Revenue (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021 USD ($) company MW	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) company MW	Sep. 30, 2020 USD ($)
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 3,113	$ 2,983	$ 8,466	$ 8,105
Total revenues	[1]	3,124	3,022	8,472	8,253
Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges		9	6	27	22
Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,509	1,481	4,100	3,935
Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,041	989	2,782	2,689
Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		122	70	272	194
Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		411	408	1,223	1,185
Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		30	35	89	102
ARP
Disaggregation of Revenue [Line Items]
Total revenues		0	25	(27)	108
Other non-customer revenue
Disaggregation of Revenue [Line Items]
Total revenues		11	14	33	40
Derivative revenue | Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges		3	8	5	14
Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 2,588	2,508	$ 6,997	6,735
Refund of revenue			1		2
Number of existing utility operating companies | company		10		10
Megawatts of net demonstrated capacity of competitive segment | MW		3,580		3,580
Utility customer payment period				30 days
Regulated Distribution | Residential
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 1,666	1,621	$ 4,410	4,220
Regulated Distribution | Commercial
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		619	589	1,722	1,640
Regulated Distribution | Industrial
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		284	278	810	814
Regulated Distribution | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		19	20	55	61
Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		411	408	1,223	1,185
Refund of revenue			3		6
Regulated Transmission | ATSI
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		206	202	604	598
Regulated Transmission | TrAIL
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		59	61	176	182
Regulated Transmission | MAIT
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		75	68	222	183
Regulated Transmission | JCP&L
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		41	43	126	122
Regulated Transmission | MP, PE and WP
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		30	34	95	100
Operating Segments | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,735	2,610	7,346	7,025
Total revenues		2,759	2,661	7,387	7,207
Operating Segments | Regulated Distribution | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,534	1,503	4,177	4,000
Operating Segments | Regulated Distribution | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,054	1,005	2,820	2,735
Operating Segments | Regulated Distribution | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		117	67	260	188
Operating Segments | Regulated Distribution | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Operating Segments | Regulated Distribution | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		30	35	89	102
Operating Segments | Regulated Distribution | ARP
Disaggregation of Revenue [Line Items]
Total revenues		0	25	(27)	108
Operating Segments | Regulated Distribution | Other non-customer revenue
Disaggregation of Revenue [Line Items]
Total revenues		24	26	68	74
Operating Segments | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		411	408	1,223	1,185
Total revenues		415	413	1,233	1,198
Operating Segments | Regulated Transmission | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Operating Segments | Regulated Transmission | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Operating Segments | Regulated Transmission | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Operating Segments | Regulated Transmission | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		411	408	1,223	1,185
Operating Segments | Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Operating Segments | Regulated Transmission | ARP
Disaggregation of Revenue [Line Items]
Total revenues		0	0	0	0
Operating Segments | Regulated Transmission | Other non-customer revenue
Disaggregation of Revenue [Line Items]
Total revenues		4	5	10	13
Corporate/Other and Reconciling Adjustments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(33)	(35)	(103)	(105)
Total revenues		(50)	(52)	(148)	(152)
Corporate/Other and Reconciling Adjustments | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(25)	(22)	(77)	(65)
Corporate/Other and Reconciling Adjustments | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(13)	(16)	(38)	(46)
Corporate/Other and Reconciling Adjustments | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		5	3	12	6
Corporate/Other and Reconciling Adjustments | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Corporate/Other and Reconciling Adjustments | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Corporate/Other and Reconciling Adjustments | ARP
Disaggregation of Revenue [Line Items]
Total revenues		0	0	0	0
Corporate/Other and Reconciling Adjustments | Other non-customer revenue
Disaggregation of Revenue [Line Items]
Total revenues		$ (17)	$ (17)	$ (45)	$ (47)

[1] Includes excise and gross receipts tax collections of $103 million and $100 million during the three months ended September 30, 2021 and 2020, respectively, and $283 million and $276 million during the nine months ended September 30, 2021 and 2020, respectively.