Commitments, Guarantees and Contingencies - Nuclear Insurance, Commitments and Collateral (Details)	12 Months Ended
Dec. 31, 2019 USD ($)
Loss Contingencies [Line Items]
Coverage of decontamination costs	$ 150,000,000
Liability assessed with respect to single nuclear incident	560,000,000
Outstanding guarantees and other assurances aggregated	1,600,000,000
Potential additional collateral obligations	357,000,000
FE
Loss Contingencies [Line Items]
Outstanding guarantees and other assurances aggregated	350,000,000
Subsidiaries' Guarantees
Loss Contingencies [Line Items]
Outstanding guarantees and other assurances aggregated	1,000,000,000.0
Other Guarantees
Loss Contingencies [Line Items]
Outstanding guarantees and other assurances aggregated	114,000,000
Other Assurances
Loss Contingencies [Line Items]
Outstanding guarantees and other assurances aggregated	151,000,000
Regulated Distribution
Loss Contingencies [Line Items]
Potential additional collateral obligations	99,000,000
JCP& L, ME and PE
Loss Contingencies [Line Items]
Annual retrospective premium assessments	$ 1,200,000
FEV \| Signal Peak \| Senior Secured Term Loan \| Senior Loans \| Global Holding
Loss Contingencies [Line Items]
Investment ownership percentage	33.33%
WMB Marketing Ventures, LLC \| Signal Peak \| Senior Secured Term Loan \| Senior Loans \| Global Holding
Loss Contingencies [Line Items]
Investment ownership percentage	33.33%
Global Holding \| Senior Secured Term Loan \| Senior Loans
Loss Contingencies [Line Items]
Long-term debt and other long-term obligations	$ 114,000,000
Global Holding \| Signal Peak, Global Rail and Affiliates \| Senior Secured Term Loan \| Senior Loans
Loss Contingencies [Line Items]
Investment ownership percentage	69.99%
AE Supply
Loss Contingencies [Line Items]
Potential additional collateral obligations	$ 1,000,000
Surety Bond \| Little Bull Run \| Line of Credit
Loss Contingencies [Line Items]
Maximum amount borrowed under revolving credit facility	169,000,000
Surety Bond \| Hatfield Ferry \| Line of Credit
Loss Contingencies [Line Items]
Maximum amount borrowed under revolving credit facility	31,000,000
Term Loan Facility Due March 2020 \| Line of Credit \| Global Holding
Loss Contingencies [Line Items]
Face amount of loan	$ 120,000,000

Coverage of Decontamination Costs As Per Property Damage Insurance

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Decommissioning Costs Coverage, Retrospective Premium Assessment, Annual Amount

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Investment, Ownership Percentage Pledged as Collateral

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Public Utilities, Liability Assessed with Respect to Single Nuclear Incident Based On Act

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