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COMMITMENTS AND CONTINGENCIES - ENVIRONMENTAL MATTERS (Details) $ in Millions | 1 Months Ended | 6 Months Ended |
--- | --- | --- | ---
May 31, 2024 MMBTU performance_obligations | Feb. 29, 2024 micrograms | Oct. 31, 2023 States mo | Aug. 31, 2023 | Dec. 31, 2020 micrograms | Jun. 30, 2024 USD ($) MW | Dec. 31, 2023 USD ($)
Manufactured gas plant remediation |  |  |  |  |  |  |
Regulatory assets | $ |  |  |  |  |  | $ 3,435.0 | $ 3,274.7
Environmental remediation costs |  |  |  |  |  |  |
Manufactured gas plant remediation |  |  |  |  |  |  |
Regulatory assets | $ |  |  |  |  |  | $ 575.2 | 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 hydrogen or 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 | $ |  |  |  |  |  | $ 437.0 | 463.7
Manufactured Gas Plant Remediation | Natural gas | Environmental remediation costs |  |  |  |  |  |  |
Manufactured gas plant remediation |  |  |  |  |  |  |
Regulatory assets | $ |  |  |  |  |  | $ 575.2 | $ 596.8

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