COMMITMENTS AND CONTINGENCIES - ENVIRONMENTAL MATTERS (Details) $ in Millions	1 Months Ended				6 Months Ended
	May 31, 2024 MMBTU numberOfRevisions performance_obligations	Feb. 29, 2024 micrograms	Aug. 31, 2023	Dec. 31, 2020 micrograms	Jun. 30, 2025 USD ($) MW d numberOfRevisions performance_obligations	Dec. 31, 2024 USD ($)	Nov. 30, 2024
Environmental matters
Number of federal deregulatory actions that the EPA announced | numberOfRevisions					31
Manufactured gas plant remediation
Regulatory assets					$ 432.2	$ 449.7
Environmental remediation costs
Manufactured gas plant remediation
Regulatory assets					$ 109.5	114.0
Cross State Air Pollution Rule - Good Neighbor Plan | Electric | Maximum
Air quality
RICE unit megawatts | MW					25
Mercury and Air Toxics Standards | Electric
Air quality
Previous level of particulate matter in pounds per million british thermal unit | MMBTU	0.03
New limit for particulate matter published in the EPA's final rule | MMBTU	0.01
National Ambient Air Quality Standards | Electric
Air quality
Current number of micrograms per cubic meter that particulate matter needs to be below | micrograms				12
Current number of micrograms per cubic meter under 24-hour standard that fine particulate matter needs to be below | micrograms				35
National Ambient Air Quality Standards | Electric | Maximum
Air quality
Period of time for EPA review of ozone plan			5 years
New primary annual PM2.5 level | micrograms		9
National Ambient Air Quality Standards | Electric | Minimum
Air quality
Period of time for EPA review of ozone plan			3 years
Climate Change | Electric
Air quality
Number of applicable GHG performance standards for coal plants | performance_obligations	0
Percent capacity factor that if combined cycle natural gas plants are above it causes the rule to be highly dependent on carbon capture	40.00%
Number of applicable GHG limits for new simple cycle natural gas-fired combustion turbines | performance_obligations	0
Percent capacity factor for simple cycle natural gas fired combustion turbines that there are no applicable limits if the capacity factor is less than this	20.00%
Percent capacity factor for turbines that will require more stringent NOX limits							20.00%
Percent capacity factor for turbines that below this percentage will have less restrictive standards							20.00%
Number of potential regulatory paths that the EPA is co-proposing | performance_obligations					2
Capacity of coal-fired generation retired, in megawatts | MW					400
Capacity of fossil-fueled generation to be retired by the end of 2031, in megawatts | MW					1,200
Climate Change | Electric | Maximum
Air quality
RICE unit megawatts | MW					25
Steam Electric Effluent Limitation Guidelines | Electric
Water quality
Number of new ELG rule requirements that affect our electric utilities | performance_obligations	2
Compliance costs associated with the ELG rule that were required to achieve discharge limits					$ 8.0
Number of existing coal categories that were kept as part of the 2024 supplemental ELG rule | numberOfRevisions	1
Number of new coal categories that were created as part of the 2024 supplemental ELG rule | numberOfRevisions	1
Manufactured Gas Plant Remediation | Natural gas
Manufactured gas plant remediation
Reserves for future environmental remediation					76.8	77.3
Manufactured Gas Plant Remediation | Natural gas | Environmental remediation costs
Manufactured gas plant remediation
Regulatory assets					$ 109.5	$ 114.0
Coal Combustion Residuals Rule | Electric
Coal Combustion Residuals Rule
Number of days an abeyance was granted for | d					60