Regulatory Matters - Ohio (Details) - USD ($) $ in Millions							12 Months Ended
	Oct. 09, 2019	Oct. 01, 2019	Jul. 15, 2019	Nov. 09, 2018	Mar. 12, 2018	Oct. 12, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Regulatory Matters [Line Items]
Proposed reduction in power plants carbon pollution (percent)							90.00%
Ohio
Regulatory Matters [Line Items]
Portfolio plan estimated cost										$ 268.0
Ohio | PUCO
Regulatory Matters [Line Items]
Proposed reduction in power plants carbon pollution (percent)						90.00%
Requested removal of cost cap					4.00%
Ohio | PUCO | DMR
Regulatory Matters [Line Items]
Annual revenue cap for rider									$ 132.5
Cost recovery period									3 years
Approved annual revenue cap for rider								$ 168.0
Approved amount of rate increase		$ (28.0)
Ohio | PUCO | DCR Rider
Regulatory Matters [Line Items]
Revenue cap for Rider for years 3-6						$ 20.0
Revenue cap for Rider for years 6-8						15.0
Ohio | PUCO | DPM Plan
Regulatory Matters [Line Items]
Approved amount of rate increase				$ 516.0
Grid modernization plan period				3 years
Ohio | PUCO | Energy Conservation, Economic Development and Job Retention
Regulatory Matters [Line Items]
Contribution amount						$ 51.0
Ohio Companies | Ohio | PUCO | Ohio Consumers Counsel DMR Refund
Regulatory Matters [Line Items]
Amount of damages sought			$ 42.0
Ohio Companies | Ohio | PUCO | RTEP
Regulatory Matters [Line Items]
Approved amount of rate increase	$ 95.0