Regulatory Matters - Distribution Rate Orders (Details)	12 Months Ended
	Dec. 31, 2019
CEI
Public Utilities, General Disclosures [Line Items]
Allowed Debt	51.00%
Allowed Equity	49.00%
Approved ROE	10.50%
ME
Public Utilities, General Disclosures [Line Items]
Allowed Debt	48.80%
Allowed Equity	51.20%
MP
Public Utilities, General Disclosures [Line Items]
Allowed Debt	54.00%
Allowed Equity	46.00%
JCP&L
Public Utilities, General Disclosures [Line Items]
Allowed Debt	55.00%
Allowed Equity	45.00%
Approved ROE	9.60%
OE
Public Utilities, General Disclosures [Line Items]
Allowed Debt	51.00%
Allowed Equity	49.00%
Approved ROE	10.50%
PN
Public Utilities, General Disclosures [Line Items]
Allowed Debt	47.40%
Allowed Equity	52.60%
Penn
Public Utilities, General Disclosures [Line Items]
Allowed Debt	49.90%
Allowed Equity	50.10%
Penn | West Virginia
Public Utilities, General Disclosures [Line Items]
Allowed Debt	54.00%
Allowed Equity	46.00%
Penn | Maryland
Public Utilities, General Disclosures [Line Items]
Allowed Debt	47.00%
Allowed Equity	53.00%
Approved ROE	9.65%
TE
Public Utilities, General Disclosures [Line Items]
Allowed Debt	51.00%
Allowed Equity	49.00%
Approved ROE	10.50%
WP
Public Utilities, General Disclosures [Line Items]
Allowed Debt	49.70%
Allowed Equity	50.30%
ATSI | Regulated Transmission
Public Utilities, General Disclosures [Line Items]
Approved ROE	10.38%
MAIT | Regulated Transmission
Public Utilities, General Disclosures [Line Items]
Allowed Debt	60.00%
Approved ROE	10.30%
TrAIL | Regulated Transmission | TrAIL the Line and Black Oak SVC
Public Utilities, General Disclosures [Line Items]
Approved ROE	12.70%
TrAIL | Regulated Transmission | All Other Projects
Public Utilities, General Disclosures [Line Items]
Approved ROE	11.70%