SEGMENT INFORMATION - Segment Financial Information (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Segment Financial Information
Total revenues	[1]	$ 3,487,000	$ 3,475,000	$ 9,724,000	$ 9,282,000
Depreciation		366,000	332,000	1,088,000	1,020,000
Deferral of regulatory assets, net		(140,000)	(86,000)	(253,000)	(252,000)
Equity method investment earnings		43,000	57,000	134,000	134,000
Interest expense		289,000	248,000	828,000	788,000
Income taxes (benefits)		29,000	105,000	193,000	237,000
Earnings (losses) attributable to FE from continuing operations		421,000	334,000	948,000	809,000
Capital investments		848,000	666,000	2,266,000	1,852,000
Assets		47,471,000		47,471,000		$ 46,108,000
Goodwill		5,618,000		5,618,000		5,618,000
External Customers
Segment Financial Information
Total revenues		3,487,000	3,475,000	9,724,000	9,282,000
Internal Customers
Segment Financial Information
Total revenues		0	0	0	0
Operating Segments | Regulated Distribution
Segment Financial Information
Total revenues		3,034,000	3,023,000	8,402,000	8,038,000
Depreciation		256,000	242,000	762,000	719,000
Deferral of regulatory assets, net		(136,000)	(85,000)	(249,000)	(250,000)
Equity method investment earnings		0	0	0	0
Interest expense		159,000	132,000	456,000	389,000
Income taxes (benefits)		70,000	92,000	170,000	213,000
Earnings (losses) attributable to FE from continuing operations		275,000	361,000	688,000	828,000
Capital investments		409,000	415,000	1,136,000	1,127,000
Assets		32,434,000		32,434,000		31,749,000
Goodwill		5,004,000		5,004,000		5,004,000
Operating Segments | Regulated Distribution | External Customers
Segment Financial Information
Total revenues		2,978,000	2,965,000	8,231,000	7,867,000
Operating Segments | Regulated Distribution | Internal Customers
Segment Financial Information
Total revenues		56,000	58,000	171,000	171,000
Operating Segments | Regulated Transmission
Segment Financial Information
Total revenues		509,000	503,000	1,490,000	1,397,000
Depreciation		93,000	72,000	272,000	245,000
Deferral of regulatory assets, net		(4,000)	(1,000)	(4,000)	(2,000)
Equity method investment earnings		0	0	0	0
Interest expense		65,000	41,000	185,000	155,000
Income taxes (benefits)		45,000	5,000	131,000	85,000
Earnings (losses) attributable to FE from continuing operations		123,000	27,000	371,000	275,000
Capital investments		424,000	236,000	1,097,000	700,000
Assets		14,454,000		14,454,000		13,835,000
Goodwill		614,000		614,000		614,000
Operating Segments | Regulated Transmission | External Customers
Segment Financial Information
Total revenues		508,000	503,000	1,487,000	1,394,000
Operating Segments | Regulated Transmission | Internal Customers
Segment Financial Information
Total revenues		1,000	0	3,000	3,000
Corporate/Other
Segment Financial Information
Total revenues		(56,000)	(51,000)	(168,000)	(153,000)
Depreciation		0	3,000	3,000	6,000
Deferral of regulatory assets, net		0	0	0	0
Equity method investment earnings		43,000	57,000	134,000	134,000
Interest expense		87,000	99,000	244,000	276,000
Income taxes (benefits)		(86,000)	8,000	(108,000)	(61,000)
Earnings (losses) attributable to FE from continuing operations		23,000	(54,000)	(111,000)	(294,000)
Capital investments		15,000	15,000	33,000	25,000
Assets		583,000		583,000		524,000
Goodwill		0		0		0
Corporate/Other | External Customers
Segment Financial Information
Total revenues		1,000	7,000	6,000	21,000
Corporate/Other | Internal Customers
Segment Financial Information
Total revenues		0	0	0	0
Reconciling Adjustments
Segment Financial Information
Depreciation		17,000	15,000	51,000	50,000
Deferral of regulatory assets, net		0	0	0	0
Equity method investment earnings		0	0	0	0
Interest expense		(22,000)	(24,000)	(57,000)	(32,000)
Income taxes (benefits)		0	0	0	0
Earnings (losses) attributable to FE from continuing operations		0	0	0	0
Capital investments		0	0	0	0
Assets		0		0		0
Goodwill		0		0		$ 0
Reconciling Adjustments | External Customers
Segment Financial Information
Total revenues		0	0	0	0
Reconciling Adjustments | Internal Customers
Segment Financial Information
Total revenues		$ (57,000)	$ (58,000)	$ (174,000)	$ (174,000)

[1] Includes excise and gross receipts tax collections of $114 million and $111 million during the three months ended September 30, 2023 and 2022, respectively, and $315 million and $305 million during the nine months ended September 30, 2023 and 2022, respectively.