Commitments and Contingencies Environmental Requirements - Water and Waste (Details) - Federal Coal Ash Regulation [Domain] $ in Millions	Dec. 31, 2021 USD ($)
Loss Contingencies [Line Items]
Number of regulated ash units that will still be in operation by the end of 2019	5
Number of sites where statistically significant increases over established groundwater standards exist	4
Number of sites where corrective action options are being evaluated for locations with statistically significant increases above background concentrations	2
Number of sites where monitoring results indicate potential offsite impacts to groundwater	1
Estimated cost to remediate groundwater sampling results	$ 35
Number of impoundments where closure plans will be expedited	1
Estimated cost of construction of an alternative collection and treatment system	$ 25
Estimated cost to close Comanche station bottom ash pond	$ 3