Cover Page	9 Months Ended
	Sep. 30, 2019 shares
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	333-21011
Entity Registrant Name	FIRSTENERGY CORP
Entity Incorporation, State or Country Code	OH
Entity Address, Address Line One	76 South Main Street
Entity Address, City or Town	Akron
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	44308
City Area Code	(800)
Local Phone Number	736-3402
Entity Tax Identification Number	34-1843785
Title of 12(b) Security	Common Stock, $0.10 par value
Trading Symbol	FE
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock Shares Outstanding	540,311,707
Amendment Flag	false
Entity Central Index Key	0001031296
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31