Short-Term Borrowings and Bank Lines of Credit (Details Textuals)			12 Months Ended
	Feb. 16, 2017 USD ($) agreement	Dec. 06, 2016 USD ($) distribution_utility	Dec. 31, 2016 USD ($) money_pool	Dec. 31, 2021	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 31, 2017 USD ($)	Dec. 05, 2016 USD ($)	Dec. 31, 2015 USD ($)
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Number of regulated distribution utilities | distribution_utility		10
Short-term borrowings			$ 2,675,000,000							$ 1,708,000,000
Number of money pools | money_pool			2
Average interest rate for borrowings			2.47%							2.16%
Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility								$ 5,000,000,000
Term Loan
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Term of revolving credit facility		5 years
Face amount of loan		$ 1,200,000,000.0							$ 1,000,000,000
Term Loan | Prime Rate
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Variable rate (percent)		0.50%
Term Loan | LIBOR
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Variable rate (percent)		1.00%
Term Loan | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Debt Instrument, Number of Agreements | agreement	2
Term Loan | Variable Rate Term Loan Due 2016
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Face amount of loan									200,000,000
Term Loan | $125M Term Loan | Bank of America N.A. | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Term of revolving credit facility	3 years
Face amount of loan	$ 125,000,000
Term Loan | $125M Term Loan | The Bank of Nova Scotia | Subsequent Event
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Term of revolving credit facility	3 years
Face amount of loan	$ 125,000,000
FET
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility			$ 1,000,000,000
FES
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Short-term borrowings			0							$ 8,000,000
FES | Affiliates
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Other Short-term Borrowings			101,000,000							$ 0
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
NG | FMBs | $450M FMB's
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Face amount of loan									450,000,000
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		$ 4,000,000,000	500,000,000						3,500,000,000.0
Increase in borrowing capacity		500,000,000
Cross-default provision for other indebtedness		100,000,000
Amounts excluded from capitalization ratio		$ 2,750,000,000.00
Line of Credit | Revolving Credit Facility | Minimum
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Consolidated debt to total capitalization ratio (percent)		65.00%
Line of Credit | Revolving Credit Facility | Minimum | Forecast
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Interest coverage ratio (percent)				2.5	2.25	2	1.75
Line of Credit | Revolving Credit Facility | Maximum
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Consolidated debt to total capitalization ratio (percent)		100.00%
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
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility		$ 1,000,000,000							1,000,000,000
Line of Credit | Revolving Credit Facility | FET | Minimum
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Consolidated debt to total capitalization ratio (percent)		75.00%
Line of Credit | Revolving Credit Facility | FET | Maximum
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Consolidated debt to total capitalization ratio (percent)		100.00%
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 and AE Supply
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility									1,500,000,000.0
Amounts excluded from capitalization ratio		$ 5,500,000,000.0
Line of Credit | Revolving Credit Facility | FES
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility									900,000,000
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 | Revolving Credit Facility | AE Supply
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Maximum amount borrowed under revolving credit facility									$ 600,000,000
Line of Credit | Revolving Credit Facility | FE and FET | Prime Rate
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Variable rate (percent)		0.50%
Line of Credit | Revolving Credit Facility | FE and FET | LIBOR
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Variable rate (percent)		1.00%
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
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
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			0.69%
Money Pool | Unregulated Companies
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]
Average interest rate for borrowings			2.02%