Organization and Basis of Presentation - Narrative (Details) mi in Thousands, employee in Thousands, customer in Thousands, $ in Millions		3 Months Ended			6 Months Ended
	May 31, 2022 USD ($) director	Jun. 30, 2022 USD ($) employee company transmissionCenter MW	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) employee customer company transmissionCenter mi MW	Jun. 30, 2021 USD ($)
Property, Plant and Equipment [Line Items]
Length of transmission lines | mi					24
Number of regional transmission centers | transmissionCenter		2			2
Capitalized cost of equity		$ 11		$ 14	$ 24	$ 21
Capitalized interest		$ 6		$ 7	$ 12	$ 13
Incremental decrease to uncollectible expense due to Covid-19			$ 25
Number Of Employees Working Remotely | employee		7			7
Deferred Regulatory Assets
Property, Plant and Equipment [Line Items]
Incremental decrease to uncollectible expense due to Covid-19			$ 15
PN | Waverly, New York
Property, Plant and Equipment [Line Items]
Number of customers served by utility operating companies | customer					4
FET
Property, Plant and Equipment [Line Items]
Transaction costs	$ 37
Changes in carrying value of noncontrolling interest	$ 451
Number of directors | director	5
Minimum ownership interest	9.90%
Year one through five required debt to equity percentage	65.00%
Required debt to equity ratio thereafter	70.00%
FET | North American Transmission Company II LLC
Property, Plant and Equipment [Line Items]
Sale of ownership interest by parent	19.90%
Sale price of ownership interest by parent	$ 2,375
Number of directors | director	1
FET | FirstEnergy
Property, Plant and Equipment [Line Items]
Number of directors | director	4
Regulated Distribution
Property, Plant and Equipment [Line Items]
Number of existing utility operating companies | company		10			10
Number of customers served by utility operating companies | customer					6,000
Plant capacity (in MW's) | MW		3,580			3,580