Pension and Other Postemployment Benefits (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Feb. 01, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 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	$ 96	$ 112
Interest costs		93	93	186	186
Expected return on plan assets		(135)	(144)	(270)	(288)
Amortization of prior service costs (credits)		2	2	4	4
Special termination costs		(1)	0	14	0
Net periodic costs (credits), including amounts capitalized		7	7	30	14
Net periodic costs (credits), recognized in earnings		(14)	(18)	(8)	(32)
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		11	13	22	26
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs		1	1	2	2
Interest costs		5	6	10	12
Expected return on plan assets		(7)	(7)	(14)	(15)
Amortization of prior service costs (credits)		(9)	(20)	(18)	(40)
Special termination costs		0	0	0	0
Net periodic costs (credits), including amounts capitalized		(10)	(20)	(20)	(41)
Net periodic costs (credits), recognized in earnings		(10)	(21)	(20)	(42)
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		(1)	$ (10)	(2)	$ (20)
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		$ 19