Regulatory Matters - Pennsylvania and West Virginia (Details) - Pennsylvania $ in Millions		1 Months Ended	6 Months Ended
	Jan. 18, 2019 USD ($)	Mar. 31, 2016 USD ($)	Jun. 30, 2019 proposal
DSP June 2019- May 2023
Regulatory Matters [Line Items]
Number of RFP's | proposal			2
RFP term			2 years
Three Month Period | DSP June 2019- May 2023
Regulatory Matters [Line Items]
Term of energy contract			3 months
Twelve month period | DSP June 2019- May 2023
Regulatory Matters [Line Items]
Term of energy contract			12 months
Twenty-four month period | DSP June 2019- May 2023
Regulatory Matters [Line Items]
Term of energy contract			24 months
Pennsylvania Companies | PPUC | EE&C Phase III
Regulatory Matters [Line Items]
Approved amount of annual increase		$ 390
ME
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)	$ 45
Penn
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)	26
WP
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)	51
PN
Regulatory Matters [Line Items]
Amount of requested rate increase (decrease)	$ 25