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REGULATORY ENVIRONMENT - NSG 2021 RATE CASE (Details) - Illinois Commerce Commission (ICC) - NSG $ in Millions | Sep. 08, 2021 USD ($)
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Public Utilities, General Disclosures [Line Items] |
Approved rate increase | $ 4.1
Approved rate increase (as a percent) | 4.50%
Approved return on equity (as a percent) | 9.67%
Approved common equity component average (as a percent) | 51.58%

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