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Pension and Other Postemployment Benefits (Details Textuals) - USD ($)
$ in Millions
 1 Months Ended 12 Months Ended
Dec. 13, 2016
Jan. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]          
Mark-to-market adjustment, net of capitalized amounts     $ 141 $ 147 $ 242
Decrease in mortality rate (percent)     0.50%    
Funding contributions made for current and future years       882  
Pension contributions $ 500   $ 0 382 143
Equity contribution from parent       500  
Non-cash transaction: stock contribution to pension plan     0 500 0
Pensions and OPEB          
Defined Benefit Plan Disclosure [Line Items]          
Actual return on plan assets     $ 999 $ 472 $ (172)
Actual return on plan assets (percent)     15.10% 8.20% (2.70%)
Expected return on plan assets     $ 478 $ 429 $ 476
Pension          
Defined Benefit Plan Disclosure [Line Items]          
Company contributions     18 899  
Actual return on plan assets     $ 950 $ 442  
Expected long-term return on plan assets     7.50% 7.50% 7.75%
Expected return on plan assets     $ 448 $ 399 $ 443
Increase in benefit obligation due to RP2014 mortality table     62    
Excluded from total investments     (10) 16  
OPEB          
Defined Benefit Plan Disclosure [Line Items]          
Company contributions     16 9  
Actual return on plan assets     $ 49 $ 30  
Expected long-term return on plan assets     7.50% 7.50% 7.75%
Expected return on plan assets     $ 30 $ 30 $ 33
Excluded from total investments     (2) (4)  
Minimum          
Defined Benefit Plan Disclosure [Line Items]          
Company contributions       382  
FE | Pension          
Defined Benefit Plan Disclosure [Line Items]          
Non-cash transaction: stock contribution to pension plan       293  
FES          
Defined Benefit Plan Disclosure [Line Items]          
Pension contributions     $ 0 $ 138 $ 0
Subsequent Event          
Defined Benefit Plan Disclosure [Line Items]          
Funding contributions made for current and future years   $ 750      
Subsequent Event | Minimum          
Defined Benefit Plan Disclosure [Line Items]          
Company contributions   $ 500