COMMITMENTS AND CONTINGENCIES - ENVIRONMENTAL MATTERS (Details) $ in Millions	1 Months Ended					9 Months Ended
	May 31, 2024 MMBTU performance_obligations	Feb. 29, 2024 micrograms	Oct. 31, 2023 mo States	Aug. 31, 2023	Dec. 31, 2020 micrograms	Sep. 30, 2024 USD ($) MW	Dec. 31, 2023 USD ($)
Manufactured gas plant remediation
Regulatory assets | $						$ 3,405.6	$ 3,274.7
Environmental remediation costs
Manufactured gas plant remediation
Regulatory assets | $						$ 565.8	596.8
Cross State Air Pollution Rule - Good Neighbor Rule | 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
Number of states that failed to submit timely SIP revisions to address nonattainment areas classified as "moderate" for the 2015 standard | States			11
Number of months after May 2025 deadline for SIP that offset sanctions will take effect if the state SIP revision is not approved | mo			18
Current level of micrograms per cubic meter that particulate matter needs to be below | micrograms					12
Current level of micrograms per cubic meter under 24-hour standard that 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
Number of years between evaluation of attainment status				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%
Capacity of coal-fired generation retired, in megawatts | MW						2,500
Capacity of fossil-fueled generation to be retired by the end of 2031, in megawatts | MW						1,200
Company goal for percentage of carbon emissions reduction below 2005 levels by the end of 2025						60.00%
Company goal for percentage of carbon emissions reduction below 2005 levels by the end of 2030						80.00%
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	3
Compliance costs through 2023 associated with the ELG rule that were required to achieve discharge limits | $							105.0
Number of existing coal categories that were kept as part of the 2024 supplemental ELG rule requirements | performance_obligations	1
Number of new categories that were created as part of the 2024 supplemental ELG rule requirements | performance_obligations	1
Manufactured Gas Plant Remediation | Natural gas
Manufactured gas plant remediation
Reserves for future environmental remediation | $						$ 430.5	463.7
Manufactured Gas Plant Remediation | Natural gas | Environmental remediation costs
Manufactured gas plant remediation
Regulatory assets | $						$ 565.8	$ 596.8