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Rate and Regulatory Matters (Regulatory Framework-Illinois) (Details) - Ameren Illinois | 12 Months Ended
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Dec. 31, 2025 numberOfProposedPerformanceMetrics
FEJA |
Public Utilities, General Disclosures [Line Items] |
Public Utilities, Approved Return on Equity, Percentage | 5.80%
Return on equity adjustment | 2.00%
Natural gas |
Public Utilities, General Disclosures [Line Items] |
Number of months to complete a regulatory rate review | 11 months
Electric Distribution |
Public Utilities, General Disclosures [Line Items] |
MYRP return on equity adjustment | 0.24%
Number of performance metrics | 7
Electric Distribution | FEJA |
Public Utilities, General Disclosures [Line Items] |
Regulatory asset, amortization period | 2 years
Electric Distribution | RBA |
Public Utilities, General Disclosures [Line Items] |
Regulatory asset, amortization period | 2 years
Maximum |
Public Utilities, General Disclosures [Line Items] |
Public utilities, approved rate increase (decrease), percentage | 105.00%

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