Organization and Basis of Presentation (Details Textuals) mi² in Thousands, customer in Millions			3 Months Ended				9 Months Ended	12 Months Ended
	Jan. 01, 2019 USD ($)	Feb. 18, 2018 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2018 USD ($) mi² transmission_center company MW	Dec. 31, 2018 USD ($) mi² customer transmission_center company MW	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 26, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jan. 01, 2018 USD ($)	Aug. 31, 2017 MW	Mar. 06, 2017 MW
Regulatory Assets [Line Items]
Number of regional transmission centers | transmission_center							2	2
Amount paid to settle claims											$ 225,000,000
Regulatory assets that do not earn a current return				$ 223,000,000			$ 503,000,000	$ 503,000,000	$ 223,000,000
Regulatory assets based on prior precedent or anticipated recovery based on rate making premises with specific order							141,000,000	$ 141,000,000
Annual Composite Depreciation Rate (percent)								2.60%	2.40%	2.30%
Capitalized financing costs								$ 46,000,000	$ 35,000,000	$ 37,000,000
Interest costs capitalized								19,000,000	17,000,000	18,000,000
Property, plant and equipment				28,101,000,000			$ 29,911,000,000	29,911,000,000	28,101,000,000
Impairments of long-lived assets								0	2,399,000,000	10,665,000,000
Share-based compensation accounting change				(6,000,000)					(6,000,000)
Net cash used for financing activities								1,394,000,000	(702,000,000)	(34,000,000)
Impact of adopting new accounting pronouncements								$ 35,000,000
Regulated Distribution
Regulatory Assets [Line Items]
Number of existing utility operating companies | company							10	10
Number of customers served by utility operating companies | customer								6
Service Area | mi²							65	65
Plant generation capacity (in MW's) | MW							3,790	3,790
Property, plant and equipment, net							$ 2,000,000,000	$ 2,000,000,000
Property, plant and equipment				18,916,000,000			$ 20,016,000,000	$ 20,016,000,000	18,916,000,000
Regulated Transmission
Regulatory Assets [Line Items]
Service Area | mi²							25	25
Property, plant and equipment				8,527,000,000			$ 9,376,000,000	$ 9,376,000,000	8,527,000,000
Bath County, Virginia
Regulatory Assets [Line Items]
Plant generation capacity (in MW's) | MW							3,003	3,003
MAIT
Regulatory Assets [Line Items]
Impairments of long-lived assets					$ 13,000,000
AE Supply
Regulatory Assets [Line Items]
Amount of damages awarded to other party		$ 93,000,000
Virginia Electric and Power Company | Bath County, Virginia
Regulatory Assets [Line Items]
Proportionate ownership share (percent)							60.00%	60.00%
AGC | Bath County, Virginia
Regulatory Assets [Line Items]
Plant generation capacity (in MW's) | MW							487	487
Proportionate ownership share (percent)							16.00%	16.00%
Property, plant and equipment							$ 188,000,000	$ 188,000,000
OVEC | AE Supply
Regulatory Assets [Line Items]
Impairments of long-lived assets										43,000,000
Connecting Transmission Facilities | AGC | Bath County, Virginia
Regulatory Assets [Line Items]
Proportionate ownership share (percent)							40.00%	40.00%
Pleasants Power Station
Regulatory Assets [Line Items]
Plant generation capacity (in MW's) | MW															1,300
Purchase Agreement with Subsidiary of LS Power
Regulatory Assets [Line Items]
Plant generation capacity (in MW's) | MW														1,615
Purchase Agreement with Subsidiary of LS Power | Pleasants Power Station | AE Supply
Regulatory Assets [Line Items]
Plant generation capacity (in MW's) | MW							1,300	1,300
Utilization of Accelerated Useful Life
Regulatory Assets [Line Items]
Out-of period adjustment						$ 21,000,000			19,000,000
Accounting Standards Update 2016-09
Regulatory Assets [Line Items]
Net cash used for financing activities									8,000,000
Accounting Standards Update 2016-02 | Forecast | Operating Lease Assets
Regulatory Assets [Line Items]
Impact of adopting new accounting pronouncements	$ 190
Accounting Standards Update 2016-02 | Forecast | Operating Lease Obligations
Regulatory Assets [Line Items]
Impact of adopting new accounting pronouncements	$ 190
Retained Earnings (Accumulated Deficit)
Regulatory Assets [Line Items]
Share-based compensation accounting change				(6,000,000)					(6,000,000)
Impact of adopting new accounting pronouncements								$ 35,000,000
Retained Earnings (Accumulated Deficit) | Accounting Standards Update 2016-09
Regulatory Assets [Line Items]
Share-based compensation accounting change				22,000,000					22,000,000
Retained Earnings (Accumulated Deficit) | Accounting Standards Update 2016-01
Regulatory Assets [Line Items]
Share-based compensation accounting change													$ 57,000,000
Other Nonoperating Income (Expense) | Accounting Standards Update 2017-07
Regulatory Assets [Line Items]
Reclassification of non-service costs									27,000,000	6,000,000
Other Operating Income (Expense) | Accounting Standards Update 2017-07
Regulatory Assets [Line Items]
Reclassification of non-service costs									$ (27,000,000)	$ (6,000,000)
Line of Credit | Secured Credit Facility | FES
Regulatory Assets [Line Items]
Maximum amount borrowed under revolving credit facility											500,000,000
Line of Credit | Credit Agreement | FES
Regulatory Assets [Line Items]
Maximum amount borrowed under revolving credit facility											200,000,000
Discontinued Operations, Disposed of by Means Other than Sale | FES and FENOC
Regulatory Assets [Line Items]
Investments in subsidiaries												$ 0
Amount of damages awarded to other party								66,000,000
Income taxes paid								$ 52,000,000
Loss from discontinued operations			$ 877,000,000
Intercompany Income Tax Allocation Agreement | Loans Payable | FES
Regulatory Assets [Line Items]
Face amount of loan											628,000,000
McElroy's Run Impoundment Site | Pleasants Power Station
Regulatory Assets [Line Items]
Increase in asset retirement obligation			43,000,000
Regulation of Waste Disposal | McElroy's Run Impoundment Site | Pleasants Power Station | AE Supply
Regulatory Assets [Line Items]
Increase in asset retirement obligation			$ 43,000,000
Affiliated companies | Services Agreements | Discontinued Operations, Disposed of by Means Other than Sale | FES and FENOC | FES
Regulatory Assets [Line Items]
Amounts of transaction							$ 112,500,000
2017 | Discontinued Operations, Disposed of by Means Other than Sale | FES and FENOC
Regulatory Assets [Line Items]
Overpayment of NOL's reversed											71,000,000
2018 | Discontinued Operations, Disposed of by Means Other than Sale | FES and FENOC
Regulatory Assets [Line Items]
Overpayment of NOL's reversed											$ 88,000,000
FERC | JCP&L
Regulatory Assets [Line Items]
Impairments of long-lived assets				$ 28,000,000