REVENUE - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenues	[1]	$ 12,459	$ 11,132	$ 10,790
Operating Segments | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		10,700	9,644	9,227
Total revenues		10,801	9,711	9,363
Operating Segments | Utilities and Transmission Companies | Wholesale
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		494	362	251
Operating Segments | Utilities and Transmission Companies | Other revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		104	119	140
Operating Segments | Utilities and Transmission Companies | ARP
Disaggregation of Revenue [Line Items]
Total revenues		0	(27)	43
Operating Segments | Utilities and Transmission Companies | Other revenue unrelated to contracts with customers
Disaggregation of Revenue [Line Items]
Total revenues		101	94	93
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		1,863	1,608	1,613
Total revenues		1,868	1,618	1,630
Operating Segments | Regulated Transmission | Other revenue unrelated to contracts with customers
Disaggregation of Revenue [Line Items]
Total revenues		5	10	17
Operating Segments | Residential | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		6,180	5,713	5,539
Operating Segments | Commercial | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,499	2,284	2,140
Operating Segments | Industrial | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,338	1,091	1,076
Operating Segments | Other | Utilities and Transmission Companies
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		85	75	81
Operating Segments | ATSI | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		912	799	804
Operating Segments | TrAIL | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		270	233	247
Operating Segments | MAIT | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		340	288	250
Operating Segments | JCP&L | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		203	164	178
Operating Segments | MP, PE and WP | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		138	124	134
Corporate/Other and Reconciling Adjustments
Disaggregation of Revenue [Line Items]
Total revenues		(210)	(197)	(203)
Corporate/Other and Reconciling Adjustments | Wholesale
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		27	14	9
Corporate/Other and Reconciling Adjustments | Other revenue unrelated to contracts with customers
Disaggregation of Revenue [Line Items]
Total revenues		(51)	(57)	(64)
Corporate/Other and Reconciling Adjustments | Retail generation and distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ (186)	$ (154)	$ (148)

[1] Includes excise and gross receipts tax collections of $406 million, $374 million and $362 million in 2022, 2021 and 2020, respectively.