Consolidated Subsidiaries - Summary of Cash Dividends Received from Subsidiaries (Details) - KRW (₩) ₩ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Subsidiaries
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	₩ 3,575,130	₩ 466,268	₩ 454,255
Korea Hydro & Nuclear Power Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	1,560,120	136,010	279,779
Korea South-East Power Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	340,710	4,808	0
Korea Midland Power Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	291,558	24,694	0
Korea Western Power Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	344,756	0	0
Korea Southern Power Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	293,027	0	0
Korea East-West Power Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	300,436	4,866	0
KEPCO Engineering & Construction Company, Inc.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	7,114	5,983	7,089
KEPCO Plant Service & Engineering Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	29,952	27,517	26,301
KEPCO Nuclear Fuel Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	15,178	11,184	5,206
KEPCO KDN Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	185,549	36,986	18,854
KEPCO Energy Solution Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	9,480	1,707	0
KEPCO Solar Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	16,023	1,409	0
KEPCO MCS Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	15,353	0	0
KEPCO International HongKong Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	5,962	9,044	0
KEPCO Philippines Corporation
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	24,246	2,375	0
KEPCO Ilijan Corporation
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	1,298	9,195	7,955
KEPCO Philippines Holdings Inc.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	1,386	34,913	60,520
KOSPO Australia Pty., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	0	31,386	3,095
KEPCO Netherlands B.V.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	3,124	16,795	0
Qatrana Electric Power Company
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	6,511	2,751	2,615
KEPCO KPS Philippines Corp.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	0	302	0
Tamra Offshore Wind Power Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	3,863	2,877	0
KEPCO Netherlands S3 B.V.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	2,477	4,005	0
PT. KOMIPO Pembangkitan Jawa Bali
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	578	859	153
PT. EWP Indonesia
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	0	4,262	0
Gyeongju Wind Power Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	6,300	2,100	2,800
KOSPO Power Services Ltda.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	1,201	305	0
KEPCO Netherlands J3 B.V.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	13,144	46,510	27,237
PT. Cirebon Power Service
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	12,673	241	0
Chitose Solar Power Plant LLC
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	1,386	639	0
Fujeij Wind Power Company
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	6,047	15,102	11,920
KOSPO Jordan LLC
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	6,089	11,450	731
EWP America Inc.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	0	3,887	0
KOWEPO Lao International
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	0	12,106	0
KEPCO Neimenggu International Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	4,058	0	0
KST Electric Power Company, S.A.P.I. de C.V.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	3,145	0	0
KOMIPO Global Pte Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	31,066	0	0
KOSPO Australia Pty., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	12,558	0	0
Changjuk Wind Power Co., Ltd.
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	4,015	0	0
EWP Barbados 1 SRL
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	12,987	0	0
KEPCO Energy Service Company
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	629	0	0
Chile Solar JV SpA
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	₩ 1,127	₩ 0	₩ 0