Capitalization (Details 1) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Schedule of Capitalization [Line Items]
Secured notes	$ 2,305	$ 2,098
Unsecured debt	14,258	14,872
Capital lease obligations	104	132
Unamortized debt premiums (discounts)	(25)	(18)
Unamortized debt issuance costs	(87)	(93)
Unamortized fair value adjustments	(6)	5
Currently payable long-term debt	(1,685)	(1,166)
Total long-term debt and other long-term obligations	18,192	19,099
FES
Schedule of Capitalization [Line Items]
Secured notes	627	342
Unsecured debt	2,373	2,685
Capital lease obligations	8	13
Unamortized debt premiums (discounts)	(1)	(1)
Unamortized debt issuance costs	(15)	(17)
Currently payable long-term debt	(179)	(512)
Total long-term debt and other long-term obligations	2,813	2,510
FMBs
Schedule of Capitalization [Line Items]
FMBs	$ 3,328	3,269
FMBs | Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	3.34%
FMBs | Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	9.74%
Secured notes - fixed rate
Schedule of Capitalization [Line Items]
Secured notes	$ 2,295	2,096
Secured notes - fixed rate | Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	0.679%
Secured notes - fixed rate | Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	12.00%
Secured notes - fixed rate | FES
Schedule of Capitalization [Line Items]
Secured notes	$ 617	340
Secured notes - fixed rate | FES | Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	4.25%
Secured notes - fixed rate | FES | Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	12.00%
Secured notes - variable rate
Schedule of Capitalization [Line Items]
Secured notes	$ 10	2
Secured notes - variable rate | Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	3.50%
Secured notes - variable rate | Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	3.50%
Secured notes - variable rate | FES
Schedule of Capitalization [Line Items]
Secured notes	$ 10	2
Secured notes - variable rate | FES | Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	3.50%
Secured notes - variable rate | FES | Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	3.50%
Unsecured notes - fixed rate
Schedule of Capitalization [Line Items]
Unsecured debt	$ 13,058	13,580
Unsecured notes - fixed rate | Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	2.15%
Unsecured notes - fixed rate | Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	7.70%
Unsecured notes - fixed rate | FES
Schedule of Capitalization [Line Items]
Unsecured debt	$ 2,373	2,593
Unsecured notes - fixed rate | FES | Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	2.15%
Unsecured notes - fixed rate | FES | Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	6.80%
Unsecured notes - variable rate
Schedule of Capitalization [Line Items]
Unsecured debt	$ 1,200	1,292
Unsecured notes - variable rate | Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	2.34%
Unsecured notes - variable rate | Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	2.43%
Unsecured notes - variable rate | FES
Schedule of Capitalization [Line Items]
Unsecured debt	$ 0	$ 92