Amortization period of a regulatory asset or liability

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- Definition

The date amortization of a regulatory asset or liability begins.

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- Definition

Electric energy-efficiency rate increase

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- Definition

ICC required RTO cost benefit study duration

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No definition available.

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- Definition

The return on equity percentage estimated by the ICC staff.

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- Definition

The equity capital percentage recommend by the ICC staff.

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- Definition

The rate base recommended by the ICC staff.

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- Definition

The rate increase recommended by the ICC staff.

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- Definition

The return on equity percentage recommended by the ICC staff.

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- Definition

The equity capital structure recommended by intervenors.

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- Definition

The rate increase recommended by intervenors.

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- Definition

The return on equity recommended by intervenors.

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- Definition

The revenue requirement recommended by the ICC staff.

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No definition available.

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- Definition

Multi-Year Rate Plan Reconciliation Cap

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No definition available.

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- Definition

Ameren Illinois' requested multi-year rate plan revenue requirement.

+ References

No definition available.

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- Definition

Number of Performance Metrics

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No definition available.

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- Definition

Rate And Regulatory Matters [Line Items]

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No definition available.

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- Definition

Value established for a utility on which the entity is allowed to earn a particular rate of return

+ References

No definition available.

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- Definition

The return on equity adjustments related to the achievement of certain performance metrics requested by Ameren Illinois.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

Percentage of public utility's requested return on equity.

+ References

No definition available.

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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Rate And Regulatory Matters (Narrative-Illinois) (Details) $ in Millions	3 Months Ended			6 Months Ended		12 Months Ended
	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) numberOfProposedPerformanceMetrics	Jun. 30, 2022 USD ($)	Dec. 31, 2027 USD ($)	Dec. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Rate And Regulatory Matters [Line Items]
Revenues		$ 1,760	$ 1,726	$ 3,822	$ 3,605
Ameren Illinois Company
Rate And Regulatory Matters [Line Items]
Revenues		$ 779	$ 769	$ 1,880	$ 1,793
Ameren Illinois Company \| Minimum \| Subsequent Event
Rate And Regulatory Matters [Line Items]
ICC required RTO cost benefit study duration	5 years
Ameren Illinois Company \| Maximum \| Subsequent Event
Rate And Regulatory Matters [Line Items]
ICC required RTO cost benefit study duration	10 years
Ameren Illinois Company \| Electric Distribution
Rate And Regulatory Matters [Line Items]
Requested Return on Equity Adjustment				0.24%
Number of Performance Metrics \| numberOfProposedPerformanceMetrics				7
IETL \| Ameren Illinois Company \| Electric Distribution
Rate And Regulatory Matters [Line Items]
Public Utilities, Approved Equity Capital Structure, Percentage				50.00%
Amortization Period				2 years
Amortization Start Date				1 year
Multi-Year Rate Plan Reconciliation Cap				105.00%
IETL \| Ameren Illinois Company \| Electric Distribution \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Multi-year rate plan requested revenue requirement						$ 1,560	$ 1,484	$ 1,387	$ 1,291
Public Utilities, Requested Return on Equity, Percentage						10.50%	10.50%	10.50%	10.50%
Public Utilities, Requested Equity Capital Structure, Percentage						54.03%	54.02%	53.97%	53.99%
Rate Base						$ 5,200	$ 4,900	$ 4,600	$ 4,300
Multi-year rate plan ICC staff recommended revenue requirement						$ 1,429	$ 1,371	$ 1,292	$ 1,211
ICC recommended return on equity percentage	5.80%					8.90%	8.90%	8.90%	8.90%
ICC staff recommended equity capital structure						50.00%	50.00%	50.00%	50.00%
ICC staff recommended rate base						$ 4,800	$ 4,600	$ 4,400	$ 4,100
ICC staff estimated return on equity percentage	8.90%
Public Utilities, Requested Rate Increase (Decrease), Percentage							50.00%
Public Utilities, Requested Rate Increase (Decrease), Amount									$ 179
IETL \| Ameren Illinois Company \| Electric Distribution \| Minimum
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Percentage				50.00%
Pending Rate Case \| Ameren Illinois Company
Rate And Regulatory Matters [Line Items]
Electric energy-efficiency rate increase				$ 27
Pending Rate Case \| Ameren Illinois Company \| Electric Distribution
Rate And Regulatory Matters [Line Items]
ICC staff recommended equity capital structure				50.00%
ICC staff recommended rate increase				$ 109
Pending Rate Case \| Ameren Illinois Company \| Electric Distribution \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Equity Capital Structure, Percentage	53.99%
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 125
Pending Rate Case \| Ameren Illinois Company \| Natural gas \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Return on Equity, Percentage	10.30%
Public Utilities, Requested Equity Capital Structure, Percentage	53.99%
Rate Base	$ 2,900
ICC recommended return on equity percentage	9.89%
ICC staff recommended equity capital structure	50.00%
ICC staff recommended rate base	$ 2,900
Public Utilities, Requested Rate Increase (Decrease), Amount	148
ICC staff recommended rate increase	128
Revenues	$ 77
Intervenor recommended return on equity	9.50%
Intervenor recommended equity capital structure	52.00%
Pending Rate Case \| Ameren Illinois Company \| Natural gas \| Minimum \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Intervenor recommended rate increase	$ 98
Pending Rate Case \| Ameren Illinois Company \| Natural gas \| Maximum \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Intervenor recommended rate increase	$ 106