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Short-Term Borrowings and Bank Lines of Credit (Details Textuals) (USD $)
 12 Months Ended
Dec. 31, 2012
money_pool
Dec. 31, 2011
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Short-term borrowings $ 1,969,000,000 $ 0
Maximum amount borrowed under revolving credit facility 5,550,000,000  
Number of money pools 2  
Principal default amount specified in debt covenants 100,000,000  
Average interest rate for borrowings 1.97% 0.00%
FirstEnergy
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Maximum amount borrowed under revolving credit facility 2,000,000,000  
FET
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Maximum amount borrowed under revolving credit facility 1,000,000,000  
TrAIL
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Maximum amount borrowed under revolving credit facility 200,000,000  
Revolving Credit Facility
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Maximum amount borrowed under revolving credit facility 1,050,000,000  
Number of extension periods 2  
Term of extension period 1 year  
Revolving Credit Facility | FES / AE Supply
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Maximum amount borrowed under revolving credit facility 2,500,000,000  
Revolving Credit Facility | Parent and Certain Subsidiaries
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Number of credit facilities 2  
Term of credit facility 5 years  
Maximum amount borrowed under revolving credit facility 4,500,000,000  
Revolving Credit Facility | FirstEnergy
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Maximum amount borrowed under revolving credit facility 2,000,000,000 [1]  
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 [2]  
Revolving Credit Facility | AGC
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Maximum amount borrowed under revolving credit facility 50,000,000  
Available for Issuance of Letters of Credit
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Amount of revolving line of credit $ 700,000,000  
Money Pool | Regulated Companies
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Average interest rate for borrowings 0.58%  
Money Pool | Unregulated Companies
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Average interest rate for borrowings 1.28%  
Minimum | Revolving Credit Facility
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Term of revolving credit facility, in days 364 days  
Maximum | Money Pool
    
Short-Term Borrowings and Bank Lines of Credit (Textuals) [Abstract]    
Term of revolving credit facility, in days 364 days  
[1] FE and the Utilities
[2] Includes FET, ATSI and TrAIL as subsidiary borrowers