Discontinued Operations - Gain on Deconsolidation (Details) - FES and FENOC - Discontinued Operations, Disposed of by Means Other than Sale - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Removal of investment in FES and FENOC		$ 0	$ 2,193
Assumption of benefit obligations retained at FE	$ 820	0	(820)
Guarantees and credit support provided by FE		0	(139)
Reserve on receivables and allocated pension/OPEB mark-to-market		0	(914)
Settlement consideration and services credit		7	(1,197)
Loss on disposal of FES and FENOC, before tax		7	(877)
Income tax benefit, including estimated worthless stock deduction		52	1,312
Gain on disposal of FES and FENOC, net of tax		$ 59	$ 435	$ 0