REVENUE - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Total revenues	[1]	$ 12,870	$ 12,459	$ 11,132
Operating Segments | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		10,927	10,700	9,644
Total revenues		11,038	10,801	9,711
Operating Segments | Utilities and Transmission Companies | Wholesale
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		228	494	362
Operating Segments | Utilities and Transmission Companies | Other revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		113	104	119
Operating Segments | Utilities and Transmission Companies | Alternative Revenue Program
Disaggregation of Revenue [Line Items]
Total revenues		0	0	(27)
Operating Segments | Utilities and Transmission Companies | Other revenue unrelated to contacts with customers
Disaggregation of Revenue [Line Items]
Total revenues		111	101	94
Operating Segments | Utilities and Transmission Companies | Distribution services and retail generation | Ohio Stipulation
Disaggregation of Revenue [Line Items]
Rate refunds			58	38
Operating Segments | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,049	1,863	1,608
Total revenues		2,054	1,868	1,618
Operating Segments | Regulated Transmission | Other revenue unrelated to contacts with customers
Disaggregation of Revenue [Line Items]
Total revenues		5	5	10
Operating Segments | Residential | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		6,583	6,180	5,713
Operating Segments | Commercial | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,600	2,499	2,284
Operating Segments | Industrial | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,298	1,338	1,091
Operating Segments | Street lighting/Other | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		105	85	75
Operating Segments | ATSI | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		968	912	799
Operating Segments | TrAIL | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		279	270	233
Operating Segments | MAIT | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		395	340	288
Operating Segments | JCP&L | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		205	203	164
Operating Segments | MP, PE and WP | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		202	138	124
Corporate/Other and Reconciling Adjustments
Disaggregation of Revenue [Line Items]
Total revenues		(222)	(210)	(197)
Corporate/Other and Reconciling Adjustments | Wholesale
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		11	27	14
Corporate/Other and Reconciling Adjustments | Other revenue unrelated to contacts with customers
Disaggregation of Revenue [Line Items]
Total revenues		(52)	(51)	(57)
Corporate/Other and Reconciling Adjustments | Retail generation and distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ (181)	$ (186)	$ (154)

[1] Includes excise and gross receipts tax collections of $420 million, $406 million and $374 million in 2023, 2022 and 2021, respectively.