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COMMITMENTS AND CONTINGENCIES - ENVIRONMENTAL MATTERS (Details) $ in Millions | 1 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Feb. 28, 2026 BTU | May 31, 2024 BTU MMBTU | Feb. 29, 2024 micrograms | Aug. 31, 2018 | Jun. 30, 2026 USD ($) performance_obligations MW | Dec. 31, 2025 USD ($)
Manufactured gas plant remediation |  |  |  |  |  |
Regulatory assets |  |  |  |  | $ 3,169.1 | $ 3,173.6
Environmental remediation costs |  |  |  |  |  |
Manufactured gas plant remediation |  |  |  |  |  |
Regulatory assets |  |  |  |  | $ 545.6 | 566.0
Mercury and Air Toxics Standards | Electric |  |  |  |  |  |
Air quality |  |  |  |  |  |
Previous limit of particulate matter, in pounds per million british thermal unit | BTU |  | 0.03 |  |  |  |
New limit for particulate matter published in the EPA's 2024 Amendments, in pounds per million british thermal unit | MMBTU |  | 0.01 |  |  |  |
Level of particulate matter in pounds per million british thermal unit that the EPA reverted back to with the repeal of the 2024 amendments | BTU | 0.03 |  |  |  |  |
National Ambient Air Quality Standards | Electric |  |  |  |  |  |
Air quality |  |  |  |  |  |
Previous level of micrograms per cubic meter under 24-hour standard that particulate matter needed to be below | micrograms |  |  | 12 |  |  |
Period of time that the EPA may take to issue attainment designations |  |  |  |  | 1 year |
National Ambient Air Quality Standards | Electric | Maximum |  |  |  |  |  |
Air quality |  |  |  |  |  |
New primary annual PM2.5 level | micrograms |  |  | 9 |  |  |
National Ambient Air Quality Standards | Electric | Minimum |  |  |  |  |  |
Air quality |  |  |  |  |  |
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 |
Capacity of fossil-fueled generation retired, in megawatts | MW |  |  |  |  | 2,500 |
Capacity of additional coal-fired generation to be retired by the end of 2031, in megawatts | MW |  |  |  |  | 900 |
Manufactured Gas Plant Remediation | Natural gas |  |  |  |  |  |
Manufactured gas plant remediation |  |  |  |  |  |
Reserves for future environmental remediation |  |  |  |  | $ 466.2 | 484.1
Manufactured Gas Plant Remediation | Natural gas | Environmental remediation costs |  |  |  |  |  |
Manufactured gas plant remediation |  |  |  |  |  |
Regulatory assets |  |  |  |  | $ 545.6 | $ 566.0

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