Regulatory Matters - Maryland and New Jersey (Details) meter in Millions, $ in Millions																	3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 01, 2021	Sep. 14, 2021 USD ($)	Jun. 16, 2021 USD ($)	May 26, 2021 USD ($)	Apr. 23, 2021 USD ($)	Mar. 05, 2021 USD ($)	Mar. 01, 2021 USD ($) program	Jan. 29, 2021 USD ($)	Jan. 01, 2021 USD ($)	Dec. 18, 2020 USD ($)	Oct. 28, 2020 USD ($)	Sep. 25, 2020 program	Aug. 27, 2020 USD ($) meter	Jun. 10, 2020	Apr. 06, 2020 USD ($) MW	Mar. 22, 2019 USD ($) program	Sep. 30, 2021 USD ($) MW	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) MW	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Regulatory Matters [Line Items]
Gain on sale of Yards Creek (Note 8)																	$ 0.0	$ 0.0	$ 109.0	$ 0.0
Regulated Distribution
Regulatory Matters [Line Items]
Plant capacity (in MW's) | MW																	3,580		3,580
PE | Maryland
Regulatory Matters [Line Items]
Incremental energy savings goal per year (percent)																			0.20%
Incremental energy savings goal thereafter (percent)																			2.00%
Recovery period for expenditures for cost recovery program										3 years									3 years
Expenditures for cost recovery program																			$ 116.0
Amortization period																			5 years
Amount of requested rate increase (decrease)										$ 148.0
PE | MPSC | Maryland
Regulatory Matters [Line Items]
Amount of approved annual rate increase																$ 6.2
Number of enhanced service reliability programs | program																3
Enhanced service reliability program term																4 years
Period to file new depreciation study																18 months
Enhanced service reliability program renewal period																4 years
Distribution reporting of COVID relief funds			$ 4.0
PE | MPSC | Depreciation Expense Study | Maryland
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)								$ (9.6)
PE | Maryland Office of People's Counsel | Depreciation Expense Study | Maryland
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)								$ (10.8)
Approved amount of annual increase				$ (2.1)
JCP&L | New Jersey | Yard's Creek Energy
Regulatory Matters [Line Items]
Plant capacity (in MW's) | MW															210
Purchase price															$ 155.0
JCP&L | New Jersey | Regulated Distribution | Yard's Creek Energy
Regulatory Matters [Line Items]
Book value																					$ 45.0
Gain on sale of Yards Creek (Note 8)						$ 109.0
JCP&L | Advanced Metering Infrastructure | New Jersey | Regulated Distribution
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)													$ 732.0
JCP&L | Advanced Metering Infrastructure Supplemental Filing | New Jersey | Regulated Distribution
Regulatory Matters [Line Items]
First period of the program		6 years
Costs associated with program		$ 494.0
Amount of capital expenditures		390.0
Amount of maintenance expense		73.0
Cost of removal		$ 31.0
JCP&L | NJBPU | New Jersey
Regulatory Matters [Line Items]
Amount of revenue increase											$ 94.0
Decrease in regulatory liability									$ 86.0
JCP&L | NJBPU | New Jersey | Forecast
Regulatory Matters [Line Items]
Requested increase to ROE	9.60%
JCP&L | NJBPU | New Jersey | Yard's Creek Energy
Regulatory Matters [Line Items]
Ownership interest acquired															50.00%
JCP&L | NJBPU | JCP&L Reliability Plus | New Jersey
Regulatory Matters [Line Items]
Approved amount of annual increase																					$ 95.0
JCP&L | NJBPU | Advanced Metering Infrastructure | New Jersey | Regulated Distribution
Regulatory Matters [Line Items]
Meter deployment period													3 years
Number of meters to be deployed | meter													1.2
Expected cost of the program													$ 418.0
Time period of the program													20 years
JCP&L | NJBPU | Energy Efficiency and Peak Demand Reduction | New Jersey | Regulated Distribution
Regulatory Matters [Line Items]
Amortization period					10 years									10 years
Number of programs | program												11
JCP&L | NJBPU | Electrical Vehicle Program | New Jersey | Regulated Distribution
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)							$ 50.0
Number of programs | program							6
Electric vehicle program period							4 years
Amount of requested return on capital							$ 16.0
Requested amount for operations and maintenance expense							$ 34.0
JCP&L | NJBPU | Energy Efficiency and Peak Demand Reduction Stipulation Settlement | New Jersey | Regulated Distribution
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)					$ 203.0
Approved period of rate plan					3 years
Approved investment recovery					$ 158.0
Approved amount of operation and maintenance recovery					$ 45.0