Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Proceeds from the sale of investments in available-for-sale securities, realized gains and losses on those sales, and interest and dividend income
Sales Proceeds	$ 4,207	$ 3,172	$ 2,229
Realized gains	229	126	226
Realized losses	(90)	(107)	(155)
Interest and Dividend Income	82	79	60
FES
Proceeds from the sale of investments in available-for-sale securities, realized gains and losses on those sales, and interest and dividend income
Sales Proceeds	1,843	1,927	1,379
Realized gains	80	92	199
Realized losses	(46)	(75)	(117)
Interest and Dividend Income	47	47	27
OE
Proceeds from the sale of investments in available-for-sale securities, realized gains and losses on those sales, and interest and dividend income
Sales Proceeds	154	83	131
Realized gains	6	2	11
Realized losses	0	0	(4)
Interest and Dividend Income	3	3	4
TE
Proceeds from the sale of investments in available-for-sale securities, realized gains and losses on those sales, and interest and dividend income
Sales Proceeds	120	126	169
Realized gains	5	3	7
Realized losses	(5)	(1)	(1)
Interest and Dividend Income	2	2	2
JCP&L
Proceeds from the sale of investments in available-for-sale securities, realized gains and losses on those sales, and interest and dividend income
Sales Proceeds	779	411	397
Realized gains	39	10	6
Realized losses	(11)	(10)	(12)
Interest and Dividend Income	15	14	14
Met-Ed
Proceeds from the sale of investments in available-for-sale securities, realized gains and losses on those sales, and interest and dividend income
Sales Proceeds	860	460	68
Realized gains	64	13	2
Realized losses	(16)	(14)	(13)
Interest and Dividend Income	8	7	7
Penelec
Proceeds from the sale of investments in available-for-sale securities, realized gains and losses on those sales, and interest and dividend income
Sales Proceeds	451	165	84
Realized gains	35	6	1
Realized losses	(12)	(7)	(8)
Interest and Dividend Income	$ 6	$ 6	$ 6