Pension and Other Postemployment Benefits (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Feb. 01, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by employer	$ 500
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs		$ 48	$ 56	$ 144	$ 168
Interest costs		93	93	279	279
Expected return on plan assets		(135)	(144)	(405)	(432)
Amortization of prior service costs (credits)		2	2	6	6
Special termination costs		0	21	14	21
Net periodic costs (credits), including amounts capitalized		8	28	38	42
Net periodic costs (credits), recognized in earnings		(11)	5	(19)	(27)
Pension | FES and FENOC | Discontinued Operations, Disposed of by Means Other than Sale
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic costs (credits), including amounts capitalized		12	12	34	38
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs		1	1	3	3
Interest costs		6	6	16	18
Expected return on plan assets		(7)	(7)	(21)	(22)
Amortization of prior service costs (credits)		(9)	(20)	(27)	(60)
Special termination costs		0	6	0	6
Net periodic costs (credits), including amounts capitalized		(9)	(14)	(29)	(55)
Net periodic costs (credits), recognized in earnings		(10)	(15)	(30)	(57)
OPEB | FES and FENOC | Discontinued Operations, Disposed of by Means Other than Sale
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic costs (credits), including amounts capitalized		(14)	$ (11)	(16)	$ (31)
Affiliated Companies | Pension Plan Enhancement | FES and FENOC | Discontinued Operations, Disposed of by Means Other than Sale
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amounts of transaction				14
FES | Affiliated Companies | Benefit Obligations | FES and FENOC | Discontinued Operations, Disposed of by Means Other than Sale
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amounts of transaction		$ 9		$ 28