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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