Number of long term power purchase agreements maintained by parent company with Non utility generation entities.

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Number of variable interest contracts.

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Variable interest entities percentage of high voltage transmission line project owned By variable interest entity one in joint venture party one.

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No definition available.

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Variable Interest Entities Percentage of high voltage transmission line project owned By variable interest entity one in joint venture party two.

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Variable Interest Entities.

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All amounts that, per contract, are due to the servicer in exchange for servicing the financial asset and would no longer be received by a servicer if the beneficial owners of the serviced assets (or their trustees or agents) were to exercise their actual or potential authority under the contract to shift the servicing to another servicer. Depending on the servicing contract, those fees may include some or all of the difference between the interest rate collected on the asset being serviced and the rate to be paid to the beneficial owners of the asset.

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Face (par) amount of debt instrument at time of issuance.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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Fair value portion of investments in an entity not consolidated. Includes, but is not limited to, investments in an entity that is affiliated with the reporting entity by means of direct or indirect ownership, an entity in which the reporting entity shares control of the entity with another party or group, an entity which the company has significant influence, but does not have control and subsidiaries that are not required to be consolidated and are accounted for using the equity or cost method.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Represents the current and noncurrent portions of a debt security issued by a state, certain agencies or authorities, a local government, or development corporation to finance the construction of air- or water-pollution control facilities or sewage or solid waste disposal facilities pursuant to federal law. The bonds are backed by the credit of the beneficiary of the financing rather than the credit of the issuer.

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Long-Term transition bonds are bonds under the Competition Act in which the proceeds of Transition Bonds are required to be used principally to reduce qualified stranded costs and the related capitalization of the utility. This represents the current and noncurrent portions. The initial maturity is beyond one year or beyond the normal operating cycle, if longer.

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Amount of operating expense for purchased power of regulated operation.

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Variable Interest Entities (Details Textuals)	3 Months Ended		9 Months Ended
Variable Interest Entities (Details Textuals)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) agreement entity	Sep. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Variable Interest Entities (Textuals) [Abstract]
Long-term transition bond	$ 45,000,000		$ 45,000,000				$ 56,000,000
Long-term pollution control bond	359,000,000		359,000,000				383,000,000
Guarantor obligations	362,000,000		$ 362,000,000
Number of contracts that may contain variable interest \| entity			1
Purchased power	$ 876,000,000	$ 774,000,000	$ 2,393,000,000	$ 2,215,000,000
Power Purchase Agreements
Variable Interest Entities (Textuals) [Abstract]
Ownership interest	0.00%		0.00%
Number of long-term power purchase agreements maintained by FirstEnergy with NUG entities \| agreement			12
Phase In Recovery Bonds
Variable Interest Entities (Textuals) [Abstract]
Long-term debt and other long-term obligations	$ 292,000,000		$ 292,000,000				$ 315,000,000
Ohio Funding Companies
Variable Interest Entities (Textuals) [Abstract]
Annual servicing fees			445,000
Other FE subsidiaries \| Power Purchase Agreements
Variable Interest Entities (Textuals) [Abstract]
Purchased power	$ 27,000,000	$ 29,000,000	$ 85,000,000	$ 82,000,000
Path-WV
Variable Interest Entities (Textuals) [Abstract]
Percentage of high-voltage transmission line project owned by subsidiary of FE on the Allegheny Series	100.00%		100.00%
Percentage of high-voltage transmission line project owned by subsidiary of FE on the West Virginia Series	50.00%		50.00%
Equity method investments	$ 17,000,000		$ 17,000,000
Global Holding \| Line of Credit \| Term Loan Facility Due March 2020
Variable Interest Entities (Textuals) [Abstract]
Face amount of debt	$ 300,000,000		$ 300,000,000		$ 300,000,000
Global Holding \| Guarantee of senior secured loan facility
Variable Interest Entities (Textuals) [Abstract]
Guarantor obligations					$ 220,000,000
Signal Peak \| Global Holding \| FEV
Variable Interest Entities (Textuals) [Abstract]
Ownership interest	33.33%		33.33%
FES and FENOC \| Discontinued Operations, Disposed of by Means Other than Sale
Variable Interest Entities (Textuals) [Abstract]
Fair value of investments	$ 0		$ 0			$ 0