Commitments, Guarantees and Contingencies - Nuclear Insurance, Commitments and Collateral (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) Nuclear_Power_Plant	Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Liability assessed with respect to single nuclear incident	$ 13,400,000,000
Plants licensed to operate | Nuclear_Power_Plant	102
Portion of insurance coverage of private insurer included in single nuclear incident	$ 450,000,000
Portion of insurance coverage by industry retrospective rating plan	13,000,000,000
Losses in excess of private insurance contributed for each nuclear unit license	127,000,000
Losses in excess of private insurance contributed for each nuclear unit license per unit	19,000,000
Nuclear incidence liability per incident of parent and subsidiary companys based on their present nuclear ownership and leasehold interests	509,000,000
Nuclear incident liability not more than in any one year per incident of parent and subsidiary companies based on their present nuclear ownership and leasehold interests	76,000,000
Aggregate indemnity	$ 1,400,000,000
Waiting period	84 days
Coverage of decontamination costs	$ 2,750,000,000
Insurance coverage for replacement power costs	$ 1,060,000,000
Environmental plan, submission period	30 days
Outstanding guarantees and other assurances aggregated	$ 3,800,000,000
Potential additional collateral obligations	407,000,000
FE
Loss Contingencies [Line Items]
Outstanding guarantees and other assurances aggregated	1,200,000,000
Subsidiaries' Guarantees
Loss Contingencies [Line Items]
Outstanding guarantees and other assurances aggregated	1,800,000,000
Other Guarantees
Loss Contingencies [Line Items]
Outstanding guarantees and other assurances aggregated	275,000,000
Other Assurances
Loss Contingencies [Line Items]
Outstanding guarantees and other assurances aggregated	459,000,000
Regulated Distribution
Loss Contingencies [Line Items]
Company posted collateral related to net liability positions	4,000,000
Potential additional collateral obligations	$ 148,000,000
FEV | Signal Peak | Senior Secured Term Loan | Senior Loans | Global Holding
Loss Contingencies [Line Items]
Investment ownership percentage	33.33%
FES
Loss Contingencies [Line Items]
Company posted collateral related to net liability positions	$ 123,000,000
Potential additional collateral obligations	20,000,000
FES | CES
Loss Contingencies [Line Items]
Potential additional collateral obligations	$ 2,000,000
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	$ 275,000,000
AE Supply
Loss Contingencies [Line Items]
Company posted collateral related to net liability positions	4,000,000
Potential additional collateral obligations	2,000,000
Surety Bond | Line of Credit | FES
Loss Contingencies [Line Items]
Maximum amount borrowed under revolving credit facility		$ 31,000,000
Surety Bond | Little Bull Run | Line of Credit
Loss Contingencies [Line Items]
Maximum amount borrowed under revolving credit facility	169,000,000	$ 169,000,000
Surety Bond | Hatfield Ferry | Line of Credit
Loss Contingencies [Line Items]
Maximum amount borrowed under revolving credit facility	$ 31,000,000