Revenue (Details) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019 USD ($) company MW	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) company MW	Jun. 30, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 2,448	$ 2,549	$ 5,254	$ 5,327
ARP		55	60	117	124
Other non-customer revenue		13	16	28	36
Total revenues	[1]	2,516	2,625	5,399	5,487
Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges		9	9
Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,139	1,181	2,404	2,450
Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		792	868	1,836	1,894
Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		113	126	223	254
Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		367	336	719	655
Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		37	38	72	74
Derivative Revenue | Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Total revenues		3	4	5	14
Revenue from late payment charges | Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges				20	19
Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues		$ 1,966	2,110	4,310	4,431
Reduction in revenue			10	$ 27	82
Number of existing utility operating companies | company		10		10
Megawatts of net demonstrated capacity of competitive segment | MW		3,790		3,790
Utility customer payment period				30 days
Regulated Distribution | Residential
Disaggregation of Revenue [Line Items]
Total revenues		$ 1,123	1,255	$ 2,607	2,718
Regulated Distribution | Commercial
Disaggregation of Revenue [Line Items]
Total revenues		572	570	1,159	1,150
Regulated Distribution | Industrial
Disaggregation of Revenue [Line Items]
Total revenues		251	262	500	516
Regulated Distribution | Other
Disaggregation of Revenue [Line Items]
Total revenues		20	23	44	47
Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues		367	336	719	655
Reduction in revenue			2	7	2
Regulated Transmission | JCP&L | FERC
Disaggregation of Revenue [Line Items]
Annual revenue requirement				155
Regulated Transmission | ATSI
Disaggregation of Revenue [Line Items]
Total revenues		184	167	358	325
Regulated Transmission | TrAIL
Disaggregation of Revenue [Line Items]
Total revenues		59	63	117	123
Regulated Transmission | MAIT
Disaggregation of Revenue [Line Items]
Total revenues		50	34	99	64
Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues		74	72	145	143
Operating Segments
Disaggregation of Revenue [Line Items]
Reduction in revenue		2	8	34	84
Operating Segments | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,113	2,266	4,597	4,745
ARP		55	60	117	124
Other non-customer revenue		24	26	51	59
Total revenues		2,192	2,352	4,765	4,928
Operating Segments | Regulated Distribution | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,160	1,228	2,446	2,509
Operating Segments | Regulated Distribution | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		806	882	1,864	1,922
Operating Segments | Regulated Distribution | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		110	121	216	244
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		37	35	71	70
Operating Segments | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		367	336	719	655
ARP		0	0	0	0
Other non-customer revenue		5	5	9	9
Total revenues		372	341	728	664
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		367	336	719	655
Operating Segments | Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Corporate/Other and Reconciling Adjustments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(32)	(53)	(62)	(73)
ARP		0	0	0	0
Other non-customer revenue		(16)	(15)	(32)	(32)
Total revenues		(48)	(68)	(94)	(105)
Corporate/Other and Reconciling Adjustments | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(21)	(47)	(42)	(59)
Corporate/Other and Reconciling Adjustments | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(14)	(14)	(28)	(28)
Corporate/Other and Reconciling Adjustments | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		3	5	7	10
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	$ 3	$ 1	$ 4

[1] Includes excise and gross receipts tax collections of $81 million and $87 million during the three months ended June 30, 2019 and 2018, respectively, and $183 million and $189 million during the six months ended June 30, 2019 and 2018, respectively.