Variable Interest Entities (Details Textuals) (USD $)	3 Months Ended						12 Months Ended	1 Months Ended	12 Months Ended
	Mar. 31, 2013 entities	Mar. 31, 2012	Mar. 31, 2013 Power Purchase Agreements agreements	Mar. 31, 2013 OE	Mar. 31, 2013 Other FE subsidiaries Power Purchase Agreements	Mar. 31, 2012 Other FE subsidiaries Power Purchase Agreements	Dec. 31, 2012 Nuclear Generation Corp Beaver Valley Unit 2	Mar. 31, 2013 FGCO Bruce Mansfield Plant	Dec. 31, 2012 FGCO Bruce Mansfield Plant	Mar. 31, 2013 Signal Peak FEV Global Holding	Mar. 31, 2013 Path-WV
Variable Interest Entities (Textuals) [Abstract]
Distributions to owners	$ 5,000,000
Equity interest by unaffiliated third party in PNBV	3.00%
Equity interest by OES Ventures in PNBV				3.00%
Ownership interest										33.33%
Percentage of high-voltage transmission line project owned by subsidiary of AE on the Allegheny Series											100.00%
Percentage of high-voltage transmission line project owned by subsidiary of AE on the West Virginia Series											50.00%
Number of long-term power purchase agreements maintained by FirstEnergy with NUG entities			19
Number of contracts that may contain variable interest	2
Purchased power	943,000,000	1,259,000,000			49,000,000	60,000,000
Purchase of lessor equity interests in sale and leaseback, value							129,000,000	221,000,000	262,000,000
Net present value of FirstEnergy's consolidated sale and leaseback operating lease commitments	$ 1,200,000,000