Discontinued Operations - Summarized Results (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense (benefit)		$ (36)	$ 5
Loss from discontinued operations, net of tax		50	(24)
Income (loss) from discontinued operations	[1]	50	(35)
FES and FENOC | Discontinued Operations, Disposed of by Means Other than Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues		7	54
Fuel		(6)	(35)
Other operating expenses		(6)	(10)
General taxes		0	(4)
Other income (expense)		5
Other income (expense)			(2)
Loss from discontinued operations, before tax		0	3
Income tax expense (benefit)		0	14
Loss from discontinued operations, net of tax		0	(11)
Gain (loss) on disposal of FES and FENOC, net of tax		50	(24)
Income (loss) from discontinued operations		50	(35)
Settlement consideration		(4)	(33)
Accelerated net pension and OPEB prior service credits		18
Income tax benefit (expense), including estimated worthless stock deduction		$ 36	$ 9

[1] Net of income tax expense (benefits) of $(36) million and $5 million for the three months ended March 31, 2020 and 2019, respectively.