Commitments, Guarantees and Contingencies - Potential Collateral Obligations (Details) $ in Millions	9 Months Ended
Sep. 30, 2021 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations	$ 346
Percent of face amount of debt	100.00%
Curing period	30 days
Upon Further Downgrade
Guarantor Obligations [Line Items]
Guarantor obligations	$ 32
Surety Bond (Collateralized Amount)
Guarantor Obligations [Line Items]
Guarantor obligations	$ 314
Percent of face amount of debt	60.00%
Capped portion of surety bond obligations	$ 39
Utilities and FET
Guarantor Obligations [Line Items]
Guarantor obligations	88
Utilities and FET \| Upon Further Downgrade
Guarantor Obligations [Line Items]
Guarantor obligations	32
Utilities and FET \| Surety Bond (Collateralized Amount)
Guarantor Obligations [Line Items]
Guarantor obligations	56
FirstEnergy
Guarantor Obligations [Line Items]
Guarantor obligations	258
FirstEnergy \| Upon Further Downgrade
Guarantor Obligations [Line Items]
Guarantor obligations	0
FirstEnergy \| Surety Bond (Collateralized Amount)
Guarantor Obligations [Line Items]
Guarantor obligations	$ 258

Guarantor Obligations, Capped Portion of Surety Bond Obligations

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- Definition

Guarantor Obligations, Curing Period

+ References

No definition available.

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- Definition

Guarantor Obligations, Maximum Contractual Obligations, Percent of Face Amount of Debt

+ References

No definition available.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=124440162&loc=d3e12069-110248

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