Short-Term Borrowings and Bank Lines of Credit (Details 1) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	$ 5,000
FE
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	2,000	[1]
Regulatory and Other Short-Term Debt Limitations	0	[1]
FES
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	1,500	[2]
Regulatory and Other Short-Term Debt Limitations	0	[2]
AE Supply
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	1,000	[2]
Regulatory and Other Short-Term Debt Limitations	0	[2]
OE
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	500
Regulatory and Other Short-Term Debt Limitations	500
CEI
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	500
Regulatory and Other Short-Term Debt Limitations	500
TE
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	500
Regulatory and Other Short-Term Debt Limitations	500
JCP&L
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	425	[3]
Regulatory and Other Short-Term Debt Limitations	411	[3]
Met-Ed
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	300	[3]
Regulatory and Other Short-Term Debt Limitations	300	[3]
Penelec
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	300	[3]
Regulatory and Other Short-Term Debt Limitations	300	[3]
West Penn
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	200	[3]
Regulatory and Other Short-Term Debt Limitations	200	[3]
MP
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	150	[3]
Regulatory and Other Short-Term Debt Limitations	150	[3]
PE
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	150	[3]
Regulatory and Other Short-Term Debt Limitations	150	[3]
ATSI
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	100
Regulatory and Other Short-Term Debt Limitations	100
Penn
Borrowing sub-limits for each borrower and limitations on short-term indebtedness
Revolving Credit Facility Sub-Limit	50	[3]
Regulatory and Other Short-Term Debt Limitations	$ 33	[3]

[1] No limitations.

[2] No limitation based upon blanket financing authorization from the FERC under existing open market tariffs.

[3] Excluding amounts which may be borrowed under the regulated companies’ money pool.