Organization, Basis of Presentation and Significant Accounting Policies (Details 2) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Basic and Diluted Earnings per Share of Common Stock
Income from continuing operations	$ 142	$ 209	$ (168)	$ 192	$ (153)	$ 422	$ 184	$ 302	$ 375	$ 755	$ 856
Less: Income attributable to noncontrolling interest									0	1	(16)
Income from continuing operations available to common shareholders									375	754	872
Discontinued operations (Note 20)	0	9	4	4	5	3	4	4	17	16	13
EARNINGS AVAILABLE TO FIRSTENERGY CORP.	$ 142	$ 218	$ (164)	$ 196	$ (148)	$ 425	$ 187	$ 306	$ 392	$ 770	$ 885
Weighted average number of basic shares outstanding									418	418	399
Assumed exercise of dilutive stock options and awards									1	1	2
Weighted average number of diluted shares outstanding									419	419	401
Earnings per share:
Basic - Continuing Operations, in dollars per share	$ 0.34	$ 0.50	$ (0.40)	$ 0.46	$ (0.36)	$ 1.01	$ 0.44	$ 0.72	$ 0.90	$ 1.81	$ 2.19
Basic - Discontinued Operations (Note 20), in dollars per share	$ 0.00	$ 0.02	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.04	$ 0.04	$ 0.03
Basic - Earnings Available to FirstEnergy Corp., in dollars per share	$ 0.34	$ 0.52	$ (0.39)	$ 0.47	$ (0.35)	$ 1.02	$ 0.45	$ 0.73	$ 0.94	$ 1.85	$ 2.22
Diluted earnings per share:
Diluted - Continuing Operations, in dollars per share	$ 0.34	$ 0.50	$ (0.40)	$ 0.46	$ (0.36)	$ 1.00	$ 0.44	$ 0.72	$ 0.90	$ 1.80	$ 2.18
Diluted - Discontinued Operations (Note 20), in dollars per share	$ 0.00	$ 0.02	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.04	$ 0.04	$ 0.03
Diluted - Earnings Available to FirstEnergy Corp., in dollars per share	$ 0.34	$ 0.52	$ (0.39)	$ 0.47	$ (0.35)	$ 1.01	$ 0.45	$ 0.73	$ 0.94	$ 1.84	$ 2.21
Shares excluded from the calculation of diluted shares outstanding, in shares									2	0	0

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Antidilution

-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Diluted Earnings Per Share

-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Contingent Stock Agreement

-URI http://asc.fasb.org/extlink&oid=6508534

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

-Paragraph 40

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

-Paragraph 13, 14

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 07-4

-Paragraph 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

-Paragraph 171

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.