REGULATORY ENVIRONMENT - PGL AND NSG 2026 RATE APPLICATION (Details) - Illinois Commerce Commission (ICC) $ in Millions	1 Months Ended
Jan. 31, 2026 USD ($)	Feb. 28, 2025 in
2026 Rate Application \| PGL
Public Utilities, General Disclosures [Line Items]
Decrease to prior rate request	$ 57.3
Requested Rate Increase (Decrease), Amended, Amount	$ 144.0
Requested Rate Increase (Decrease), Amended, Percentage	14.60%
2027 capital investments planned under PRP	$ 349.0
Requested return on equity (as a percent)	10.10%
Requested common equity component average (as a percent)	54.00%
2026 Rate Application \| NSG
Public Utilities, General Disclosures [Line Items]
Decrease to prior rate request	$ 4.0
Requested Rate Increase (Decrease), Amended, Amount	$ 8.7
Requested Rate Increase (Decrease), Amended, Percentage	8.40%
Requested return on equity (as a percent)	10.10%
Requested common equity component average (as a percent)	54.00%
SMP Proceedings \| PGL
Public Utilities, General Disclosures [Line Items]
Minimum diameter of pipe that does not require replacement \| in		36

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Percentage of public utility's requested equity to capital, including debt and equity.

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Percentage of public utility's amended requested rate increase (decrease) with regulatory agency.

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Percentage of public utility's requested return on equity.

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2027 capital investments planned under PGL's Pipe Replacement Program

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Amount of increase (decrease) to public utility's previously requested rate increase (decrease) with a regulatory agency.

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All cast and ductile iron pipe with a diameter under this amount requires replacement.

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