Regulatory Matters - Maryland and New Jersey (Details) $ in Millions								9 Months Ended	36 Months Ended
	Apr. 23, 2019 USD ($) rate_adjustment	Mar. 22, 2019 USD ($) program	Aug. 24, 2018 USD ($) program	Jul. 13, 2018 USD ($)	Mar. 26, 2018 USD ($)	Jan. 19, 2018 USD ($)	Jul. 16, 2015	Sep. 30, 2019	Dec. 31, 2020 USD ($)
PE | Maryland
Regulatory Matters [Line Items]
Incremental energy savings goal per year (percent)							0.20%
Incremental energy savings goal thereafter (percent)							2.00%
Amortization period								5 years
PE | MPSC | Maryland
Regulatory Matters [Line Items]
Cost of charging equipment rebates						$ 12.0
Charging equipment rebates amortization period						5 years
Amount of requested rate increase (decrease)			$ 19.7
Approved amount of annual increase (decrease)			$ 17.6
Number of enhanced service reliability programs | program			4
Revised requested rate increase			$ 7.3
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
JCP&L | NJBPU | New Jersey
Regulatory Matters [Line Items]
Approved amount of annual increase (decrease)	$ (28.6)				$ (28.6)
Approved rider due to change in tax rate					$ 1.3
Approved amount of rate refund	7.0
JCP&L | NJBPU | JCP&L Reliability Plus
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)				$ 386.8
JCP&L | NJBPU | JCP&L Reliability Plus | New Jersey
Regulatory Matters [Line Items]
Approved amount of annual increase (decrease)	$ 97.0
Processes for rate adjustments | rate_adjustment	2
Infrastructure investment period				4 years
Scenario, Forecast | PE | Maryland
Regulatory Matters [Line Items]
Recovery period for expenditures for cost recovery program									3 years
Expenditures for cost recovery program									$ 116.0