Consolidated Statements of Common Stockholders' Equity (FirstEnergy Corp.) - USD ($) $ in Millions	Total	Common Stock	Other Paid-In Capital	Accumulated Other Comprehensive Income	Retained Earnings (Accumulated Deficit)
Beginning Balance, Shares at Dec. 31, 2014		421,102,570
Beginning Balance at Dec. 31, 2014		$ 42	$ 9,847	$ 246	$ 2,285
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 578				578
Amortized gain (loss) on derivative hedges, net of income taxes				4
Change in unrealized gain on investments, net of income taxes				(7)
Pensions and OPEB, net of income taxes				(72)
Stock-based compensation			45
Cash dividends declared on common stock					(607)
Stock Investment Plan and certain share-based benefit plans, shares		2,457,827
Stock Investment Plan and certain share-based benefit plans			60
Ending Balance, Shares at Dec. 31, 2015		423,560,397
Ending Balance at Dec. 31, 2015		$ 42	9,952	171	2,256
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (6,177)				(6,177)
Amortized gain (loss) on derivative hedges, net of income taxes				5
Change in unrealized gain on investments, net of income taxes				34
Pensions and OPEB, net of income taxes				(36)
Stock-based compensation			49
Cash dividends declared on common stock					(611)
Stock Investment Plan and certain share-based benefit plans, shares		2,685,946
Stock Investment Plan and certain share-based benefit plans			56
Stock issuance (Note 12), Shares		16,097,875
Stock issuance (Note 12)		$ 2	498
Ending Balance, Shares at Dec. 31, 2016	442,344,218	442,344,218
Ending Balance at Dec. 31, 2016		$ 44	10,555	174	(4,532)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (1,724)				(1,724)
Amortized gain (loss) on derivative hedges, net of income taxes				6
Change in unrealized gain on investments, net of income taxes				15
Pensions and OPEB, net of income taxes				(53)
Stock-based compensation			36
Cash dividends declared on common stock			(639)
Stock Investment Plan and certain share-based benefit plans, shares		2,989,893
Stock Investment Plan and certain share-based benefit plans			56
Reclass to liability awards (Note 5)			(7)
Ending Balance, Shares at Dec. 31, 2017	445,334,111	445,334,111
Ending Balance at Dec. 31, 2017		$ 44	$ 10,001	$ 142	(6,262)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation accounting change (Note 1)					$ (6)