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-Topic 230
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-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-13

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Rate And Regulatory Matters (Narrative-Illinois) (Details) - USD ($) $ in Millions	1 Months Ended			3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023	Nov. 30, 2023	Sep. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2027	Dec. 31, 2026	Dec. 31, 2025	Dec. 31, 2024
Rate And Regulatory Matters [Line Items]
Capital expenditures					$ 3,029	$ 2,571
Ameren Illinois Company
Rate And Regulatory Matters [Line Items]
Capital expenditures					1,091	$ 1,226
Ameren Illinois Company \| Natural gas
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Equity Capital Structure, Percentage		52.00%
Public Utilities, Requested Return on Equity, Percentage		9.89%
IETL \| Ameren Illinois Company \| Electric Distribution \| Forecast
Rate And Regulatory Matters [Line Items]
Approved return on equity percentage							8.72%	8.72%	8.72%	8.72%
Multi-year rate plan rehearing approved revenue requirement							$ 1,397	$ 1,350	$ 1,282	$ 1,196
Approved rate base							4,700	4,500	4,300	4,000
Revised multi-year rate plan requested revenue requirement							1,444	1,385	1,299	1,215
Revised multi-year rate plan requested rate base							5,000	4,800	4,500	4,300
ICC staff revised multi-year rate plan recommended revenue requirement							1,424	1,369	1,288	1,206
ICC staff revised multi-year rate plan recommended rate base							$ 4,800	$ 4,600	$ 4,400	$ 4,200
Public Utilities, Approved Equity Capital Structure, Percentage							50.00%	50.00%	50.00%	50.00%
Public Utilities, Approved Rate Increase (Decrease), Amount										$ 285
Public Utilities, Requested Rate Increase (Decrease), Amount										332
ICC staff recommended rate increase										311
IETL \| Ameren Illinois Company \| Electric Distribution \| Forecast \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Multi-year rate plan ALJ proposed revenue requirement							$ 1,427	$ 1,370	$ 1,287	1,206
ALJ proposed rate base							$ 4,900	$ 4,600	$ 4,400	4,200
ALJ recommended rate increase										$ 315
Pending Rate Case \| Ameren Illinois Company \| Electric Distribution
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 158
Public Utilities, Requested Equity Capital Structure, Percentage				50.00%
Pending Rate Case \| Ameren Illinois Company \| Electric Energy-Efficiency
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount					$ 26
Pending Rate Case \| Ameren Illinois Company \| Natural gas
Rate And Regulatory Matters [Line Items]
Capital expenditures	$ 30
Over-Recovery Challenged by the Attorney General	$ 1
Final Rate Order \| Ameren Illinois Company \| Natural gas
Rate And Regulatory Matters [Line Items]
Approved return on equity percentage			9.44%
Approved rate base			$ 2,850
Public Utilities, Approved Equity Capital Structure, Percentage			50.00%
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 112
Capital expenditures		$ 93	$ 93