Organization and Basis of Presentation - Narrative (Details) mi in Thousands, customer in Thousands, $ in Millions		3 Months Ended
	Apr. 14, 2022 USD ($)	Mar. 31, 2022 USD ($) customer company transmissionCenter mi MW	Mar. 31, 2021 USD ($)	Apr. 30, 2022 director
Property, Plant and Equipment [Line Items]
Length of transmission lines | mi		24
Number of regional transmission centers | transmissionCenter		2
Capitalized cost of equity		$ 13	$ 7
Capitalized interest		6	$ 6
Incremental decrease to uncollectible expense due to Covid-19		25
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 | Forecast
Property, Plant and Equipment [Line Items]
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 | Forecast
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 | Forecast
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
Number of customers served by utility operating companies | customer		6,000
Plant capacity (in MW's) | MW		3,580