Consolidated Statements of Common Stockholders' Equity (FirstEnergy Corp.) - USD ($) $ in Millions		Total	Common Stock	OPIC	AOCI	Retained Earnings (Accumulated Deficit)	Series A Convertible Preferred Stock
Beginning Balance (in shares) at Dec. 31, 2016			442,000,000				0
Beginning Balance at Dec. 31, 2016		$ 6,241	$ 44	$ 10,555	$ 174	$ (4,532)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)		(1,724)				(1,724)
Other comprehensive loss, net of tax		(32)			(32)
Stock-based compensation		36		36
Cash dividends declared on common stock		(639)		(639)
Reclass to liability awards		(7)		(7)
Stock Investment Plan and certain share-based benefit plans (in shares)			3,000,000
Stock Investment Plan and certain share-based benefit plans		56		56
Ending Balance (in shares) at Dec. 31, 2017			445,000,000				0
Ending Balance at Dec. 31, 2017		3,925	$ 44	10,001	142	(6,262)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of adopting new accounting pronouncements		(6)				(6)
Net Income (Loss)		1,348				1,348
Other comprehensive loss, net of tax		(101)			(101)
Stock-based compensation		60		60
Cash dividends declared on common stock		(906)		(906)
Cash dividends declared on preferred stock		(71)		(71)
Stock Investment Plan and certain share-based benefit plans (in shares)			4,000,000
Stock Investment Plan and certain share-based benefit plans		62	$ 1	61
Stock issuance (Note 11) (in shares)	[1]		30,000,000				1,600,000
Stock issuance (Note 11)	[1]	2,462	$ 3	2,297			$ 162
Conversion of Series A Convertible Stock (Note 11) (in shares)			33,000,000				(900,000)
Conversion of Series A Convertible Stock (Note 11)		$ 0	$ 3	88			$ (91)
Ending Balance (in shares) at Dec. 31, 2018		511,915,450	512,000,000				700,000
Ending Balance at Dec. 31, 2018		$ 6,814	$ 51	11,530	41	(4,879)	$ 71
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of adopting new accounting pronouncements		35				35
Net Income (Loss)		912				912
Other comprehensive loss, net of tax		(21)			(21)
Stock-based compensation		41		41
Cash dividends declared on common stock		(824)		(824)
Cash dividends declared on preferred stock		(3)		(3)
Stock Investment Plan and certain share-based benefit plans (in shares)			3,000,000
Stock Investment Plan and certain share-based benefit plans		56		56
Conversion of Series A Convertible Stock (Note 11) (in shares)			26,000,000				(700,000)
Conversion of Series A Convertible Stock (Note 11)		$ 0	$ 3	68			$ (71)
Ending Balance (in shares) at Dec. 31, 2019		540,652,222	541,000,000				0
Ending Balance at Dec. 31, 2019		$ 6,975	$ 54	$ 10,868	$ 20	$ (3,967)	$ 0

[1] The Preferred Stock included an embedded conversion option at a price that is below the fair value of the Common Stock on the commitment date. This beneficial conversion feature (BCF), which was approximately $296 million, was recorded to OPIC as well as the amortization of the BCF (deemed dividend) through the period from the issue date to the first allowable conversion date (July 22, 2018) and as such there is no net impact to OPIC for the year ended December 31, 2018. See Note 1, "Organization and Basis of Presentation - Earnings per share," and Note 11, "Capitalization" for additional information on the BCF and the equity issuance.