Discontinued Operations - Narrative (Details) $ in Millions			1 Months Ended	3 Months Ended					6 Months Ended
	Feb. 27, 2020 USD ($)	Feb. 18, 2020 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2020 USD ($)		Mar. 31, 2020 USD ($)	Jun. 30, 2019 USD ($)		Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Worthless stock deduction	$ 4,900
Unrecognized tax benefits from worthless stock deduction	316
Worthless stock deduction, net of tax	1,000
Unrecognized tax benefits from worthless stock deduction, net of tax	72
Discontinued operations, net of tax				$ 2	[1]		$ (29)	[1]	$ 52	$ (64)
Pleasants Power Station | AE Supply | Purchase Agreement with Subsidiary of LS Power
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Plant capacity (in MW's) | MW											1,300
Discontinued Operations, Disposed of by Means Other than Sale | FES and FENOC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued operations, net of tax				$ 2			$ (29)		$ 52	$ (64)
Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from asset sales						$ 65
FES Key Creditor Groups | Affiliated Companies | FES
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement of certain claims			$ 853
Settlement of claims upon emergence	853
IT Access Agreement | Affiliated Companies | FES
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement of certain claims		$ 125
Settlement of claims upon emergence	125
State and Local Jurisdiction
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Worthless stock deduction, net of tax	$ 83

[1] Net of income tax expense of $1 million and $39 million for the three months ended June 30, 2020 and 2019, respectively, and $(35) million and $44 million for the six months ended June 30, 2020 and 2019, respectively.