Discontinued Operations - Summarized Results (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020	Jun. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense	$ 1		$ 39		$ (35)	$ 44
Loss from discontinued operations, net of tax					52	(39)
Accelerated net pension and OPEB prior service credits			0			0
Gain (loss) on Disposal of FES and FENOC, before tax	3		10		17	(23)
Income (loss) from discontinued operations	2	[1]	(29)	[1]	52	(64)
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	0		31		7	85
Fuel	0		(20)		(6)	(55)
Other operating expenses	0		(16)		(6)	(26)
General taxes	0		(5)		0	(9)
Other income (expense)	0		10		5	8
Loss from discontinued operations, before tax	0		0		0	3
Income tax expense	0		14		0	28
Loss from discontinued operations, net of tax	0		(14)		0	(25)
Settlement consideration	3		10		(1)	(23)
Accelerated net pension and OPEB prior service credits	0				18
Income tax expense (benefit) including worthless stock deduction	1		25		(35)	16
Gain (loss) on disposal of FES and FENOC, net of tax	2		(15)		52	(39)
Income (loss) from discontinued operations	$ 2		$ (29)		$ 52	$ (64)

[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.