Earnings Per Share of Common Stock (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Earnings Per Share [Abstract]
Income from continuing operations	$ 122		$ 192
Discontinued operations (Note 13)	86		4
EARNINGS AVAILABLE TO FIRSTENERGY CORP.	$ 208		$ 196
Weighted average number of basic shares outstanding	419		418
Assumed exercise of dilutive stock options and awards	1	[1]	1	[1]
Weighted average number of diluted shares outstanding	420		419
Basic earnings per share:
Income from continuing operations, in dollars per share	$ 0.29		$ 0.46
Discontinued operations (Note 13), in dollars per share	$ 0.21		$ 0.01
Basic - Earnings Available to FirstEnergy Corp., in dollars per share	$ 0.50		$ 0.47
Diluted earnings per share:
Income from continuing operations, in dollars per share	$ 0.29		$ 0.46
Discontinued operations (Note 13), in dollars per share	$ 0.20		$ 0.01
Diluted - Earnings Available to FirstEnergy Corp., in dollars per share	$ 0.49		$ 0.47
Shares excluded from the calculation of diluted shares outstanding, in shares	2		0

[1] For the three months ended March 31, 2014, 2 million shares were excluded from the calculation of diluted shares outstanding, as their inclusion would be antidilutive. The number of potentially dilutive securities not included in the calculation of diluted shares outstanding due to their antidilutive effect was not significant for the three months ended March 31, 2013.