Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Reconciliation of basic and diluted earnings per share of common stock
Weighted average number of basic shares outstanding	418		342
Assumed exercise of dilutive stock options and awards	2	[1]	1	[1]
Weighted average number of diluted shares outstanding	420		343
Earnings available to FirstEnergy Corp.	$ 306		$ 52
Basic Earnings Per Share of Common Stock	$ 0.73		$ 0.15
Diluted Earnings Per Share of Common Stock	$ 0.73		$ 0.15

[1] The number of potentially dilutive securities not included in the calculation of diluted shares outstanding due to their antidilutive effect were not significant for the three months ended March 31, 2012 and 2011.