Regulatory Matters - Maryland and New Jersey (Details) $ in Millions												12 Months Ended	36 Months Ended
	Dec. 17, 2018 USD ($)	Nov. 20, 2018 USD ($)	Oct. 22, 2018 USD ($)	Oct. 05, 2018 USD ($)	Aug. 24, 2018 USD ($) program	Aug. 17, 2018 USD ($)	Jul. 13, 2018 USD ($)	Mar. 02, 2018 USD ($)	Jan. 19, 2018 USD ($)	Jul. 16, 2015	Feb. 27, 2013 USD ($)	Dec. 31, 2018	Dec. 31, 2020 USD ($)	Feb. 15, 2018 USD ($)
Maryland
Regulatory Matters [Line Items]
Expected infrastructure investments											$ 2,700.0
Expected infrastructure investments, period											15 years
PE | MDPSC
Regulatory Matters [Line Items]
Cost of charging equipment rebates									$ 12.0
Charging equipment rebates amortization period									5 years
PE | Maryland
Regulatory Matters [Line Items]
Incremental energy savings goal per year (percent)										0.20%
Incremental energy savings goal thereafter (percent)										2.00%
Incremental energy savings goal in the next 12 months (percent)										0.97%
Amortization period for expenditures for cost recovery program												5 years
PE | Maryland | MDPSC
Regulatory Matters [Line Items]
Requested increase (decrease) in revenues				$ (5.0)		$ (6.5)
Requested rate increase (decrease)					$ 19.7
Number of enhanced service reliability programs | program					4,000,000
Revised requested rate increase			$ 17.6
Revised rate increase		$ 12.9			$ 7.3
Recommended decrease due to jobs act		$ 11.1
PE | Maryland | MDPSC | Minimum
Regulatory Matters [Line Items]
Impact on base rate due to Tax Act														$ 7.0
PE | Maryland | MDPSC | Maximum
Regulatory Matters [Line Items]
Impact on base rate due to Tax Act														$ 8.0
JCP&L
Regulatory Matters [Line Items]
Approved ROE												9.60%
JCP&L | New Jersey | NJBPU
Regulatory Matters [Line Items]
Requested increase (decrease) in revenues								$ (28.6)
Approved rate increase due to changes in deferred taxes								$ 1.3
Forecast | PE | Maryland
Regulatory Matters [Line Items]
Recovery period for expenditures for cost recovery program													3 years
Expenditures for cost recovery program													$ 116.0
JCP&L Reliability Plus | JCP&L | NJBPU
Regulatory Matters [Line Items]
Requested rate increase (decrease)							$ 386.8
JCP&L Reliability Plus | JCP&L | New Jersey | NJBPU
Regulatory Matters [Line Items]
Requested increase (decrease) in revenues	$ 97.0
Infrastructure investment period							4 years
Approved ROE	8.75%
Cost of debt	5.38%