Fair Value Measurements (Details Textuals) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Fair Value of Financial Instruments [Line Items]
Investment excludes Receivables, Payables and Accrued income	$ 110	$ (52)
Cash balance excluded from available for sale securities	326	164
Investments not required to be disclosed	644	693
Decrease in retained earnings resulting from change from cost to equity method investment	9
NUG contracts
Fair Value of Financial Instruments [Line Items]
Period of future observable data to determine contract price	3 years
FES
Fair Value of Financial Instruments [Line Items]
Investment excludes Receivables, Payables and Accrued income	94	(58)
Cash balance excluded from available for sale securities	196	74
OE
Fair Value of Financial Instruments [Line Items]
Investment excludes Receivables, Payables and Accrued income	1	1
Cash balance excluded from available for sale securities	4	2
JCP&L
Fair Value of Financial Instruments [Line Items]
Investment excludes Receivables, Payables and Accrued income	3	2
Cash balance excluded from available for sale securities	$ 38	$ 19