Revenue (Details) $ in Millions		3 Months Ended
		Mar. 31, 2021 USD ($) company MW	Mar. 31, 2020 USD ($)
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 2,743	$ 2,629
Total revenues	[1]	2,726	2,709
Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges		9	10
Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,313	1,235
Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		923	889
Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		73	72
Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		401	397
Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		33	36
ARP
Disaggregation of Revenue [Line Items]
Total revenues		(27)	68
Other non-customer revenue
Disaggregation of Revenue [Line Items]
Total revenues		10	12
Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues		$ 2,274	2,160
Number of existing utility operating companies | company		10
Megawatts of net demonstrated capacity of competitive segment | MW		3,580
Utility customer payment period		30 days
Regulated Distribution | Residential
Disaggregation of Revenue [Line Items]
Total revenues		$ 1,457	1,319
Regulated Distribution | Commercial
Disaggregation of Revenue [Line Items]
Total revenues		541	544
Regulated Distribution | Industrial
Disaggregation of Revenue [Line Items]
Total revenues		258	277
Regulated Distribution | Other
Disaggregation of Revenue [Line Items]
Total revenues		18	20
Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues		401	397
Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues		27	33
Regulated Transmission | ATSI
Disaggregation of Revenue [Line Items]
Total revenues		207	204
Regulated Transmission | TrAIL
Disaggregation of Revenue [Line Items]
Total revenues		59	63
Regulated Transmission | MAIT
Disaggregation of Revenue [Line Items]
Total revenues		68	57
Regulated Transmission | JCP&L
Disaggregation of Revenue [Line Items]
Total revenues		40	40
Operating Segments | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,376	2,267
Total revenues		2,370	2,358
Operating Segments | Regulated Distribution | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,339	1,256
Operating Segments | Regulated Distribution | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		935	904
Operating Segments | Regulated Distribution | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		69	71
Operating Segments | Regulated Distribution | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Operating Segments | Regulated Distribution | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		33	36
Operating Segments | Regulated Distribution | ARP
Disaggregation of Revenue [Line Items]
Total revenues		(27)	68
Operating Segments | Regulated Distribution | Other non-customer revenue
Disaggregation of Revenue [Line Items]
Total revenues		21	23
Operating Segments | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		401	397
Total revenues		405	401
Operating Segments | Regulated Transmission | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Operating Segments | Regulated Transmission | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Operating Segments | Regulated Transmission | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Operating Segments | Regulated Transmission | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		401	397
Operating Segments | Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Operating Segments | Regulated Transmission | ARP
Disaggregation of Revenue [Line Items]
Total revenues		0	0
Operating Segments | Regulated Transmission | Other non-customer revenue
Disaggregation of Revenue [Line Items]
Total revenues		4	4
Corporate/Other and Reconciling Adjustments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(34)	(35)
Total revenues		(49)	(50)
Corporate/Other and Reconciling Adjustments | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(26)	(21)
Corporate/Other and Reconciling Adjustments | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(12)	(15)
Corporate/Other and Reconciling Adjustments | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		4	1
Corporate/Other and Reconciling Adjustments | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Corporate/Other and Reconciling Adjustments | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Corporate/Other and Reconciling Adjustments | ARP
Disaggregation of Revenue [Line Items]
Total revenues		0	0
Corporate/Other and Reconciling Adjustments | Other non-customer revenue
Disaggregation of Revenue [Line Items]
Total revenues		$ (15)	$ (15)

[1] Includes excise and gross receipts tax collections of $95 million and $92 million during the three months ended March 31, 2021 and 2020, respectively.