PROPERTY, PLANT, AND EQUIPMENT - PLANT TO BE RETIRED (Details) $ in Millions	Sep. 30, 2023 USD ($) MW	Jun. 30, 2023 MW
WE | OCPP
Property, plant, and equipment
Net book value of plant to be retired	$ 798.9
WE | West Riverside Energy Center
Property, plant, and equipment
Capacity of generation unit | MW	100	100
WPS | Columbia Energy Center
Property, plant, and equipment
Net book value of plant to be retired	$ 261.8