Organization and Basis of Presentation (Details Textuals) customer in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) customer transmission_center company mi MW	Mar. 31, 2017 USD ($)	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Property, Plant and Equipment [Line Items]
Length of transmission lines | mi	24,500
Number of regional transmission centers | transmission_center	2
Capitalized cost of equity	$ 11	$ 8
Capitalized interest	$ 4	4
Accounting Standards Update 2018-02 | Retained Earnings
Property, Plant and Equipment [Line Items]
Cumulative effect of new accounting principle			$ 22
Regulated Distribution
Property, Plant and Equipment [Line Items]
Number of existing utility operating companies | company	10
Number of customers served by utility operating companies | customer	6
Plant capacity (in MW's) | MW	3,790
FES | Accounting Standards Update 2016-01 | Retained Earnings
Property, Plant and Equipment [Line Items]
Cumulative effect of new accounting principle				$ 115
FES and FENOC | Accounting Standards Update 2018-02 | Retained Earnings
Property, Plant and Equipment [Line Items]
Cumulative effect of new accounting principle			$ 8
Discontinued Operations, Disposed of by Means Other than Sale | FES and FENOC
Property, Plant and Equipment [Line Items]
Gain on deconsolidation, net of tax	$ 1,239	$ 0
Other Operating Expense | Accounting Standards Update 2017-07
Property, Plant and Equipment [Line Items]
Effect of change on net income	(8)
Miscellaneous Income | Accounting Standards Update 2017-07
Property, Plant and Equipment [Line Items]
Effect of change on net income	$ 8