Capitalization (Details 1) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Capitalization [Line Items]
Unsecured debt	$ 14,824us-gaap_UnsecuredDebt	$ 12,035us-gaap_UnsecuredDebt
Capital lease obligations	160us-gaap_CapitalLeaseObligations	188us-gaap_CapitalLeaseObligations
Unamortized debt premiums (discounts)	(8)	9
Unamortized fair value adjustments	21	44
Currently payable long-term debt	(804)us-gaap_LongTermDebtCurrent	(1,415)us-gaap_LongTermDebtCurrent
Total long-term debt and other long-term obligations	19,176	15,831
FES
Schedule of Capitalization [Line Items]
Unsecured debt	2,971	2,813
Capital lease obligations	18	22
Unamortized debt premiums (discounts)	(1)	(1)
Currently payable long-term debt	(506)	(892)
Total long-term debt and other long-term obligations	2,608	2,130
FMBs
Schedule of Capitalization [Line Items]
FMBs	3,190	3,166
FMBs \| Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	3.34%
FMBs \| Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	9.74%
Secured notes - fixed rate
Schedule of Capitalization [Line Items]
Secured notes	1,793	1,804
Secured notes - fixed rate \| Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	0.00%
Secured notes - fixed rate \| Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	7.88%
Secured notes - fixed rate \| FES
Schedule of Capitalization [Line Items]
Secured notes	126	188
Secured notes - fixed rate \| FES \| Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	0.00%
Secured notes - fixed rate \| FES \| Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	12.00%
Unsecured notes - fixed rate
Schedule of Capitalization [Line Items]
Unsecured debt	13,532	11,076
Unsecured notes - fixed rate \| Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	2.15%
Unsecured notes - fixed rate \| Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	7.70%
Unsecured notes - fixed rate \| FES
Schedule of Capitalization [Line Items]
Unsecured debt	2,879	2,077
Unsecured notes - fixed rate \| FES \| Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	2.15%
Unsecured notes - fixed rate \| FES \| Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	6.80%
Unsecured notes - variable rate
Schedule of Capitalization [Line Items]
Unsecured debt	1,292	959
Unsecured notes - variable rate \| Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	0.03%
Unsecured notes - variable rate \| Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	1.92%
Unsecured notes - variable rate \| FES
Schedule of Capitalization [Line Items]
Unsecured debt	$ 92	$ 736
Unsecured notes - variable rate \| FES \| Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	0.03%
Unsecured notes - variable rate \| FES \| Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	0.05%

Debt Instrument, Unamortized Merger Fair Value Adjustments

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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Contractual interest rate for funds borrowed, under the debt agreement.

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The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Including both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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