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, 2013		418,628,559
Beginning Balance at Dec. 31, 2013		$ 42	$ 9,776	$ 284	$ 2,590
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 299				299
Amortized gain (loss) on derivative hedges, net of income taxes				(1)
Change in unrealized gain on investments, net of income taxes				16
Pensions and OPEB, net of income taxes				(53)
Stock-based compensation			20
Cash dividends declared on common stock					(604)
Stock Investment Plan and certain share-based benefit plans, Shares		2,474,011
Stock Investment Plan and certain share-based benefit plans			51
Ending Balance, Shares at Dec. 31, 2014		421,102,570
Ending 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	423,560,397
Ending Balance at Dec. 31, 2015	$ 12,421	$ 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)		$ 2	498
Stock issuance (Note 12), Shares		16,097,875
Ending Balance, Shares at Dec. 31, 2016	442,344,218	442,344,218
Ending Balance at Dec. 31, 2016	$ 6,241	$ 44	$ 10,555	$ 174	$ (4,532)