Fair Value Measurements (Details Textuals) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended	3 Months Ended		6 Months Ended			3 Months Ended	6 Months Ended		1 Months Ended					1 Months Ended								0 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 NUG contracts	Jun. 30, 2013 FES	Jun. 30, 2012 FES	Jun. 30, 2013 FES	Jun. 30, 2012 FES	Dec. 31, 2012 FES	Jun. 30, 2013 FGCO	Jun. 30, 2013 FGCO	Jun. 03, 2013 FGCO	Jun. 30, 2013 Ohio Funding Companies	Mar. 31, 2013 Senior Notes FE	Mar. 31, 2013 Senior Notes FES	Mar. 31, 2013 Senior Notes FES Year 2021	Mar. 31, 2013 Senior Notes FES Year 2039	Mar. 31, 2013 Senior Notes Allegheny Energy Inc	Mar. 31, 2013 Senior Notes Allegheny Energy Inc Year 2019	Mar. 31, 2013 Senior Notes Allegheny Energy Inc Year 2039	Jun. 30, 2013 Senior Notes FES Corp and Allegheny Energy Inc Minimum	Jun. 30, 2013 Senior Notes FES Corp and Allegheny Energy Inc Maximum	Mar. 31, 2013 Senior Notes, 2.75% Due 2018 Senior Notes FE	Mar. 31, 2013 Senior Notes, 4.25% Due 2023 Senior Notes FE	Mar. 31, 2013 Senior Notes, 3.50% Due 2023 Senior Notes Met-Ed	Apr. 15, 2013 Senior Notes, 4.80% Due 2015 Senior Notes FES	Mar. 31, 2013 Senior Notes, 4.80% Due 2015 Senior Notes FES	Jun. 30, 2013 Phase In Recovery Bonds Ohio Funding Companies	Mar. 31, 2013 Senior Notes, 4.95% Due 2013 Senior Notes, 3.50% Due 2023 Senior Notes Met-Ed	Jun. 30, 2013 Existing Taxable Bonds Ohio Funding Companies	Jun. 30, 2013 Existing Taxable Bonds Ohio Funding Companies Year 2013	Jun. 30, 2013 Existing Taxable Bonds Ohio Funding Companies Year 2015	Jun. 30, 2013 Existing Taxable Bonds Ohio Funding Companies Year 2020
Fair Value of Financial Instruments [Line Items]
Period of future observable data to determine contract price						3 years
Investment excludes Receivables, Payables and Accrued income	$ 4,000,000		$ 4,000,000		$ 110,000,000		$ 2,000,000		$ 2,000,000		$ 94,000,000
Cash balance excluded from available for sale securities	116,000,000		116,000,000		326,000,000		58,000,000		58,000,000		196,000,000
Investments not required to be disclosed	640,000,000		640,000,000		644,000,000
Debt instrument, face amount																1,500,000,000									650,000,000	850,000,000	300,000,000			445,000,000		410,000,000	225,000,000	150,000,000	35,000,000
Stated interest rate percentage																							5.75%	6.80%	2.75%	4.25%	3.50%	4.80%	4.80%		4.95%
Debt repurchased																	369,000,000	252,000,000	117,000,000	294,000,000	194,000,000	100,000,000						400,000,000
Face amount of debt repurchased														235,000,000																	150,000,000
Payments of debt redemption premiums																	67,000,000			43,000,000								31,000,000
Debt repurchase notice amount																													400,000,000
Loss on debt redemptions	(24,000,000)	0	(141,000,000)	0			(32,000,000)	0	(103,000,000)	0		0	0			119,000,000	71,000,000											32,000,000
Weighted average interest rate on debt																														2.48%		5.71%
Make-whole premiums paid on debt redemptions			$ 61,000,000	$ 0					$ 31,000,000	$ 0					$ 30,000,000