Fair Value Measurements (Details 1) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010
FES | Debt Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	$ 227	[1]	$ 980	[2]
Unrealized Gains	1	[1]	13	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	228	[1]	993	[2]
FES | Equity Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	83	[1]	0	[2]
Unrealized Gains	4	[1]	0	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	87	[1]	0	[2]
OE | Debt Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	0	[1]	123	[2]
Unrealized Gains	0	[1]	1	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	0	[1]	124	[2]
TE | Debt Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	45	[1]	42	[2]
Unrealized Gains	0	[1]	0	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	45	[1]	42	[2]
TE | Equity Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	23	[1]	0	[2]
Unrealized Gains	1	[1]	0	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	24	[1]	0	[2]
JCP&L | Debt Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	253	[1]	281	[2]
Unrealized Gains	8	[1]	9	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	261	[1]	290	[2]
JCP&L | Equity Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	19	[1]	80	[2]
Unrealized Gains	0	[1]	17	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	19	[1]	97	[2]
Met-Ed | Debt Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	41	[1]	127	[2]
Unrealized Gains	0	[1]	4	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	41	[1]	131	[2]
Met-Ed | Equity Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	30	[1]	125	[2]
Unrealized Gains	1	[1]	35	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	31	[1]	160	[2]
Penelec | Debt Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	123	[1]	145	[2]
Unrealized Gains	2	[1]	4	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	125	[1]	149	[2]
Penelec | Equity Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	19	[1]	63	[2]
Unrealized Gains	0	[1]	16	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	19	[1]	79	[2]
Debt Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	689	[1]	1,699	[2]
Unrealized Gains	11	[1]	31	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	700	[1]	1,730	[2]
Equity Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	174	[1]	268	[2]
Unrealized Gains	6	[1]	69	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	$ 180	[1]	$ 337	[2]

[1] Excludes cash investments, receivables, payables, taxes and accrued income: FirstEnergy – $1,526 million; FES – $872 million; OE – $136 million; TE – $9 million; JCP&L – $133 million; Met-Ed – $229 million and Penelec – $147 million.

[2] Excludes cash investments, receivables, payables, taxes and accrued income: FirstEnergy – $193 million; FES – $153 million; OE – $3 million; TE – $34 million; JCP&L – $3 million; Met-Ed – $(3) million and Penelec – $4 million.