REVENUE - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total revenues	[1]	$ 3,231	$ 2,989
Operating Segments | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,796	2,558
Total revenues		2,826	2,589
Operating Segments | Regulated Distribution | Wholesale
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		47	90
Operating Segments | Regulated Distribution | Other Services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		24	26
Operating Segments | Regulated Distribution | Product and Service, Other
Disaggregation of Revenue [Line Items]
Total revenues		30	31
Operating Segments | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		460	451
Total revenues		461	453
Operating Segments | Regulated Transmission | Product and Service, Other
Disaggregation of Revenue [Line Items]
Total revenues		1	2
Operating Segments | Residential | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,702	1,542
Operating Segments | Commercial | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		645	597
Operating Segments | Industrial | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		353	283
Operating Segments | Other | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		25	20
Operating Segments | ATSI | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		226	217
Operating Segments | TrAIL | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		66	63
Operating Segments | MAIT | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		89	79
Operating Segments | JCP&L | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		43	60
Operating Segments | MP, PE and WP | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		36	32
Corporate/Other and Reconciling Adjustments
Disaggregation of Revenue [Line Items]
Total revenues		(56)	(53)
Corporate/Other and Reconciling Adjustments | Wholesale
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2	6
Corporate/Other and Reconciling Adjustments | Product and Service, Other
Disaggregation of Revenue [Line Items]
Total revenues		(13)	(14)
Corporate/Other and Reconciling Adjustments | Retail Generation and Distribution Services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ (45)	$ (45)

[1] Includes excise and gross receipts tax collections of $109 million and $103 million during the three months ended March 31, 2023 and 2022, respectively.