Revenue (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($) company MW	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) company MW		Dec. 31, 2017 USD ($)	[1]	Dec. 31, 2016 USD ($)	[1]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									$ 10,944
ARP									254
Other									63
Total revenues	$ 2,710	$ 3,064	$ 2,625	$ 2,862	$ 2,681	$ 2,910	$ 2,561	$ 2,776	$ 11,261	[1]	$ 10,928		$ 10,700
Utility customer payment period									30 days
Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges									$ 39
Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									5,055
Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									3,882
Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									524
Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									1,335
Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									148
Derivative Revenue | Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Total revenues									18
Regulated Distribution
Disaggregation of Revenue [Line Items]
Reduction in revenue									$ 131
Number of existing utility operating companies | company	10								10
Megawatts of net demonstrated capacity of competitive segment (in MW's) | MW	3,790								3,790
Regulated Distribution | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues									$ 9,095
Regulated Distribution | Retail generation | Residential
Disaggregation of Revenue [Line Items]
Total revenues									5,598
Regulated Distribution | Retail generation | Commercial
Disaggregation of Revenue [Line Items]
Total revenues									2,350
Regulated Distribution | Retail generation | Industrial
Disaggregation of Revenue [Line Items]
Total revenues									1,056
Regulated Distribution | Retail generation | Other
Disaggregation of Revenue [Line Items]
Total revenues									91
Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues									1,335
Reduction in revenue									16
Regulated Transmission | JCP&L | FERC
Disaggregation of Revenue [Line Items]
Annual revenue requirement									155
Regulated Transmission | ATSI
Disaggregation of Revenue [Line Items]
Total revenues									664
Regulated Transmission | TrAIL
Disaggregation of Revenue [Line Items]
Total revenues									237
Regulated Transmission | MAIT
Disaggregation of Revenue [Line Items]
Total revenues									150
Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues									284
Operating Segments | Customer
Disaggregation of Revenue [Line Items]
Reduction in revenue									147
Operating Segments | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									9,741
ARP									254
Other									108
Total revenues									10,103
Operating Segments | Regulated Distribution | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									5,159
Operating Segments | Regulated Distribution | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									3,936
Operating Segments | Regulated Distribution | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									502
Operating Segments | Regulated Distribution | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									0
Operating Segments | Regulated Distribution | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									144
Operating Segments | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									1,335
ARP									0
Other									18
Total revenues									1,353
Operating Segments | Regulated Transmission | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									0
Operating Segments | Regulated Transmission | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									0
Operating Segments | Regulated Transmission | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									0
Operating Segments | Regulated Transmission | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									1,335
Operating Segments | Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers
Reconciling Adjustments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									(132)
ARP									0
Other									(63)
Total revenues									(195)
Reconciling Adjustments | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									(104)
Reconciling Adjustments | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									(54)
Reconciling Adjustments | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									22
Reconciling Adjustments | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									0
Reconciling Adjustments | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers									$ 4

[1] Includes excise and gross receipts tax collections of $386 million, $370 million and $378 million in 2018, 2017 and 2016, respectively.