Short-Term Borrowings and Bank Lines of Credit (Details Textuals)			1 Months Ended	12 Months Ended
	Jan. 22, 2018 USD ($)	Dec. 06, 2016	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) money_pool	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jan. 31, 2018 USD ($)	Feb. 16, 2017 USD ($) agreement
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Number of money pools | money_pool				2
Short-term borrowings			$ 2,675,000,000	$ 300,000,000	$ 2,675,000,000
Average interest rate for borrowings			2.47%	3.24%	2.47%
Repayments of debt				$ 2,291,000,000	$ 2,331,000,000	$ 879,000,000
Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Available Liquidity							$ 4,740,000,000
Maximum amount borrowed under revolving credit facility							5,000,000,000
Repayments of debt	$ 1,450,000,000
Term Loan
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Face amount of loan				$ 1,200,000,000.0
Number of agreements | agreement								2
Term Loan | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Repayments of debt	$ 1,200,000,000
Term Loan | $125M Term Loan
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Face amount of loan								$ 125,000,000
FET | Minimum
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Consolidated debt to total capitalization ratio (percent)				65.00%
FET | Maximum
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Consolidated debt to total capitalization ratio (percent)				75.00%
FES
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Short-term borrowings			$ 101,000,000	$ 102,000,000	101,000,000
Repayments of debt				163,000,000	507,000,000	$ 411,000,000
FES | Affiliates
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Other Short-term Borrowings			101,000,000	$ 105,000,000	101,000,000
FES | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility							500,000,000
FG | FMBs | $250M FMB's
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Face amount of loan			250,000,000		250,000,000
NG | FMBs | $450M FMB's
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Face amount of loan			$ 450,000,000		450,000,000
Line of Credit | FE and the Utilities | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Available Liquidity							10,000,000
Line of Credit | FET | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Available Liquidity							1,000,000,000
Line of Credit | FES | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Available Liquidity							500,000,000
Line of Credit | Letter of Credit [Member]
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Term of revolving credit facility				1 year
Line of Credit | Letter of Credit [Member] | FET
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility				$ 100,000,000
Line of Credit | Revolving Credit Facility
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Term of revolving credit facility			2 years
Maximum amount borrowed under revolving credit facility			$ 500,000,000	5,000,000,000	500,000,000
Line of Credit | Revolving Credit Facility | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility							5,000,000,000
Line of Credit | Revolving Credit Facility | FET | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility							1,000,000,000
Line of Credit | Revolving Credit Facility | FES
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility			500,000,000		500,000,000
Line of Credit | Revolving Credit Facility | FES | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility							500,000,000
Line of Credit | Secured Debt
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility			200,000,000		200,000,000
Line of Credit | Surety Bond | Little Bull Run
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility			169,000,000	169,000,000	169,000,000
Line of Credit | Surety Bond | FES
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility			$ 31,000,000		$ 31,000,000
Revolving Credit Facility | Parent and Certain Subsidiaries
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Term of revolving credit facility		5 years
Available for Issuance of Letters of Credit | Minimum
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Cross-default provision for other indebtedness				$ 100,000,000
Money Pool | Maximum
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Term of revolving credit facility				364 days
Money Pool | Regulated Companies
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Average interest rate for borrowings				1.48%
Money Pool | Unregulated Companies
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Average interest rate for borrowings				2.30%
FE | Line of Credit | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Available Liquidity							3,740,000,000
FE | Line of Credit | Letter of Credit [Member]
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility				$ 250,000,000
FE | Line of Credit | Revolving Credit Facility | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility							$ 4,000,000,000