Fair Value Measurements (Details 1) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Debt Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	$ 1,980	[1]	$ 1,699	[2]
Unrealized Gains	25	[1]	31	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	2,005	[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	222	[1]	268	[2]
Unrealized Gains	36	[1]	69	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	258	[1]	337	[2]
FES | Debt Securities
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities
Cost Basis	1,012	[1]	980	[2]
Unrealized Gains	13	[1]	13	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	1,025	[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	104	[1]	0	[2]
Unrealized Gains	20	[1]	0	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	124	[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	134	[1]	123	[2]
Unrealized Gains	0	[1]	1	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	134	[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	53	[1]	42	[2]
Unrealized Gains	1	[1]	0	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	54	[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	22	[1]	0	[2]
Unrealized Gains	5	[1]	0	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	27	[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	356	[1]	281	[2]
Unrealized Gains	7	[1]	9	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	363	[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	27	[1]	80	[2]
Unrealized Gains	3	[1]	17	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	30	[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	232	[1]	127	[2]
Unrealized Gains	2	[1]	4	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	234	[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	46	[1]	125	[2]
Unrealized Gains	5	[1]	35	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	51	[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	193	[1]	145	[2]
Unrealized Gains	2	[1]	4	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	195	[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	23	[1]	63	[2]
Unrealized Gains	3	[1]	16	[2]
Unrealized Losses	0	[1]	0	[2]
Fair Value	$ 26	[1]	$ 79	[2]

[1] Excludes short-term cash investments: FirstEnergy — $164 million; FES — $74 million; OE — $2 million; TE — $2 million; JCP&L — $19 million; Met-Ed — $25 million and Penelec — $41 million.

[2] Excludes short-term cash investments: FirstEnergy — $193 million; FES — $153 million; OE — $3 million; TE — $34 million; JCP&L — $3 million; Met-Ed — $(3) million and Penelec — $4 million.