Revenue (Details) $ in Millions		3 Months Ended
		Mar. 31, 2019 USD ($) company MW	Mar. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 2,806	$ 2,778
ARP		62	64
Other non-customer revenue		15	20
Total revenues	[1]	2,883	2,862
Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges		11	10
Distribution services | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,265	1,269
Retail generation | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,044	1,026
Wholesale sales | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		110	128
Transmission | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		352	319
Other | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		35	36
Derivative Revenue | Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Total revenues		2	10
Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues		2,344	2,321
Reduction in revenue		$ 27	72
Number of existing utility operating companies | company		10
Megawatts of net demonstrated capacity of competitive segment | MW		3,790
Utility customer payment period		30 days
Regulated Distribution | Residential
Disaggregation of Revenue [Line Items]
Total revenues		$ 1,484	1,463
Regulated Distribution | Commercial
Disaggregation of Revenue [Line Items]
Total revenues		587	580
Regulated Distribution | Industrial
Disaggregation of Revenue [Line Items]
Total revenues		249	254
Regulated Distribution | Other
Disaggregation of Revenue [Line Items]
Total revenues		24	24
Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues		352	319
Reduction in revenue		5	4
Regulated Transmission | JCP&L | FERC
Disaggregation of Revenue [Line Items]
Annual revenue requirement		155
Regulated Transmission | ATSI
Disaggregation of Revenue [Line Items]
Total revenues		174	158
Regulated Transmission | TrAIL
Disaggregation of Revenue [Line Items]
Total revenues		58	60
Regulated Transmission | MAIT
Disaggregation of Revenue [Line Items]
Total revenues		49	30
Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues		71	71
Operating Segments | Customer
Disaggregation of Revenue [Line Items]
Reduction in revenue		32	76
Operating Segments | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,484	2,479
ARP		62	64
Other non-customer revenue		27	33
Total revenues		2,573	2,576
Operating Segments | Regulated Distribution | Distribution services | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,286	1,281
Operating Segments | Regulated Distribution | Retail generation | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,058	1,040
Operating Segments | Regulated Distribution | Wholesale sales | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		106	123
Operating Segments | Regulated Distribution | Transmission | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Operating Segments | Regulated Distribution | Other | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		34	35
Operating Segments | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		352	319
ARP		0	0
Other non-customer revenue		4	4
Total revenues		356	323
Operating Segments | Regulated Transmission | Distribution services | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Operating Segments | Regulated Transmission | Retail generation | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Operating Segments | Regulated Transmission | Wholesale sales | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Operating Segments | Regulated Transmission | Transmission | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		352	319
Operating Segments | Regulated Transmission | Other | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Corporate/Other and Reconciling Adjustments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(30)	(20)
ARP		0	0
Other non-customer revenue		(16)	(17)
Total revenues		(46)	(37)
Corporate/Other and Reconciling Adjustments | Distribution services | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(21)	(12)
Corporate/Other and Reconciling Adjustments | Retail generation | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(14)	(14)
Corporate/Other and Reconciling Adjustments | Wholesale sales | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		4	5
Corporate/Other and Reconciling Adjustments | Transmission | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Corporate/Other and Reconciling Adjustments | Other | Customer
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 1	$ 1

[1] Includes excise and gross receipts tax collections of $102 million in the three months ended March 31, 2019 and 2018