Commitments and Contingencies - Environmental Requirements - Water and Waste (Details) $ in Millions	Sep. 30, 2023 USD ($) sites
Site Contingency [Line Items]
Number of sites that will excavate and process ash for beneficial use | sites	2
Number of sites where investigation and feasibility studies for additional corrective action related to offsite groundwater are ongoing | sites	3
Federal Coal Ash Regulation
Site Contingency [Line Items]
Number of sites where regulated ash units will still be in operation at a specified date	5
Estimated cost to remediate groundwater sampling results | $	$ 40
Federal Coal Ash Regulation | Maximum [Member]
Site Contingency [Line Items]
Cost of Beneficial Use Coal Ash Project | $	$ 45