 1,181 ₩ 1,181  
Book value [Abstract]      
Book value ₩ 1,120 ₩ 1,621 1,157
Solar Philippines Calatagan Corporation      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Philippines Philippines  
Percentage of ownership 38.00% 38.00%  
Acquisition cost ₩ 47,903 ₩ 47,903  
Book value [Abstract]      
Book value ₩ 58,231 ₩ 49,017 48,930
Saemangeum Solar Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 81.01% 81.00%  
Acquisition cost ₩ 26,400 ₩ 26,399  
Book value [Abstract]      
Book value ₩ 23,939 ₩ 24,292 8,324
Chungsongmeon BongSan wind power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.00% 29.00%  
Acquisition cost ₩ 2,900 ₩ 2,900  
Book value [Abstract]      
Book value ₩ 3,808 ₩ 4,124 2,764
Jaeun Resident Wind Power Plant Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.00% 29.00%  
Acquisition cost ₩ 2,494 ₩ 2,494  
Book value [Abstract]      
Book value ₩ 1,958 ₩ 2,195 2,198
DE Energia SpA      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Chile Chile  
Percentage of ownership 49.00% 49.00%  
Acquisition cost ₩ 8,364 ₩ 8,364  
Book value [Abstract]      
Book value ₩ 8,921 ₩ 8,187 8,665
Dangjin Eco Power Co., Ltd. (newly)      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 34.00% 34.00%  
Acquisition cost ₩ 25,661 ₩ 25,661  
Book value [Abstract]      
Book value ₩ 26,109 ₩ 25,523 25,661
Haemodum Solar Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 49.00% 49.00%  
Acquisition cost ₩ 2,940 ₩ 2,940  
Book value [Abstract]      
Book value ₩ 3,081 ₩ 3,065 2,940
Yangyang Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 50.00% 50.00%  
Acquisition cost ₩ 12,000 ₩ 10,800  
Book value [Abstract]      
Book value ₩ 11,191 ₩ 10,485 10,800
Horus Solar S.A. De C.V.      
Disclosure of joint ventures [line items]      
Key operation activities Renewable power generation Renewable power generation  
Location Mexico Mexico  
Percentage of ownership 14.95% 14.95%  
Acquisition cost ₩ 5,068 ₩ 5,068  
Book value [Abstract]      
Book value ₩ 5,842 ₩ 3,394 3,403
Recursos Solares PV De Mexico II, S.S. De C.V.      
Disclosure of joint ventures [line items]      
Key operation activities Renewable power generation Renewable power generation  
Location Mexico Mexico  
Percentage of ownership 14.95% 14.95%  
Acquisition cost ₩ 3,678 ₩ 3,678  
Book value [Abstract]      
Book value ₩ 4,536 ₩ 3,660 672
Sunmex Renovables, S.A. De C.V.      
Disclosure of joint ventures [line items]      
Key operation activities Renewable power generation Renewable power generation  
Location Mexico Mexico  
Percentage of ownership 14.95% 14.95%  
Acquisition cost ₩ 1,678 ₩ 307  
Book value [Abstract]      
Book value ₩ 1,610 ₩ 240 222
Stavro Holding II AB      
Disclosure of joint ventures [line items]      
Key operation activities Holding company Holding company  
Location Sweden Sweden  
Percentage of ownership 20.00% 20.00%  
Acquisition cost ₩ 17,615 ₩ 8,829  
Book value [Abstract]      
Book value ₩ 17,627 ₩ 9,277 5,625
Solaseado Solar Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 38.90% 38.90%  
Acquisition cost ₩ 7,020 ₩ 7,020  
Book value [Abstract]      
Book value ₩ 9,891 ₩ 9,915 0
Yeongam Solar Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 19.00% 19.00%  
Acquisition cost ₩ 6,460 ₩ 6,460  
Book value [Abstract]      
Book value ₩ 6,838 ₩ 6,042 0
Samsu Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 19.00% 19.00%  
Acquisition cost ₩ 2,637 ₩ 2,637  
Book value [Abstract]      
Book value ₩ 2,828 ₩ 2,607 0
Pulau Indah Power Plant Sdn. Bhd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Malaysia Malaysia  
Percentage of ownership 25.00% 25.00%  
Acquisition cost ₩ 23,833 ₩ 11,569  
Book value [Abstract]      
Book value ₩ 22,099 ₩ 11,204 0
Sam-Yang Photovoltaic Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 49.00% 49.00%  
Acquisition cost ₩ 5,245 ₩ 5,245  
Book value [Abstract]      
Book value ₩ 4,993 ₩ 5,535 0
NH-Amundi Global Infrastructure Investment Private Investment Trust 21      
Disclosure of joint ventures [line items]      
Key operation activities Holding company Holding company  
Location Korea Korea  
Percentage of ownership 29.53% 29.53%  
Acquisition cost ₩ 19,983 ₩ 20,952  
Book value [Abstract]      
Book value ₩ 21,456 ₩ 22,242 0
Shin-han BNPP Private Investment Trust for East-West Sunlight Dream      
Disclosure of joint ventures [line items]      
Key operation activities Holding company Holding company  
Location Korea Korea  
Percentage of ownership 90.00% 90.00%  
Acquisition cost ₩ 15,699 ₩ 15,699  
Book value [Abstract]      
Book value ₩ 16,288 ₩ 16,129 0
PT Barito Wahana Tenaga      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Indonesia Indonesia  
Percentage of ownership 30.61% 30.61%  
Acquisition cost ₩ 59,535 ₩ 59,395  
Book value [Abstract]      
Book value ₩ 81,595 ₩ 63,029 0
Cheongna Energy Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Generating and distributing vapor and hot/cold water Generating and distributing vapor and hot/cold water  
Location Korea Korea  
Percentage of ownership 50.10% 50.10%  
Acquisition cost ₩ 49,344 ₩ 49,344  
Book value [Abstract]      
Book value ₩ 11,198 ₩ 4,940 0
Naepo Green Energy Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 29.20% 29.20%  
Acquisition cost ₩ 29,200 ₩ 29,200  
Book value [Abstract]      
Book value ₩ 0 ₩ 0 0
Dayone Energy Co., Ltd. (formerly, Hyundai Energy Co., Ltd.)      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 30.66% 30.66%  
Acquisition cost ₩ 71,070 ₩ 71,070  
Book value [Abstract]      
Book value ₩ 0 ₩ 0 0
OneEnergy Asia Limited      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Vietnam Vietnam  
Percentage of ownership 40.00% 40.00%  
Acquisition cost ₩ 76,916 ₩ 56,654  
Book value [Abstract]      
Book value ₩ 79,700 ₩ 56,654 0
KAS Investment I LLC      
Disclosure of joint ventures [line items]      
Key operation activities Holding company Holding company  
Location USA USA  
Percentage of ownership 29.89% 29.89%  
Acquisition cost ₩ 23,437 ₩ 23,437  
Book value [Abstract]      
Book value ₩ 15,273 ₩ 23,437 0
KAS Investment II LLC      
Disclosure of joint ventures [line items]      
Key operation activities Holding company Holding company  
Location USA USA  
Percentage of ownership 29.89% 29.89%  
Acquisition cost ₩ 23,343 ₩ 23,343  
Book value [Abstract]      
Book value 15,213 ₩ 23,343 0
Energyco LLC      
Disclosure of joint ventures [line items]      
Key operation activities   Power generation  
Location   Korea  
Percentage of ownership   29.00%  
Acquisition cost   ₩ 1,659  
Book value [Abstract]      
Book value ₩ 1,535 ₩ 1,659 0
CAES, LLC      
Disclosure of joint ventures [line items]      
Key operation activities Holding company Holding company  
Location USA USA  
Percentage of ownership 36.00% 36.00%  
Acquisition cost ₩ 19,414 ₩ 19,414  
Book value [Abstract]      
Book value ₩ 18,435 ₩ 17,626 0
Hapcheon Floating Photovoltaic Power Plant Inc.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 49.00% 19.47%  
Acquisition cost ₩ 7,512 ₩ 1,890  
Book value [Abstract]      
Book value ₩ 6,971 ₩ 1,890 0
Busan Industrial Solar Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 28.02% 28.02%  
Acquisition cost ₩ 510 ₩ 510  
Book value [Abstract]      
Book value ₩ 612 ₩ 510 0
Bitsolar Energy Co., Ltd.,      
Disclosure of joint ventures [line items]      
Key operation activities Power generation Power generation  
Location Korea Korea  
Percentage of ownership 27.10% 27.10%  
Acquisition cost ₩ 352 ₩ 352  
Book value [Abstract]      
Book value ₩ 352 352 ₩ 0
Energyco Co., Ltd. (formerly, Energyco LLC)      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Korea    
Percentage of ownership 29.00%    
Acquisition cost ₩ 1,659    
Book value [Abstract]      
Book value ₩ 1,535    
Pulau Indah O&M Sdn. Bhd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Malaysia    
Percentage of ownership 60.00%    
Acquisition cost ₩ 0    
Book value [Abstract]      
Book value ₩ 0    
Guadalupe Solar SpA      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Chile    
Percentage of ownership 60.00%    
Acquisition cost ₩ 1,397    
Book value [Abstract]      
Book value ₩ 659 0  
Omisan Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Korea    
Percentage of ownership 42.00%    
Acquisition cost ₩ 10,752    
Book value [Abstract]      
Book value ₩ 10,633 0  
Foresight Iberian Solar Group Holding, S.L      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Spain    
Percentage of ownership 75.00%    
Acquisition cost ₩ 9,697    
Book value [Abstract]      
Book value ₩ 9,743    
Yeongwol Eco Wind Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Korea    
Percentage of ownership 29.00%    
Acquisition cost ₩ 3,089    
Book value [Abstract]      
Book value ₩ 3,196 0  
Gurae Resident Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Korea    
Percentage of ownership 29.00%    
Acquisition cost ₩ 386    
Book value [Abstract]      
Book value ₩ 395 0  
Cheongju Eco Park Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Korea    
Percentage of ownership 29.00%    
Acquisition cost ₩ 5,858    
Book value [Abstract]      
Book value ₩ 5,465 0  
Enel X Midland Photovoltaic, LLC      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Korea    
Percentage of ownership 20.00%    
Acquisition cost ₩ 1,695    
Book value [Abstract]      
Book value ₩ 1,688 0  
Geumsungsan Wind Power Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Korea    
Percentage of ownership 29.00%    
Acquisition cost ₩ 6,531    
Book value [Abstract]      
Book value ₩ 6,053 0  
KEPCO KPS Carabao Corp.      
Disclosure of joint ventures [line items]      
Key operation activities Utility plant maintenance    
Location Philippines    
Percentage of ownership 40.00%    
Acquisition cost ₩ 93    
Book value [Abstract]      
Book value ₩ 386 0  
Prime Swedish Holding AB      
Disclosure of joint ventures [line items]      
Key operation activities Holding company    
Location Sweden    
Percentage of ownership 45.00%    
Acquisition cost ₩ 14,514    
Book value [Abstract]      
Book value ₩ 15,441 0  
Goheung New Energy Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Korea    
Percentage of ownership 46.15%    
Acquisition cost ₩ 12,959    
Book value [Abstract]      
Book value ₩ 11,708 0  
Gunsan Land Solar Co., Ltd.      
Disclosure of joint ventures [line items]      
Key operation activities Power generation    
Location Korea    
Percentage of ownership 75.29%    
Acquisition cost ₩ 19,091    
Book value [Abstract]      
Book value ₩ 19,317 0  
Capman Lynx SCA, SICAR      
Disclosure of joint ventures [line items]      
Key operation activities Holding company    
Location Luxembourg    
Percentage of ownership 50.00%    
Acquisition cost ₩ 9,601    
Book value [Abstract]      
Book value ₩ 9,976 0  
International Offshore Power Transmission Holding Company Limited      
Disclosure of joint ventures [line items]      
Key operation activities Undersea transmission network operation    
Location UAE    
Percentage of ownership 35.00%    
Acquisition cost ₩ 0    
Book value [Abstract]      
Book value ₩ 0 ₩ 0  
[1] The effective percentage of ownership is more than 50%. However, according to the shareholders’ agreement, all critical financial and operating decisions must be agreed to by all ownership parties. Accordingly, the entities are classified as joint ventures.