Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified																																			12 Months Ended
	Dec. 31, 2012 Non Utility Generation Contract JCP&L	Dec. 31, 2012 Level 3 FTRs	Dec. 31, 2011 Level 3 FTRs	Dec. 31, 2010 Level 3 FTRs	Dec. 31, 2012 Level 3 FTRs FES	Dec. 31, 2011 Level 3 FTRs FES	Dec. 31, 2010 Level 3 FTRs FES	Dec. 31, 2012 Level 3 Non Utility Generation Contract		Dec. 31, 2011 Level 3 Non Utility Generation Contract		Dec. 31, 2010 Level 3 Non Utility Generation Contract		Dec. 31, 2012 Level 3 Non Utility Generation Contract JCP&L		Dec. 31, 2011 Level 3 Non Utility Generation Contract JCP&L		Dec. 31, 2010 Level 3 Non Utility Generation Contract JCP&L		Dec. 31, 2012 Level 3 LCAPP Contracts		Dec. 31, 2011 Level 3 LCAPP Contracts		Dec. 31, 2010 Level 3 LCAPP Contracts		Dec. 31, 2012 Level 3 LCAPP Contracts JCP&L	Dec. 31, 2011 Level 3 LCAPP Contracts JCP&L	Dec. 31, 2010 Level 3 LCAPP Contracts JCP&L	Dec. 31, 2012 Model Level 3 FTRs	Dec. 31, 2012 Model Level 3 FTRs FES	Dec. 31, 2012 Model Level 3 Non Utility Generation Contract	Dec. 31, 2012 Model Level 3 Non Utility Generation Contract JCP&L	Dec. 31, 2012 Model Level 3 LCAPP Contracts	Dec. 31, 2012 Model Level 3 LCAPP Contracts JCP&L	Dec. 31, 2012 Model Level 3 Minimum FTRs	Dec. 31, 2012 Model Level 3 Minimum FTRs FES	Dec. 31, 2012 Model Level 3 Minimum Non Utility Generation Contract MWh	Dec. 31, 2012 Model Level 3 Minimum Non Utility Generation Contract JCP&L MWh	Dec. 31, 2012 Model Level 3 Minimum LCAPP Contracts	Dec. 31, 2012 Model Level 3 Minimum LCAPP Contracts JCP&L	Dec. 31, 2012 Model Level 3 Maximum FTRs	Dec. 31, 2012 Model Level 3 Maximum FTRs FES	Dec. 31, 2012 Model Level 3 Maximum Non Utility Generation Contract MWh	Dec. 31, 2012 Model Level 3 Maximum Non Utility Generation Contract JCP&L MWh	Dec. 31, 2012 Model Level 3 Maximum LCAPP Contracts	Dec. 31, 2012 Model Level 3 Maximum LCAPP Contracts JCP&L	Dec. 31, 2012 Model Level 3 Weighted Average [Member] FTRs	Dec. 31, 2012 Model Level 3 Weighted Average [Member] FTRs FES	Dec. 31, 2012 Model Level 3 Weighted Average [Member] Non Utility Generation Contract MWh	Dec. 31, 2012 Model Level 3 Weighted Average [Member] Non Utility Generation Contract JCP&L MWh	Dec. 31, 2012 Model Level 3 Weighted Average [Member] LCAPP Contracts	Dec. 31, 2012 Model Level 3 Weighted Average [Member] LCAPP Contracts JCP&L
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value	$ (120)	$ (1)	$ (22)	$ 0	$ 0	$ (6)	$ 0	$ (254)	[1]	$ (292)	[1]	$ (344)	[1]	$ (120)	[2]	$ (143)	[2]	$ (227)	[2]	$ (144)	[1]	$ 0	[1]	$ 0	[1]	$ (144)	$ 0	$ 0	$ (1)	$ 0	$ (254)	$ (120)	$ (144)	$ (144)
Fair Value Inputs, Power																																					700						6,525,000						1,920,000
Fair Value Inputs, RTO Auction Clearing Prices																																			(3.2)	(3.2)					6.3	6.3					0.50	0.30
Fair Value Inputs, Generation																																						76,000						1,417,000						257,000
Fair Value Inputs, Power, Regional Prices																																					50	52.2	158.60	158.60			57.3	59.5	197.30	197.30			53.90	56.10	174.50	174.50

[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.