COMMITMENTS AND CONTINGENCIES - ENVIRONMENTAL MATTERS (Details) $ in Millions	1 Months Ended				9 Months Ended	15 Months Ended
	May 31, 2022 micrograms	Mar. 31, 2022 micrograms	Jun. 30, 2021 area	Dec. 31, 2020 micrograms performance_obligations	Sep. 30, 2022 USD ($) generating_units States performance_obligations MW	Mar. 31, 2019 MW	Dec. 31, 2021 USD ($)	Oct. 31, 2021 performance_obligations
Manufactured gas plant remediation
Regulatory assets | $					$ 3,251.2		$ 3,367.1
Environmental remediation costs
Manufactured gas plant remediation
Regulatory assets | $					$ 616.3		630.9
Cross State Air Pollution Rule - Good Neighbor Plan | Electric
Air quality
Number of states the EPA is proposing to update and expand cross state air pollution rules to regulate NOx emissions in | States					26
Cross State Air Pollution Rule - Good Neighbor Plan | Electric | Maximum
Air quality
RICE unit megawatts | MW					25
National Ambient Air Quality Standards | Electric
Air quality
Number of changes to the 2015 ozone standards | performance_obligations								0
Number of counties to have boundaries revised | area			13
Number of nonattainment areas as designated by the EPA | area			6
Number of revisions necessary to meet the 2012 standard for particulate matter | performance_obligations				0
Current number of micrograms per cubic meter that particulate matter needs to be below				12
24-hour standard for fine particulate matter				35
Lowest limit that will cause nonattainment		10
National Ambient Air Quality Standards | Electric | Maximum
Air quality
Majority of CASAC members support this range in the peer review they completed		10
Minority of CASAC members support this range in the peer review they completed		11
Upper range of the annual standard the EPA staff supported	12
Lower range of the annual standard the EPA staff supported	10
National Ambient Air Quality Standards | Electric | Minimum
Air quality
Majority of CASAC members support this range in the peer review they completed		8
Minority of CASAC members support this range in the peer review they completed		10
Upper range of the annual standard the EPA staff supported	10
Lower range of the annual standard the EPA staff supported	8
Climate Change | Electric
Air quality
Capacity of coal-fired generation retired, in megawatts | MW						1,800
Capacity of fossil-fueled generation to be retired by the end of 2026, in megawatts | MW					1,600
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%
Clean Water Act Cooling Water Intake Structure Rule | Electric
Water quality
Number of generating units that may be retired | generating_units					4
Steam Electric Effluent Limitation Guidelines | Electric
Water quality
Number of new ELG rule requirements that affect our electric utilities | performance_obligations					2
Capital investment to achieve required discharge limits | $					$ 100.0
Manufactured Gas Plant Remediation | Natural gas
Manufactured gas plant remediation
Reserves for future environmental remediation | $					497.7		532.6
Manufactured Gas Plant Remediation | Natural gas | Environmental remediation costs
Manufactured gas plant remediation
Regulatory assets | $					$ 616.3		$ 630.9