Fair Value Measurements (Details 6) (USD $) In Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2011		Dec. 31, 2010
JCP&L | Non Utility Generation Contract
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	$ 6	[1]	$ 8	[1]
Beginning Balance, Derivative Liability	(233)	[1]	(399)	[1]
Beginning Balance, Derivative, Total	(227)	[1]	(391)	[1]
Realized gain (loss), Derivative Asset	0	[1]	0	[1]
Realized gain (loss), Derivative Liability	0	[1]	0	[1]
Realized gain (loss), Derivative Total	0	[1]	0	[1]
Unrealized gain (loss), Derivative Asset	(2)	[1]	(1)	[1]
Unrealized gain (loss), Derivative Liability	(71)	[1]	36	[1]
Unrealized gain (loss), Derivative total	(73)	[1]	35	[1]
Purchases, Derivative Asset	0	[1]	0	[1]
Purchases, Derivative Liability	0	[1]	0	[1]
Purchases, Derivative Asset and Liability, total	0	[1]	0	[1]
Issuances, Derivative Asset	0	[1]	0	[1]
Issuances, Derivative Liability	0	[1]	0	[1]
Issuances, Derivative Asset and Liability, total	0	[1]	0	[1]
Sales, Derivative Asset	0	[1]	0	[1]
Sales, Derivative Liability	0	[1]	0	[1]
Sales, Derivative Asset and Liability, total	0	[1]	0	[1]
Settlements, Derivative Asset	0	[1]	(1)	[1]
Settlements, Derivative Liability	82	[1]	130	[1]
Settlements, Derivative Asset and Liability, total	82	[1]	129	[1]
Transfers into Level 3, Derivative Asset	0	[1]	0	[1]
Transfers into Level 3, Derivative Liability	0	[1]	0	[1]
Transfers into Level 3, Derivative Asset and Liability, total	0	[1]	0	[1]
Ending Balance, Derivative Asset	4	[1]	6	[1]
Ending Balance, Derivative Liability	(222)	[1]	(233)	[1]
Ending Balance, Derivative, Total	(218)	[1]	(227)	[1]
Met-Ed | Non Utility Generation Contract
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	112	[1]	176	[1]
Beginning Balance, Derivative Liability	(116)	[1]	(143)	[1]
Beginning Balance, Derivative, Total	(4)	[1]	33	[1]
Realized gain (loss), Derivative Asset	0	[1]	0	[1]
Realized gain (loss), Derivative Liability	0	[1]	0	[1]
Realized gain (loss), Derivative Total	0	[1]	0	[1]
Unrealized gain (loss), Derivative Asset	(54)	[1]	(59)	[1]
Unrealized gain (loss), Derivative Liability	(61)	[1]	(38)	[1]
Unrealized gain (loss), Derivative total	(115)	[1]	(97)	[1]
Purchases, Derivative Asset	0	[1]	0	[1]
Purchases, Derivative Liability	0	[1]	0	[1]
Purchases, Derivative Asset and Liability, total	0	[1]	0	[1]
Issuances, Derivative Asset	0	[1]	0	[1]
Issuances, Derivative Liability	0	[1]	0	[1]
Issuances, Derivative Asset and Liability, total	0	[1]	0	[1]
Sales, Derivative Asset	0	[1]	0	[1]
Sales, Derivative Liability	0	[1]	0	[1]
Sales, Derivative Asset and Liability, total	0	[1]	0	[1]
Settlements, Derivative Asset	(6)	[1]	(5)	[1]
Settlements, Derivative Liability	45	[1]	65	[1]
Settlements, Derivative Asset and Liability, total	39	[1]	60	[1]
Transfers into Level 3, Derivative Asset	0	[1]	0	[1]
Transfers into Level 3, Derivative Liability	0	[1]	0	[1]
Transfers into Level 3, Derivative Asset and Liability, total	0	[1]	0	[1]
Ending Balance, Derivative Asset	52	[1]	112	[1]
Ending Balance, Derivative Liability	(132)	[1]	(116)	[1]
Ending Balance, Derivative, Total	(80)	[1]	(4)	[1]
Penelec | Non Utility Generation Contract
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	4	[1]	16	[1]
Beginning Balance, Derivative Liability	(117)	[1]	(101)	[1]
Beginning Balance, Derivative, Total	(113)	[1]	(85)	[1]
Realized gain (loss), Derivative Asset	0	[1]	0	[1]
Realized gain (loss), Derivative Liability	0	[1]	0	[1]
Realized gain (loss), Derivative Total	0	[1]	0	[1]
Unrealized gain (loss), Derivative Asset	0	[1]	(11)	[1]
Unrealized gain (loss), Derivative Liability	(139)	[1]	(108)	[1]
Unrealized gain (loss), Derivative total	(139)	[1]	(119)	[1]
Purchases, Derivative Asset	0	[1]	0	[1]
Purchases, Derivative Liability	0	[1]	0	[1]
Purchases, Derivative Asset and Liability, total	0	[1]	0	[1]
Issuances, Derivative Asset	0	[1]	0	[1]
Issuances, Derivative Liability	0	[1]	0	[1]
Issuances, Derivative Asset and Liability, total	0	[1]	0	[1]
Sales, Derivative Asset	0	[1]	0	[1]
Sales, Derivative Liability	0	[1]	0	[1]
Sales, Derivative Asset and Liability, total	0	[1]	0	[1]
Settlements, Derivative Asset	(1)	[1]	(1)	[1]
Settlements, Derivative Liability	68	[1]	92	[1]
Settlements, Derivative Asset and Liability, total	67	[1]	91	[1]
Transfers into Level 3, Derivative Asset	0	[1]	0	[1]
Transfers into Level 3, Derivative Liability	0	[1]	0	[1]
Transfers into Level 3, Derivative Asset and Liability, total	0	[1]	0	[1]
Ending Balance, Derivative Asset	3	[1]	4	[1]
Ending Balance, Derivative Liability	(188)	[1]	(117)	[1]
Ending Balance, Derivative, Total	(185)	[1]	(113)	[1]
Non Utility Generation Contract
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	122	[2]	200	[2]
Beginning Balance, Derivative Liability	(466)	[2]	(643)	[2]
Beginning Balance, Derivative, Total	(344)	[2]	(443)	[2]
Realized gain (loss), Derivative Asset	0	[2]	0	[2]
Realized gain (loss), Derivative Liability	0	[2]	0	[2]
Realized gain (loss), Derivative Total	0	[2]	0	[2]
Unrealized gain (loss), Derivative Asset	(52)	[2]	(71)	[2]
Unrealized gain (loss), Derivative Liability	(285)	[2]	(110)	[2]
Unrealized gain (loss), Derivative total	(337)	[2]	(181)	[2]
Purchases, Derivative Asset	13	[2]	0	[2]
Purchases, Derivative Liability	(3)	[2]	0	[2]
Purchases, Derivative Asset and Liability, total	10	[2]	0	[2]
Issuances, Derivative Asset	0	[2]	0	[2]
Issuances, Derivative Liability	0	[2]	0	[2]
Issuances, Derivative Asset and Liability, total	0	[2]	0	[2]
Sales, Derivative Asset	0	[2]	0	[2]
Sales, Derivative Liability	0	[2]	0	[2]
Sales, Derivative Asset and Liability, total	0	[2]	0	[2]
Settlements, Derivative Asset	(20)	[2]	(7)	[2]
Settlements, Derivative Liability	211	[2]	287	[2]
Settlements, Derivative Asset and Liability, total	191	[2]	280	[2]
Transfers into Level 3, Derivative Asset	0	[2]	0	[2]
Transfers into Level 3, Derivative Liability	(12)	[2]	0	[2]
Transfers into Level 3, Derivative Asset and Liability, total	(12)	[2]	0	[2]
Ending Balance, Derivative Asset	63	[2]	122	[2]
Ending Balance, Derivative Liability	(555)	[2]	(466)	[2]
Ending Balance, Derivative, Total	(492)	[2]	(344)	[2]
FES | FTRs
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	0
Beginning Balance, Derivative Liability	0
Beginning Balance, Derivative, Total	0
Realized gain (loss), Derivative Asset	0
Realized gain (loss), Derivative Liability	0
Realized gain (loss), Derivative Total	0
Unrealized gain (loss), Derivative Asset	4
Unrealized gain (loss), Derivative Liability	(4)
Unrealized gain (loss), Derivative total	0
Purchases, Derivative Asset	2
Purchases, Derivative Liability	0
Purchases, Derivative Asset and Liability, total	2
Issuances, Derivative Asset	0
Issuances, Derivative Liability	0
Issuances, Derivative Asset and Liability, total	0
Sales, Derivative Asset	0
Sales, Derivative Liability	0
Sales, Derivative Asset and Liability, total	0
Settlements, Derivative Asset	(4)
Settlements, Derivative Liability	0
Settlements, Derivative Asset and Liability, total	(4)
Transfers into Level 3, Derivative Asset	0
Transfers into Level 3, Derivative Liability	0
Transfers into Level 3, Derivative Asset and Liability, total	0
Ending Balance, Derivative Asset	2
Ending Balance, Derivative Liability	(4)
Ending Balance, Derivative, Total	$ (2)

[1] Changes in the fair value of NUG contracts are subject to regulatory accounting and do not impact earnings.

[2] Changes in the fair value of NUG contracts are generally subject to regulatory accounting and do not materially impact earnings.