Short-Term Borrowings and Bank Lines of Credit (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2012 Revolving Credit Facility	Jan. 31, 2013 Subsequent Event	Dec. 31, 2012 FirstEnergy	Dec. 31, 2012 FirstEnergy Revolving Credit Facility		Jan. 31, 2013 FirstEnergy Subsequent Event Revolving Credit Facility		Dec. 31, 2012 FES / AE Supply Revolving Credit Facility	Jan. 31, 2013 FES / AE Supply Subsequent Event Revolving Credit Facility	Dec. 31, 2012 FET	Dec. 31, 2012 FET Revolving Credit Facility		Jan. 31, 2013 FET Subsequent Event Revolving Credit Facility		Dec. 31, 2012 AGC Revolving Credit Facility	Jan. 31, 2013 AGC Subsequent Event Revolving Credit Facility
Short-term Debt [Line Items]
Maximum amount borrowed under revolving credit facility	$ 5,550,000,000	$ 1,050,000,000		$ 2,000,000,000	$ 2,000,000,000	[1]			$ 2,500,000,000		$ 1,000,000,000	$ 1,000,000,000	[2]			$ 50,000,000
Available Liquidity			3,279,000,000				776,000,000	[1]		2,488,000,000				0	[2]		15,000,000
Cash, Available Liquidity			61,000,000
Total Available Liquidity			$ 3,340,000,000

[1] FE and the Utilities

[2] Includes FET, ATSI and TrAIL as subsidiary borrowers