Fair Value Measurements (Details 1) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Non Utility Generation Contract | JCP&L
Reconciliation of changes in the fair value of NUG contracts
Ending Balance, Derivative, Total	$ (120)
Level 3 | Non Utility Generation Contract
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	57	[1]	122	[1]
Beginning Balance, Derivative Liability	(349)	[1]	(466)	[1]
Beginning Balance, Derivative, Total	(292)	[1]	(344)	[1]
Unrealized gain (loss), Derivative Asset	(20)	[1]	(58)	[1]
Unrealized gain (loss), Derivative Liability	(180)	[1]	(144)	[1]
Unrealized gain (loss), Derivative total	(200)	[1]	(202)	[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]
Settlements, Derivative Asset	(1)	[1]	(7)	[1]
Settlements, Derivative Liability	239	[1]	261	[1]
Settlements, Derivative Asset and Liability, total	238	[1]	254	[1]
Transfers into Level 3, Derivative Asset			0	[1]
Transfers into Level 3, Derivative Liability			0	[1]
Transfers into Level 3, Derivative Asset and Liability, total			0	[1]
Ending Balance, Derivative Asset	36	[1]	57	[1]
Ending Balance, Derivative Liability	(290)	[1]	(349)	[1]
Ending Balance, Derivative, Total	(254)	[1]	(292)	[1]
Level 3 | Non Utility Generation Contract | JCP&L
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	4	[2]	6	[2]
Beginning Balance, Derivative Liability	(147)	[2]	(233)	[2]
Beginning Balance, Derivative, Total	(143)	[2]	(227)	[2]
Unrealized gain (loss), Derivative Asset	(3)	[2]	(2)	[2]
Unrealized gain (loss), Derivative Liability	(27)	[2]	(11)	[2]
Unrealized gain (loss), Derivative total	(30)	[2]	(13)	[2]
Purchases, Derivative Asset	0	[2]
Purchases, Derivative Liability	0	[2]
Purchases, Derivative Asset and Liability, total	0	[2]
Settlements, Derivative Asset	0	[2]	0	[2]
Settlements, Derivative Liability	53	[2]	97	[2]
Settlements, Derivative Asset and Liability, total	53	[2]	97	[2]
Ending Balance, Derivative Asset	1	[2]	4	[2]
Ending Balance, Derivative Liability	(121)	[2]	(147)	[2]
Ending Balance, Derivative, Total	(120)	[2]	(143)	[2]
Level 3 | LCAPP Contracts
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	0	[1]	0	[1]
Beginning Balance, Derivative Liability	0	[1]	0	[2]
Beginning Balance, Derivative, Total	0	[1]	0	[1]
Unrealized gain (loss), Derivative Asset	0	[1]	0	[1]
Unrealized gain (loss), Derivative Liability	1	[2]	0	[2]
Unrealized gain (loss), Derivative total	1	[1]	0	[1]
Purchases, Derivative Asset	0	[1]	0	[1]
Purchases, Derivative Liability	(145)	[2]
Purchases, Derivative Asset and Liability, total	(145)	[1]	0	[1]
Settlements, Derivative Asset	0	[1]	0	[1]
Settlements, Derivative Liability	0	[2]	0	[2]
Settlements, Derivative Asset and Liability, total	0	[1]	0	[1]
Transfers into Level 3, Derivative Asset			0	[1]
Transfers into Level 3, Derivative Asset and Liability, total			0	[1]
Ending Balance, Derivative Asset	0	[1]	0	[1]
Ending Balance, Derivative Liability	(144)	[1]	0	[1]
Ending Balance, Derivative, Total	(144)	[1]	0	[1]
Level 3 | LCAPP Contracts | JCP&L
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	0	[2]	0
Beginning Balance, Derivative Liability	0	[2]	0
Beginning Balance, Derivative, Total	0		0
Unrealized gain (loss), Derivative Asset	0		0
Unrealized gain (loss), Derivative Liability	1		0
Unrealized gain (loss), Derivative total	1		0
Purchases, Derivative Asset	0
Purchases, Derivative Liability	(145)		0
Purchases, Derivative Asset and Liability, total	(145)
Settlements, Derivative Asset	0		0
Settlements, Derivative Liability	0		0
Settlements, Derivative Asset and Liability, total	0		0
Transfers into Level 3, Derivative Liability			0	[1]
Ending Balance, Derivative Asset	0	[2]	0	[2]
Ending Balance, Derivative Liability	(144)	[2]	0	[2]
Ending Balance, Derivative, Total	(144)		0
Level 3 | FTRs
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	1		0
Beginning Balance, Derivative Liability	(23)		0
Beginning Balance, Derivative, Total	(22)		0
Unrealized gain (loss), Derivative Asset	6		2
Unrealized gain (loss), Derivative Liability	(6)		(27)
Unrealized gain (loss), Derivative total	0		(25)
Purchases, Derivative Asset	13		13
Purchases, Derivative Liability	(10)		(4)
Purchases, Derivative Asset and Liability, total	3		9
Settlements, Derivative Asset	(12)		(14)
Settlements, Derivative Liability	30		20
Settlements, Derivative Asset and Liability, total	18		6
Transfers into Level 3, Derivative Asset			0
Transfers into Level 3, Derivative Liability			(12)
Transfers into Level 3, Derivative Asset and Liability, total			(12)
Ending Balance, Derivative Asset	8		1
Ending Balance, Derivative Liability	(9)		(23)
Ending Balance, Derivative, Total	(1)		(22)
Level 3 | FTRs | FES
Reconciliation of changes in the fair value of NUG contracts
Beginning Balance, Derivative Asset	1		0
Beginning Balance, Derivative Liability	(7)		0
Beginning Balance, Derivative, Total	(6)		0
Unrealized gain (loss), Derivative Asset	4		4
Unrealized gain (loss), Derivative Liability	(4)		(8)
Unrealized gain (loss), Derivative total	0		(4)
Purchases, Derivative Asset	9		2
Purchases, Derivative Liability	(7)		(1)
Purchases, Derivative Asset and Liability, total	2		1
Settlements, Derivative Asset	(8)		(5)
Settlements, Derivative Liability	12		2
Settlements, Derivative Asset and Liability, total	4		(3)
Ending Balance, Derivative Asset	6		1
Ending Balance, Derivative Liability	(6)		(7)
Ending Balance, Derivative, Total	$ 0		$ (6)

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

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