Union Electric (UEPEN) 10-K 18 Feb 25 2024 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2024	Jan. 31, 2025	Jun. 30, 2024
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2024
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-14756
Entity Registrant Name	Ameren Corporation
Entity Tax Identification Number	43-1723446
Entity Incorporation, State or Country Code	MO
Entity Address, Address Line One	1901 Chouteau Avenue
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63103
City Area Code	(314)
Local Phone Number	621-3222
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol(s)	AEE
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Emerging growth company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 18,953,889,643
Entity Common Stock, Shares Outstanding		269,906,252
Documents Incorporated by Reference	Portions of the definitive proxy statement of Ameren Corporation and portions of the definitive information statements of Union Electric Company and Ameren Illinois Company for the 2025 annual meetings of shareholders are incorporated by reference into Part III of this Form 10-K.
Entity Central Index Key	0001002910
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false
Ameren Missouri
Entity Information [Line Items]
Current Fiscal Year End Date	--12-31
Entity File Number	1-2967
Entity Registrant Name	Union Electric Company
Entity Tax Identification Number	43-0559760
Entity Incorporation, State or Country Code	MO
Entity Address, Address Line One	1901 Chouteau Avenue
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63103
City Area Code	(314)
Local Phone Number	621-3222
Title of 12(g) Security	Preferred Stock, cumulative, no par value, stated value $100 per share
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Emerging growth company	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		102,123,834
Entity Central Index Key	0000100826
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false
No Trading Symbol Flag	true
Ameren Illinois
Entity Information [Line Items]
Current Fiscal Year End Date	--12-31
Entity File Number	1-3672
Entity Registrant Name	Ameren Illinois Company
Entity Tax Identification Number	37-0211380
Entity Incorporation, State or Country Code	IL
Entity Address, Address Line One	10 Richard Mark Way
Entity Address, City or Town	Collinsville
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	62234
City Area Code	(618)
Local Phone Number	343-8150
Title of 12(g) Security	Preferred Stock, cumulative, $100 par value
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Emerging growth company	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		25,452,373
Entity Central Index Key	0000018654
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false
No Trading Symbol Flag	true

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2024
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	St. Louis, Missouri
Auditor Firm ID	238
Ameren Missouri
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	St. Louis, Missouri
Auditor Firm ID	238
Ameren Illinois
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	St. Louis, Missouri
Auditor Firm ID	238

Consolidated Statement Of Incom

Consolidated Statement Of Income (Loss) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Operating Revenues:
Operating revenues	$ 7,623	$ 7,500	$ 7,957
Operating Expenses:
Utilities Operating Expense, Fuel Used and Purchased Power	1,681	1,812	2,020
Natural gas purchased for resale	320	355	657
Other operations and maintenance	1,969	1,866	1,937
Depreciation and amortization	1,590	1,387	1,289
Taxes other than income taxes	547	522	539
Total operating expenses	6,107	5,942	6,442
Operating Income	1,516	1,558	1,515
Other Income, Net	417	348	226
Interest Charges	663	566	486
Income Before Income Taxes	1,270	1,340	1,255
Income Taxes	83	183	176
Net Income	1,187	1,157	1,079
Less: Net Income Attributable to Noncontrolling Interests	5	5	5
Net Income Attributable to Ameren Common Shareholders	1,182	1,152	1,074
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $—, $(2), and $(4), respectively	(3)	(5)	(14)
Unrealized net gain on derivative hedging instruments, net of income taxes of $—, $—, and $—, respectively	3	0	0
Comprehensive Income	1,187	1,152	1,065
Less: Comprehensive Income Attributable to Noncontrolling Interests	5	5	5
Comprehensive Income Attributable to Ameren Common Shareholders	1,182	1,147	1,060
Preferred Stock Dividends	$ 5	$ 5	$ 5
Earnings per Common Share – Basic
Earnings per Common Share – Basic	$ 4.43	$ 4.39	$ 4.16
Earnings per Common Share – Diluted
Earnings per Common Share – Diluted	$ 4.42	$ 4.38	$ 4.14
Weighted-average Common Shares Outstanding – Basic	266.8	262.8	258.4
Weighted-average Common Shares Outstanding – Diluted	267.4	263.4	259.5
Ameren Missouri
Operating Revenues:
Operating revenues	$ 3,993	$ 3,859	$ 4,046
Operating Expenses:
Utilities Operating Expense, Fuel Used and Purchased Power	1,071	997	1,150
Natural gas purchased for resale	60	79	104
Other operations and maintenance	1,050	1,003	1,028
Depreciation and amortization	917	783	732
Taxes other than income taxes	372	360	363
Total operating expenses	3,470	3,222	3,377
Operating Income	523	637	669
Other Income, Net	196	130	99
Interest Charges	244	227	213
Income Before Income Taxes	475	540	555
Income Taxes	(87)	(8)	(10)
Net Income	562	548	565
Net Income Attributable to Ameren Common Shareholders	559	545	562
Preferred Stock Dividends	3	3	3
Ameren Illinois
Operating Revenues:
Operating revenues	3,472	3,482	3,756
Operating Expenses:
Purchased power	621	820	880
Natural gas purchased for resale	260	276	553
Other operations and maintenance	906	818	882
Depreciation and amortization	619	556	514
Taxes other than income taxes	157	146	161
Total operating expenses	2,563	2,616	2,990
Operating Income	909	866	766
Other Income, Net	147	156	96
Interest Charges	241	204	168
Income Before Income Taxes	815	818	694
Income Taxes	193	209	179
Net Income	622	609	515
Net Income Attributable to Ameren Common Shareholders	620	607	513
Preferred Stock Dividends	2	2	2
Electric
Operating Revenues:
Operating revenues	6,540	6,439	6,581
Electric | Ameren Missouri
Operating Revenues:
Operating revenues	3,847	3,694	3,849
Electric | Ameren Illinois
Operating Revenues:
Operating revenues	2,534	2,585	2,576
Natural gas
Operating Revenues:
Operating revenues	1,083	1,061	1,376
Natural gas | Ameren Missouri
Operating Revenues:
Operating revenues	146	165	197
Natural gas | Ameren Illinois
Operating Revenues:
Operating revenues	$ 938	$ 897	$ 1,180

Consolidated Statement Of Inc_2

Consolidated Statement Of Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Pension and other postretirement benefit plan activity, tax (benefit)	$ 0	$ (2)	$ (4)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	$ 0	$ 0	$ 0

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Current Assets:
Cash and cash equivalents	$ 7	$ 25
Accounts receivable - trade (less allowance for doubtful accounts)	525	494
Unbilled revenue	346	319
Inventories	762	733
Current regulatory assets	366	365
Other current assets	162	139
Total current assets	2,264	2,181
Property, Plant, and Equipment, Net	36,304	33,776
Investments and Other Assets:
Nuclear decommissioning trust fund	1,342	1,150
Goodwill	411	411
Regulatory Asset, Noncurrent	2,397	1,810
Pension and other postretirement benefits	757	581
Other assets	1,123	921
Total investments and other assets	6,030	4,873
TOTAL ASSETS	44,598	40,830
Current Liabilities:
Long-Term Debt, Current Maturities	317	849
Short-term debt	1,143	536
Accounts and wages payable	1,059	1,136
Interest accrued	196	147
Customer deposits	223	176
Other current liabilities	475	501
Total current liabilities	3,413	3,345
Long-Term Debt, Excluding Current Maturities	17,262	15,121
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	4,474	4,176
Regulatory liabilities	5,897	5,512
Asset retirement obligations	822	772
Other deferred credits and liabilities	487	426
Total deferred credits and other liabilities	11,680	10,886
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	3	3
Other paid-in capital, principally premium on common stock	7,513	7,216
Retained earnings	4,604	4,136
Accumulated other comprehensive loss	(6)	(6)
Total shareholders' equity	12,114	11,349
Noncontrolling Interests	129	129
Total equity	12,243	11,478
TOTAL LIABILITIES AND EQUITY	$ 44,598	$ 40,830

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts receivable - trade, allowance for doubtful accounts	$ 30	$ 30
Regulatory Asset, Noncurrent	2,397	1,810
Long-Term Debt, Current Maturities	317	849
Long-Term Debt, Excluding Current Maturities	$ 17,262	$ 15,121
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000	400,000,000
Common Stock, Shares, Outstanding	269,900,000	266,300,000	262,000,000	257,700,000
Variable Interest Entity, Primary Beneficiary
Regulatory Asset, Noncurrent	$ 465
Long-Term Debt, Current Maturities	17
Long-Term Debt, Excluding Current Maturities	$ 448

Consolidated Balance Sheet - UE

Consolidated Balance Sheet - UE - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Current Assets:
Cash and cash equivalents	$ 7	$ 25
Accounts receivable - trade (less allowance for doubtful accounts)	525	494
Unbilled revenue	346	319
Inventories	762	733
Current regulatory assets	366	365
Other current assets	162	139
Total current assets	2,264	2,181
Property, Plant, and Equipment, Net	36,304	33,776
Investments and Other Assets:
Nuclear decommissioning trust fund	1,342	1,150
Regulatory Asset, Noncurrent	2,397	1,810
Pension and other postretirement benefits	757	581
Other assets	1,123	921
Total investments and other assets	6,030	4,873
TOTAL ASSETS	44,598	40,830
Current Liabilities:
Long-Term Debt, Current Maturities	317	849
Short-term debt	1,143	536
Accounts and wages payable	1,059	1,136
Interest accrued	196	147
Other current liabilities	475	501
Total current liabilities	3,413	3,345
Long-Term Debt, Excluding Current Maturities	17,262	15,121
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	4,474	4,176
Regulatory liabilities	5,897	5,512
Asset retirement obligations	822	772
Other deferred credits and liabilities	487	426
Total deferred credits and other liabilities	11,680	10,886
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	3	3
Other paid-in capital, principally premium on common stock	7,513	7,216
Retained earnings	4,604	4,136
Total shareholders' equity	12,114	11,349
TOTAL LIABILITIES AND EQUITY	44,598	40,830
Ameren Missouri
Current Assets:
Cash and cash equivalents	0	0
Advances to money pool	43	0
Unbilled revenue	170	163
Inventories	514	508
Current regulatory assets	66	101
Other current assets	70	68
Total current assets	1,145	1,142
Property, Plant, and Equipment, Net	18,788	17,250
Investments and Other Assets:
Nuclear decommissioning trust fund	1,342	1,150
Regulatory Asset, Noncurrent	1,366	755
Pension and other postretirement benefits	211	157
Other assets	254	152
Total investments and other assets	3,173	2,214
TOTAL ASSETS	23,106	20,606
Current Liabilities:
Long-Term Debt, Current Maturities	17	350
Short-term debt	0	170
Interest accrued	88	69
Other current liabilities	235	181
Total current liabilities	1,019	1,747
Long-Term Debt, Excluding Current Maturities	7,671	5,991
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	2,217	2,122
Regulatory liabilities	3,176	2,959
Asset retirement obligations	818	768
Other deferred credits and liabilities	150	56
Total deferred credits and other liabilities	6,361	5,905
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	511	511
Other paid-in capital, principally premium on common stock	3,201	2,725
Preferred stock	80	80
Retained earnings	4,206	3,647
Total shareholders' equity	7,998	6,963
TOTAL LIABILITIES AND EQUITY	23,106	20,606
Ameren Missouri | Nonrelated Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	209	204
Current Liabilities:
Short-term debt	0	170
Accounts and wages payable	629	618
Ameren Missouri | Related Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	40	72
Current Liabilities:
Short-term debt	0	306
Accounts and wages payable	50	53
Long-Term Debt, Excluding Current Maturities	57	0
Ameren Illinois
Current Assets:
Cash and cash equivalents	0	0
Unbilled revenue	175	156
Inventories	244	225
Current regulatory assets	281	252
Other current assets	8	13
Total current assets	1,110	1,047
Property, Plant, and Equipment, Net	15,530	14,632
Investments and Other Assets:
Regulatory Asset, Noncurrent	1,011	1,035
Pension and other postretirement benefits	471	394
Other assets	697	603
Total investments and other assets	2,590	2,443
TOTAL ASSETS	19,230	18,122
Current Liabilities:
Long-Term Debt, Current Maturities	300	0
Short-term debt	88	366
Other current liabilities	231	298
Total current liabilities	1,318	1,433
Long-Term Debt, Excluding Current Maturities	5,549	5,232
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	2,143	1,906
Regulatory liabilities	2,573	2,418
Other deferred credits and liabilities	273	308
Total deferred credits and other liabilities	4,989	4,632
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	0	0
Other paid-in capital, principally premium on common stock	3,056	3,020
Preferred stock	49	49
Retained earnings	4,266	3,756
Total shareholders' equity	7,371	6,825
TOTAL LIABILITIES AND EQUITY	19,230	18,122
Ameren Illinois | Nonrelated Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	300	273
Current Liabilities:
Short-term debt	88	366
Accounts and wages payable	324	370
Ameren Illinois | Related Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	15	35
Current Liabilities:
Short-term debt	37	135
Accounts and wages payable	74	52
Long-Term Debt, Excluding Current Maturities	$ 3	$ 0

Consolidated Balance Sheet - _2

Consolidated Balance Sheet - UE (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Accounts receivable - trade, allowance for doubtful accounts	$ 30	$ 30
Regulatory Asset, Noncurrent	2,397	1,810
Long-Term Debt, Current Maturities	317	849
Long-Term Debt, Excluding Current Maturities	$ 17,262	$ 15,121
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000	400,000,000
Common Stock, Shares, Outstanding	269,900,000	266,300,000
Variable Interest Entity, Primary Beneficiary
Regulatory Asset, Noncurrent	$ 465
Long-Term Debt, Current Maturities	17
Long-Term Debt, Excluding Current Maturities	448
Ameren Missouri
Accounts receivable - trade, allowance for doubtful accounts	12	$ 12
Regulatory Asset, Noncurrent	1,366	755
Long-Term Debt, Current Maturities	17	350
Long-Term Debt, Excluding Current Maturities	$ 7,671	5,991
Common Stock, No Par Value (in dollars per share)	$ 5
Common stock, shares authorized	150,000,000
Common Stock, Shares, Outstanding	102,100,000
Ameren Missouri | Variable Interest Entity, Primary Beneficiary
Regulatory Asset, Noncurrent	$ 465	0
Long-Term Debt, Current Maturities	17	0
Long-Term Debt, Excluding Current Maturities	$ 448	$ 0

Consolidated Balance Sheet - AI

Consolidated Balance Sheet - AIC - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Current Assets:
Cash and cash equivalents	$ 7	$ 25
Accounts receivable - trade (less allowance for doubtful accounts)	525	494
Unbilled revenue	346	319
Advances to money pool	96	106
Inventories	762	733
Current regulatory assets	366	365
Other current assets	162	139
Total current assets	2,264	2,181
Property, Plant, and Equipment, Net	36,304	33,776
Investments and Other Assets:
Goodwill	411	411
Regulatory Asset, Noncurrent	2,397	1,810
Pension and other postretirement benefits	757	581
Other assets	1,123	921
Total investments and other assets	6,030	4,873
TOTAL ASSETS	44,598	40,830
Current Liabilities:
Long-Term Debt, Current Maturities	317	849
Short-term debt	1,143	536
Accounts and wages payable	1,059	1,136
Customer deposits	223	176
Other current liabilities	475	501
Total current liabilities	3,413	3,345
Long-Term Debt, Excluding Current Maturities	17,262	15,121
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	4,474	4,176
Regulatory liabilities	5,897	5,512
Other deferred credits and liabilities	487	426
Total deferred credits and other liabilities	11,680	10,886
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	3	3
Other paid-in capital, principally premium on common stock	7,513	7,216
Retained earnings	4,604	4,136
Total shareholders' equity	12,114	11,349
TOTAL LIABILITIES AND EQUITY	44,598	40,830
Ameren Illinois
Current Assets:
Cash and cash equivalents	0	0
Unbilled revenue	175	156
Advances to money pool	28	44
Inventories	244	225
Prepaid assets	59	49
Current regulatory assets	281	252
Other current assets	8	13
Total current assets	1,110	1,047
Property, Plant, and Equipment, Net	15,530	14,632
Investments and Other Assets:
Goodwill	411	411
Regulatory Asset, Noncurrent	1,011	1,035
Pension and other postretirement benefits	471	394
Other assets	697	603
Total investments and other assets	2,590	2,443
TOTAL ASSETS	19,230	18,122
Current Liabilities:
Long-Term Debt, Current Maturities	300	0
Short-term debt	88	366
Customer deposits	185	141
Current regulatory liabilities	79	71
Other current liabilities	231	298
Total current liabilities	1,318	1,433
Long-Term Debt, Excluding Current Maturities	5,549	5,232
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	2,143	1,906
Regulatory liabilities	2,573	2,418
Other deferred credits and liabilities	273	308
Total deferred credits and other liabilities	4,989	4,632
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	0	0
Other paid-in capital, principally premium on common stock	3,056	3,020
Preferred stock	49	49
Retained earnings	4,266	3,756
Total shareholders' equity	7,371	6,825
TOTAL LIABILITIES AND EQUITY	19,230	18,122
Ameren Illinois | Nonrelated Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	300	273
Current Liabilities:
Short-term debt	88	366
Accounts and wages payable	324	370
Ameren Illinois | Related Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	15	35
Current Liabilities:
Short-term debt	37	135
Accounts and wages payable	74	52
Long-Term Debt, Excluding Current Maturities	3	0
Ameren Missouri
Current Assets:
Cash and cash equivalents	0	0
Unbilled revenue	170	163
Advances to money pool	33	26
Inventories	514	508
Current regulatory assets	66	101
Other current assets	70	68
Total current assets	1,145	1,142
Property, Plant, and Equipment, Net	18,788	17,250
Investments and Other Assets:
Regulatory Asset, Noncurrent	1,366	755
Pension and other postretirement benefits	211	157
Other assets	254	152
Total investments and other assets	3,173	2,214
TOTAL ASSETS	23,106	20,606
Current Liabilities:
Long-Term Debt, Current Maturities	17	350
Short-term debt	0	170
Current regulatory liabilities	37	15
Other current liabilities	235	181
Total current liabilities	1,019	1,747
Long-Term Debt, Excluding Current Maturities	7,671	5,991
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	2,217	2,122
Regulatory liabilities	3,176	2,959
Other deferred credits and liabilities	150	56
Total deferred credits and other liabilities	6,361	5,905
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	511	511
Other paid-in capital, principally premium on common stock	3,201	2,725
Preferred stock	80	80
Retained earnings	4,206	3,647
Total shareholders' equity	7,998	6,963
TOTAL LIABILITIES AND EQUITY	23,106	20,606
Ameren Missouri | Nonrelated Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	209	204
Current Liabilities:
Short-term debt	0	170
Accounts and wages payable	629	618
Ameren Missouri | Related Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	40	72
Current Liabilities:
Short-term debt	0	306
Accounts and wages payable	50	53
Long-Term Debt, Excluding Current Maturities	$ 57	$ 0

Consolidated Balance Sheet - _3

Consolidated Balance Sheet - AIC (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Accounts receivable - trade, allowance for doubtful accounts	$ 30	$ 30
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000	400,000,000
Common Stock, Shares, Outstanding	269,900,000	266,300,000
Ameren Illinois
Accounts receivable - trade, allowance for doubtful accounts	$ 18	$ 18
Common Stock, No Par Value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	45,000,000	45,000,000
Common Stock, Shares, Outstanding	25,500,000	25,500,000

Consolidated Statement Of Cash

Consolidated Statement Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash Flows From Operating Activities:
Net income	$ 1,187	$ 1,157	$ 1,079
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,524	1,432	1,373
Amortization of nuclear fuel	81	68	65
Amortization of debt issuance costs and premium/discounts	19	16	21
Deferred income taxes and production and investment tax credits, net	127	229	170
Allowance for equity funds used during construction	76	54	43
Stock-based compensation costs	28	26	24
Other	87	16	68
Changes in assets and liabilities:
Receivables	(91)	144	(317)
Inventories	(31)	(67)	(77)
Accounts and wages payable	4	(104)	136
Taxes accrued	34	(4)	(13)
Regulatory assets and liabilities	99	(165)	(72)
Assets, other	(34)	(109)	(74)
Liabilities, other	22	115	52
Pension and other postretirement benefits	(216)	(283)	(65)
Counterparty collateral, net	(1)	147	(64)
Net cash provided by operating activities	2,763	2,564	2,263
Cash Flows From Investing Activities:
Capital expenditures	(4,319)	(3,597)	(3,351)
Nuclear fuel expenditures	(91)	(174)	(29)
Purchases of securities – nuclear decommissioning trust fund	(584)	(266)	(229)
Proceeds from sales and maturities	564	240	216
Other	(26)	(1)	23
Net cash used in investing activities	(4,456)	(3,798)	(3,370)
Cash Flows From Financing Activities:
Dividends on common stock	(714)	(662)	(610)
Dividends paid to noncontrolling interest holders	(5)	(5)	(5)
Short-term debt, net	607	(533)	522
Maturities and extinguishment of long-term debt	(893)	(100)	(505)
Issuances of long-term debt	2,535	2,295	1,467
Issuances of common stock	273	346	333
Employee payroll taxes related to stock-based compensation	(8)	(20)	(16)
Debt issuance costs	(31)	(21)	(18)
Other	(15)	(10)	0
Net cash provided by financing activities	1,749	1,290	1,168
Net change in cash, cash equivalents, and restricted cash	56	56	61
Cash, cash equivalents, and restricted cash at beginning of year	272	216	155
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	611	546	476
Income Taxes Paid, Net	(92)	(24)	(8)
Ameren Missouri
Cash Flows From Operating Activities:
Net Income Attributable to Ameren Common Shareholders	562	548	565
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	851	827	816
Amortization of nuclear fuel	81	68	65
Amortization of debt issuance costs and premium/discounts	7	7	7
Deferred income taxes and production and investment tax credits, net	(29)	28	21
Allowance for equity funds used during construction	58	30	24
Other	74	(8)	14
Changes in assets and liabilities:
Receivables	(26)	39	(68)
Inventories	(6)	(74)	(15)
Accounts and wages payable	17	(8)	19
Taxes accrued	60	(17)	(21)
Regulatory assets and liabilities	51	(7)	(206)
Assets, other	0	(25)	1
Liabilities, other	18	3	7
Pension and other postretirement benefits	(76)	(106)	(16)
Counterparty collateral, net	(3)	96	(35)
Net cash provided by operating activities	1,523	1,341	1,130
Cash Flows From Investing Activities:
Capital expenditures	(2,712)	(1,760)	(1,690)
Nuclear fuel expenditures	(91)	(174)	(29)
Purchases of securities – nuclear decommissioning trust fund	(584)	(266)	(229)
Proceeds from sales and maturities	564	240	216
Money pool advances, net	(43)	0	0
Other	(32)	0	29
Net cash used in investing activities	(2,898)	(1,960)	(1,703)
Cash Flows From Financing Activities:
Dividends on common stock	0	(9)	(46)
Dividends on preferred stock	(3)	(3)	(3)
Short-term debt, net	(170)	(159)	164
Money pool borrowings, net	(306)	306	0
Maturities and extinguishment of long-term debt	(350)	0	(55)
Issuances of long-term debt	1,771	499	524
Debt issuance costs	(21)	(8)	(6)
Capital contribution from parent	476	0	0
Other	(15)	(10)	0
Net cash provided by financing activities	1,382	616	578
Net change in cash, cash equivalents, and restricted cash	7	(3)	5
Cash, cash equivalents, and restricted cash at beginning of year	10	13	8
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	244	225	230
Income Taxes Paid, Net	(136)	(19)	(20)
Ameren Illinois
Cash Flows From Operating Activities:
Net Income Attributable to Ameren Common Shareholders	622	609	515
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	619	557	514
Amortization of debt issuance costs and premium/discounts	6	5	11
Deferred income taxes and production and investment tax credits, net	188	177	117
Allowance for equity funds used during construction	17	19	18
Other	41	40	29
Changes in assets and liabilities:
Receivables	(70)	129	(250)
Inventories	(21)	7	(62)
Accounts and wages payable	1	(107)	117
Taxes accrued	55	(73)	34
Regulatory assets and liabilities	53	(152)	134
Assets, other	(33)	(123)	(67)
Liabilities, other	2	106	42
Pension and other postretirement benefits	(88)	(112)	(39)
Counterparty collateral, net	11	54	(29)
Net cash provided by operating activities	1,369	1,098	1,048
Cash Flows From Investing Activities:
Capital expenditures	(1,467)	(1,731)	(1,601)
Other	1	(2)	(1)
Net cash used in investing activities	(1,466)	(1,733)	(1,602)
Cash Flows From Financing Activities:
Dividends on common stock	(110)	(41)	0
Dividends on preferred stock	(2)	(2)	(2)
Short-term debt, net	(277)	102	161
Money pool borrowings, net	(98)	135	0
Maturities and extinguishment of long-term debt	0	(100)	(400)
Issuances of long-term debt	624	498	848
Debt issuance costs	(8)	(5)	(10)
Capital contribution from parent	36	91	15
Net cash provided by financing activities	165	678	612
Net change in cash, cash equivalents, and restricted cash	68	43	58
Cash, cash equivalents, and restricted cash at beginning of year	234	191	133
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	213	195	152
Income Taxes Paid, Net	$ (46)	$ 102	$ 23

Consolidated Statement Of Cas_2

Consolidated Statement Of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Interest Paid, Capitalized, Investing Activities	$ 56	$ 48	$ 26
Proceeds from Income Tax Refunds	95	49	0
Ameren Missouri
Interest Paid, Capitalized, Investing Activities	39	27	13
Proceeds from Income Tax Refunds	95	49	0
Ameren Illinois
Interest Paid, Capitalized, Investing Activities	$ 15	$ 17	$ 12

Consolidated Statement Of Stock

Consolidated Statement Of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Other Paid-In Capital	Retained Earnings	Derivative Financial Instruments	Deferred Retirement Benefit Costs	Accumulated Other Comprehensive Income (Loss)	Total Ameren Corporation Stockholders' Equity	Noncontrolling Interest	Ameren Missouri	Ameren Missouri Common Stock	Ameren Missouri Other Paid-In Capital	Ameren Missouri Preferred Stock Not Subject To Mandatory Redemption	Ameren Missouri Retained Earnings	Ameren Illinois	Ameren Illinois Common Stock	Ameren Illinois Other Paid-In Capital	Ameren Illinois Preferred Stock Not Subject To Mandatory Redemption	Ameren Illinois Retained Earnings
Common Stock at Dec. 31, 2021			$ 6,502	$ 3,182	$ 0	$ 13			$ 129			$ 2,725		$ 2,595			$ 2,914		$ 2,677
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, New Issues			292
Shares issued under the DRPlus and 401(k) plan			49
Stock-based compensation activity			17
Capital contribution from parent										$ 0		0			$ 15		15
Net income	$ 1,079													565					515
Net Income (Loss) Available to Common Stockholders, Basic	1,074			1,074						562					513
Common stock dividends				(610)										(46)					0
Preferred stock dividends														(3)					(2)
Change in derivative financial instruments					0
Change in deferred retirement benefit costs	(14)					(14)
Net income attributable to noncontrolling interest holders	$ (5)								5
Dividends paid to noncontrolling interest holders									(5)
Beginning of year (shares) at Dec. 31, 2021	257,700,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues	3,400,000
Shares issued under the DRPlus and 401(k) plan	500,000
Shares issued (in shares)	400,000
End of year (shares) at Dec. 31, 2022	262,000,000
End of year at Dec. 31, 2022	$ 10,637	$ 3	6,860	3,646	0	(1)	$ (1)		129		$ 511	2,725	$ 80	3,111		$ 0	2,929	$ 49	3,190
Stockholders' equity, end of year at Dec. 31, 2022								$ 10,508		6,427					6,168
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Cash Paid	$ 2.36
Stock Issued During Period, Value, New Issues			299
Shares issued under the DRPlus and 401(k) plan			46
Stock-based compensation activity			11
Capital contribution from parent										0		0			91		91
Net income	$ 1,157													548					609
Net Income (Loss) Available to Common Stockholders, Basic	1,152			1,152						545					$ 607
Common stock dividends				(662)										(9)					(41)
Preferred stock dividends														(3)					(2)
Change in derivative financial instruments					0
Change in deferred retirement benefit costs	(5)					(5)
Net income attributable to noncontrolling interest holders	$ (5)								5
Dividends paid to noncontrolling interest holders									(5)
Stock Issued During Period, Shares, New Issues	3,200,000
Shares issued under the DRPlus and 401(k) plan	600,000
Shares issued (in shares)	500,000
End of year (shares) at Dec. 31, 2023	266,300,000														25,500,000
End of year at Dec. 31, 2023	$ 11,478	3	7,216	4,136	0	(6)	(6)		129		511	2,725	80	3,647		0	3,020	49	3,756
Stockholders' equity, end of year at Dec. 31, 2023	$ 11,349							11,349		6,963					$ 6,825
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Cash Paid	$ 2.52
Stock Issued During Period, Value, New Issues			233
Shares issued under the DRPlus and 401(k) plan			40
Stock-based compensation activity			24
Capital contribution from parent										476		476			36		36
Net income	$ 1,187													562					622
Net Income (Loss) Available to Common Stockholders, Basic	1,182			1,182						$ 559					$ 620
Common stock dividends				(714)										0					(110)
Preferred stock dividends														(3)					(2)
Change in derivative financial instruments					(3)
Change in deferred retirement benefit costs	(3)					(3)
Net income attributable to noncontrolling interest holders	$ (5)								5
Dividends paid to noncontrolling interest holders									(5)
Stock Issued During Period, Shares, New Issues	2,900,000
Shares issued under the DRPlus and 401(k) plan	500,000
Shares issued (in shares)	200,000
End of year (shares) at Dec. 31, 2024	269,900,000									102,100,000					25,500,000
End of year at Dec. 31, 2024	$ 12,243	$ 3	$ 7,513	$ 4,604	$ 3	$ (9)	$ (6)		$ 129		$ 511	$ 3,201	$ 80	$ 4,206		$ 0	$ 3,056	$ 49	$ 4,266
Stockholders' equity, end of year at Dec. 31, 2024	$ 12,114							$ 12,114		$ 7,998					$ 7,371
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Cash Paid	$ 2.68

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2024
Accounting Policies [Abstract]
Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES General Ameren, headquartered in St. Louis, Missouri, is a public utility holding company whose primary assets are its equity interests in its subsidiaries. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below. Ameren also has other subsidiaries that conduct other activities, such as providing shared services. • Union Electric Company, doing business as Ameren Missouri, operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri. Ameren Missouri was incorporated in Missouri in 1922 and is successor to a number of companies, the oldest of which was organized in 1881. It is the largest electric utility in the state of Missouri. It supplies electric and natural gas service to a 24,000-square-mile area in central and eastern Missouri, which includes the Greater St. Louis area. Ameren Missouri supplies electric service to 1.3 million customers and natural gas service to 0.1 million customers. • Ameren Illinois Company, doing business as Ameren Illinois, operates rate-regulated electric transmission, electric distribution, and natural gas distribution businesses in Illinois. Ameren Illinois was incorporated in Illinois in 1923 and is the successor to a number of companies, the oldest of which was organized in 1902. Ameren Illinois supplies electric and natural gas utility service to a 43,700 square mile area in central and southern Illinois. Ameren Illinois supplies electric service to 1.2 million customers and natural gas service to 0.8 million customers. • ATXI operates a FERC rate-regulated electric transmission business in the MISO. ATXI was incorporated in Illinois in 2006. ATXI operates, among other assets, the Spoon River, Mark Twain, and Illinois Rivers transmission lines. Ameren’s and Ameren Missouri’s financial statements are prepared on a consolidated basis and therefore include the accounts of their majority-owned subsidiaries. All intercompany transactions have been eliminated. Ameren Illinois has no subsidiaries. All tabular dollar amounts are in millions, unless otherwise indicated. Our accounting policies conform to GAAP. Our financial statements reflect all adjustments (which include normal, recurring adjustments) that are necessary, in our opinion, for a fair presentation of our results. The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. Such estimates and assumptions affect reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of financial statements, and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates. Regulation Our customer rates are regulated by the MoPSC, the ICC, and the FERC. We defer certain costs as assets pursuant to actions of rate regulators or because of expectations that we will be able to recover such costs in future rates charged to customers. We also defer certain amounts as liabilities pursuant to actions of rate regulators or based on the expectation that such amounts will be refunded to customers in future rates. Regulatory assets and liabilities are amortized consistent with the period of expected regulatory treatment. See Note 2 – Rate and Regulatory Matters for additional information on our regulatory frameworks, regulatory recovery mechanisms, and regulatory assets and liabilities recorded at December 31, 2024 and 2023. We periodically assess the recoverability of our regulatory assets and probability of refund of our regulatory liabilities. Regulatory assets are charged to earnings when it is no longer probable that such amounts will be recovered through future revenues. To the extent that refunds to customers related to regulatory liabilities are eliminated by the regulator or are no longer probable, the amounts are credited to earnings. Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents include short-term, highly liquid investments purchased with an original maturity of three months or less. Cash and cash equivalents subject to legal or contractual restrictions and not readily available for use for general corporate purposes are classified as restricted cash. See Note 15 – Supplemental Information for a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets and the statements of cash flows. Allowance for Doubtful Accounts Receivable The allowance for doubtful accounts represents our estimate of existing accounts receivable that will ultimately be uncollectible. The allowance is calculated by applying estimated loss factors to various classes of outstanding receivables, including unbilled revenue. The loss factors used to estimate uncollectible accounts are based upon both historical collections experience and management’s estimate of future collections success given the existing and anticipated future collections environment. Ameren Illinois has bad debt riders that adjust rates for net write-offs of customer accounts receivable above or below those being collected in rates. Inventories Inventories are recorded at the lower of weighted-average cost or net realizable value. Inventories are charged to expense or capitalized to property, plant and equipment when issued, as appropriate, using the weighted-average cost method. See Note 15 – Supplemental Information for the components of inventories. Property, Plant, and Equipment, Net We capitalize the cost of additions to, and betterments of, units of property, plant, and equipment. The cost includes labor, material, applicable taxes, and overhead. An allowance for funds used during construction, as discussed below, is also capitalized as a cost of our rate-regulated assets. Maintenance expenses related to scheduled Callaway nuclear refueling and maintenance outages are deferred and amortized over the number of expected months until the completion of the next refueling outage, which historically has been approximately 18 months . Other maintenance expenditures are expensed as incurred. When units of depreciable property are retired, the original costs, and the associated removal cost, net of salvage, are charged to accumulated depreciation. If environmental expenditures are related to assets currently in use, as in the case of the installation of pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset. See Asset Retirement Obligations and Removal Costs section below and Note 3 – Property, Plant, and Equipment, Net for additional information. Ameren Missouri’s cost of nuclear fuel is capitalized as a part of “Property, Plant, and Equipment, Net” on Ameren and Ameren Missouri’s balance sheets and then amortized to “Operating Expenses – Fuel and purchased power” in their respective statements of income on a unit-of-production basis. Nuclear fuel amortization is reflected as a part of “Amortization of nuclear fuel” on their respective statements of cash flow. Plant to be Abandoned, Net When it becomes probable an asset will be retired significantly in advance of its previously expected useful life and in the near term, the Ameren Companies must assess the probability of recovery of the remaining net book value of the asset to be abandoned. We recognize a loss on abandonment when it becomes probable that all or part of the cost of an asset, including a return at the applicable WACC, will be disallowed from recovery either through customer rates or through the issuance of securitized utility tariff bonds and such amount is reasonably estimable. An abandonment loss, if any, would equal the difference between the remaining net book value of the asset and the present value of the expected future cash flows. If the asset is still in service, the net book value is classified as plant to be abandoned, net, within “Property, Plant, and Equipment, Net” on the balance sheet. The net book value will be classified as a regulatory asset on the balance sheet when the asset is no longer in service or as required by a rate order. In relation to the NSR and Clean Air Act litigation discussed in Note 14 – Commitments and Contingencies, Ameren Missouri retired the Rush Island Energy Center on October 15, 2024. In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance costs related to the accelerated retirement of the Rush Island Energy Center. In December 2024, AMF issued $476 million of securitized utility tariff bonds. As a result of the financing order and the issuance of the securitized utility tariff bonds, Ameren Missouri concluded no abandonment loss was required for the Rush Island Energy Center and classified the remaining net book value as a regulatory asset as of December 31, 2024. See Variable Interest Entities below, Note 2 – Rate and Regulatory Matters, and Note 5 – Long-term Debt and Equity Financings for additional information on Ameren Missouri's securitization of the Rush Island Energy Center's costs. As of December 31, 2023, Ameren and Ameren Missouri determined that the Rush Island Energy Center met the criteria to be considered probable of abandonment and classified its remaining net book value as plant to be abandoned, net, within “Property, Plant, and Equipment, Net” on Ameren’s and Ameren Missouri’s balance sheets. See Note 3 – Property, Plant, and Equipment, Net for our plant to be abandoned balance as of December 31, 2023. Depreciation Depreciation is provided over the estimated lives of the various classes of depreciable tangible property by applying composite rates on a straight-line basis to the cost basis of such property. The composite rates include a provision for the estimated removal cost of property, plant, and equipment retired from service, net of salvage. See Asset Retirement Obligation and Removal Costs section below for additional information. The provision for depreciation for the Ameren Companies in 2024, 2023, and 2022 ranged from 3% to 4% of the average depreciable cost. See Note 3 – Property, Plant, and Equipment, Net for additional information on estimated depreciable lives. Allowance for Funds Used During Construction As a part of “Property, Plant, and Equipment, Net” on the balance sheet, we capitalize allowance for funds used during construction, which is the cost of borrowed funds and the cost of equity funds (preferred and common shareholders’ equity) applicable to eligible rate-regulated construction work in progress, in accordance with the utility industry’s accounting practice and GAAP. The amount of allowance for funds used during construction is calculated using a FERC-prescribed formula based on a rate, which incorporates the average cost of short-term debt, the average cost of long-term debt, and the cost of equity funds. The portion attributable to borrowed funds is recorded as a reduction of “Interest Charges” on the statements of income. The portion attributable to equity funds is recorded within “Other Income, Net” on the statements of income. This accounting practice offsets the effect on earnings of the cost of financing during construction. See Note 15 – Supplemental Information for the amount of allowance for funds used during construction capitalized and the average rate applied to eligible construction work in progress. Allowance for funds used during construction does not represent a current source of cash funds. Under accepted ratemaking practice, cash recovery of allowance for funds used during construction and other construction costs occurs when completed projects are placed in service and reflected in customer rates. Goodwill Goodwill represents the excess of the purchase price of an acquisition over the fair value of the net assets acquired. Ameren and Ameren Illinois had goodwill of $411 million at December 31, 2024 and 2023. Ameren has four reporting units: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission. Ameren Illinois has three reporting units: Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission. Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission had goodwill of $238 million, $80 million, and $93 million, respectively, at December 31, 2024 and 2023. The Ameren Transmission reporting unit had the same $93 million of goodwill as the Ameren Illinois Transmission reporting unit at December 31, 2024 and 2023. Ameren and Ameren Illinois evaluate goodwill for impairment in each of their reporting units as of October 31 each year, or more frequently if events occur or circumstances change that would more likely than not reduce the fair value of their reporting units below their carrying amounts. To determine whether the fair value of a reporting unit is more likely than not greater than its carrying amount, Ameren and Ameren Illinois can elect to perform either a qualitative assessment or to bypass the qualitative assessment and perform a quantitative test. Ameren and Ameren Illinois elected to perform a qualitative assessment for their annual goodwill impairment test conducted as of October 31, 2024. As part of this qualitative assessment, Ameren and Ameren Illinois evaluated, among other things, macroeconomic conditions, industry and market considerations such as observable industry market multiples, regulatory frameworks, cost factors, overall financial performance, and entity-specific events. The results of Ameren’s and Ameren Illinois’ qualitative assessment indicated that it was more likely than not that the fair value of each reporting unit exceeded its carrying value as of October 31, 2024, resulting in no impairment of Ameren’s or Ameren Illinois’ goodwill. Impairment of Long-lived Assets We evaluate long-lived assets classified as held and used for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. Whether an impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets to the carrying value of the assets. If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount by which the carrying value exceeds the estimated fair value of the assets. In the period in which we determine that an asset meets held for sale criteria, we record an impairment charge to the extent the book value exceeds its estimated fair value less cost to sell. We did not identify any events or changes in circumstances that indicated that the carrying value of material long-lived assets may not be recoverable in 2024, 2023, or 2022. Variable Interest Entities Variable Interest Entities that are Consolidated AMF was formed in 2024, for the purpose of issuing and servicing securitized utility tariff bonds related to costs for the accelerated retirement of the Rush Island Energy Center. Ameren Missouri is the primary beneficiary of this entity because it has the power to direct the activities that most significantly impact the economic performance of the company, as well as the obligation to absorb losses or the right to receive benefits from the company. The entity is considered a variable interest entity primarily because its equity capitalization is insufficient to support its operations. The entity’s primary assets and liabilities are comprised of regulatory assets related to the unrecovered net plant balance associated with the facility, among other costs, and long-term debt. Ameren and Ameren Missouri consolidate AMF, which Ameren Missouri wholly owns, and both manages and controls the entity’s operating activities. For additional information on the securitization of the Rush Island Energy Center costs, see Note 2 – Rate and Regulatory Matters. For additional information on the securitized tariff bond issuance, see Note 5 – Long-term Debt and Equity Financings. The following table presents the carrying values of AMF’s assets and liabilities included on Ameren’s and Ameren Missouri’s consolidated balance sheets as of December 31, 2024: 2024 Other current assets (a) $ 2 Noncurrent regulatory assets (a) 465 Current maturities of long term debt (b) 17 Interest accrued (b) 1 Long-term debt, net (b) 448 (a) Assets may be used only to meet AMF’s obligations and commitments. (b) The securitized tariff bondholders have no recourse to Ameren Missouri. Variable Interest Entities that are not Consolidated As of December 31, 2024 and 2023, Ameren had unconsolidated variable interests in various equity method investments, primarily to advance clean and resilient energy technologies, totaling $74 million and $73 million, respectively, included in “Other assets” on Ameren’s consolidated balance sheet. Any earnings or losses related to these investments are included in “Other Income, Net” on Ameren’s consolidated statement of income and comprehensive income. Ameren is not the primary beneficiary of these investments because it does not have the power to direct matters that most significantly affect the activities of these variable interest entities. As of December 31, 2024, the maximum exposure to loss related to these variable interest entities is limited to the investment in these partnerships of $74 million plus associated outstanding funding commitments of $35 million. Environmental Costs Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are expensed or deferred as a regulatory asset when it is expected that the costs will be recovered from customers in future rates. See Note 14 – Commitments and Contingencies for additional information on liabilities for environmental costs. Asset Retirement Obligations and Removal Costs We record the estimated fair value of legal obligations associated with the retirement of tangible long-lived assets in the period in which the liabilities are incurred and capitalize a corresponding amount as part of the book value of the related long-lived asset. In subsequent periods, we adjust AROs for accretion and changes in the estimated fair values of the obligations, with a corresponding increase or decrease in the asset book value for the fair value changes. Asset book values, reflected within “Property, Plant, and Equipment, Net” on the balance sheet, are depreciated over the remaining useful life of the related asset. Depreciation is deferred as a regulatory balance. The depreciation of the asset book values at Ameren Missouri was $2 million , $9 million, and $7 million for the years ended December 31, 2024, 2023, and 2022, respectively, which was deferred as a reduction to the net regulatory liability. The net regulatory liability also reflects a deferral for the nuclear decommissioning trust fund balance for the Callaway Energy Center. The depreciation deferred to the regulatory asset at Ameren Illinois was immaterial in each respective period. Uncertainties as to the probability, timing, or amount of cash expenditures associated with AROs affect our estimates of fair value. Ameren and Ameren Missouri have recorded AROs for retirement costs associated with decommissioning of Ameren Missouri’s Callaway and wind renewable energy centers, certain Ameren Missouri solar energy centers, CCR facilities, and river structures at certain energy centers used for unloading coal and circulating water systems. Additionally, Ameren, Ameren Missouri, and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal and the disposal of certain transformers. See Note 15 – Supplemental Information for a reconciliation of the beginning and ending carrying amounts of AROs. Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment retired from service, net of salvage, represent a cost of removal regulatory liability. See the cost of removal regulatory liability balance in Note 2 – Rate and Regulatory Matters. COLI Ameren (parent) and Ameren Illinois have COLI, which is recorded at the net cash surrender value. The net cash surrender value is the amount that can be realized under the insurance policies at the balance sheet date. As of December 31, 2024, the cash surrender value of COLI at Ameren and Ameren Illinois was $260 million (December 31, 2023 – $248 million) and $118 million (December 31, 2023 – $111 million), respectively, while total borrowings against the policies were $110 million (December 31, 2023 – $104 million) at both Ameren and Ameren Illinois. Ameren and Ameren Illinois have the right to offset the borrowings against the cash surrender value of the policies and, consequently, present the net asset in “Other assets” on their respective balance sheets. The net cash surrender value of Ameren’s COLI is affected by the investment performance of a separate account in which Ameren holds a beneficial interest. Operating Revenues We record revenues from contracts with customers for various electric and natural gas services, which primarily consist of retail distribution, electric transmission, and off-system arrangements. When more than one performance obligation exists in a contract, the consideration under the contract is allocated to the performance obligations based on the relative standalone selling price. Electric and natural gas retail distribution revenues are earned when the commodity is delivered to our customers. We accrue an estimate of electric and natural gas retail distribution revenues for service provided but unbilled at the end of each accounting period. Electric transmission revenues are earned as electric transmission services are provided. Off-system revenues are primarily comprised of MISO revenues and wholesale bilateral revenues. MISO revenues include the sale of electricity, capacity, and ancillary services. Wholesale bilateral revenues include the sale of electricity and capacity. MISO-related electricity and wholesale bilateral electricity revenues are earned as electricity is delivered. Capacity and ancillary service revenues are earned as services are provided. Retail distribution, electric transmission, and off-system revenues, including the underlying components described above, represent a series of goods or services that are substantially the same and have the same pattern of transfer over time to our customers. Revenues from contracts with customers are equal to the amounts billed and our estimate of electric and natural gas retail distribution services provided but unbilled at the end of each accounting period. Customers are billed at least monthly, and payments are due less than one month after goods and/or services are provided. See Note 16 – Segment Information for disaggregated revenue information. For certain regulatory recovery mechanisms that are alternative revenue programs rather than revenues from contracts with customers, we recognize revenues that have been authorized for rate recovery, are objectively determinable and probable of recovery, and are expected to be collected from customers within two years from the end of the year. Our alternative revenue programs include revenue requirement reconciliations, the MEEIA, the RBA, the VBA, and the WNAR. These revenues are subsequently recognized as revenues from contracts with customers when billed, with an offset to alternative revenue program revenues. As of December 31, 2024 and 2023, our remaining performance obligations were immaterial. The Ameren Companies elected not to disclose the aggregate amount of the transaction price allocated to the performance obligations that are unsatisfied as of the end of the reporting period for contracts with an initial expected term of one year or less. Accounting for MISO Transactions MISO-related purchase and sale transactions are recorded by Ameren, Ameren Missouri, and Ameren Illinois using settlement information provided by the MISO. Ameren Missouri records these purchase and sale transactions on a net hourly position. Ameren Missouri records net purchases in a single hour in “Operating Expenses – Fuel and purchased power” and net sales in a single hour in “Operating Revenues – Electric” in its statement of income. Ameren Illinois records net purchases in “Operating Expenses – Fuel and purchased power” in its statement of income to reflect all of its MISO transactions relating to the procurement of power for its customers. Stock-based Compensation Stock-based compensation cost is measured at the grant date based on the fair value of the award, net of an assumed forfeiture rate. Ameren recognizes as compensation expense the estimated fair value of stock-based compensation on a straight-line basis over the requisite vesting period. To the extent that actual forfeitures differ from estimated forfeitures, such differences are accounted for as an adjustment to compensation expense and recorded in the period that estimates are revised. Compensation cost is ultimately recognized only for awards for which the requisite service was provided. See Note 11 – Stock-based Compensation for additional information. Unamortized Debt Discounts, Premiums, and Issuance Costs Long-term debt discounts, premiums, and issuance costs are amortized over the lives of the related issuances. Credit agreement fees are amortized over the term of the agreement. Income Taxes Ameren uses an asset and liability approach for its financial accounting and reporting of income taxes. Deferred tax assets and liabilities are recognized for transactions that are treated differently for financial reporting and income tax return purposes. These deferred tax assets and liabilities are based on statutory tax rates. We expect that regulators will reduce future revenues for deferred tax liabilities that were initially recorded at rates in excess of the current statutory rate. Therefore, reductions in certain excess deferred tax liabilities that were recorded because of decreases in the statutory rate have been credited to a regulatory liability. A regulatory asset has been established to recognize the probable recovery through future customer rates of tax benefits related to the equity component of allowance for funds used during construction, as well as the effects of tax rate increases. To the extent deferred tax balances are included in rate base, the revaluation of deferred taxes caused by a change in the statutory rate is recorded as a regulatory asset or liability on the balance sheet and will be collected from, or refunded to, customers. For deferred tax balances not included in rate base, the revaluation of deferred taxes caused by a change in the statutory rate is recorded as an adjustment to income tax expense on the income statement. Tax credits other than investment tax credits are recognized as a reduction to income tax expense when earned. The benefits for investment tax credits not transferred under the IRA are amortized over the book depreciable lives of the related property. For production and other tax credits otherwise eligible to be recognized when earned and for investment tax credits transferred under the IRA, Ameren considers the impact of rate regulation to determine if these credits and related adjustments should be deferred as regulatory liabilities. See Note 2 – Rate and Regulatory Matters for additional information on Ameren Missouri’s production and investment tax credit tracker and the RESRAM. Ameren Missouri, Ameren Illinois, and all the other Ameren subsidiary companies are parties to a tax allocation agreement with Ameren (parent) that provides for the allocation of consolidated tax liabilities. The tax allocation agreement specifies that each subsidiary be allocated an amount of tax using a stand-alone calculation ratio to the total amount of tax owed by the consolidated group. Any net benefit attributable to Ameren (parent) is reallocated to the other subsidiaries. This reallocation is treated as a capital contribution to the subsidiary receiving the benefit. See Note 13 – Related-party Transactions for information regarding capital contributions under the tax allocation agreement.

Rate And Regulatory Matters

Rate And Regulatory Matters	12 Months Ended
	Dec. 31, 2024
Public Utilities, General Disclosures [Abstract]
Rate and Regulatory Matters	RATE AND REGULATORY MATTERS Below is a summary of our regulatory frameworks and significant regulatory proceedings and related lawsuits. We are unable to predict the ultimate outcome of these matters, the timing of final decisions of the various agencies and courts, or the effect on our results of operations, financial position, or liquidity. Regulatory Frameworks The following table presents the regulatory frameworks and significant regulatory recovery mechanisms for each of Ameren’s rate-regulated businesses, which are discussed in more detail below: Ameren Missouri Ameren Illinois’ electric distribution business Ameren Illinois’ natural gas delivery business Ameren Illinois’ and ATXI’s electric transmission businesses Regulatory framework • Historical test year ratemaking • Natural gas revenues for residential customers adjusted for sales volume deviations resulting from weather through the WNAR • MYRP • Initial rates based on future test years • Revenues decoupled from sales volumes and wholesale and miscellaneous revenues through the RBA • Future test year ratemaking • Revenues for residential and small nonresidential customers decoupled from sales volumes through the VBA • Formula ratemaking • Initial rates based on future test year • Revenues decoupled from sales volumes Regulatory mechanisms • PISA Riders: • RESRAM • FAC • Rush Island Securitization • MEEIA • PGA • WNAR Trackers: • Pension and postretirement benefit costs • Certain excess deferred income taxes • Renewable energy standard costs • Property taxes • Production and investment tax credits or proceeds from the sale of certain tax credits allowed under the IRA • Electric distribution service and energy-efficiency revenue requirement reconciliation adjustments (a) Riders: • RBA • Power procurement • Transmission services • Renewable energy credit compliance • Zero emission credits • Customer generation rebate program costs • Certain environmental costs • Bad debt write-offs • Costs of certain asbestos-related claims Riders: • PGA • VBA • Energy-efficiency program costs • Certain environmental costs • Bad debt write-offs • Invested capital taxes • Revenue requirement reconciliation adjustment (a) Reconciliation adjustments under an MYRP are subject to a reconciliation cap which limits annual adjustment to 105%. See below for additional information regarding the reconciliation cap. Missouri The MoPSC regulates rates and other matters for Ameren Missouri’s electric service and natural gas distribution businesses. The rates Ameren Missouri charges customers for these services are established in a traditional regulatory rate review, which takes up to 11 months to complete, based on a historical test year and the revenue requirement established in the review. Ameren Missouri has recovery mechanisms, including the RESRAM, FAC, MEEIA, PGA, and WNAR, as well as a rider related to the securitization of the Rush Island Energy Center, that allow customer rates to be adjusted without a traditional regulatory rate review. These riders, along with the PISA, each described in more detail below, partially mitigate the effects of regulatory lag. Ameren Missouri also employs other recovery mechanisms, including a renewable energy standard cost tracker, as well as electric and natural gas trackers for certain excess deferred income taxes, property taxes, and pension and postretirement benefit costs. Each of these trackers allows Ameren Missouri to defer the difference between actual costs incurred and costs included in customer rates as a regulatory asset or regulatory liability, with the difference expected to be reflected in base rates in a subsequent MoPSC rate order. Ameren Missouri also employs a tracker for the utilization of production and investment tax credits or proceeds from the sale of such tax credits allowed under the IRA. Production and investment tax credits produced by renewable energy centers that support compliance with the state of Missouri’s renewable energy standard, such as the High Prairie, Atchison, and Huck Finn energy centers, are not eligible for tracking under this mechanism as they are included in the RESRAM. Ameren Missouri’s cost recovery under any of its recovery mechanisms is subject to MoPSC prudence reviews. The PISA permits Ameren Missouri to defer and recover 85% of the depreciation expense for investments in qualifying property, plant, and equipment placed in service and not included in base rates. Investments not eligible for recovery under the PISA include amounts related to new nuclear and natural gas generating units and service to new customer premises. Additionally, the PISA permits Ameren Missouri to earn a return at the applicable WACC on 85% of rate base that incorporates those qualifying investments, as well as changes in total accumulated depreciation excluding retirements and plant-related deferred income taxes since the previous regulatory rate review. The regulatory asset for accumulated PISA deferrals also earns a return at the applicable WACC until added to rate base prospectively. Ameren Missouri recognizes an offset to “Interest Charges” on its consolidated statement of income for its carrying cost of debt relating to each return allowed under the PISA, with the difference between the applicable WACC and its carrying cost of debt recognized in revenues when recovery of PISA deferrals is reflected in customer rates. Approved PISA deferrals are recovered over a period of 20 years following a regulatory rate review. Additionally, under the RESRAM, Ameren Missouri is permitted to recover the 15% of depreciation expense not recovered under the PISA, and earn a return at the applicable WACC for investments in renewable generation plant placed in service to comply with Missouri’s renewable energy standard. The RESRAM deferrals are a regulatory asset until they are included in customer rates and collected in a subsequent period. Those investments not eligible for recovery under the PISA and the remaining 15% of certain property, plant, and equipment placed in service, unless eligible for recovery under the RESRAM, remain subject to regulatory lag. As a result of the PISA election, additional provisions of the law apply to Ameren Missouri, including limitations on electric customer rate increases. Pursuant to a Missouri law, Ameren Missouri’s PISA election was extended through December 2028 and an additional extension through December 2033 is allowed if requested by Ameren Missouri and approved by the MoPSC, among other things. This law also established a 2.5% annual limit on increases to the electric service revenue requirement used to set customer rates, compared to the revenue requirement established in the immediately preceding rate order, due to the inclusion of incremental PISA deferrals in the revenue requirement. The limitation is effective for revenue requirements approved by the MoPSC after January 1, 2024. The RESRAM permits Ameren Missouri to recover or refund, through customer rates, the difference between the cost of compliance, net of production and investment tax credits, with Missouri’s renewable energy standard and the amount set in base rates. All sales from the High Prairie, Atchison, and Huck Finn energy centers are included in the RESRAM. Customer rates are adjusted for the RESRAM on an annual basis without a traditional regulatory rate review, subject to MoPSC prudence reviews. The difference between actual compliance costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either collected from, or refunded to, customers in a subsequent period. RESRAM regulatory assets earn carrying costs at short-term interest rates. The RESRAM permits Ameren Missouri to recover investments in wind generation and other renewables related to compliance with Missouri’s renewable energy standard, and earn a return at the applicable WACC on those investments not already provided for in customer rates or any other recovery mechanism, such as the renewable energy standard cost tracker. The renewable energy standard cost tracker allows Ameren Missouri to defer differences between actual costs primarily associated with the Maryland Heights Energy Center and renewable energy credits obtained through a 102-MW power purchase agreement with a wind farm operator, which expired in August 2024, and those costs included in customer rates. The FAC permits Ameren Missouri to recover or refund, through customer rates, 95% of the variance in net energy costs from the amount set in base rates without a traditional regulatory rate review, subject to MoPSC prudence reviews, with the remaining 5% of changes retained by Ameren Missouri. As such, Ameren Missouri’s results of operations are affected by the 5% not recovered or refunded under the FAC. The 95% variance in net energy costs in a given period is deferred as a regulatory asset or liability, and is either collected from, or refunded to, customers in a subsequent period. FAC regulatory assets earn carrying costs at short-term interest rates. Ameren Missouri’s base rates for electric service are required to be reset at least every four years to allow for continued use of the FAC. In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance $476 million of costs related to the accelerated retirement of the Rush Island Energy Center, which included the remaining unrecovered net plant balance associated with the facility, among other costs. Ameren Missouri will collect the amounts necessary to repay the bonds through a rider over approximately 15 years from the date of the December 2024 bond issuance. The MEEIA permits Ameren Missouri to recover customer energy-efficiency and demand response program costs, the related lost electric revenues, and any performance incentive through the MEEIA without a traditional regulatory rate review, subject to MoPSC prudence reviews. MEEIA assets earn carrying costs at short-term interest rates. Ameren Missouri is a member of the MISO, and its transmission rate is calculated in accordance with the MISO Open Access Transmission, Energy, and Operating Reserve Markets Tariff. The FERC regulates the rates charged and the terms and conditions for wholesale electric transmission service. The transmission rate update each June is based on Ameren Missouri’s actual historical cost from the prior calendar year. This rate is not directly charged to Missouri retail customers because, in Missouri, the revenue requirement used to set bundled retail base rates includes an amount for transmission-related costs and revenues. The PGA allows Ameren Missouri to recover costs of natural gas purchased on behalf of its customers without a traditional regulatory rate review, subject to MoPSC prudence reviews. These pass-through purchased gas costs do not affect Ameren Missouri’s net income, as any change in costs is offset by a corresponding change in revenues. The difference between actual natural gas costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either collected from, or refunded to, customers in a subsequent period. PGA regulatory assets earn carrying costs at short-term interest rates. The WNAR allows Ameren Missouri to adjust natural gas delivery service rates charged to residential customers without a traditional regulatory rate review when deviations from normal weather conditions cause natural gas revenues to vary from the related revenue requirement approved by the MoPSC in the previous regulatory rate review. The impact of deviations from normal weather on natural gas delivery service revenues billed to residential customers in a given period are deferred as a regulatory asset or liability. WNAR regulatory assets earn carrying costs at short-term interest rates. The deferred amount is either collected from, or refunded to, residential customers in a subsequent period. Illinois The ICC regulates rates and other matters for Ameren Illinois’ electric distribution service and natural gas distribution businesses. Pursuant to the CEJA, Ameren Illinois may elect to establish electric distribution service rates through either an MYRP or a traditional regulatory rate review. See below for additional information regarding the MYRP approved by the ICC, which established rates effective for 2024 through 2027. The rates Ameren Illinois charges customers for natural gas distribution service are established in a traditional regulatory rate review, which takes up to 11 months to complete, based on a future test year and the revenue requirement established in the review. Ameren Illinois’ electric distribution service has cost recovery mechanisms in place that allow customer rates to be adjusted without an MYRP or a traditional regulatory rate review. This includes the RBA, which is described in more detail below, and riders for power procurement and transmission services incurred on behalf of its customers, renewable energy credit compliance, zero emission credits, customer generation rebate program costs, and certain environmental costs, as well as bad debt write-offs and the costs of certain asbestos-related claims not recovered in base rates. These pass-through costs do not affect Ameren Illinois’ net income, as any change in costs is offset by a corresponding change in revenues. Ameren Illinois’ cost recovery under any of its recovery mechanisms is subject to ICC prudence reviews. Under the MYRP, Ameren Illinois is allowed to reconcile its actual electric distribution revenue requirement, as adjusted for certain cost variations, to the ICC-approved revenue requirement on an annual basis, subject to a reconciliation cap. The reconciliation cap limits the annual adjustment to 105% of the annual revenue requirement approved by the ICC. Certain variations from forecasted costs are excluded from the reconciliation cap, including those associated with major storms; new business and facility relocations; changes in the timing of certain expenditures or investments into or out of the applicable calendar year; and changes in interest rates, income taxes, taxes other than income taxes, pension and other post-retirement benefits costs, and amortization of certain assets. The reconciliation cap also excludes costs recovered outside of base rates through riders, such as those described above and the electric energy-efficiency rider discussed below, among others. The actual revenue requirement for a particular year incorporates Ameren Illinois’ year-end rate base and actual capital structure for such year, provided that the resulting revenue requirement does not exceed the 105% reconciliation cap and the common equity ratio in such capital structure may not exceed that approved by the ICC in the MYRP. Ameren Illinois did not exceed the reconciliation cap for the 2024 revenue requirement, which is subject to final reconciliation and ICC review. Subject to the reconciliation cap, if a given year’s actual revenue requirement collected from customers varies from the approved revenue requirement, an adjustment is made to electric operating revenues with an offset to a regulatory asset or liability to reflect that year’s actual revenue requirement. The regulatory balance is then collected from, or refunded to, customers within two years from the end of the applicable annual period. Regulatory assets applicable to the MYRP earn a return at the applicable WACC. However, Ameren Illinois recognizes the carrying cost of debt on these regulatory assets in revenue, instead of the applicable WACC, with the difference recognized in revenues when recovery of such regulatory assets is reflected in customer rates. Ameren Illinois’ existing riders continue to be effective under the MYRP. The RBA allows Ameren Illinois to adjust electric distribution service rates charged to customers under an MYRP or a traditional regulatory rate review when electric distribution revenues vary from the related revenue requirement approved by the ICC in the previous MYRP or traditional regulatory rate review. If a given year’s actual revenue billed to customers varies from the approved revenue requirement as a result of sales volumes and/or wholesale and miscellaneous revenue, an adjustment is made to electric operating revenues with an offset to a regulatory asset or liability to reflect that year’s actual revenue. RBA regulatory assets do not earn carrying costs or a return. The regulatory balance is either collected from, or refunded to, customers within two years from the end of the applicable annual period. Ameren Illinois used the IEIMA formula framework to establish annual customer electric distribution service rates effective through 2023. Under the framework, Ameren Illinois was allowed to reconcile its revenue requirement for customer rates established through 2023. Ameren Illinois’ 2022 and 2023 revenues reflected each year’s actual recoverable costs, year-end rate base, and a return at the applicable WACC, with the ROE component based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points. The 2022 revenue requirement reconciliation adjustment was collected from customers in 2024, and the 2023 adjustment will be collected in 2025. Ameren Illinois’ electric customer energy-efficiency rider provides Ameren Illinois’ electric distribution service business with recovery of, and return on, energy-efficiency investments. Under formula ratemaking for its electric energy-efficiency investments, the revenue requirements are based on recoverable costs, year-end rate base, and a year-end ratemaking capital structure, and earn a return at the applicable WACC. The ROE component of the applicable WACC is based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points and any performance-related basis-point adjustments, described in more detail below. Therefore, Ameren Illinois’ annual ROE for its electric energy-efficiency investments is directly correlated to the yields on such bonds. Regulatory assets applicable to formula ratemaking for electric energy-efficiency investments earn a return at the applicable WACC. However, Ameren Illinois recognizes the carrying cost of debt on these regulatory assets in revenue, instead of the applicable WACC, with the difference recognized in revenues when recovery of such regulatory assets is reflected in customer rates. Ameren Illinois’ electric distribution service business is also subject to performance metrics. Failure to achieve the metrics would result in a reduction in the company’s allowed ROE calculated under the MYRP. In 2022, the ICC issued an order approving total ROE incentives and penalties of 24 basis points under the MYRP, allocated among seven performance metrics. These performance metrics include improvements in service reliability in both the frequency and duration of outages, a reduction in peak loads, an increased percentage of spend with diverse suppliers, a reduction in disconnections for certain customers, and improved timeliness in response to customer requests for interconnection of distributed energy resources. These performance metrics apply annually from 2024 through 2027 under the MYRP, and the impact of any incentives and penalties will be excluded from the reconciliation cap described above. In addition, the allowed ROE on energy-efficiency investments can be increased or decreased up to 200 basis points, depending on the achievement of annual energy savings goals. Any adjustments to the allowed ROE for energy-efficiency investments will depend on annual performance for a historical period relative to energy savings goals. In 2024, 2023, and 2022, there were no performance-related basis-point adjustments that materially affected financial results. Ameren Illinois’ natural gas distribution business has recovery mechanisms, including the PGA and VBA, that allow customer rates to be adjusted without a traditional regulatory rate review. These riders, described in more detail below, mitigate the effects of regulatory lag. Ameren Illinois employs other riders for natural gas customer energy-efficiency program costs and certain environmental costs, as well as bad debt write-offs and invested capital taxes not recovered in base rates. Pass-through costs under the riders do not affect Ameren Illinois’ net income, as any change in costs is offset by a corresponding change in revenues. Ameren Illinois’ cost recovery under any of its recovery mechanisms is subject to ICC prudence reviews. The PGA allows Ameren Illinois to recover costs of natural gas purchased on behalf of its customers without a traditional regulatory rate review, subject to ICC prudence reviews. These pass-through purchased gas costs do not affect Ameren Illinois’ net income, as any change in costs is offset by a corresponding change in revenues. The difference between actual natural gas costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either collected from, or refunded to, customers in a subsequent period. PGA regulatory assets earn carrying costs at short-term interest rates. The VBA ensures recoverability of the natural gas distribution service revenue requirement that is dependent on sales volumes for residential and small nonresidential customers. For these rate classes, the VBA allows Ameren Illinois to adjust natural gas distribution service rates without a traditional regulatory rate review when changes occur in sales volumes from those volumes approved by the ICC in a previous regulatory rate review. The difference between allowed sales revenues and amounts billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either collected from, or refunded to, customers in a subsequent period. VBA regulatory assets for a given year that are not fully collected by the end of the following year begin earning carrying costs at short-term interest rates. Federal The FERC regulates rates and other matters for Ameren Illinois’ transmission business and ATXI, as well as for Ameren Missouri. See the discussion above related to Ameren Missouri. Both Ameren Illinois and ATXI are members of the MISO, and their transmission rates are calculated in accordance with the MISO Open Access Transmission, Energy, and Operating Reserve Markets Tariff. Ameren Illinois and ATXI have received FERC approval to use a company-specific, forward-looking formula ratemaking framework in setting their transmission rates. These forward-looking rates are updated annually and become effective each January with forecasted information. The formula rate framework provides for an annual reconciliation of the electric transmission service revenue requirement, which reflects the actual recoverable costs incurred and the 13-month average rate base for a given year, with the revenue requirement in customer rates, including an allowed ROE. If a given year’s revenue requirement varies from the amount collected from customers, an adjustment is made to electric operating revenues with an offset to a regulatory asset or liability to reflect that year’s actual revenue requirement, independent of actual sales volumes. The regulatory balance is collected from, or refunded to, customers within two years from the end of the year. FERC revenue requirement reconciliation adjustment regulatory assets earn carrying costs at each company’s short-term interest rates. In addition, the FERC has approved transmission rate incentives, including a 50-basis-point incentive adder to the allowed base ROE for Ameren Illinois and ATXI for participation in an RTO. Proceedings and Updates Missouri 2024 Electric Service Regulatory Rate Review In June 2024, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for electric service. In February 2025, Ameren Missouri filed an updated electric rate increase request seeking approval to increase its annual revenues for electric service by $446 million. The electric rate increase request is based on a 10.25% ROE, a capital structure composed of 52% common equity, a rate base of $13.9 billion, and a test year ended March 31, 2024, with certain pro-forma adjustments through the true-up date of December 31, 2024. Ameren Missouri also requested the continued use of all of its existing riders and trackers. The electric rate increase request reflects the following: • increased infrastructure investments made under Ameren Missouri’s Smart Energy Plan, including increased cost of capital and depreciation expense. Included in these investments are 500 megawatts of solar generation investment for the Boomtown, Cass County and Huck Finn projects along with investments in the Callaway nuclear energy center and other dispatchable generation to support a reliable, low-cost and cleaner mix of energy resources; • decreased costs resulting from the retirement of the Rush Island Energy Center; and • decreased costs related to the extension of the retirement date of the Sioux Energy Center from 2030 to 2032 to ensure reliability. In February 2025, the MoPSC staff recommended an increase to Ameren Missouri's annual electric service revenues of $384 million based on a 9.74% ROE, a capital structure composed of 52% common equity, and a rate base of $13.9 billion. The MoPSC staff’s recommendation includes adjustments for lower off-system sales revenue, production tax credits, and renewable energy credits as a result of the curtailed nighttime operations at the High Prairie Energy Center to limit its impact on protected species. See Note 14 – Commitments and Contingencies for additional information on the curtailed nighttime operations at the High Prairie Energy Center. The MoPSC staff supported the continued use of all of Ameren Missouri’s existing riders and trackers. In December 2024, the MoOPC challenged 25% to 45% of the costs and requested return associated with the High Prairie Energy Center investment included in Ameren Missouri’s requested revenue requirement as a result of the curtailed nighttime operations at the energy center discussed above. The MoPSC proceeding relating to the proposed electric service rate changes will take place over a period of up to 11 months, with a decision by the MoPSC expected by May 2025 and new rates effective by June 2025. Ameren Missouri cannot predict the level of any electric service rate change the MoPSC may approve, whether the requested regulatory recovery mechanisms will be continued, or whether any rate change that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and earn a reasonable return on its investments when the rate change goes into effect. 2024 Natural Gas Delivery Service Regulatory Rate Review In September 2024, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for natural gas delivery service by $40 million. The natural gas rate increase request is based on a 10.25% ROE, a capital structure composed of 52% common equity, a rate base of $531 million, and a test year ended March 31, 2024, with certain pro-forma adjustments expected through the true-up date of December 31, 2024. The request includes the continued use of all of Ameren Missouri’s existing riders and trackers. The natural gas rate increase request reflects investments in our existing natural gas infrastructure to ensure the safe delivery of natural gas. The MoPSC proceeding relating to the proposed natural gas delivery service rate changes will take place over a period of up to 11 months, with a decision by the MoPSC expected by August 2025 and new rates effective by September 2025. Ameren Missouri cannot predict the level of any natural gas delivery service rate change the MoPSC may approve, whether the requested regulatory recovery mechanisms will be continued, or whether any rate change that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and earn a reasonable return on its investments when the rate change goes into effect. Generation Facilities Ameren Missouri, and certain subsidiaries of Ameren Missouri, are parties to agreements to acquire and/or construct various generation facilities. The solar generation facilities are eligible for recovery under the PISA. The Castle Bluff Natural Gas Project is eligible for recovery under the post-construction cost deferral discussed below. The following table provides information with respect to each agreement: Agreement type Facility size Status of MoPSC CCN Status of FERC approval of acquisition In-service date (a) Huck Finn Solar Project (b)(c) Build-transfer 200-MW Approved February 2023 Received March 2023 December 2024 Boomtown Solar Project (c)(d) Build-transfer 150-MW Approved April 2023 Received October 2023 December 2024 Cass County Solar Project (c)(d) Development-transfer 150-MW Approved June 2024 Not applicable December 2024 Vandalia Solar Project (e)(f) Self-build 50-MW Approved March 2024 Not applicable Fourth quarter 2025 Bowling Green Solar Project (e)(f) Self-build 50-MW Approved March 2024 Not applicable First quarter 2026 Split Rail Solar Project (e)(f) Build-transfer 300-MW Approved March 2024 Received November 2024 Mid-2026 Castle Bluff Natural Gas Project (e) Self-build 800-MW Approved October 2024 (g) Not applicable Fourth quarter 2027 (a) In-service dates are dependent on the timing of construction completion, among other things. The assets of the Huck Finn, Boomtown, and Cass County solar projects were placed in service in December 2024. (b) The Huck Finn Solar Project is expected to support Ameren Missouri’s compliance with the state of Missouri’s renewable energy standard. Investments in the project are eligible for recovery under the RESRAM. (c) Ameren Missouri acquired the Cass County, Boomtown, and Huck Finn solar projects in June 2024, September 2024, and October 2024, respectively, and placed the assets of the projects, totaling $1 billion, in service in December 2024. (d) The Boomtown and Cass County solar projects are expected to support Ameren Missouri’s transition to renewable energy generation and serve customers under the Renewable Solutions Program, which allows certain commercial, industrial, and governmental customers who enroll in the program to receive up to 100% of their energy from renewable resources. (e) These projects collectively represent approximately $1.7 billion of expected capital expenditures. (f) These solar projects are expected to support Ameren Missouri’s transition to renewable energy generation. (g) For additional information see Castle Bluff Natural Gas Project CCN and Post-Construction Cost Deferral below. Castle Bluff Natural Gas Project CCN and Post-Construction Cost Deferral In October 2024, the MoPSC issued an order approving a nonunanimous stipulation and agreement filed by Ameren Missouri, the MoPSC staff, and other intervenors requesting a CCN for the Castle Bluff Natural Gas Project. The order also includes the use of a post-construction cost deferral related to the Castle Bluff Natural Gas Project, which allows Ameren Missouri to defer and recover depreciation expense, financing costs, and applicable income taxes incurred from the date the project is placed in service to the date when project costs are reflected in updated base rates as a result of a regulatory rate review. The period of deferral would be limited to the earlier of the time the project costs are reflected in base rates or six months. Securitization of Rush Island Energy Center Costs In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance $476 million of costs related to the accelerated retirement of the Rush Island Energy Center, which included the remaining unrecovered net plant balance associated with the facility, among other costs. Ameren Missouri will collect the amounts necessary to repay the bonds over approximately 15 years from the date of bond issuance. The securitized tariff bonds were issued in December 2024. The financing order also included a determination that the decision to retire the Rush Island Energy Center was reasonable and prudent. The MoPSC did not make a determination regarding the prudency of Ameren Missouri's prior actions that resulted in the adverse ruling in the NSR and Clean Air Act litigation discussed in Note 14 – Commitments and Contingencies, however, claims r

Property And Plant, Net

Property And Plant, Net	12 Months Ended
	Dec. 31, 2024
Property, Plant and Equipment [Abstract]
PROPERTY AND PLANT, NET	PROPERTY, PLANT, AND EQUIPMENT, NET The following table presents components of “Property, plant, and equipment, net” at December 31, 2024 and 2023: Ameren Ameren Other Ameren 2024 Property, plant, and equipment at original cost (a) : Electric generation: Coal (b) $ 3,556 $ — $ — $ 3,556 Natural gas 938 — — 938 Nuclear 5,931 — — 5,931 Renewable (c) 2,901 19 — 2,920 Electric distribution 9,469 8,160 — 17,629 Electric transmission 2,406 5,725 2,031 10,162 Natural gas 776 4,421 — 5,197 Other (d) 2,427 1,770 260 4,457 28,404 20,095 2,291 50,790 Less: Accumulated depreciation and amortization 10,875 5,184 436 16,495 17,529 14,911 1,855 34,295 Construction work in progress: Nuclear fuel in progress 268 — — 268 Other 991 619 131 1,741 Property, plant, and equipment, net $ 18,788 $ 15,530 $ 1,986 $ 36,304 2023 Property, plant, and equipment at original cost (a) : Electric generation: Coal (b) $ 3,452 $ — $ — $ 3,452 Natural gas 921 — — 921 Nuclear 5,879 — — 5,879 Renewable (c) 1,973 11 — 1,984 Electric distribution 8,638 7,820 — 16,458 Electric transmission 2,134 5,381 1,993 9,508 Natural gas 688 4,186 — 4,874 Other (d) 2,191 1,657 255 4,103 25,876 19,055 2,248 47,179 Less: Accumulated depreciation and amortization (f) 10,243 4,783 400 15,426 15,633 14,272 1,848 31,753 Construction work in progress: Nuclear fuel in progress 173 — — 173 Other 914 360 46 1,320 Plant to be abandoned, net (e) 530 — — 530 Property, plant, and equipment, net $ 17,250 $ 14,632 $ 1,894 $ 33,776 (a) The estimated lives for each asset group are as follows: 5 to 72 years for electric generation, excluding Ameren Missouri’s hydroelectric generating assets, which have useful lives of up to 150 years; 20 to 80 years for electric distribution; 50 to 75 years for electric transmission; 20 to 80 years for natural gas; and 2 to 55 years for other. (b) Includes $30 million and $29 million of oil-fired generation at December 31, 2024 and 2023, respectively. (c) Renewable includes hydroelectric, wind, solar, and methane gas generation facilities. (d) Other property, plant, and equipment includes assets used to support electric and natural gas services. (e) Represents the net book value of the Rush Island Energy Center as Ameren Missouri retired the energy center in October 2024, significantly in advance of its previously expected useful life. See Plant to be Abandoned, Net under Note 1 – Summary of Significant Accounting Policies, NSR and Clean Air Act Litigation under Note 14 – Commitments and Contingencies, and Securitization of Rush Island Energy Center Costs under Note 2 – Rate and Regulatory Matters for additional information on the accelerated retirement of the Rush Island Energy Center. Capitalized software costs are classified within “Property, Plant, and Equipment, Net” on the balance sheet and are amortized on a straight-line basis over the expected period of benefit, ranging from 2 to 15 years, with the amortization expense included in “Depreciation and amortization” on the statement of income. Deferred cloud implementation costs are classified within “Other Assets” on the balance sheet and are amortized on a straight-line basis over the term of the associated hosting arrangement, ranging from 5 to 15 years, with the amortization expense included in “Other operations and maintenance” on the statement of income. The following table presents the amortization expense, gross carrying value, and related accumulated amortization of capitalized software and deferred cloud implementation costs by year: Amortization Expense Gross Carrying Value Accumulated Amortization 2024 2023 2022 2024 2023 2024 2023 Capitalized software costs: Ameren $ 224 $ 212 $ 159 $ 1,996 $ 1,823 $ (1,348) $ (1,126) Ameren Missouri 118 114 85 881 795 (567) (453) Ameren Illinois 100 92 69 867 786 (552) (452) Deferred cloud implementation costs: Ameren $ 20 $ 17 $ 15 $ 157 $ 142 $ (71) $ (51) Ameren Missouri 9 8 7 71 63 (32) (23) Ameren Illinois 10 9 8 82 76 (36) (26) Annual amortization expense for capitalized software placed in service as of December 31, 2024, is estimated to be as follows: 2025 2026 2027 2028 2029 Ameren $ 190 $ 147 $ 110 $ 69 $ 38 Ameren Missouri 98 73 54 33 17 Ameren Illinois 85 70 53 34 20

Short-Term Debt And Liquidity

Short-Term Debt And Liquidity	12 Months Ended
	Dec. 31, 2024
Line of Credit Facility [Abstract]
SHORT-TERM DEBT AND LIQUIDITY	SHORT-TERM DEBT AND LIQUIDITY The liquidity needs of the Ameren Companies are supported through the use of available cash, drawings under committed credit agreements, commercial paper issuances, and/or, in the case of Ameren Missouri and Ameren Illinois, short-term affiliate borrowings. Short-Term Borrowings In December 2024, the Credit Agreements, which were scheduled to mature in December 2027, were extended and now mature in December 2028. The Credit Agreements provide $2.6 billion of credit cumulatively through maturity in December 2028. The total facility size of the Missouri Credit Agreement and Illinois Credit Agreement is $1.4 billion and $1.2 billion, respectively. The maturity date of each Credit Agreement may be extended for an additional one-year period upon the mutual consent of the respective borrowers and the lenders. Credit available under the agreements is provided by 20 international, national, and regional lenders, with no single lender providing more than $156 million of credit in aggregate. The obligations of each borrower under the respective Credit Agreements to which it is a party are several and not joint. Except under limited circumstances relating to expenses and indemnities, the obligations of Ameren Missouri and Ameren Illinois under the respective Credit Agreements are not guaranteed by Ameren (parent) or any other subsidiary of Ameren. The following table presents the maximum aggregate amount available to each borrower under each facility: Missouri Illinois Ameren (parent) $ 1,000 $ 700 Ameren Missouri 1,000 (a) Ameren Illinois (a) 1,000 (a) Not applicable. The borrowers have the option to seek additional commitments from existing or new lenders to increase the total facility size of the Credit Agreements to a maximum of $1.7 billion for the Missouri Credit Agreement and $1.5 billion for the Illinois Credit Agreement. Ameren (parent) borrowings are due and payable no later than the maturity date of the Credit Agreements. Ameren Missouri and Ameren Illinois borrowings under the applicable Credit Agreement are due and payable no later than the earlier of the maturity date or 364 days after the date of the borrowing. The obligations of the borrowers under the Credit Agreements are unsecured. Loans are available on a revolving basis under each of the Credit Agreements. Funds borrowed may be repaid and, subject to satisfaction of the conditions to borrowing, reborrowed from time to time. At the election of each borrower, the interest rates on such loans will be the alternate base rate plus the margin applicable to the particular borrower and/or the eurodollar rate plus the margin applicable to the particular borrower. The applicable margins will be determined by the borrower’s long-term unsecured credit ratings or, if no such ratings are in effect, the borrower’s corporate/issuer ratings then in effect. The borrowers have received commitments from the lenders to issue letters of credit up to $100 million under each of the Credit Agreements. In addition, the issuance of letters of credit is subject to the $2.6 billion overall combined facility borrowing limitations of the Credit Agreements. The borrowers will use the proceeds from any borrowings under the Credit Agreements for general corporate purposes, including working capital, loan funding under the Ameren money pool arrangements, and other short-term affiliate loan arrangements. The Missouri Credit Agreement and the Illinois Credit Agreement are available to support issuances under Ameren (parent)’s, Ameren Missouri’s and Ameren Illinois’ commercial paper programs, respectively, subject to borrowing sublimits, as well as to support issuance of letters of credit for the borrowers. As of December 31, 2024, based on credit capacity available under the Credit Agreements, along with cash and cash equivalents, the net liquidity available to Ameren (parent), Ameren Missouri, and Ameren Illinois, collectively, was $1.4 billion. The following table summarizes the activity and relevant interest rates for Ameren (parent)’s, Ameren Missouri’s, and Ameren Illinois’ commercial paper issuances under the Credit Agreements in the aggregate for the years ended December 31, 2024 and 2023: Ameren (parent) Ameren Missouri Ameren Illinois Ameren Consolidated 2024 Average daily amount outstanding $ 377 $ 192 $ 193 $ 762 Commercial paper issuances outstanding at period-end 1,055 — 88 1,143 Weighted-average interest rate 5.10 % 5.34 % 5.57 % 5.28 % Peak amount outstanding during period (a) $ 1,091 $ 595 $ 694 $ 1,569 Peak interest rate 5.60 % 5.68 % 5.68 % 5.68 % 2023 Average daily amount outstanding $ 726 $ 274 $ 166 $ 1,166 Commercial paper issuances outstanding at period-end — 170 366 536 Weighted-average interest rate 5.38 % 5.22 % 5.23 % 5.32 % Peak amount outstanding during period (a) $ 1,298 $ 592 $ 450 $ 1,526 Peak interest rate 5.65 % 5.68 % 5.68 % 5.68 % (a) The timing of peak outstanding commercial paper issuances and borrowings under the Credit Agreements varies by company. Therefore, the sum of individual company peak amounts may not equal the Ameren consolidated peak amount for the period. Indebtedness Provisions and Other Covenants The information below is a summary of the Ameren Companies’ compliance with indebtedness provisions and other covenants. The Credit Agreements contain conditions for borrowings and issuances of letters of credit. These conditions include the absence of default or unmatured default, material accuracy of representations and warranties (excluding any representation after the closing date as to the absence of material adverse change and material litigation, and the absence of any notice of violation, liability, or requirement under any environmental laws that could have a material adverse effect), and obtaining required regulatory authorizations. In addition, it is a condition for any Ameren Illinois borrowing that, at the time of and after giving effect to such borrowing, Ameren Illinois not be in violation of any limitation on its ability to incur unsecured indebtedness contained in its articles of incorporation. The Credit Agreements also contain nonfinancial covenants, including restrictions on the ability to incur certain liens, to transact with affiliates, to dispose of assets, to make investments in or transfer assets to its affiliates, and to merge with other entities. The Credit Agreements require each of Ameren, Ameren Missouri, and Ameren Illinois to maintain consolidated indebtedness of not more than 65% of its consolidated total capitalization pursuant to a defined calculation set forth in the agreements. As of December 31, 2024, the ratios of consolidated indebtedness to total consolidated capitalization, calculated in accordance with the provisions of the Credit Agreements, were 60%, 48%, and 45%, for Ameren, Ameren Missouri, and Ameren Illinois, respectively. The Credit Agreements contain default provisions that apply separately to each borrower. However, a default of Ameren Missouri or Ameren Illinois under the applicable credit agreement is also deemed to constitute a default of Ameren (parent) under such agreement. Defaults include a cross-default resulting from a default of such borrower under any other agreement covering outstanding indebtedness of such borrower and certain subsidiaries (other than project finance subsidiaries, nonmaterial subsidiaries, and certain special purposes entities contemplated in the Credit Agreements) in excess of $100 million in the aggregate (including under the other credit agreement). However, under the default provisions of the Credit Agreements, any default of Ameren (parent) under either credit agreement that results solely from a default of Ameren Missouri or Ameren Illinois does not result in a cross-default of Ameren (parent) under the other credit agreement. Further, the Credit Agreements default provisions provide that an Ameren (parent) default under either of the Credit Agreements does not constitute a default by Ameren Missouri or Ameren Illinois. None of the Credit Agreements or financing agreements contain credit rating triggers that would cause a default or acceleration of repayment of outstanding balances. The Ameren Companies were in compliance with the provisions and covenants of the Credit Agreements at December 31, 2024 . Money Pools Ameren (parent) has money pool agreements with and among its subsidiaries to coordinate and provide for certain short-term cash and working capital requirements. Ameren Missouri, Ameren Illinois, and ATXI may participate in the utility money pool as both lenders and borrowers. Ameren (parent) and Ameren Services may participate in the utility money pool only as lenders. Surplus internal funds are contributed to the money pool from participants. The primary sources of external funds for the utility money pool are the Credit Agreements and the commercial paper programs. The total amount available to the pool participants from the utility money pool at any given time is reduced by the amount of borrowings made by participants, but it is increased to the extent that the pool participants advance surplus funds to the utility money pool or remit funds from other external sources. The availability of funds is also determined by funding requirement limits established by regulatory authorizations. Participants receiving a loan under the utility money pool agreement must repay the principal amount of such loan, together with accrued interest. The rate of interest depends on the composition of internal and external funds in the utility money pool. The average interest rate for borrowing under the utility money pool for the year ended December 31, 2024, was 5.19% (2023 – 5.29%). See Note 13 – Related-party Transactions for the amount of interest income and expense from the utility money pool agreement recorded by Ameren Missouri and Ameren Illinois for the years ended December 31, 2024, 2023, and 2022.

Long-Term Debt And Equity Finan

Long-Term Debt And Equity Financings	12 Months Ended
	Dec. 31, 2024
Long-Term Debt And Equity Financings [Abstract]
LONG-TERM DEBT AND EQUITY FINANCINGS	LONG-TERM DEBT AND EQUITY FINANCINGS The following table presents long-term debt outstanding, including maturities due within one year, as of December 31, 2024 and 2023: 2024 2023 Ameren (Parent): 2.50% Senior unsecured notes due 2024 $ — $ 450 3.65% Senior unsecured notes due 2026 350 350 5.70% Senior unsecured notes due 2026 600 600 1.95% Senior unsecured notes due 2027 500 500 1.75% Senior unsecured notes due 2028 450 450 5.00% Senior unsecured notes due 2029 700 700 3.50% Senior unsecured notes due 2031 800 800 Total long-term debt, gross 3,400 3,850 Less: Unamortized discount and premium (3) (4) Less: Unamortized debt issuance costs (14) (17) Less: Maturities due within one year — (450) Long-term debt, net $ 3,383 $ 3,379 Ameren Missouri: Bonds and notes: 3.50% Senior secured notes due 2024 (a) $ — $ 350 2.95% Senior secured notes due 2027 (a) 400 400 3.50% First mortgage bonds due 2029 (b) 450 450 2.95% First mortgage bonds due 2030 (b) 465 465 2.15% First mortgage bonds due 2032 (b) 525 525 2.90% 1998 Series A bonds due 2033 (c) 60 60 2.90% 1998 Series B bonds due 2033 (c) 50 50 2.75% 1998 Series C bonds due 2033 (c) 50 50 5.20% First mortgage bonds due 2034 (b) 500 — 5.50% Senior secured notes due 2034 (a) 184 184 5.30% Senior secured notes due 2037 (a) 300 300 8.45% Senior secured notes due 2039 (a)(d) 350 350 4.85% Securitized utility tariff bonds due 2039 (e) 476 — 3.90% Senior secured notes due 2042 (a)(d) 485 485 3.65% Senior secured notes due 2045 (a) 400 400 4.00% First mortgage bonds due 2048 (b) 425 425 3.25% First mortgage bonds due 2049 (b) 330 330 2.625% First mortgage bonds due 2051 (b) 550 550 3.90% First mortgage bonds due 2052 (b) 525 525 5.45% First mortgage bonds due 2053 (b) 500 500 5.25% First mortgage bonds due 2054 (b) 350 — 5.125% First mortgage bonds due 2055 (b) 450 — Total long-term debt, gross 7,825 6,399 Less: Long-term debt – related parties, gross (58) — Less: Unamortized discount and premium (17) (13) Less: Unamortized debt issuance costs (62) (45) Less: Maturities due within one year (17) (350) Long-term debt, net $ 7,671 $ 5,991 2024 2023 Ameren Illinois: Bonds and notes: 3.25% Senior secured notes due 2025 (f) $ 300 $ 300 6.125% Senior secured notes due 2028 (f) 60 60 3.80% First mortgage bonds due 2028 (g) 430 430 1.55% First mortgage bonds due 2030 (g) 375 375 3.85% First mortgage bonds due 2032 (g) 500 500 4.95% First mortgage bonds due 2033 (g) 500 500 6.70% Senior secured notes due 2036 (f) 61 61 6.70% Senior secured notes due 2036 (f) 42 42 4.80% Senior secured notes due 2043 (f) 280 280 4.30% Senior secured notes due 2044 (f) 250 250 4.15% Senior secured notes due 2046 (f) 490 490 3.70% First mortgage bonds due 2047 (g) 500 500 4.50% First mortgage bonds due 2049 (g) 500 500 3.25% First mortgage bonds due 2050 (g) 300 300 2.90% First mortgage bonds due 2051 (g) 350 350 5.90% First mortgage bonds due 2052 (g) 350 350 5.55% First mortgage bonds due 2054 (g) 625 — Total long-term debt, gross 5,913 5,288 Less: Long-term debt – related parties, gross (3) — Less: Unamortized discount and premium (10) (9) Less: Unamortized debt issuance costs (51) (47) Less: Maturities due within one year (300) — Long-term debt, net $ 5,549 $ 5,232 ATXI: 2.45% Senior unsecured notes due 2036 (h) $ 75 $ 75 5.17% Senior unsecured notes due 2039 70 — 3.43% Senior unsecured notes due 2050 (i) 351 400 2.96% Senior unsecured notes due 2052 (j) 95 95 5.42% Senior unsecured notes due 2053 70 — Total long-term debt, gross 661 570 Less: Unamortized debt issuance costs (2) (2) Less: Maturities due within one year — (49) Long-term debt, net $ 659 $ 519 Ameren consolidated long-term debt, net $ 17,262 $ 15,121 (a) These notes are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Missouri mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the 2055 maturity date of the 5.125% first mortgage bonds and the restrictions preventing a release date to occur that are attached to certain senior secured notes described in footnote (d) below, Ameren Missouri does not expect the first mortgage lien protection associated with these notes to fall away. (b) These bonds are first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. They are secured by substantially all Ameren Missouri property and franchises. (c) These bonds are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture and have a fall-away lien provision similar to that of Ameren Missouri’s senior secured notes. (d) Ameren Missouri has agreed that so long as any of the 3.90% senior secured notes due 2042 are outstanding, Ameren Missouri will not permit a release date to occur, and so long as any of the 8.45% senior secured notes due 2039 are outstanding, Ameren Missouri will not optionally redeem, purchase, or otherwise retire in full the outstanding first mortgage bonds not subject to release provisions. (e) These bonds were issued by AMF. The bondholders of AMF have no recourse to Ameren Missouri’s assets. Ameren Missouri collects securitization surcharges to cover the principal and interest on the bonds as well as certain other qualified costs. The surcharges collected by Ameren Missouri on behalf of AMF are remitted to AMF and are not available to creditors of Ameren Missouri. Principal and interest payments on these bonds are payable semiannually on April 1 and October 1 of each year, beginning October 1, 2025, with final principal and interest payment due October 1, 2039. (f) These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Illinois mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the 2054 maturity date of the 5.55% first mortgage bonds, Ameren Illinois does not expect the first mortgage lien protection associated with these notes to fall away. (g) These bonds are first mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. They are secured by substantially all Ameren Illinois property and franchises. (h) The following table presents the principal maturities schedule for the 2.45% senior unsecured notes due 2036: Payment Date Principal Payment November 2029 $ 30 November 2036 45 Total $ 75 (i) The following table presents the principal maturities schedule for the 3.43% senior unsecured notes due 2050: Payment Date Principal Payment August 2027 $ 50 August 2030 49 August 2032 50 August 2038 49 August 2043 77 August 2050 76 Total $ 351 (j) The following table presents the principal maturities schedule for the 2.96% senior unsecured notes due 2052: Payment Date Principal Payment August 2040 $ 45 August 2052 50 Total $ 95 The following table presents the aggregate maturities of long-term debt, including current maturities, at December 31, 2024: Ameren (parent) (a) Ameren Missouri (a) Ameren Illinois (a) ATXI (a) Ameren Consolidated (a) 2025 $ — $ 17 $ 300 $ — $ 317 2026 950 24 — — 974 2027 500 424 — 50 974 2028 450 26 490 — 966 2029 700 477 — 30 1,207 Thereafter 800 6,857 5,123 581 13,361 Total $ 3,400 $ 7,825 $ 5,913 $ 661 $ 17,799 (a) Excludes unamortized discount, premium, and debt issuance costs of $17 million, $79 million, $61 million, and $2 million at Ameren (parent), Ameren Missouri, Ameren Illinois, and ATXI, respectively. In November and December 2024, Ameren (parent) purchased senior secured notes and first mortgage bonds issued by Ameren Missouri and first mortgage bonds issued by Ameren Illinois for $44 million in the aggregate. On a consolidated basis, Ameren (parent)’s repurchase of these senior secured notes and first mortgage bonds were accounted for as a debt extinguishment and resulted in a pre-tax gain of $16 million, which is reflected in “Other Income, Net” on Ameren’s consolidated statement of income. Interest expense related to the repurchased bonds was less than $1 million for the year ended December 31, 2024. The following table presents Ameren Missouri’s and Ameren Illinois’ “Long-term Debt, Net - Related Parties” as of December 31, 2024 and 2023: 2024 2023 Ameren Missouri: 3.65% Senior secured notes due 2045 $ 7 $ — 3.25% First mortgage bonds due 2049 33 — 2.625% First mortgage bonds due 2051 4 — 3.90% First mortgage bonds due 2052 14 — Total long-term debt - related parties, gross 58 — Less: Unamortized debt issuance costs (1) — Long-term debt - related parties, net $ 57 $ — Ameren Illinois: 3.70% First mortgage bonds due 2047 $ 1 $ — 3.25% First mortgage bonds due 2050 2 — Long-term debt - related parties, net $ 3 $ — All classes of Ameren Missouri’s and Ameren Illinois’ preferred stock are entitled to cumulative dividends, have voting rights, and are not subject to mandatory redemption. The preferred stock of Ameren’s subsidiaries is included in “Noncontrolling Interests” on Ameren’s consolidated balance sheet. The following table presents the outstanding preferred stock of Ameren Missouri and Ameren Illinois, which is redeemable at the option of the issuer, at the prices shown below as of December 31, 2024 and 2023: Shares Outstanding Redemption Price (per share) 2024 2023 Ameren Missouri: Without par value and stated value of $100 per share, 25 million shares authorized $3.50 Series 130,000 shares $ 110.00 $ 13 $ 13 $3.70 Series 40,000 shares 104.75 4 4 $4.00 Series 150,000 shares 105.625 15 15 $4.30 Series 40,000 shares 105.00 4 4 $4.50 Series 213,595 shares 110.00 (a) 21 21 $4.56 Series 200,000 shares 102.47 20 20 $4.75 Series 20,000 shares 102.176 2 2 $5.50 Series A 14,000 shares 110.00 1 1 Total $ 80 $ 80 Ameren Illinois: With par value of $100 per share, 2 million shares authorized 4.00% Series 144,275 shares $ 101.00 $ 14 $ 14 4.08% Series 45,224 shares 103.00 5 5 4.20% Series 23,655 shares 104.00 2 2 4.25% Series 50,000 shares 102.00 5 5 4.26% Series 16,621 shares 103.00 2 2 4.42% Series 16,190 shares 103.00 2 2 4.70% Series 18,429 shares 104.30 2 2 4.90% Series 73,825 shares 102.00 7 7 4.92% Series 49,289 shares 103.50 5 5 5.16% Series 50,000 shares 102.00 5 5 Total $ 49 $ 49 Total Ameren $ 129 $ 129 (a) In the event of voluntary liquidation, $105.50. Ameren has 100 million shares of $0.01 par value preferred stock authorized, with no such shares outstanding. Ameren Missouri has 7.5 million shares of $1 par value preference stock authorized, with no such shares outstanding. Ameren Illinois has 2.6 million shares of no par value preferred stock authorized, with no such shares outstanding. Ameren Under the DRPlus and its 401(k) plan, Ameren issued 0.5 million, 0.6 million, and 0.5 million shares of common stock in 2024, 2023, and 2022, respectively, received proceeds of $33 million, $39 million, and $41 million for the respective years, and had a receivable of $7 million and $7 million as of December 31, 2024 and 2023. In addition, Ameren issued 0.2 million, 0.5 million, and 0.4 million shares of common stock valued at $16 million, $40 million, and $31 million in 2024, 2023, 2022, respectively, for no cash consideration in connection with stock-based compensation. In May 2023, Ameren filed a Form S-3 registration statement with the SEC, authorizing the offering of 3 million additional shares of its common stock under the DRPlus, which expires in May 2026. Shares of common stock sold under the DRPlus are, at Ameren’s option, newly issued shares, treasury shares, or shares purchased in the open market or in privately negotiated contracts. In October 2023, Ameren, Ameren Missouri, and Ameren Illinois filed a Form S-3 shelf registration statement with the SEC, registering the issuance of an unspecified amount of certain types of securities. This registration statement expires in October 2026. In May 2022, Ameren filed a Form S-8 registration statement with the SEC, authorizing the offering of 7.5 million additional shares of its common stock under its 401(k) plan. Shares of common stock issuable under the 401(k) plan are, at Ameren’s option, newly issued shares, treasury shares, or shares purchased in the open market or in privately negotiated contracts. Ameren has entered into an equity distribution sales agreement pursuant to which Ameren may offer and sell from time to time up to $1.75 billion of its common stock through an ATM program, which includes the ability to enter into forward sale agreements. Under the ATM, Ameren issued 2.9 million, 3.2 million, and 3.4 million shares of common stock and received proceeds of $233 million, $299 million, and $292 million in 2024, 2023 and 2022, respectively. These proceeds were net of $2 million, $3 million and $3 million, respectively, in compensation paid to selling agents. As of December 31, 2024, Ameren had approximately $550 million of common stock available for sale under the ATM program, which takes into account the forward sale agreements in effect as of December 31, 2024 discussed below. The forward sale agreements outstanding as of December 31, 2024, can be settled at Ameren’s discretion on or prior to dates ranging from January 23, 2026 to March 6, 2026. On a settlement date or dates, if Ameren elects to physically settle a forward sale agreement, Ameren will issue shares of common stock to the counterparties at the then-applicable forward sale price. The initial forward sale price for the agreements ranged from $81.00 to $93.06, with an average initial forward sale price of $84.14. Each forward sale price is subject to adjustment based on a floating interest rate factor equal to the overnight bank funding rate less a spread of 75 basis points, and will be subject to decrease on certain dates specified in the forward sale agreements by specified amounts related to expected dividends on shares of the common stock during the term of the forward sale agreements. If the overnight bank funding rate is less than or more than the spread on any day, the interest rate factor will result in a reduction or an increase, respectively, of the forward sale price. The forward sale agreements will be physically settled unless Ameren elects to settle in cash or to net share settle. At December 31, 2024, Ameren could have settled the forward sale agreements with physical delivery of 2.5 million shares of common stock to the respective counterparties in exchange for cash of $213 million. Alternatively, the forward sale agreements could have also been settled at December 31, 2024, with delivery of approximately $13 million of cash or approximately 0.1 million shares of common stock to the counterparties. In connection to the forward sale agreements, the various counterparties, or their affiliates, borrowed from third parties and sold 2.5 million shares of common stock. The gross sales price of these shares totaled $215 million. Ameren does not receive any proceeds from such sales of borrowed shares. The forward sale agreements have been classified as equity transactions. In January 2025, Ameren entered into a forward sale agreement under the ATM program related to 0.6 million shares of common stock. The January 2025 forward sale agreement can be settled at Ameren’s discretion on or prior to February 9, 2026. The forward sale price was initially $87.43 for the January 2025 forward sale agreement. In September 2024, $450 million principal amount of Ameren (parent)’s 2.50% senior unsecured notes matured and was repaid with commercial paper borrowings. In November 2023, Ameren (parent) issued $600 million of 5.70% senior unsecured notes due December 2026, with interest payable semiannually on June 1 and December 1 of each year, beginning June 1, 2024. Net proceeds from this issuance were used to repay short-term debt. In December 2023, Ameren (parent) issued $700 million of 5.00% senior unsecured notes due January 2029, with interest payable semiannually on January 15 and July 15 of each year, beginning July 15, 2024. Net proceeds from this issuance were used for general corporate purposes, including the repayment of short-term debt. Ameren Missouri In January 2024, Ameren Missouri issued $350 million of 5.25% first mortgage bonds due January 2054, with interest payable semiannually on January 15 and July 15 of each year, beginning July 15, 2024. Net proceeds from this issuance were used for capital expenditures and to repay short-term debt. In April 2024, Ameren Missouri issued $500 million of 5.20% first mortgage bonds due April 2034, with interest payable semiannually on April 1 and October 1 of each year, beginning October 1, 2024. Net proceeds from this issuance were used for capital expenditures and to repay short-term debt. In April 2024, $350 million principal amount of Ameren Missouri’s 3.50% senior secured notes matured and was repaid with cash on hand. In October 2024, Ameren Missouri issued $450 million of 5.125% first mortgage bonds due March 2055, with interest payable semiannually on March 15 and September 15 of each year, beginning March 15, 2025. Net proceeds from this issuance were used for capital expenditures and to repay short-term debt. In December 2024, AMF issued $476 million of 4.85% securitized utility tariff bonds due October 2039, with principal and interest payable semiannually on April 1 and October 1 of each year, beginning October 1, 2025. Net proceeds from this issuance were used to finance energy transition costs related to the accelerated retirement of the Rush Island Energy Center, which included the remaining unrecovered net plant balance associated with the facility, among other costs, and to repay short-term debt. See Note 2 – Rate and Regulatory Matters for additional information on the securitization of Rush Island Energy Center costs. In January 2023, Ameren Missouri and Audrain County mutually agreed to terminate a financing obligation agreement related to the CT energy center in Audrain County, which was scheduled to expire in December 2023. No cash was exchanged in connection with the termination of the agreement as the $240 million principal amount of the financing obligation due from Ameren Missouri was equal to the amount of bond service payments due to Ameren Missouri. Ownership of the energy center was transferred to Ameren Missouri in January 2023, at which time the property, plant, and equipment became subject to the lien of the Ameren Missouri mortgage bond indenture. In March 2023, Ameren Missouri issued $500 million of 5.45% first mortgage bonds due March 2053, with interest payable semiannually on March 15 and September 15 of each year, beginning September 15, 2023. Net proceeds from this issuance were used for capital expenditures and to repay short-term debt. For information on Ameren Missouri’s capital contributions, refer to Capital Contributions in Note 13 – Related-party Transactions. Ameren Illinois In June 2024, Ameren Illinois issued $625 million of 5.55% first mortgage bonds due July 2054, with interest payable semiannually on January 1 and July 1 of each year, beginning January 1, 2025. Net proceeds from this issuance were used to repay short-term debt. In May 2023, Ameren Illinois issued $500 million of 4.95% first mortgage bonds due June 2033, with interest payable semiannually on June 1 and December 1 of each year, beginning December 1, 2023. Net proceeds from this issuance were used to repay $100 million principal amount of its 0.375% first mortgage bonds that matured in June 2023 and short-term debt. For information on Ameren Illinois’ capital contributions, refer to Capital Contributions in Note 13 – Related-party Transactions. ATXI In August 2024, ATXI issued $70 million of 5.17% senior unsecured notes due September 2039 and $70 million of 5.42% senior unsecured notes due September 2053, pursuant to an August 2024 note purchase agreement. Both series of senior unsecured notes have interest payable semiannually on March 1 and September 1 of each year, beginning March 1, 2025, and were issued through a private placement offering exempt from registration under the Securities Act of 1933, as amended. Net proceeds from these issuances were used to repay a $49 million principal payment of ATXI’s 3.43% senior unsecured notes at maturity and to repay short-term debt. Indenture Provisions and Other Covenants Ameren Missouri’s and Ameren Illinois’ indentures and articles of incorporation include covenants and provisions related to issuances of first mortgage bonds and preferred stock. Ameren Missouri and Ameren Illinois are required to meet certain ratios to issue additional first mortgage bonds and preferred stock. A failure to achieve these ratios would not result in a default under these covenants and provisions but would restrict the companies’ ability to issue bonds or preferred stock. The following table summarizes the required and actual interest coverage ratios for interest charges, dividend coverage ratios, and bonds and preferred stock issuable as of December 31, 2024, at an assumed interest rate of 7% and dividend rate of 8%. Required Interest Coverage Ratio (a) Actual Interest Bonds Issuable (b) Required Dividend Coverage Ratio (c) Actual Dividend Preferred Stock Ameren Missouri > 2.0 2.4 $2,283 > 2.5 164.4 $2,769 Ameren Illinois > 2.0 6.8 9,225 > 1.5 3.5 203 (d) (a) Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds. (b) Amount of bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include bonds issuable based on retired bond capacity of $1,509 million and $1,143 million at Ameren Missouri and Ameren Illinois, respectively. (c) Coverage required on the annual dividend on preferred stock outstanding and to be issued, as required in the respective company’s articles of incorporation. (d) Preferred stock issuable is restricted by the amount of preferred stock that is currently authorized by Ameren Illinois’ articles of incorporation. Ameren’s indenture does not require Ameren to comply with any quantitative financial covenants. The indenture does, however, include certain cross-default provisions. Specifically, either (1) the failure by Ameren to pay when due and upon expiration of any applicable grace period any portion of any Ameren indebtedness in excess of $25 million, or (2) the acceleration upon default of the maturity of any Ameren indebtedness in excess of $25 million under any indebtedness agreement, including borrowings under the Credit Agreements or the Ameren commercial paper program, constitutes a default under the indenture, unless such past due or accelerated debt is discharged or the acceleration is rescinded or annulled within a specified period. Ameren Missouri and Ameren Illinois and certain other nonregistrant Ameren subsidiaries are subject to Section 305(a) of the Federal Power Act, which makes it unlawful for any officer or director of a public utility, as defined in the Federal Power Act, to participate in the making or paying of any dividend from any funds “properly included in capital account.” The FERC has consistently interpreted the provision to allow dividends to be paid as long as (1) the source of the dividends is clearly disclosed, (2) the dividends are not excessive, and (3) there is no self-dealing on the part of corporate officials. At a minimum, Ameren believes that dividends can be paid by its subsidiaries that are public utilities from net income and retained earnings. In addition, under Illinois law, Ameren Illinois and ATXI may not pay any dividend on their respective stock unless, among other things, their respective earnings and earned surplus are sufficient to declare and pay a dividend after provisions are made for reasonable and proper reserves, or unless Ameren Illinois or ATXI has specific authorization from the ICC. Ameren Illinois’ articles of incorporation require dividend payments on its common stock to be based on ratios of common stock to total capitalization and other provisions related to certain operating expenses and accumulations of earned surplus. Ameren Illinois has made a commitment to the FERC to maintain a minimum 30% ratio of common stock equity to total capitalization. As of December 31, 2024, using the FERC-agreed upon calculation method, Ameren Illinois’ ratio of common stock equity to total capitalization was 54%. ATXI’s note purchase agreements includes financial covenants that require ATXI not to permit at any time (1) debt to exceed 70% of total capitalization or (2) secured debt to exceed 10% of total assets. At December 31, 2024, the Ameren Companies were in compliance with the provisions and covenants contained in their indentures and articles of incorporation, as applicable, and ATXI was in compliance with the provisions and covenants contained in its note purchase agreements. In order for the Ameren Companies to issue securities in the future, they will have to comply with all applicable requirements in effect at the time of any such issuances. Off-Balance-Sheet Arrangements At December 31, 2024, none of the Ameren Companies had any material off-balance-sheet financing arrangements, other than their investments in variable interest entities, letters of credit, and the multiple forward sale agreements under the ATM program relating to common stock. See Note 1 – Summary of Significant Accounting Policies for further detail concerning variable interest entities.

Other Income, Net

Other Income, Net	12 Months Ended
	Dec. 31, 2024
Other Nonoperating Income (Expense) [Abstract]
OTHER INCOME AND EXPENSES	OTHER INCOME, NET The following table presents the components of “Other Income, Net” in the Ameren Companies’ statements of income for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren: Other Income, Net Allowance for equity funds used during construction $ 76 $ 54 $ 43 Interest income on industrial development revenue bonds — 1 24 Other interest income 41 32 11 Non-service cost components of net periodic benefit income (a) 304 295 184 Miscellaneous income 9 7 10 Gain on extinguishment of debt (b) 16 — — Earnings (losses) related to equity method investments (4) 1 2 Donations (5) (24) (26) Miscellaneous expense (20) (18) (22) Total Other Income, Net $ 417 $ 348 $ 226 Ameren Missouri: Other Income, Net Allowance for equity funds used during construction $ 58 $ 30 $ 24 Interest income on industrial development revenue bonds — 1 24 Other interest income 8 10 4 Non-service cost components of net periodic benefit income (a) 139 97 55 Miscellaneous income 4 3 4 Donations (2) (2) (3) Miscellaneous expense (11) (9) (9) Total Other Income, Net $ 196 $ 130 $ 99 Ameren Illinois: Other Income, Net Allowance for equity funds used during construction $ 17 $ 19 $ 18 Other Interest income 32 21 7 Non-service cost components of net periodic benefit income 105 124 84 Miscellaneous income 4 4 5 Donations (3) (4) (8) Miscellaneous expense (8) (8) (10) Total Other Income, Net $ 147 $ 156 $ 96 (a) For the years ended December 31, 2024, 2023, and 2022, the non-service cost components of net periodic benefit income were adjusted by amounts deferred of $(41) million, $27 million, and $22 million, respectively, due to a regulatory tracking mechanism for the difference between the level of such costs incurred by Ameren Missouri under GAAP and the level of such costs included in rates. See Note 10 – Retirement Benefits for additional information. (b)

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	DERIVATIVE FINANCIAL INSTRUMENTS We use derivatives to manage the risk of changes in market prices for natural gas, power, uranium, and interest rates, as well as the risk of changes in rail transportation surcharges through fuel oil hedges. Such price fluctuations may cause the following: • an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices; • market values of natural gas and uranium inventories that differ from the cost of those commodities in inventory; • actual cash outlays for interest expense and the purchase of commodities that differ from anticipated cash outlays; and • actual off-system sales revenues that differ from anticipated revenues. The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty. All contracts considered to be derivative instruments are required to be recorded on the balance sheet at their fair values, unless the NPNS exception applies. See Note 8 – Fair Value Measurements for discussion of our methods of assessing the fair value of derivative instruments. Many of our physical contracts, such as our purchased power contracts, qualify for the NPNS exception to derivative accounting rules. The revenue or expense on NPNS contracts is recognized at the contract price upon physical delivery. The following disclosures exclude NPNS contracts and other non-derivative commodity contracts that are accounted for under the accrual method of accounting. If we determine that a contract meets the definition of a derivative and is not eligible for the NPNS exception, we review the contract to determine whether the resulting gains or losses qualify for regulatory deferral. Derivative contracts that qualify for regulatory deferral are recorded at fair value, with changes in fair value recorded as regulatory assets or liabilities in the period in which the change occurs. We believe derivative losses and gains deferred as regulatory assets and liabilities are probable of recovery, or refund, through future rates charged to customers. Regulatory assets and liabilities are amortized to operating income as related losses and gains are reflected in rates charged to customers. Therefore, gains and losses on these derivatives have no effect on operating income. As of December 31, 2024 and 2023, all commodity contracts that met the definition of a derivative and were not eligible for the NPNS exception received regulatory deferral. Interest rate hedges discussed below do not receive regulatory deferral and were included in accumulated OCI. The cash flows from our derivative financial instruments follow the cash flow classification of the hedged item. In 2024, Ameren (parent) entered into interest rate swaps to hedge a portion of our interest rate risk on cash flows related to forecasted debt issuances through 2026. The interest rate swaps are designated as cash flow hedges and the corresponding changes in fair value each period are initially recorded on the balance sheet in “Accumulated other comprehensive loss” and reclassified into earnings when the debt is issued and the corresponding interest payments affect earnings during the debt term. At December 31, 2024, Ameren had interest rate swaps with notional amounts of $140 million. The changes in fair value of the interest rate swaps were immaterial at December 31, 2024 . The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of December 31, 2024 and 2023. As of December 31, 2024, these contracts extended through October 2028, October 2029, and May 2032 for fuel oils, natural gas, and power, respectively. Quantity (in millions, except as indicated) 2024 2023 Commodity Ameren Missouri Ameren Ameren Ameren Missouri Ameren Ameren Fuel oils (in gallons) 23 — 23 17 — 17 Natural gas (in mmbtu) 45 213 258 53 218 271 Power (in MWhs) — 4 4 — 5 5 Uranium (pounds in thousands) — — — 186 — 186 The following table presents the carrying value and balance sheet location of all derivative commodity contracts, none of which were designated as hedging instruments, as of December 31, 2024 and 2023: 2024 2023 Commodity Balance Sheet Location Ameren Ameren Ameren Ameren Ameren Ameren Fuel oils Other current assets $ — $ — $ — $ 2 $ — $ 2 Other assets — — — — — — Natural gas Other current assets 2 2 4 — — — Other assets 2 4 6 3 3 6 Power Other current assets 6 — 6 5 — 5 Other assets — — — — — — Uranium Other current assets — — — 9 — 9 Other assets — — — — — — Total assets $ 10 $ 6 $ 16 $ 19 $ 3 $ 22 Fuel oils Other current liabilities $ 2 $ — $ 2 $ 1 $ — $ 1 Other deferred credits and liabilities 2 — 2 1 — 1 Natural gas Other current liabilities 5 22 27 12 45 57 Other deferred credits and liabilities 6 13 19 10 30 40 Power Other current liabilities — 10 10 1 12 13 Other deferred credits and liabilities — 43 43 — 56 56 Total liabilities $ 15 $ 88 $ 103 $ 25 $ 143 $ 168 The Ameren Companies elect to present the fair value amounts of derivative assets and derivative liabilities subject to an enforceable master netting arrangement or similar agreement at the gross amounts on the balance sheet. However, if the gross amounts recognized on the balance sheet were netted with derivative instruments and cash collateral received or posted, the net amounts would not be materially different from the gross amounts at December 31, 2024 and 2023. Credit Risk In determining our concentrations of credit risk related to derivative instruments, we review our individual counterparties and categorize each counterparty into groupings according to the primary business in which each engages. As of December 31, 2024, if counterparty groups were to fail completely to perform on contracts, the Ameren Companies’ maximum exposure related to derivative assets, predominantly from financial institutions, would have been immaterial with or without consideration of the application of master netting arrangements or similar agreements and collateral held.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Fair value is defined as the price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We use various methods to determine fair value, including market, income, and cost approaches. With these approaches, we adopt certain assumptions that market participants would use in pricing the asset or liability, including assumptions about market risk or the risks inherent in the inputs to the valuation. Inputs to valuation can be readily observable, market-corroborated, or unobservable. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Authoritative accounting guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value. All financial assets and liabilities carried at fair value are classified and disclosed in one of the following three hierarchy levels: Level 1 (quoted prices in active markets for identical assets or liabilities): Inputs based on quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities are primarily exchange-traded derivatives, cash and cash equivalents, and listed equity securities. The market approach is used to measure the fair value of equity securities held in Ameren Missouri’s nuclear decommissioning trust fund. Equity securities in this fund are representative of the S&P 500 index, excluding securities of Ameren Corporation, owners and/or operators of nuclear power plants, and the trustee and investment managers. The S&P 500 index comprises stocks of large-capitalization companies. Level 2 (significant other observable inputs) : Market-based inputs corroborated by third-party brokers or exchanges based on transacted market data. Level 2 assets and liabilities include certain assets held in Ameren Missouri’s nuclear decommissioning trust fund, including United States Treasury and agency securities, corporate bonds and other fixed-income securities, and certain over-the-counter derivative instruments, including natural gas and financial power transactions. Fixed income securities are valued by using prices from independent industry-recognized data vendors who provide values that are either exchange-based or matrix-based. The fair value measurements of fixed-income securities classified as Level 2 are based on inputs other than quoted prices that are observable for the asset or liability. Examples are matrix pricing, market corroborated pricing, and inputs such as yield curves and indices. Derivative instruments classified as Level 2 are valued by corroborated observable inputs, such as pricing services or prices from similar instruments that trade in liquid markets. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. To derive our forward view to price our derivative instruments at fair value, we average the bid/ask spreads to the midpoints. Additionally, a review of all sources is performed to identify any anomalies or potential errors. Further, we consider the volume of transactions on certain trading platforms in our reasonableness assessment of the averaged midpoints. The value of natural gas derivative contracts is based upon exchange closing prices without significant unobservable adjustments. The value of power derivative contracts is based upon exchange closing prices or the use of multiple forward prices provided by third parties. Level 3 (significant other unobservable inputs): Unobservable inputs that are not corroborated by market data. Level 3 assets and liabilities are valued by internally developed models and assumptions or methodologies that use significant unobservable inputs. Level 3 assets and liabilities include derivative instruments that trade in less liquid markets, where pricing is largely unobservable. We value Level 3 instruments by using pricing models with inputs that are often unobservable in the market, such as certain internal assumptions, quotes or prices from outside sources not supported by a liquid market, or trend rates. We perform an analysis each quarter to determine the appropriate hierarchy level of the assets and liabilities subject to fair value measurements. Financial assets and liabilities are classified in their entirety according to the lowest level of input that is significant to the fair value measurement. All assets and liabilities whose fair value measurement is based on significant unobservable inputs are classified as Level 3. We consider nonperformance risk in our valuation of derivative instruments by analyzing our own credit standing and the credit standing of our counterparties, and by considering any credit enhancements (e.g., collateral). Included in our valuation, and based on current market conditions, is a valuation adjustment for counterparty default derived from market data such as the price of credit default swaps, bond yields, and credit ratings. No material gains or losses related to valuation adjustments for counterparty default risk were recorded at Ameren, Ameren Missouri, or Ameren Illinois in 2024, 2023, or 2022. At December 31, 2024 and 2023, the counterparty default risk valuation adjustment related to derivative contracts was immaterial for Ameren, Ameren Missouri, and Ameren Illinois. The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Ameren Missouri Derivative assets – commodity contracts: Fuel oils $ — $ — $ — $ — $ 2 $ — $ — $ 2 Natural gas — 4 — 4 — 3 — 3 Power — — 6 6 — — 5 5 Uranium — — — — — — 9 9 Total derivative assets – commodity contracts $ — $ 4 $ 6 $ 10 $ 2 $ 3 $ 14 $ 19 Nuclear decommissioning trust fund: Equity securities: U.S. large capitalization $ 911 $ — $ — $ 911 $ 787 $ — $ — $ 787 Debt securities: U.S. Treasury and agency securities — 191 — 191 — 150 — 150 Corporate bonds — 145 — 145 — 136 — 136 Other — 86 — 86 — 68 — 68 Total nuclear decommissioning trust fund $ 911 $ 422 $ — $ 1,333 (a) $ 787 $ 354 $ — $ 1,141 (a) Total Ameren Missouri $ 911 $ 426 $ 6 $ 1,343 $ 789 $ 357 $ 14 $ 1,160 Ameren Illinois Derivative assets – commodity contracts: Natural gas $ — $ 3 $ 3 $ 6 $ — $ 1 $ 2 $ 3 Total Ameren Illinois $ — $ 3 $ 3 $ 6 $ — $ 1 $ 2 $ 3 Ameren Derivative assets – commodity contracts (b) $ — $ 7 $ 9 $ 16 $ 2 $ 4 $ 16 $ 22 Nuclear decommissioning trust fund (c) 911 422 — 1,333 (a) 787 354 — 1,141 (a) Total Ameren $ 911 $ 429 $ 9 $ 1,349 $ 789 $ 358 $ 16 $ 1,163 Liabilities: Ameren Missouri Derivative liabilities – commodity contracts: Fuel oils $ 4 $ — $ — $ 4 $ 2 $ — $ — $ 2 Natural gas $ — $ 11 $ — $ 11 $ — $ 19 $ 3 $ 22 Power — — — — — — 1 1 Total Ameren Missouri $ 4 $ 11 $ — $ 15 $ 2 $ 19 $ 4 $ 25 Ameren Illinois Derivative liabilities – commodity contracts: Natural gas $ 1 $ 28 $ 6 $ 35 $ 4 $ 60 $ 11 $ 75 Power — — 53 53 — — 68 68 Total Ameren Illinois $ 1 $ 28 $ 59 $ 88 $ 4 $ 60 $ 79 $ 143 Ameren Derivative liabilities – commodity contracts (b) $ 5 $ 39 $ 59 $ 103 $ 6 $ 79 $ 83 $ 168 (a) Balance excludes $9 million and $9 million of cash and cash equivalents, receivables, payables, and accrued income, net for December 31, 2024 and 2023, respectively. (b) See the Ameren Missouri and Ameren Illinois sections of the table for the fair value of Ameren’s derivative assets and liabilities by type of commodity. (c) See the Ameren Missouri section of the table for Ameren’s nuclear decommissioning trust fund by investment type. See Note 10 – Retirement Benefits for tables that set forth, by level within the fair value hierarchy, Ameren’s pension and postretirement plan assets as of December 31, 2024 and 2023. Level 3 fuel oils, natural gas and uranium derivative contract assets and liabilities measured at fair value on a recurring basis were immaterial for all periods presented. The following table presents the fair value reconciliation of Level 3 power derivative contract assets and liabilities measured at fair value on a recurring basis for the years ended December 31, 2024 and 2023: 2024 2023 Ameren Ameren Ameren Ameren Ameren Ameren Beginning balance at January 1 $ 4 $ (68) $ (64) $ 12 $ (33) $ (21) Realized and unrealized gains (losses) included in regulatory assets/liabilities 12 (1) 11 1 (48) (47) Settlements (10) 16 6 (9) 13 4 Ending balance at December 31 $ 6 $ (53) $ (47) $ 4 $ (68) $ (64) Change in unrealized gains (losses) related to assets/liabilities held at December 31 $ 6 $ 3 $ 9 $ 4 $ (36) $ (32) All gains or losses related to our Level 3 derivative commodity contracts are expected to be recovered or returned through customer rates; therefore, there is no impact to either net income or OCI resulting from changes in the fair value of these instruments. The following table describes the valuation techniques and significant unobservable inputs utilized for the fair value of our Level 3 power derivative contract assets and liabilities as of December 31, 2024 and 2023: Fair Value Weighted Average (b) Commodity Assets Liabilities Valuation Technique(s) Unobservable Input (a) Range 2024 Power (c) $ 6 $ (53) Discounted cash flow Average forward peak and off-peak pricing – forwards/swaps ($/MWh) 32 – 69 45 Nodal basis ($/MWh) (8) – (2) (5) 2023 Power (c) $ 5 $ (69) Discounted cash flow Average forward peak and off-peak pricing – forwards/swaps ($/MWh) 31 – 65 43 Nodal basis ($/MWh) (8) – (1) (5) (a) Generally, significant increases (decreases) in these inputs in isolation would result in a significantly higher (lower) fair value measurement. (b) Unobservable inputs were weighted by relative fair value. (c) Valuations use visible forward prices adjusted for nodal-to-hub basis differentials. The following table sets forth the carrying amount and, by level within the fair value hierarchy, the fair value of long-term debt (including current portion), disclosed, but not recorded, at at fair value as of December 31, 2024 and 2023: Carrying Amount (a) Fair Value Long-Term Debt (Including Current Portion): Level 2 Level 3 Total December 31, 2024 Ameren (b) 17,579 15,395 538 (c) 15,933 Ameren Missouri (d) 7,745 6,926 — 6,926 Ameren Illinois (d) 5,852 5,243 — 5,243 December 31, 2023 Ameren 15,970 14,366 467 (c) 14,833 Ameren Missouri 6,341 5,800 — 5,800 Ameren Illinois 5,232 4,867 — 4,867 (a) Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $129 million, $62 million, and $51 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2024. Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $111 million, $45 million, and $47 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2023. (b) Amount excludes Ameren (parent)’s repurchase of Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds in 2024 that were accounted for as a debt extinguishment. See Note 5 – Long-term Debt and Equity Financings for additional information. (c) The Level 3 fair value amount consists of ATXI’s senior unsecured notes. (d) Amount includes Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were repurchased by Ameren (parent) in 2024. The Ameren Companies’ carrying amounts of cash, cash equivalents, and restricted cash approximate fair value and are considered Level 1 in the fair value hierarchy. The Ameren Companies’ short-term borrowings approximate fair value because of the short-term nature of these instruments and are considered Level 2 in the fair value hierarchy.

Callaway Energy Center

Callaway Energy Center	12 Months Ended
	Dec. 31, 2024
Nuclear Waste Matters [Abstract]
CALLAWAY ENERGY CENTER	CALLAWAY ENERGY CENTER Spent Nuclear Fuel Under the Nuclear Waste Policy Act of 1982, as amended, the DOE is responsible for disposing of spent nuclear fuel from the Callaway Energy Center and other commercial nuclear energy centers. As required by the act, Ameren Missouri and other utilities have entered into standard contracts with the DOE, which stated that the DOE would begin to dispose of spent nuclear fuel by 1998. However, the DOE failed to fulfill its disposal obligations, and Ameren Missouri and other nuclear energy center owners sued the DOE to recover costs incurred for ongoing storage of their spent fuel. Ameren Missouri’s lawsuit against the DOE resulted in a settlement agreement that provides for annual reimbursement of additional spent fuel storage and related costs. Ameren Missouri received immaterial reimbursements from the DOE in the years ended December 31, 2024, 2023, and 2022. Ameren Missouri will continue to apply for reimbursement from the DOE for allowable costs associated with the ongoing storage of spent fuel. The DOE’s delay in carrying out its obligation to dispose of spent nuclear fuel from the Callaway Energy Center is not expected to adversely affect the continued operations of the energy center. Decommissioning Electric rates charged to customers provide for the recovery of the Callaway Energy Center’s decommissioning costs, which include decontamination, dismantling, and site restoration costs, over the expected life of the nuclear energy center. Amounts collected from customers are deposited into the external nuclear decommissioning trust fund to provide for the Callaway Energy Center’s decommissioning. It is assumed that the Callaway Energy Center site will be decommissioned after its retirement through the immediate dismantlement method and removed from service. The Callaway Energy Center’s operating license expires in 2044. Ameren and Ameren Missouri have recorded an ARO for the Callaway Energy Center decommissioning costs at fair value. Annual decommissioning costs of $7 million are included in the costs used to establish electric rates for Ameren Missouri’s customers. Every three years, the MoPSC requires Ameren Missouri to file an updated cost study and funding analysis for decommissioning its Callaway Energy Center. An updated cost study and funding analysis was filed with the MoPSC in December 2023 and reflected within the ARO. Ameren Missouri’s filing supported no change in electric service rates for decommissioning costs. There is no deadline by which the MoPSC must issue an order regarding the filing. Ameren and Ameren Missouri have classified the investments in debt and equity securities that are held in the nuclear decommissioning trust fund as available for sale, and have recorded all such investments at their fair market value at December 31, 2024 and 2023. Investments in the nuclear decommissioning trust fund have a target allocation of 60% to 70% in equity securities, with the balance invested in debt securities. The fair value of the trust fund for Ameren Missouri’s Callaway Energy Center is reported as “Nuclear decommissioning trust fund” in Ameren’s and Ameren Missouri’s balance sheets. This amount is legally restricted and may be used only to fund the costs of nuclear decommissioning. Changes in the fair value of the trust fund are recorded as an increase or decrease to the nuclear decommissioning trust fund, with an offsetting adjustment to the regulatory liability related to AROs. This reporting is consistent with the method used to account for the decommissioning costs recovered in rates. See Note 2 – Rate and Regulatory Matters for the regulatory liability recorded at December 31, 2024. If the assumed return on trust assets is not earned, Ameren Missouri believes that it is probable that any additional funding requirements resulting from such earnings deficiency will be recovered in customer rates. The following table presents proceeds from the sales and maturities of investments in Ameren Missouri’s nuclear decommissioning trust fund and the gross realized gains and losses resulting from those sales for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Proceeds from sales and maturities $ 564 $ 240 $ 216 Gross realized gains 44 6 40 Gross realized losses 28 11 10 The following table presents the cost and fair value of investments in debt and equity securities in Ameren’s and Ameren Missouri’s nuclear decommissioning trust fund at December 31, 2024 and 2023: Security Type Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value 2024 Debt securities $ 437 $ 2 $ 17 $ 422 Equity securities 179 740 8 911 Cash and cash equivalents 10 — — 10 Other (a) (1) — — (1) Total $ 625 $ 742 $ 25 $ 1,342 2023 Debt securities $ 382 $ 3 $ 31 $ 354 Equity securities 191 603 7 787 Cash and cash equivalents 5 — — 5 Other (a) 4 — — 4 Total $ 582 $ 606 $ 38 $ 1,150 (a) Represents net receivables and payables relating to pending securities sales, interest, and securities purchases. The following table presents the costs and fair values of investments in debt securities in Ameren’s and Ameren Missouri’s nuclear decommissioning trust fund according to their contractual maturities at December 31, 2024: Cost Fair Value Less than 5 years $ 186 $ 184 5 years to 10 years 117 112 Due after 10 years 134 126 Total $ 437 $ 422 Insurance The following table presents insurance coverage at Ameren Missouri’s Callaway Energy Center at January 1, 2025: Type and Source of Coverage Most Recent Maximum Coverages Maximum Assessments Public liability and nuclear worker liability: American Nuclear Insurers January 1, 2025 $ 500 $ — Pool participation (a) 15,763 (a) 166 (b) $ 16,263 (c) $ 166 Property damage: NEIL and EMANI April 1, 2024 $ 3,200 (d) $ 28 (e) Accidental outage: NEIL April 1, 2024 $ 490 (f) $ 11 (e) (a) Provided through mandatory participation in an industrywide retrospective premium assessment program. The maximum coverage available is dependent on the number of United States commercial reactors participating in the program. (b) Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $500 million in the event of an incident at any licensed United States commercial reactor, payable at $25 million per year. (c) Limit of liability for each incident under the Price-Anderson liability provisions of the Atomic Energy Act of 1954, as amended. This limit is subject to change to account for the effects of inflation and changes in the number of licensed power reactors. (d) NEIL provides $2.7 billion in property damage, stabilization, decontamination, and premature decommissioning insurance for radiation events and $0.7 billion in property damage insurance for nonradiation events. EMANI provides $490 million in property damage insurance for both radiation and nonradiation events. (e) All NEIL-insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL. (f) Accidental outage insurance provides for lost sales in the event of a prolonged accidental outage. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first 12 weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter for a total not exceeding the policy limit of $490 million. Nonradiation events are limited to $291 million. The Price-Anderson Act is a federal law that limits the liability for claims from an incident involving any licensed United States commercial nuclear energy center. The limit is based on the number of licensed reactors. The limit of liability and the maximum potential annual payments are adjusted at least every five years for inflation to reflect changes in the Consumer Price Index. The most recent five-year inflationary adjustment became effective in October 2023. Owners of a nuclear reactor cover this exposure through a combination of private insurance and mandatory participation in a financial protection pool, as established by the Price-Anderson Act. Losses resulting from terrorist attacks on nuclear facilities insured by NEIL are subject to industrywide aggregates, such that terrorist acts against one or more commercial nuclear power plants within a stated time period would be treated as a single event, and the owners of the nuclear power plants would share the limit of liability. NEIL policies have an aggregate limit of $3.2 billion within a 12-month period for radiation events, or $1.8 billion for events not involving radiation contamination, resulting from terrorist attacks. The EMANI policies are not subject to industrywide aggregates in the event of terrorist attacks on nuclear facilities. If losses from a nuclear incident at the Callaway Energy Center exceed the limits of, or are not covered by insurance, or if coverage is unavailable, Ameren Missouri is at risk for any uninsured losses. If a serious nuclear incident were to occur, it could have a material adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial position, or liquidity.

Retirement Benefits

Retirement Benefits	12 Months Ended
	Dec. 31, 2024
Retirement Benefits [Abstract]
RETIREMENT BENEFITS	RETIREMENT BENEFITS The primary objective of the Ameren pension and postretirement benefit plans is to provide eligible employees with pension and postretirement health care and life insurance benefits. Ameren has defined benefit pension plans covering substantially all of its employees and has a postretirement benefit plan covering non-union employees hired before October 2015 and union employees hired before January 2020. Ameren Missouri and Ameren Illinois each participate in Ameren’s single-employer pension and other postretirement plans. All non-union employees participate in a cash balance pension plan. Ameren Missouri union employees hired after June 2013, and Ameren Illinois union employees hired after mid-October 2012, participate in a cash balance pension plan. Ameren uses a measurement date of December 31 for its pension and postretirement benefit plans. Ameren’s qualified pension plan is the Ameren Retirement Plan. Ameren’s other postretirement plan is the Ameren Retiree Welfare Benefit Plan. Ameren also has an unfunded nonqualified pension plan, the Ameren Supplemental Retirement Plan, which is available to provide certain non-union employees and retirees with a supplemental benefit when their qualified pension plan benefits are capped in compliance with Internal Revenue Code limitations. Only Ameren subsidiaries participate in the plans listed above. Ameren’s pension and other postretirement benefit plans were overfunded by $734 million and $551 million in the aggregate as of December 31, 2024 and 2023, respectively. These net assets are recorded in “Pension and other postretirement benefits,” “Other current liabilities,” and “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet. The increase in the overfunded pension and postretirement benefit plans during 2024 was primarily the result of a 45-basis-point increase in the pension and other postretirement benefit plan discount rates used to determine the present value of the obligation and an increase in the actual return on plan assets of the pension and postretirement trusts. The overfunded pension and other postretirement benefit plans also resulted in regulatory liabilities on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets. The following table presents the net benefit liability/(asset) recorded on the balance sheets as of December 31, 2024 and 2023: 2024 2023 Ameren (a) $ (734) $ (551) Ameren Missouri (a) (201) (142) Ameren Illinois (a) (438) (351) (a) Liabilities associated with pension and other postretirement benefits are recorded in “Other current liabilities” and “Other deferred credits and liabilities” on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets. Ameren recognizes the overfunded and underfunded status of its pension and postretirement plans as an asset or a liability on its consolidated balance sheet, with offsetting entries to accumulated OCI and regulatory assets or liabilities. The following table presents the funded status of Ameren’s pension and postretirement benefit plans as of December 31, 2024 and 2023. It also provides the amounts included in regulatory assets or liabilities and accumulated OCI at December 31, 2024 and 2023, that have not been recognized in net periodic benefit costs. 2024 2023 Pension Postretirement Pension Postretirement Accumulated benefit obligation at end of year $ 3,962 $ (a) $ 4,102 $ (a) Change in benefit obligation: Net benefit obligation at beginning of year $ 4,258 $ 856 $ 4,061 $ 838 Service cost 88 12 79 12 Interest cost 222 44 221 45 Participant contributions — 7 — 7 Actuarial (gain) loss (143) (51) 170 17 Benefits paid (291) (61) (273) (63) Net benefit obligation at end of year 4,134 807 4,258 856 Change in plan assets: Fair value of plan assets at beginning of year 4,272 1,393 4,027 1,249 Actual return on plan assets 193 150 514 197 Employer contributions 8 4 4 3 Participant contributions — 7 — 7 Benefits paid (291) (61) (273) (63) Fair value of plan assets at end of year 4,182 1,493 4,272 1,393 Funded status – surplus (48) (686) (14) (537) Accrued benefit asset at December 31 $ (48) $ (686) $ (14) $ (537) Amounts recognized in the balance sheet consist of: Noncurrent asset $ (71) $ (686) $ (44) $ (537) Current liability (b) 2 — 2 — Noncurrent liability (c) 21 — 28 — Net asset recognized $ (48) $ (686) $ (14) $ (537) Amounts recognized in regulatory assets or liabilities consist of: Net actuarial (gain) loss $ 42 $ (379) $ (10) $ (311) Prior service credit — (21) — (25) Amounts recognized in accumulated OCI (pretax) consist of: Net actuarial (gain) loss 26 (7) 22 (4) Total $ 68 $ (407) $ 12 $ (340) (a) Not applicable. (b) Included in “Other current liabilities” on Ameren’s consolidated balance sheet. (c) Included in “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet. The following table presents the assumptions used to determine our benefit obligations at December 31, 2024 and 2023: Pension Benefits Postretirement Benefits 2024 2023 2024 2023 Discount rate at measurement date 5.70 % 5.25 % 5.70 % 5.25 % Increase in future compensation 4.00 3.50 (a) 4.00 3.50 (a) Cash balance pension plan interest crediting rate 5.50 5.50 (b) (b) Medical cost trend rate (initial) (c) (b) (b) (d) (d) Medical cost trend rate (ultimate) (c) (b) (b) 5.00 5.00 (a) As of December 31, 2023, increase in future compensation was 4.00% in 2024, and 3.50% thereafter. (b) Not applicable. (c) Initial and ultimate medical cost trend rate for certain Medicare-eligible participants was 2.50% at December 31, 2024 and 2023. (d) Initial medical cost trend rates of 7.00% and 6.93% for pre-Medicare plan participants and 7.00% and 6.50% for post-Medicare plan participants at December 31, 2024 and 2023, respectively, trend down to the ultimate rate by 2033 and 2030, respectively, with a 3.00% upward adjustment to the post-Medicare trend rate in 2025. Ameren determines discount rate assumptions by identifying a theoretical settlement portfolio of high-quality corporate bonds sufficient to provide for a plan’s projected benefit payments. The settlement portfolio of bonds is selected from a pool of approximately 860 high-quality corporate bonds. A single discount rate is then determined; that rate results in a discounted value of the plan’s benefit payments that equates to the market value of the selected bonds. In 2024, Ameren elected to continue to use the Society of Actuaries mortality table and the Society of Actuaries 2020 Mortality Improvement Scale. Funding Pension benefits are based on the employees’ years of service, age, and compensation. Ameren’s pension plans are funded in compliance with income tax regulations, federal funding requirements, and other regulatory requirements. As a result, Ameren expects to fund its pension plans at a level equal to the greater of the pension cost or the legally required minimum contribution. Based on its assumptions at December 31, 2024, its investment performance in 2024, and its pension funding policy, Ameren does not expect to make material contributions in 2025 and expects to make aggregate contributions of $170 million in 2026 through 2029. Ameren Missouri and Ameren Illinois estimate that their portion of the future funding requirements will be 40% and 50%, respectively. These estimated contributions may change based on actual investment performance, changes in interest rates, changes in our assumptions, changes in government regulations, and any voluntary contributions. Our funding policy for postretirement benefits is primarily to fund the Voluntary Employee Beneficiary Association (VEBA) trusts to match the annual postretirement expense. The following table presents the cash contributions made to our defined benefit retirement plans and to our postretirement plan during 2024, 2023, and 2022: Pension Benefits Postretirement Benefits 2024 2023 2022 2024 2023 2022 Ameren Missouri $ 1 $ 1 $ 1 $ 2 $ 2 $ 1 Ameren Illinois 1 2 3 1 1 1 Ameren Services 6 1 1 1 — — Ameren $ 8 $ 4 $ 5 $ 4 $ 3 $ 2 Investment Strategy and Policies Ameren manages plan assets in accordance with the “prudent investor” guidelines contained in ERISA. The investment committee, which includes members of senior management, approves and implements investment strategy and asset allocation guidelines for the plan assets. The investment committee’s goals are twofold: first, to ensure that sufficient funds are available to provide the benefits at the time they are payable; and second, to maximize total return on plan assets and to minimize expense volatility consistent with its tolerance for risk. Ameren delegates the task of investment management to specialists in each asset class. As appropriate, Ameren provides each investment manager with guidelines that specify allowable and prohibited investment types. The investment committee regularly monitors manager performance and compliance with investment guidelines. The expected return on plan assets assumption is based on historical and projected rates of return for current and planned asset classes in the investment portfolio. Projected rates of return for each asset class were estimated after an analysis of historical experience, future expectations, and the volatility of the various asset classes. After considering the target asset allocation for each asset class, we reviewed the overall expected rate of return for the portfolio for historical and expected experience of active portfolio management results compared with benchmark returns and for the effect of expenses paid from plan assets. Ameren will use an expected return on plan assets for its pension and postretirement plan assets of 6.75% in 2025. Ameren’s investment committee strives to assemble a portfolio of diversified assets that does not create a significant concentration of risks. The investment committee develops asset allocation guidelines between asset classes, and it creates diversification through investments in assets that differ by type (equity, debt, real estate), duration, market capitalization, country, style (growth or value), and industry, among other factors. The diversification of assets is displayed in the target allocation table below. The investment committee also routinely rebalances the plan assets to adhere to the diversification goals. The investment committee’s strategy reduces the concentration of investment risk; however, Ameren is still subject to overall market risk. Ameren’s investment committee developed and implemented a liability hedging investment strategy for its qualified pension plan designed to reduce interest rate risk as part of an objective for its long-term investment strategy. The plan invests in derivative instruments mainly consisting of interest rate futures intended to extend the duration of the pension plan assets so that the assets are more closely aligned with the duration of the liabilities. In addition, part of Ameren’s investment strategy includes participation in a securities lending program, which allows it to lend eligible securities to third party borrowers. All loans are collateralized by at least 102% of the loaned asset’s market value and the collateral is invested in the form of cash, government obligations, and U.S. agency obligations. Ameren’s fair value of securities loaned was $454 million and $234 million as of December 31, 2024 and 2023, respectively. Cash and securities obtained as collateral exceeded the fair value of the securities loaned as of December 31, 2024 and 2023. The following table presents our target allocations and our pension and postretirement plans’ asset categories as of December 31, 2024 and 2023: Asset Target Allocation 2024 Percentage of Plan Assets at December 31, 2024 2023 Pension Plan: Cash and cash equivalents 0% – 5% 3 % 1 % Equity securities: U.S. large-capitalization 10% – 20% 16 % 15 % U.S. small- and mid-capitalization 3% – 13% 9 % 8 % Global 10% – 20% 15 % 16 % International 4% – 14% 9 % 12 % Total equity 42% – 52% 49 % 51 % Debt securities 32% – 42% 35 % (a) 35 % (a) Diversified credit 6% – 16% 8 % 7 % Real estate 0% – 10% 5 % 6 % Private equity 0% – 5% (b) (b) Total 100 % 100 % Postretirement Plans: Cash and cash equivalents 0% – 7% 2 % 1 % Equity securities: U.S. large-capitalization 23% – 33% 33 % 32 % U.S. small- and mid-capitalization 3% – 13% 8 % 8 % Global 9% – 19% 13 % 15 % International 5% – 15% 8 % 8 % Total equity 55% – 65% 62 % 63 % Debt securities 33% – 43% 36 % 36 % Total 100 % 100 % (a) Includes interest rate futures derivative instruments. (b) Less than 1% of plan assets. In general, the United States large-capitalization equity investments are passively managed or indexed, whereas the international, global, United States small-capitalization, and United States mid-capitalization equity investments are actively managed by investment managers. Debt securities include a broad range of fixed-income vehicles. Debt security investments in high-yield securities and non-United-States-dollar-denominated securities are owned by the plans, but in limited quantities to reduce risk. Most of the debt security investments are under active management by investment managers. Diversified credit investments include but are not limited to, sub-investment grade rated bonds and loans, securitized credit, and emerging market debt. Real estate investments include private real estate vehicles; however, Ameren does not, by policy, hold direct investments in real estate property. In addition to the derivative investments included in the liability hedging investment strategy described above, Ameren’s investment committee also allo ws investment managers to use derivatives, such as index futures, foreign exchange futures, and options, in certain situations to increase or to reduce market exposure in an efficient and timely manner. Fair Value Measurements of Plan Assets Investments in the pension and postretirement benefit plans were stated at fair value as of December 31, 2024. Fair value is defined as the price that would be received for an asset in the principal or most advantageous market for the asset in an orderly transaction between market participants on the measurement date. Cash and cash equivalents have initial maturities of three months or less and are recorded at cost plus accrued interest. Investments traded in active markets on national or international securities exchanges are valued at closing prices on the measurement date or, if that is not a business day, on the last business day before that date. Securities traded in over-the-counter markets are valued by quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Investments measured under NAV as a practical expedient are based on the fair values of the underlying assets provided by the funds and their administrators. The fair value of real estate investments is based on NAV; it is determined by annual appraisal reports prepared by an independent real estate appraiser. Investments measured at NAV often provide for daily, monthly, or quarterly redemptions with 60 or less days of notice depending on the fund. For some funds, redemption may also require approval from the fund’s board of directors. Derivative contracts are valued at fair value, as determined by the investment managers (or independent third parties on behalf of the investment managers), who use proprietary models and take into consideration exchange quotations on underlying instruments, dealer quotations, and other market information. The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plans’ assets measured at fair value and NAV as of December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Level 1 Level 2 NAV Total Level 1 Level 2 NAV Total Cash and cash equivalents $ — $ — $ 75 $ 75 $ — $ — $ 90 $ 90 Equity securities: U.S. large-capitalization — — 689 689 — — 663 663 U.S. small- and mid-capitalization 375 — — 375 353 — — 353 International 182 — 226 408 316 — 229 545 Global — — 680 680 — — 721 721 Debt securities: Corporate bonds — 463 — 463 — 479 — 479 Municipal bonds — 36 — 36 — 43 — 43 U.S. Treasury and agency securities — 1,032 — 1,032 — 994 — 994 Diversified credit — — 344 344 — — 305 305 Other (17) 11 — (6) 49 13 — 62 Real estate — — 233 233 — — 248 248 Total $ 540 $ 1,542 $ 2,247 $ 4,329 $ 718 $ 1,529 $ 2,256 $ 4,503 Less: Medical benefit assets (a) (200) (196) Plus: Net receivables (payables) (b) 53 (35) Fair value of pension plans’ assets $ 4,182 $ 4,272 (a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation. (b) Net of receivables related to pending securities sales and payables related to pending securities purchases. The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans’ assets measured at fair value and NAV as of December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Level 1 Level 2 NAV Total Level 1 Level 2 NAV Total Cash and cash equivalents $ 25 $ — $ — $ 25 $ 10 $ — $ — $ 10 Equity securities: U.S. large-capitalization 332 — 91 423 302 — 81 383 U.S. small- and mid-capitalization 106 — — 106 96 — — 96 International 54 — 52 106 51 — 49 100 Global — — 165 165 — — 174 174 Debt securities: Municipal bonds — 173 — 173 — 161 — 161 Other — — 293 293 — — 271 271 Total $ 517 $ 173 $ 601 $ 1,291 $ 459 $ 161 $ 575 $ 1,195 Plus: Medical benefit assets (a) 200 196 Plus: Net receivables (b) 2 2 Fair value of postretirement benefit plans’ assets $ 1,493 $ 1,393 (a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above. (b) Net of receivables related to pending securities sales and payables related to pending securities purchases. Net Periodic Benefit Cost The following table presents the components of the net periodic benefit cost (income) of Ameren’s pension and postretirement benefit plans during 2024, 2023, and 2022: Pension Benefits Postretirement Benefits 2024 2023 2022 2024 2023 2022 Service cost (a) $ 88 $ 79 $ 128 $ 12 $ 12 $ 20 Non-service cost components: Interest cost 222 221 163 44 45 34 Expected return on plan assets (b) (327) (333) (320) (93) (91) (85) Amortization of (b) : Prior service cost (credit) — — — (4) (4) (4) Actuarial (gain) loss (67) (115) 25 (38) (45) (19) Total non-service cost components (c) $ (172) $ (227) $ (132) $ (91) $ (95) $ (74) Net periodic benefit cost (income) (d) $ (84) $ (148) $ (4) $ (79) $ (83) $ (54) (a) Service cost, net of capitalization, is reflected in “Operating Expenses - Other operations and maintenance” on Ameren’s statement of income. (b) Prior service cost (credit) is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment. Net actuarial gains or losses related to the net benefit obligation subject to amortization are amortized on a straight-line basis over 10 years. The difference between the actual and expected return on plan assets is amortized over 4 years. (c) Non-service cost components are reflected in “Other Income, Net” on Ameren’s consolidated statement of income. See Note 6 – Other Income, Net for additional information. (d) Does not include the impact of the tracker for the difference between the level of pension and postretirement benefit costs (income) incurred by Ameren Missouri under GAAP and the level of such costs included in rates. The Ameren Companies are responsible for their share of the pension and postretirement benefit costs (income). The following table presents the pension and postretirement benefit costs (income) incurred for the years ended December 31, 2024, 2023, and 2022: Pension Costs Postretirement Costs 2024 2023 2022 2024 2023 2022 Ameren Missouri (a) $ (44) $ (76) $ (3) $ (27) $ (30) $ (14) Ameren Illinois (34) (62) 3 (52) (54) (41) Other (6) (10) (4) — 1 1 Ameren $ (84) $ (148) $ (4) $ (79) $ (83) $ (54) (a) Does not include the impact of the tracker for the difference between the level of pension and postretirement benefit costs (income) incurred by Ameren Missouri under GAAP and the level of such costs included in customer rates. The expected pension and postretirement benefit payments from qualified trust and company funds, which reflect expected future service, as of December 31, 2024, are as follows: Pension Benefits Postretirement Benefits Paid from Paid from Paid from Paid from 2025 $ 284 $ 2 $ 56 $ 3 2026 289 2 57 3 2027 292 2 57 4 2028 295 2 57 4 2029 297 2 57 4 2030 – 2034 1,504 13 284 18 The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2024, 2023, and 2022: Pension Benefits Postretirement Benefits 2024 2023 2022 2024 2023 2022 Discount rate at measurement date 5.25 % 5.55 % 3.00 % 5.25 % 5.55 % 3.00 % Expected return on plan assets 6.75 6.75 6.50 6.75 6.75 6.50 Increase in future compensation (a) 3.50 3.50 3.50 3.50 3.50 3.50 Cash balance pension plan interest crediting rate (b) 5.50 5.00 5.00 (c) (c) (c) Medical cost trend rate (initial) (d) (c) (c) (c) (e) (f) 5.00 Medical cost trend rate (ultimate) (d) (c) (c) (c) 5.00 5.00 5.00 (a) Increase in future compensation is 4.00% for 2024 and 3.50% thereafter for the year ended December 31, 2024, and was 4.50% for 2023, 4.00% for 2024, and 3.50% thereafter for the year ended December 31, 2023. (b) Cash balance pension plan interest crediting rate is 6.42% for 2024 and 5.50% thereafter for the year ended December 31, 2024, and was 5.50% for 2023 and 2024, and 5.00% thereafter for the year ended December 31, 2023. (c) Not applicable. (d) Initial and ultimate medical cost trend rate for certain Medicare-eligible participants is 2.50% for the years ended December 31, 2024 and 2023, and 3.00% for the year ended December 31, 2022. (e) Initial medical cost trend rates of 6.93% for pre-Medicare plan participants and 6.50% for post-Medicare plan participants trend down to the ultimate rate by 2030, with a 3.00% upward adjustment to the post-Medicare trend rate in 2025. (f) Initial medical cost trend rates of 7.25% for pre-Medicare plan participants and 6.75% for post-Medicare plan participants trend down to the ultimate rate by 2030, with a 3.00% upward adjustment to the post-Medicare trend rate in 2025. Other Ameren sponsors a 401(k) plan for eligible employees. The Ameren 401(k) plan covered all eligible Ameren employees at December 31, 2024. The plan allows employees to contribute a portion of their compensation in accordance with specific guidelines. Ameren matches a percentage of the employee contributions up to certain limits. The following table presents the portion of the matching contribution to the Ameren 401(k) plan attributable to each of the Ameren Companies for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren Missouri $ 26 $ 27 $ 23 Ameren Illinois 22 21 19 Other 1 1 1 Ameren $ 49 $ 49 $ 43

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2024
Share-Based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION The 2022 Omnibus Incentive Compensation Plan is Ameren’s long-term incentive plan available for eligible employees and directors. It provides for a maximum of 8.8 million common shares to be available for grant to eligible employees and directors. At December 31, 2024, there were 7.7 million common shares remaining for grant. Awards may be restricted stock, restricted stock units, stock options (incentive stock options and nonqualified stock options), stock appreciation rights, performance awards, cash-based awards and other stock-based awards. Ameren used newly issued shares to fulfill its stock-based compensation obligations for 2024, 2023, and 2022, and intends to use newly issued shares to fulfill its stock-based compensation obligations for 2025. The following table summarizes Ameren’s outstanding performance share unit and restricted stock unit activity for the year ended December 31, 2024: Performance Share Units – Market Condition (a) Performance Share Units – Performance Condition (b) Restricted Stock Units Share Weighted-average Fair Value per Share Unit Share Weighted-average Fair Value per Share Unit Stock Weighted-average Fair Value per Stock Unit Outstanding at January 1, 2024 (c) 761,712 $ 89.22 112,391 $ 83.36 377,864 $ 83.82 Granted 314,456 56.73 51,938 68.83 159,050 69.09 Forfeitures (46,636) 73.97 (7,691) 77.22 (29,330) 79.59 Dividend equivalents (d) 27,508 77.74 4,127 79.03 13,580 79.59 Vested and distributed (248,090) 87.10 (39,768) 78.11 (125,644) 78.58 Outstanding at December 31, 2024 (c) 808,950 $ 77.73 120,997 $ 79.09 395,520 $ 79.73 (a) The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the specified market conditions. Compensation cost on nonforfeited awards is recognized regardless of whether Ameren achieves the specified market conditions. (b) The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the performance goals. Compensation cost is recognized ratably over the requisite service period only for awards for which it is probable that the performance condition will be satisfied. (c) Outstanding awards include awards that vest on a pro-rata basis due to attainment of retirement eligibility by employees, but have not yet been distributed. In these cases, the pro-rata basis awards have not yet been distributed as the entire performance period has not been completed. The number of shares issued for retirement-eligible employees will vary depending on actual performance over the three-year performance period. (d) Dividend equivalents represent the right to receive shares measured by the dividend payable with respect to the corresponding number of outstanding share units. Dividend equivalents will accrue and be reinvested in additional share units throughout the performance period. Performance Share Units – Market Condition A market condition performance share unit vests and entitles an employee to receive shares of Ameren common stock (plus accumulated dividends) if, at the end of the three-year performance period, certain specified market conditions have been met and if the individual remains employed by Ameren through the required vesting period. The vesting period for share units awarded extends beyond the three-year performance period to the payout date, which is approximately 38 months after the grant date. In the event of a participant’s death or retirement at age 55 or older with five years or more of service, awards vest on a pro-rata basis over the three-year performance period. The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the specified market conditions. The fair value of each share unit is based on a Monte Carlo simulation. The Monte Carlo simulation is used to estimate expected share payout based on Ameren’s TSR for a three-year performance period relative to the designated peer group beginning January 1st of the award year. The simulation can produce a greater or lesser fair value for the share unit than the applicable closing common share price because it includes the weighted payout scenarios in which an increase or decrease in the share price has occurred and/or in which the payout is above 100% due to Ameren’s projected TSR performance. The key assumptions used to calculate fair value also include a three-year risk-free rate, Ameren’s common stock volatility, and volatility for the peer group. The following table presents the fair value of each share unit along with the significant assumptions used to calculate the fair value of each share unit for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Fair value of share units awarded $56.73 $91.07 $92.75 Three-year risk-free rate 4.25% 4.19% 1.80% Ameren’s common stock volatility (a) 21% 26% 29% Volatility range for the peer group (a) 19% – 23% 24% – 32% 26% – 35% (a) Based on a historical period that is equal to the remaining term of the performance period as of the grant date. In addition to the market condition performance share units described above, there are an immaterial number of market condition performance share units with different vesting conditions and target payout percentages. Performance Share Units – Performance Condition A performance condition share unit vests and entitles an employee to receive shares of Ameren common stock (plus accumulated dividends) if, at the end of the three-year performance period, Ameren has met the specified performance condition and if the individual remains employed by Ameren through the required vesting period. The vesting period for share units awarded extends beyond the three-year performance period to the payout date, which is approximately 38 months after the grant date. In the event of a participant’s death or retirement at age 55 or older with five years or more of service, awards vest on a pro-rata basis over the three-year performance period. The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual performance conditions achieved. The specified performance condition in each award year is based on Ameren’s clean energy transition. The grant-date fair value for an individual outcome of a performance condition is determined by Ameren’s closing common share price on the grant date. Restricted Stock Units Restricted stock units vest and entitle an employee to receive shares of Ameren common stock (plus accumulated dividends) if the individual remains employed with Ameren through the payment date of the awards. Generally, in the event of a participant’s death or retirement at age 55 or older with five years or more of service, awards vest on a pro-rata basis. The payout date of the awards is approximately 38 months after the grant date. The fair value of each restricted stock unit is determined by Ameren’s closing common share price on the grant date. Stock-Based Compensation Expense The following table presents the stock-based compensation expense for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren Missouri $ 8 $ 6 $ 4 Ameren Illinois 4 4 2 Other (a) 16 16 18 Ameren 28 26 24 Less: Income tax benefit 7 7 6 Stock-based compensation expense, net $ 21 $ 19 $ 18 (a) Represents compensation expense for employees of Ameren Services. These amounts are not included in the Ameren Missouri and Ameren Illinois amounts above. Ameren settled performance share units and restricted stock units of $24 million, $60 million, and $47 million for the years ended December 31, 2024, 2023, and 2022, respectively. There were no significant stock-based compensation costs capitalized during the years ended December 31, 2024, 2023, and 2022. As of December 31, 2024, total compensation cost of $39 million related to outstanding awards not yet recognized is expected to be recognized over a weighted-average period of 23 months. For the years ended December 31, 2024, 2023, and 2022, excess tax benefits (deficiencies) associated with the settlement of stock-based compensation awards reduced (increased) income tax expense by $(1) million, $6 million, and $5 million, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2024
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES IRA The IRA was enacted in August 2022, and includes various income tax provisions, among other things. The law extends federal production and investment tax credits for projects beginning construction through 2024 and allows for a 10% adder to the production and investment tax credits for siting projects at existing energy communities as defined in the law, which includes sites previously used for coal-fired generation. The law also creates clean energy tax credits for projects beginning construction after 2024. The clean energy tax credits will apply to renewable energy production and investments, along with certain nuclear energy production, and will be phased out beginning in 2033, at the earliest. The phase-out is triggered when greenhouse gas emissions from the electric generation industry are reduced by at least 75% from the annual 2022 emission rate or at the beginning of 2033, whichever is later. The law allows for transferability to an unrelated party for cash of up to 100% of certain tax credits generated after 2022. In addition, the law imposes a 15% minimum tax on adjusted financial statement income, as defined in the law, for corporations whose average annual adjusted financial statement income exceeds $1 billion for three consecutive preceding tax years effective for tax years beginning after December 31, 2022. Once a corporation exceeds this three-year average annual adjusted financial statement income threshold, it will be subject to the minimum tax for all future tax years. Additional regulations, interpretations, amendments, or technical corrections to or in connection with the IRA have been and are expected to be issued by the IRS or United States Department of Treasury, which may impact the timing of when the 15% minimum tax becomes applicable for Ameren. IRS Natural Gas Repairs and Maintenance Guidance In April 2023, the IRS issued guidance providing a safe harbor method of accounting for the capitalization or deduction of certain expenditures to maintain, repair, replace, or improve natural gas distribution and transmission property. Ameren adopted this guidance for the 2024 tax year and, as a result, during December 2024, Ameren, Ameren Missouri, and Ameren Illinois recorded increases to their “plant-related” deferred tax liabilities of $123 million, $12 million, and $111 million, respectively. The following table presents the principal reasons for the difference between the effective income tax rate and the federal statutory corporate income tax rate for the years ended December 31, 2024, 2023, and 2022: Ameren Missouri Ameren Illinois Ameren 2024 Federal statutory corporate income tax rate 21 % 21 % 21 % Increases (decreases) from: Amortization of excess deferred income taxes (a) (17) (4) (9) Amortization of deferred investment tax credit (1) — — Renewable and other tax credits (b) (24) — (9) State tax 3 7 5 Depreciation differences — — (1) Effective income tax rate (18) % 24 % 7 % 2023 Federal statutory corporate income tax rate 21 % 21 % 21 % Increases (decreases) from: Amortization of excess deferred income taxes (a) (15) (2) (8) Amortization of deferred investment tax credit (1) — — Renewable and other tax credits (b) (10) — (4) State tax 3 7 5 Effective income tax rate (2) % 26 % 14 % 2022 Federal statutory corporate income tax rate 21 % 21 % 21 % Increases (decreases) from: Amortization of excess deferred income taxes (a) (15) (2) (8) Amortization of deferred investment tax credit (1) — — Renewable and other tax credits (b) (10) — (4) State tax 3 7 5 Effective income tax rate (2) % 26 % 14 % (a) Reflects the amortization of a regulatory liability resulting from the revaluation of accumulated deferred income taxes subject to regulatory ratemaking, which are being refunded to customers. (b) The benefit of the credits associated with Missouri renewable energy standard compliance is refunded to customers through the RESRAM. The benefit of the credits associated with the production and investment tax credit tracker will be refunded to customers based on MoPSC approval in a regulatory rate review. The following table presents the components of income tax expense (benefit) for the years ended December 31, 2024, 2023, and 2022: Ameren Missouri Ameren Illinois Other Ameren 2024 Current taxes: Federal $ (55) $ 5 $ 7 $ (43) State (3) — 2 (1) Deferred taxes: Federal 45 144 (12) 177 State 8 76 (19) 65 Amortization of excess deferred income taxes (79) (32) (1) (112) Amortization of deferred investment tax credits (3) — — (3) Total income tax expense (benefit) $ (87) $ 193 $ (23) $ 83 2023 Current taxes: Federal $ (37) $ 27 $ (37) $ (47) State 1 5 (5) 1 Deferred taxes: Federal 102 123 35 260 State 9 71 (10) 70 Amortization of excess deferred income taxes (80) (17) (1) (98) Amortization of deferred investment tax credits (3) — — (3) Total income tax expense (benefit) $ (8) $ 209 $ (18) $ 183 2022 Current taxes: Federal $ (26) $ 46 $ (15) $ 5 State (5) 16 (10) 1 Deferred taxes: Federal 93 82 19 194 State 18 48 14 80 Amortization of excess deferred income taxes (86) (13) (1) (100) Amortization of deferred investment tax credits (4) — — (4) Total income tax expense (benefit) $ (10) $ 179 $ 7 $ 176 The following table presents the accumulated deferred income tax assets and liabilities recorded as a result of temporary differences and accumulated deferred production and investment tax credits at December 31, 2024 and 2023: Ameren Missouri Ameren Illinois Other Ameren 2024 Accumulated deferred income taxes, net liability (asset): Plant-related $ 2,429 $ 2,250 $ 261 $ 4,940 Regulatory assets and liabilities, net (193) (170) (22) (385) Deferred employee benefit costs (25) 77 (25) 27 Tax carryforwards (355) (45) (103) (503) Other 131 28 3 162 Total net accumulated deferred income tax liabilities (assets) 1,987 2,140 114 4,241 Accumulated deferred investment tax credits 230 3 — 233 Accumulated deferred income taxes and investment tax credits $ 2,217 $ 2,143 $ 114 $ 4,474 2023 Accumulated deferred income taxes, net liability (asset): Plant-related $ 2,370 $ 2,030 $ 246 $ 4,646 Regulatory assets and liabilities, net (206) (184) (23) (413) Deferred employee benefit costs (48) 55 (33) (26) Tax carryforwards (124) (33) (61) (218) Other 104 38 19 161 Total net accumulated deferred income tax liabilities (assets) 2,096 1,906 148 4,150 Accumulated deferred investment tax credits 26 — — 26 Accumulated deferred income taxes and investment tax credits $ 2,122 $ 1,906 $ 148 $ 4,176 The following table presents the components of accumulated deferred income tax assets relating to net operating loss carryforwards and tax credit carryforwards at December 31, 2024 and 2023: Ameren Missouri Ameren Illinois Other Ameren 2024 Net operating loss carryforwards: Federal (a) $ — $ — $ 30 $ 30 State (b) — 34 29 63 Total net operating loss carryforwards $ — $ 34 $ 59 $ 93 Tax credit carryforwards: Federal (c) $ 355 $ 9 $ 44 $ 408 State (d) — 2 — 2 Total tax credit carryforwards $ 355 $ 11 $ 44 $ 410 2023 Net operating loss carryforwards: Federal $ — $ — $ — $ — State — 26 16 42 Total net operating loss carryforwards $ — $ 26 $ 16 $ 42 Tax credit carryforwards: Federal $ 124 $ 5 $ 45 $ 174 State — 2 — 2 Total tax credit carryforwards $ 124 $ 7 $ 45 $ 176 (a) No expiration date. (b) Will expire between 2032 and 2044. (c) Will expire between 2031 and 2044. (d) Will expire between 2025 and 2028. Uncertain Tax Positions As of December 31, 2024 and 2023, the Ameren Companies did not record any uncertain tax positions. Ameren is a part of the IRS’s compliance assurance process program, which involves real-time review of compliance with federal income tax law. State income tax returns are generally subject to examination for a period of three years after filing. The state impact of any federal changes remains subject to examination by various states for up to one year after formal notification to the states. Ameren’s federal tax return for the 2023 tax year is open, but, at the time of this filing, the Ameren Companies do not have material income tax issues under examination, administrative appeals, or litigation.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2024
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED-PARTY TRANSACTIONS In the normal course of business, Ameren Missouri and Ameren Illinois engage in affiliate transactions. These transactions primarily consist of natural gas and power purchases and sales, services received or rendered, and borrowings and lendings. Transactions between Ameren’s subsidiaries are reported as affiliate transactions on their individual financial statements, but those transactions are eliminated in consolidation for Ameren’s consolidated financial statements. Below are the material related-party agreements. Electric Power Supply Agreements Ameren Illinois must acquire capacity and energy sufficient to meet its obligations to customers. Ameren Illinois uses periodic RFP processes, administered by the IPA and approved by the ICC, to contract capacity and energy on behalf of its customers. Ameren Missouri participates in the RFP process and has been a winning supplier for certain periods. Capacity Supply Agreements In procurement events in 2021, Ameren Missouri contracted to supply a portion of Ameren Illinois’ capacity requirements for $2 million from June 2022 through May 2023. Energy Product Agreements Based on the outcome of IPA-administered procurement events, Ameren Missouri and Ameren Illinois have entered into energy product agreements by which Ameren Missouri agreed to sell, and Ameren Illinois agreed to purchase, a set amount of MWhs at a predetermined price over a specified period of time. The following table presents the specified performance period, amount of MWhs, and average price per MWh included in the agreements: IPA Procurement Event Performance Period MWhs Average Price per MWh September 2020 September 2021 – November 2022 204,800 31 April 2021 July 2022 – November 2022 33,600 34 September 2021 January 2022 – September 2023 136,000 37 Interconnection Agreements Ameren Missouri and Ameren Illinois are parties to an interconnection agreement that governs the connection of their respective transmission lines and other facilities used for the distribution of power. These agreements have no contractual expiration date, but may be terminated by either party with three years’ notice. Ameren Missouri and ATXI are parties to an interconnection agreement that governs the connection of the High Prairie Energy Center to an ATXI transmission line that allows Ameren Missouri to distribute power generated from the High Prairie Energy Center. Ameren Missouri and Ameren Illinois are parties to interconnection agreements that govern the connection of the Cass County and Boomtown energy centers to Ameren Illinois transmission lines that allows Ameren Missouri to distribute power generated from the Cass County and Boomtown energy centers. Support Services Agreements Ameren Services provides support services to its affiliates. The costs of support services including wages, employee benefits, professional services, and other expenses, are based on, or are an allocation of, actual costs incurred. The support services agreement can be terminated at any time by the mutual agreement of Ameren Services and that affiliate or by either party with 60 days’ notice before the end of a calendar year. In addition, Ameren Missouri and Ameren Illinois provide affiliates with access to their facilities for administrative purposes and with use of other assets. The costs of the rent and facility services and other assets are based on, or are an allocation of, actual costs incurred. Ameren Missouri and Ameren Illinois also provide storm-related and miscellaneous support services to each other on an as-needed basis. Ameren Missouri and Ameren Illinois had long-term receivables included in “Other assets” from Ameren Services of $29 million and $32 million, respectively, as of December 31, 2024, and $31 million and $34 million, respectively, as of December 31, 2023, related to Ameren Services’ allocated portion of Ameren’s pension and postretirement benefit plans. Transmission Services Ameren Missouri and Ameren Illinois each receives transmission services from ATXI for their respective retail loads. Electric Transmission Maintenance and Construction Agreements ATXI entered into separate agreements with Ameren Missouri and Ameren Illinois in which Ameren Missouri or Ameren Illinois, as applicable, may perform certain maintenance and construction services related to ATXI’s electric transmission assets. Money Pool See Note 4 – Short-term Debt and Liquidity for a discussion of affiliate borrowing arrangements. Long-Term Debt, Net - Related Parties In November and December 2024, Ameren (parent) purchased senior secured notes and first mortgage bonds issued by Ameren Missouri, and first mortgage bonds issued by Ameren Illinois. See Note 5 – Long-term Debt and Equity Financings for additional information. Tax Allocation Agreement See Note 1 – Summary of Significant Accounting Policies for a discussion of the tax allocation agreement. The following table presents the affiliate balances related to income taxes for Ameren Missouri and Ameren Illinois as of December 31, 2024 and 2023: 2024 2023 Ameren Missouri Ameren Illinois Ameren Missouri Ameren Illinois Income taxes payable to parent (a) $ — $ 32 $ — $ 2 Income taxes receivable from parent (b) 28 — 56 22 (a) Included in “Accounts payable – affiliates” on the balance sheet. (b) Included in “Accounts receivable – affiliates” on the balance sheet. Capital Contributions The following table presents cash capital contributions received from Ameren (parent) by Ameren Missouri and Ameren Illinois for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren Missouri (a) $ 476 $ — $ — Ameren Illinois (a) 36 91 15 (a) Includes capital contributions made as a result of the tax allocation agreement. Effects of Related-party Transactions on the Statement of Income The following table presents the impact on Ameren Missouri and Ameren Illinois of related-party transactions for the years ended December 31, 2024, 2023, and 2022. It is based primarily on the agreements discussed above and the money pool arrangements discussed in Note 4 – Short-term Debt and Liquidity. Agreement Income Statement Line Item Ameren Ameren Ameren Missouri power supply agreements Operating Revenues 2024 $ — $ (a) with Ameren Illinois 2023 2 (a) 2022 9 (a) Ameren Missouri and Ameren Illinois Operating Revenues 2024 31 1 rent and facility services 2023 32 (b) 2022 25 (b) Ameren Missouri and Ameren Illinois Operating Revenues 2024 2 2 miscellaneous support services 2023 (b) 2 2022 (b) 2 Total Operating Revenues 2024 $ 33 $ 3 2023 34 2 2022 34 2 Ameren Illinois power supply Purchased Power 2024 $ (a) $ — agreements with Ameren Missouri 2023 (a) 2 2022 (a) 9 Ameren Missouri and Ameren Illinois Purchased Power 2024 9 2 transmission services from ATXI 2023 2 1 2022 1 (b) Total Purchased Power 2024 $ 9 $ 2 2023 2 3 2022 1 9 Ameren Missouri and Ameren Illinois Other Operations and 2024 $ 1 $ 1 rent and facility services Maintenance 2023 (b) 3 2022 (b) 3 Ameren Services support services Other Operations and 2024 169 158 agreement Maintenance 2023 148 138 2022 150 141 Total Other Operations and 2024 $ 170 $ 159 Maintenance Expenses 2023 148 141 2022 150 144 Money pool borrowings (advances) (Interest Charges) 2024 $ (4) $ (b) Other Income, Net 2023 (b) (b) 2022 (b) (b) Long-term debt, net - related parties (Interest Charges) 2024 (b) (b) 2023 (a) (a) 2022 (a) (a) (a) Not applicable. (b) Amount less than $1 million.

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES We are involved in legal, tax, and regulatory proceedings before various courts, regulatory commissions, authorities, and governmental agencies with respect to matters that arise in the ordinary course of business, some of which involve substantial amounts of money. We believe that the final disposition of these proceedings, except as otherwise disclosed in the notes to our financial statements, will not have a material adverse effect on our results of operations, financial position, or liquidity. See also Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 9 – Callaway Energy Center, Note 13 – Related-party Transactions, and Note 15 – Supplemental Information in this report. Environmental Matters Our electric generation, transmission, and distribution and natural gas distribution and storage operations must comply with a variety of statutes and regulations relating to the protection of the environment and human health and safety, including permitting programs implemented by federal, state, and local authorities. Such environmental laws regulate air emissions; protect water bodies; manage the handling and disposal of hazardous substances and waste materials; siting and land use requirements; and potential ecological impacts. Complex and lengthy processes are required to obtain and renew approvals, permits, and licenses for new, existing, or modified energy-related facilities. Additionally, the use and handling of various chemicals or hazardous materials require release prevention plans and emergency response procedures. Environmental regulations have a significant impact on the electric utility industry and compliance with these regulations could be costly for Ameren Missouri, which operates coal-fired and natural gas-fired energy centers. Compliance obligations under the Clean Air Act include the NSPS, the MATS, emission allowance programs and the CSAPR, and the National Ambient Air Quality Standards, which are subject to periodic review for certain pollutants. Collectively, these regulations cover a variety of pollutants, such as SO 2 , particulate matter, NO x , mercury, toxic metals and acid gases, and CO 2 emissions. Regulations implementing the Clean Water Act govern potential impacts from our operations on water bodies including wetlands subject to the Act, as well as evaluation of the ecological and biological impact of those operations. Implementation of the Clean Air Act and the Clean Water Act requirements typically occurs through the issuance of permits by state regulators or resource agencies, and capital expenditures associated with compliance could be significant. Coal-fired energy centers must comply with management and disposal requirements for coal ash under the Resource Conservation and Recovery Act and federal regulations known as the CCR Rule. Surface impoundments at Ameren Missouri’s coal-fired energy centers are subject to closure and groundwater monitoring requirements and the implementations of corrective measures if necessary. The individual or combined effects of compliance with existing and new environmental regulations could result in significant capital expenditures, increased operating costs, or the closure or alteration of operations at some of Ameren Missouri’s energy centers. Ameren and Ameren Missouri expect that such compliance costs would be recoverable through rates, subject to MoPSC prudence review, but the timing of costs and their recovery could be subject to regulatory lag. Additionally, Ameren Missouri’s wind generation facilities may be subject to operating restrictions to limit the impact on protected species. Since 2021, Ameren Missouri’s High Prairie Energy Center curtailed nighttime operations from April through October to limit impacts on protected species during the critical biological season. The extent and duration of future curtailments are currently unknown as assessment of mitigation technologies is ongoing. In Ameren Missouri’s 2024 electric service regulatory rate review, the MoPSC staff and the MoOPC have recommended reductions to the revenue requirement associated with the nighttime curtailment of the High Prairie Energy Center. See Note 2 – Rate and Regulatory Matters for additional information. Ameren and Ameren Missouri estimate that they may need to make capital expenditures of $900 million to $1 billion from 2025 through 2029 to comply with environmental regulations. Additional capital expenditures for environmental controls beyond 2029 could be required. These estimates include capital expenditures that may be necessary to comply with regulations issued by the EPA in 2024 relating to CO 2 emissions and MATS discussed below, assuming these regulations are not revised or overturned. This estimate of capital expenditures also includes surface impoundment closure and corrective action measures required by the 2015 CCR Rule and modifications to cooling water intake structures at existing power plants under Clean Water Act rules in place prior to 2024, all of which are discussed below. Congress and the EPA could review and revise compliance requirements. In addition to planned retirements of coal-fired energy centers that will be included in Ameren Missouri’s 2025 Change to the 2023 PRP and as noted below with respect to the NSR and Clean Air Act litigation and Illinois emissions standards, Ameren Missouri’s current plan for compliance with existing air emission regulations includes burning low-sulfur coal and installing new or optimizing existing air pollution control equipment. Accordingly, the actual amount of capital expenditures required to comply with existing environmental regulations may vary substantially from the above estimates because of uncertainty as to future permitting requirements by state regulators and the EPA, revisions to regulatory obligations, and varying cost of potential compliance strategies, among other things. The following sections describe the significant environmental statutes and regulations and environmental enforcement and remediation matters that affect or could affect our operations. The EPA periodically amends and revises its regulations and proposes amendments to regulations and guidelines, which could ultimately result in the revision of all or part of such regulations. Clean Air Act Federal and state laws, including the CSAPR, regulate emissions of SO 2 and NO x through the reduction of emissions at their source and the use and retirement of emission allowances. In April 2022, the EPA proposed the Good Neighbor Rule of the Clean Air Act, which includes additional NO x emission reductions from power plants in Missouri, Illinois, and other states through revisions to the CSAPR. In January 2023, the EPA issued its final disapproval of Missouri’s proposed state implementation plan for addressing the transport of ozone under the Good Neighbor Rule of the Clean Air Act. The disapproval of the state plan allowed the EPA to implement revisions to the CSAPR through a federal implementation plan that reduced the amount of NO x allowances available for state budgets and imposed NO x emission limits on electric generating units for Missouri, Illinois, and other states under the Good Neighbor Rule of the Clean Air Act. In April 2023, the Missouri Attorney General and Ameren Missouri separately filed lawsuits in the United States Court of Appeals for the Eighth Circuit challenging the EPA’s disapproval of the Missouri state plan. Ameren expected a decision on Missouri’s proposed state implementation plan under the Good Neighbor Rule by the United States Court of Appeals for the Eighth Circuit in 2025, but, in February 2025, the EPA requested that the appellate court suspend the case indefinitely and indicated it was reviewing the basis for the disapproval of the state implementation plans, including Missouri’s. Ameren Missouri complies with the current CSAPR requirements by minimizing emissions through the use of low-sulfur coal, operation of two scrubbers at its Sioux Energy Center, and optimization of existing NO x air pollution control equipment. Reducing the amount of state budget NO x allowances for compliance with NO x emission limits under the Good Neighbor Rule could result in additional controls being required on Ameren Missouri’s generating units and/or the reduction of operations. Any costs for compliance are expected to be recovered from customers, subject to MoPSC prudence review, through the FAC or higher base rates. CO 2 Emissions Standards In April 2024, the EPA issued a final rule that sets CO 2 emission standards for existing coal-fired and new natural gas-fired power plants based on the emissions expected from adoption of carbon capture technology and/or natural gas co-firing for coal-fired power plants and carbon capture technology for new natural gas-fired power plants. Affected power plants are required to comply with the rule through a phased-in approach or retire. Compliance with the new rule could be required as early as 2030 for certain existing coal-fired power plants and 2032 for certain new natural gas-fired power plants. In December 2024, the United States Court of Appeals for the District of Columbia Circuit heard arguments from various stakeholders including the EPA, environmental organizations, state attorney generals, and industry groups regarding the legal merits of the final rule. In February 2025, the EPA requested that the appellate court suspend the case for 60 days and not issue an opinion so the EPA can decide how to proceed. Ameren and Ameren Missouri estimate capital expenditures of approximately $580 million may be necessary to comply with the final rule assuming it is not revised or overturned. Ameren and Ameren Missouri are monitoring the legal challenges and assessing the impacts of the final rule and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity. MATS In April 2024, the EPA revised the MATS by establishing a more stringent standard for emissions of particulate matter, as well as requiring the use of continuous emissions monitoring systems. Compliance with the revised rule is required by July 2027, with a possible one-year extension if certain conditions are met. Requests for a stay of the revised rule have been denied by the United States Court of Appeals for the District of Columbia Circuit and the United States Supreme Court. Arguments regarding the legal merits of the revised rule will be considered by the United States Court of Appeals for the District of Columbia Circuit. Ameren and Ameren Missouri estimate capital expenditures of approximately $320 million may be necessary to comply with the final rule assuming it is not revised or overturned. Ameren and Ameren Missouri are monitoring the legal challenges and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity. NSPS In November 2024, the EPA issued a proposed rule revising the NSPS to limit emissions of NO x from natural gas-fired stationary CTs. If adopted as proposed, the rule would require such natural gas facilities which began construction after December 13, 2024, to install certain pollution control equipment to limit emissions of NO x . In addition, the EPA proposed to maintain the current limits for SO 2 at such natural gas facilities. Ameren and Ameren Missouri cannot predict the potential impacts of any such rule on their results of operations, financial position, and liquidity until a final rule is adopted. NSR and Clean Air Act Litigation In January 2011, the United States Department of Justice, on behalf of the EPA, filed a complaint against Ameren Missouri in the United States District Court for the Eastern District of Missouri alleging that projects performed in 2007 and 2010 at the coal-fired Rush Island Energy Center violated provisions of the Clean Air Act and Missouri law. In January 2017, the district court issued a liability ruling against Ameren Missouri and, in September 2019, entered a remedy order that required Ameren Missouri to install a flue gas desulfurization system at the Rush Island Energy Center. In September 2023, the district court modified the remedy order to allow the early retirement of the Rush Island Energy Center in lieu of installing a flue gas desulfurization system. Ameren Missouri retired the Rush Island Energy Center on October 15, 2024. In December 2024, the United States District Court for the Eastern District of Missouri issued an order resolving all outstanding claims in this case. The order requires Ameren Missouri to fund a program to provide electric buses and charging stations to schools in the metro St. Louis area and a program to provide air purifiers to eligible Ameren Missouri electric residential customers. These programs are estimated to cost approximately $64 million. As of December 31, 2024, Ameren and Ameren Missouri each recorded liabilities of $40 million and $24 million in “Other current liabilities” and “Other deferred credits and liabilities”, respectively, on their consolidated balance sheets and recorded charges of $59 million in “Other operations and maintenance” on their consolidated statements of income in 2024 related to the cost of these programs. In connection with the accelerated retirement of the Rush Island Energy Center, the MoPSC issued an order in June 2024 authorizing Ameren Missouri to finance the costs associated with the retirement, including the remaining unrecovered net plant balance associated with the facility, through the issuance of securitized utility tariff bonds pursuant to Missouri’s securitization statute. Costs associated with the retirement exclude any additional mitigation relief ordered in the NSR and Clean Air Act litigation discussed above. The securitized tariff bonds were issued in December 2024. See Note 2 – Rate and Regulatory Matters for additional information. Clean Water Act Among other items, the Clean Water Act requires power plant operators to evaluate cooling water intake structures and identify measures for reducing the number of aquatic organisms impinged on a power plant’s cooling water intake screens or entrained through the plant’s cooling water system. All of Ameren Missouri’s coal-fired and nuclear energy centers are subject to this cooling water intake structures rule. Requirements of the rule are implemented by state regulators through the permit renewal process of each power plant’s water discharge permit. Permits for Ameren Missouri’s coal-fired and nuclear energy centers have been issued or are in the process of renewal. In April 2024, the EPA issued new effluent limitation guidelines that established a zero discharge limit for flue gas desulfurization wastewater, bottom ash transport water, and combustion residual leachate. Ameren and Ameren Missouri expect the impacts of the new guidelines on their results of operations, financial position, and liquidity to be immaterial. CCR Management The EPA’s 2015 CCR Rule establishes requirements for the management and disposal of CCR from coal-fired power plants and has resulted in the closure of surface impoundments at Ameren Missouri’s energy centers, with closures of surface impoundments in process at its Sioux Energy Center and retired Meramec Energy Center. Ameren Missouri plans to substantially complete the closures of remaining surface impoundments by the end of 2026 . Ameren Missouri’s CCR management compliance plan includes installation of groundwater monitoring equipment and groundwater treatment facilities. In April 2024, the EPA revised the CCR Rule to impose groundwater monitoring, and corrective action, closure, and post-closure requirements on certain active and inactive CCR surface impoundments and disposal units not previously included in the 2015 CCR Rule. Ameren and Ameren Missouri have AROs of $46 million associated with CCR storage facilities recorded on their respective balance sheets as of December 31, 2024. This amount includes an immaterial incremental ARO related to the 2024 CCR Rule, which may be revised as additional site studies are performed. Ameren and Ameren Missouri are assessing the impacts of this rule revision and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity. Remediation The Ameren Companies are involved in a number of remediation actions to clean up sites impacted by the use or disposal of materials containing hazardous substances. Federal and state laws can require responsible parties to fund remediation regardless of their degree of fault, the legality of original disposal, or the ownership of a disposal site. As of December 31, 2024, Ameren Illinois has remediated the majority of the 44 former MGP sites in Illinois with an estimated remaining obligation primarily related to three of these former MGP sites at $44 million to $91 million. Ameren and Ameren Illinois recorded a liability of $44 million to represent the estimated minimum obligation for these sites, as no other amount within the range was a better estimate. Ameren cannot estimate the completion date of the estimated remaining obligation due to site accessibility, among other things. The scope of the remediation activities at these former MGP sites may increase as remediation efforts continue. Considerable uncertainty remains in these estimates because many site-specific factors can influence the actual costs, including unanticipated underground structures, the degree to which groundwater is impacted, regulatory changes, local ordinances, and site accessibility. The actual costs and timing of completion may vary substantially from these estimates. The ICC allows Ameren Illinois to recover MGP remediation and related litigation costs from its electric and natural gas utility customers through environmental cost riders that are subject to annual prudence reviews by the ICC. Our operations or those of our predecessor companies involve the use of, disposal of, and, in appropriate circumstances, the cleanup of substances regulated under environmental laws. We are unable to determine whether such historical practices will result in future environmental commitments, including additional or more stringent cleanup standards, or will affect our results of operations, financial position, or liquidity. Illinois Emission Standards Currently as required by the CEJA, Ameren Missouri's natural gas-fired energy centers in Illinois are subject to annual limits on emissions, including CO 2 and NO x . Further reductions to emissions limits will become effective between 2030 and 2040, resulting in the closure of the Venice Energy Center by the end of 2029. The reductions could also limit the operations of Ameren Missouri's four other natural gas-fired energy centers located in the state of Illinois, and will result in their closure by 2040. These energy centers are utilized to support peak loads. Subject to conditions in the CEJA, these energy centers may be allowed to exceed the emissions limits in order to maintain reliability of electric utility service.

Supplemental Information

Supplemental Information	12 Months Ended
	Dec. 31, 2024
Supplemental Information [Abstract]
Supplemental Information	SUPPLEMENTAL INFORMATION Cash, Cash Equivalents, and Restricted Cash The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets and the statements of cash flows as of December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Ameren Ameren Ameren Ameren Ameren Ameren “Cash and cash equivalents” $ 7 $ — $ — $ 25 $ — $ — Restricted cash included in “Other current assets” 15 7 6 13 5 5 Restricted cash included in “Other assets” 296 — 296 229 — 229 Restricted cash included in “Nuclear decommissioning trust fund” 10 10 — 5 5 — Total cash, cash equivalents, and restricted cash $ 328 $ 17 $ 302 $ 272 $ 10 $ 234 Restricted cash included in “Other current assets” represents funds held by an irrevocable Voluntary Employee Beneficiary Association (VEBA) trust, which provides health care benefits for active employees on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets and AMF’s restricted cash for payments for securitized utility tariff bonds on Ameren’s and Ameren Missouri’s balance sheets. Restricted cash included in “Other assets” on Ameren’s and Ameren Illinois’ balance sheets primarily represents amounts collected under a cost recovery rider restricted for use in the procurement of renewable energy credits and amounts in a trust fund restricted for the use of funding certain asbestos-related claims. Accounts Receivable “Accounts receivable – trade” on Ameren’s and Ameren Illinois’ balance sheets include certain receivables purchased at a discount from alternative retail electric suppliers that elect to participate in the utility consolidated billing program. At December 31, 2024 and 2023, “Other current liabilities” on Ameren’s and Ameren Illinois’ balance sheets included payables for purchased receivables of $43 million and $42 million, respectively. The following table provides a reconciliation of the beginning and ending amount of the allowance for doubtful accounts for the years ended December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Ameren Missouri Ameren Illinois (a) Ameren Ameren Missouri Ameren Illinois (a) Ameren Beginning balance at January 1 $ 12 $ 18 $ 30 $ 13 $ 18 $ 31 Bad debt expense 11 28 39 11 40 51 Charged to other accounts (b) — 8 8 — 5 5 Net write-offs (11) (36) (47) (12) (45) (57) Ending balance at December 31 $ 12 $ 18 $ 30 $ 12 $ 18 $ 30 (a) Ameren Illinois has rate-adjustment mechanisms that allow it to recover the difference between its actual net bad debt write-offs under GAAP, including those associated with receivables purchased from alternative retail electric suppliers, and the amount of net bad debt write-offs included in its base rates. (b) Amounts associated with the allowance for doubtful accounts related to receivables purchased by Ameren Illinois from alternative retail electric suppliers, as required by the Illinois Public Utilities Act. Leases Ameren and Ameren Missouri have lease agreements primarily relating to rail cars and land related to solar generation facilities. The land leases are related to the Cass County, Boomtown, and Huck Finn energy centers. See Note 2 – Rate and Regulatory Matters for additional information on the acquisitions. Rail cars are leased for the transportation of coal to its energy centers. For rail car leases, we account for the lease and non-lease components as a single lease component, and for the land leases related to solar generation projects, we account for the components separately for each agreement. Certain of the land leases related to the acquisitions of the Cass County, Boomtown, and Huck Finn energy centers have options to renew or terminate those leases. Termination and renewal options are not expected to be exercised and are not included in any of the lease measurements used to record the leased assets and liabilities in the tables below. The following table provides supplemental balance sheet information related to operating leases as of December 31, 2024: Ameren Ameren Missouri Other assets $ 72 $ 69 Other current liabilities 5 4 Other deferred credits and liabilities 67 65 Weighted average remaining operating lease term 29 years 30 years Weighted average discount rate (a) 5.3 % 5.3 % (a) As an implicit rate is not readily determinable under most of our lease agreements, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We use an implicit rate when readily determinable. The following table presents Ameren’s and Ameren Missouri’s remaining maturities of operating lease liabilities as of December 31, 2024: Ameren Ameren Missouri 2025 $ 8 $ 7 2026 5 4 2027 4 3 2028 4 4 2029 4 4 Thereafter 131 131 Total lease payments $ 156 $ 153 Less imputed interest 84 84 Total $ 72 $ 69 Inventories The following table presents the components of inventories for each of the Ameren Companies at December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Ameren Ameren Ameren Ameren Ameren Ameren Fuel (a) $ 113 $ — $ 113 $ 109 $ — $ 109 Natural gas stored underground 9 82 91 8 87 95 Materials, supplies, and other 392 162 558 391 138 529 Total inventories $ 514 $ 244 $ 762 $ 508 $ 225 $ 733 (a) Consists of coal, oil, and propane. Asset Retirement Obligations The following table provides a reconciliation of the beginning and ending carrying amount of AROs for the years ended December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Ameren Ameren Ameren Ameren Ameren Ameren Beginning balance at January 1 $ 787 (a) $ 4 (b) $ 791 (a) $ 782 $ 4 $ 786 Liabilities incurred 21 (c) — 21 (c) — — — Liabilities settled (13) — (13) (10) — (10) Accretion (d) 35 (d) — 35 (d) 33 — 33 Change in estimates (7) — (7) (18) — (18) Ending balance at December 31 $ 823 (a)(e) $ 4 (b) $ 827 (a)(e) $ 787 (a) $ 4 (b) $ 791 (a) (a) Balance included $5 million and $19 million in “Other current liabilities” on the balance sheet as of December 31, 2024 and 2023, respectively. (b) Included in “Other deferred credits and liabilities” on the balance sheet. (c) In 2024, Ameren and Ameren Missouri recorded an ARO related to decommissioning for the Cass County, Boomtown, and Huck Finn energy centers. In addition, as a result of the 2024 CCR Rule, Ameren and Ameren Missouri recorded an increase to their AROs associated with CCR storage facilities. See Note 14 – Commitments and Contingencies for additional information. (d) Accretion expense attributable to Ameren Missouri was recorded as a decrease to regulatory liabilities. (e) The balance as of December 31, 2024, included an ARO related to the decommissioning of the Callaway Enter Center of $648 million. Deferred Compensation As of December 31, 2024, and 2023, the present value of benefits to be paid for deferred compensation obligations was $79 million and $85 million, respectively, which was primarily reflected in “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet. Deferred compensation obligations are primarily recorded on the balance sheet of Ameren (parent). Excise Taxes Ameren Missouri and Ameren Illinois collect from their customers excise taxes, including municipal and state excise taxes and gross receipts taxes, that are levied on the sale or distribution of natural gas and electricity. The following table presents the excise taxes recorded on a gross basis in “Operating Revenues – Electric,” “Operating Revenues – Natural gas” and “Operating Expenses – Taxes other than income taxes” on the statements of income for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren Missouri $ 169 $ 166 $ 162 Ameren Illinois 130 121 133 Ameren $ 299 $ 287 $ 295 Allowance for Funds Used During Construction The following table presents the average rate that was applied to eligible construction work in progress and the amounts of allowance for funds used during construction capitalized in 2024, 2023, and 2022: 2024 2023 2022 Average rate: Ameren Missouri 6 % 6 % 5 % Ameren Illinois 6 % 6 % 5 % Ameren: Allowance for equity funds used during construction $ 76 $ 54 $ 43 Allowance for borrowed funds used during construction 56 48 26 Total Ameren $ 132 $ 102 $ 69 Ameren Missouri: Allowance for equity funds used during construction $ 58 $ 30 $ 24 Allowance for borrowed funds used during construction 39 27 13 Total Ameren Missouri $ 97 $ 57 $ 37 Ameren Illinois: Allowance for equity funds used during construction $ 17 $ 19 $ 18 Allowance for borrowed funds used during construction 15 17 12 Total Ameren Illinois $ 32 $ 36 $ 30 Earnings per Share Earnings per basic and diluted share are computed by dividing “Net Income Attributable to Ameren Common Shareholders” by the weighted-average number of basic and diluted common shares outstanding, respectively, during the applicable period. The weighted-average shares outstanding for earnings per diluted share includes the incremental effects resulting from performance share units, restricted stock units, and forward sale agreements relating to common stock when the impact would be dilutive, as calculated using the treasury stock method. For information regarding performance share units and restricted stock units, see Note 11 – Stock-based Compensation. For information regarding forward sale agreements, see Note 5 – Long-term Debt and Equity Financings. The following table reconciles the weighted-average number of common shares outstanding to the diluted weighted-average number of common shares outstanding for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Weighted-average Common Shares Outstanding – Basic 266.8 262.8 258.4 Assumed settlement of performance share units and restricted stock units 0.5 0.6 1.0 Dilutive effect of forward sale agreements 0.1 — 0.1 Weighted-average Common Shares Outstanding – Diluted (a) 267.4 263.4 259.5 (a) There was an immaterial number of anti-dilutive securities excluded from the earnings per diluted share calculations for the years ended December 31, 2024, 2023, and 2022 related to performance share units and restricted stock units. Outstanding forward sale agreements as of December 31, 2024 that were anti-dilutive for the year ended December 31, 2024 were excluded from the earnings per diluted share calculation as calculated using the treasury stock method. The outstanding forward sale agreements as of December 31, 2023, were anti-dilutive for the year ended December 31, 2023, and excluded from the earnings per diluted share calculation as calculated using the treasury stock method. For additional information about the outstanding forward sale agreements, see Note 5 – Long-term Debt and Equity Financings. Supplemental Cash Flow Information The following table provides noncash financing and investing activity excluded from the statements of cash flows for the years ended December 31, 2024, 2023, and 2022: December 31, 2024 December 31, 2023 December 31, 2022 Ameren Ameren Ameren Ameren Ameren Ameren Ameren Ameren Ameren Investing Accrued capital expenditures, including nuclear fuel expenditures $ 480 $ 303 $ 157 $ 518 $ 270 $ 212 $ 441 $ 243 $ 181 Net realized and unrealized gain (loss) – nuclear decommissioning trust fund 165 165 — 167 167 — (218) (218) — Return of investment in industrial development revenue bonds (a) — — — 240 240 — — — — Financing Issuance of common stock for stock-based compensation $ 16 $ — $ — $ 40 $ — $ — $ 31 $ — $ — Issuance of common stock under the DRPlus 7 — — 7 — — 8 — — Termination of a financing agreement (a) — — — 240 240 — — — — (a)

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2024
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION Ameren has four segments: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission. The Ameren Missouri segment includes all of the operations of Ameren Missouri. Ameren Illinois Electric Distribution consists of the electric distribution business of Ameren Illinois. Ameren Illinois Natural Gas consists of the natural gas business of Ameren Illinois. Ameren Transmission primarily consists of the aggregated electric transmission businesses of Ameren Illinois and ATXI. The category called Other primarily includes Ameren (parent) activities and Ameren Services. Ameren Missouri has one segment. Ameren Illinois has three segments: Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission. See Note 1 – Summary of Significant Accounting Policies for additional information regarding the operations of Ameren Missouri, Ameren Illinois, and ATXI. Segment operating revenues and a majority of operating expenses are directly recognized and incurred by Ameren Illinois in each Ameren Illinois segment. Common operating expenses, miscellaneous income and expenses, interest charges, and income tax expense are allocated by Ameren Illinois to each Ameren Illinois segment based on certain factors, which primarily relate to the nature of the cost. Additionally, Ameren Illinois Transmission earns revenue from transmission service provided to Ameren Illinois Electric Distribution, other retail electric suppliers, and wholesale customers. The transmission expense for Illinois customers who have elected to purchase their power from Ameren Illinois is recovered through a cost recovery mechanism with no net effect on Ameren Illinois Electric Distribution earnings, as costs are offset by corresponding revenues. Transmission revenues from these transactions are reflected in Ameren Transmission’s and Ameren Illinois Transmission’s operating revenues. An intersegment elimination at Ameren and Ameren Illinois occurs to eliminate these transmission revenues and expenses. The CODMs for Ameren, Ameren Missouri, and Ameren Illinois are the Chief Executive Officer of Ameren and Chief Financial Officer of Ameren. The CODMs use net income to evaluate income generated from the segments to make decisions about resources allocated to each segment and assess segment performance. Net income is also used to monitor budget versus actual results when assessing segment performance. The following tables present information about the reported revenue and specified items reflected in net income attributable to common shareholders and capital expenditures by segment at Ameren and Ameren Illinois for the years ended December 31, 2024, 2023, and 2022. Ameren, Ameren Missouri, and Ameren Illinois management review segment capital expenditure information rather than any individual or total asset amount. Ameren Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Other Intersegment Eliminations Ameren 2024 External revenues $ 3,960 $ 2,088 $ 938 $ 637 $ — $ — $ 7,623 Intersegment revenues 33 1 — 144 — (178) — Revenue 3,993 2,089 938 781 — (178) 7,623 Fuel and purchased power (a) (1,071) (740) — — — 130 (1,681) Natural gas purchased for resale (a) (60) — (260) — — — (320) Other operations and maintenance expenses (a) (1,050) (619) (230) (70) (48) 48 (1,969) Other segment items Depreciation and amortization (917) (369) (129) (167) (8) — (1,590) Taxes other than income taxes (372) (75) (78) (9) (13) — (547) Other income, net 196 97 27 26 83 (12) 417 Interest charges (244) (98) (63) (117) (b) (153) 12 (663) Income taxes (benefit) 87 (50) (56) (120) 56 — (83) Noncontrolling interests – preferred stock dividends (3) (1) — (1) — — (5) Net income (loss) attributable to Ameren common shareholders 559 234 149 323 (83) — 1,182 Interest income 8 28 1 6 10 (12) 41 Capital expenditures 2,712 579 264 758 7 (1) 4,319 Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Other Intersegment Eliminations Ameren 2023 External revenues $ 3,825 $ 2,217 $ 897 $ 561 $ — $ — $ 7,500 Intersegment revenues 34 1 — 116 — (151) — Revenue 3,859 2,218 897 677 — (151) 7,500 Fuel and purchased power (a) (997) (933) — — — 118 (1,812) Natural gas purchased for resale (a) (79) — (276) — — — (355) Other operations and maintenance expenses (a) (1,003) (532) (237) (60) (67) 33 (1,866) Other segment items Depreciation and amortization (783) (351) (108) (138) (7) — (1,387) Taxes other than income taxes (360) (75) (67) (8) (12) — (522) Other income, net 130 103 30 28 62 (5) 348 Interest charges (227) (89) (55) (96) (b) (104) 5 (566) Income taxes (benefit) 8 (82) (50) (106) 47 — (183) Noncontrolling interests – preferred stock dividends (3) (1) — (1) — — (5) Net income (loss) attributable to Ameren common shareholders 545 258 134 296 (81) — 1,152 Interest income 11 19 1 2 5 (5) 33 Capital expenditures 1,760 752 299 804 9 (27) 3,597 2022 External revenues $ 4,012 $ 2,255 $ 1,180 $ 510 $ — $ — $ 7,957 Intersegment revenues 34 1 — 105 — (140) — Revenue 4,046 2,256 1,180 615 — (140) 7,957 Fuel and purchased power (a) (1,150) (984) — — — 114 (2,020) Natural gas purchased for resale (a) (104) — (553) — — — (657) Other operations and maintenance expenses (a) (1,028) (580) (253) (60) (42) 26 (1,937) Other segment items Depreciation and amortization (732) (332) (98) (123) (4) — (1,289) Taxes other than income taxes (363) (75) (82) (9) (10) — (539) Other income, net 99 60 19 17 32 (1) 226 Interest charges (213) (74) (44) (84) (b) (72) 1 (486) Income taxes (benefit) 10 (68) (46) (92) 20 — (176) Noncontrolling interests – preferred stock dividends (3) (1) — (1) — — (5) Net income (loss) attributable to Ameren common shareholders 562 202 123 263 (76) — 1,074 Interest income 28 7 — — 1 (1) 35 Capital expenditures 1,690 621 308 741 7 (16) 3,351 (a) Significant segment expense that is regularly provided to the CODMs. Intersegment expenses are included within the amounts shown. (b) Ameren Transmission interest charges include an allocation of financing costs from Ameren (parent). Ameren Illinois Ameren Illinois Electric Distribution Ameren Illinois Ameren Illinois Transmission Intersegment Eliminations Ameren Illinois 2024 External revenues $ 2,089 $ 938 $ 445 $ — $ 3,472 Intersegment revenues — — 119 (119) — Revenue 2,089 938 564 (119) 3,472 Purchased power (a) (740) — — 119 (621) Natural gas purchased for resale (a) — (260) — — (260) Other operations and maintenance expenses (a) (619) (230) (57) — (906) Other segment items Depreciation and amortization (369) (129) (121) — (619) Taxes other than income taxes (75) (78) (4) — (157) Other income, net 97 27 23 — 147 Interest charges (98) (63) (80) — (241) Income taxes (50) (56) (87) — (193) Noncontrolling interests – preferred stock dividends (1) — (1) — (2) Net income available to common shareholder 234 149 237 — 620 Interest income 28 1 3 — 32 Capital expenditures 579 264 624 — 1,467 2023 External revenues $ 2,218 $ 897 $ 367 $ — $ 3,482 Intersegment revenues — — 113 (113) — Revenue 2,218 897 480 (113) 3,482 Purchased power (a) (933) — — 113 (820) Natural gas purchased for resale (a) — (276) — — (276) Other operations and maintenance expenses (a) (532) (237) (49) — (818) Other segment items Depreciation and amortization (351) (108) (97) — (556) Taxes other than income taxes (75) (67) (4) — (146) Other income, net 103 30 23 — 156 Interest charges (89) (55) (60) — (204) Income taxes (82) (50) (77) — (209) Noncontrolling interests – preferred stock dividends (1) — (1) — (2) Net income available to common shareholder 258 134 215 — 607 Interest income 19 1 1 — 21 Capital expenditures 752 299 680 — 1,731 Ameren Illinois Electric Distribution Ameren Illinois Ameren Illinois Transmission Intersegment Eliminations Ameren Illinois 2022 External revenues $ 2,256 $ 1,180 $ 320 $ — $ 3,756 Intersegment revenues — — 104 (104) — Revenue 2,256 1,180 424 (104) 3,756 Purchased power (a) (984) — — 104 (880) Natural gas purchased for resale (a) — (553) — — (553) Other operations and maintenance expenses (a) (580) (253) (49) — (882) Other segment items Depreciation and amortization (332) (98) (84) — (514) Taxes other than income taxes (75) (82) (4) — (161) Other income, net 60 19 17 — 96 Interest charges (74) (44) (50) — (168) Income taxes (68) (46) (65) — (179) Noncontrolling interests – preferred stock dividends (1) — (1) — (2) Net income available to common shareholder 202 123 188 — 513 Interest income 7 — — — 7 Capital expenditures 621 308 672 — 1,601 (a) Significant segment expense that is regularly provided to the CODMs. Intersegment expenses are included within the amounts shown. The following tables present disaggregated revenues by segment at Ameren and Ameren Illinois for the years ended December 31, 2024, 2023, and 2022. Economic factors affect the nature, timing, amount, and uncertainty of revenues and cash flows in a similar manner across customer classes. Revenues from alternative revenue programs have a similar distribution among customer classes as revenues from contracts with customers. Other revenues not associated with contracts with customers are presented in the Other customer classification, along with electric transmission and off-system sales and capacity revenues. Ameren Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Intersegment Eliminations Ameren 2024 Residential $ 1,638 $ 1,254 $ — $ — $ — $ 2,892 Commercial 1,313 680 — — — 1,993 Industrial 311 178 — — — 489 Other 585 (23) — 781 (177) 1,166 Total electric revenues $ 3,847 $ 2,089 $ — $ 781 $ (177) $ 6,540 Residential $ 90 $ — $ 661 $ — $ — $ 751 Commercial 37 — 166 — — 203 Industrial 4 — 10 — — 14 Other 15 — 101 — (1) 115 Total gas revenues $ 146 $ — $ 938 $ — $ (1) $ 1,083 Total revenues (a) $ 3,993 $ 2,089 $ 938 $ 781 $ (178) $ 7,623 2023 Residential $ 1,577 $ 1,344 $ — $ — $ — $ 2,921 Commercial 1,280 747 — — — 2,027 Industrial 306 186 — — — 492 Other 531 (59) — 677 (150) 999 Total electric revenues $ 3,694 $ 2,218 $ — $ 677 $ (150) $ 6,439 Residential $ 100 $ — $ 657 $ — $ — $ 757 Commercial 46 — 164 — — 210 Industrial 5 — 14 — — 19 Other 14 — 62 — (1) 75 Total gas revenues $ 165 $ — $ 897 $ — $ (1) $ 1,061 Total revenues (a) $ 3,859 $ 2,218 $ 897 $ 677 $ (151) $ 7,500 2022 Residential $ 1,578 $ 1,325 $ — $ — $ — $ 2,903 Commercial 1,219 768 — — — 1,987 Industrial 290 199 — — — 489 Other 762 (36) — 615 (139) 1,202 Total electric revenues $ 3,849 $ 2,256 $ — $ 615 $ (139) $ 6,581 Residential $ 119 $ — $ 846 $ — $ — $ 965 Commercial 56 — 221 — — 277 Industrial 7 — 41 — — 48 Other 15 — 72 — (1) 86 Total gas revenues $ 197 $ — $ 1,180 $ — $ (1) $ 1,376 Total revenues (a) $ 4,046 $ 2,256 $ 1,180 $ 615 $ (140) $ 7,957 (a) The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the years ended December 31, 2024, 2023, and 2022: Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Ameren 2024 Revenues from alternative revenue programs $ 4 $ (43) $ (3) $ 33 $ (9) Other revenues not from contracts with customers 7 (a) 10 2 — 19 (a) 2023 Revenues from alternative revenue programs $ (5) $ 116 $ 49 $ 19 $ 179 Other revenues not from contracts with customers (9) (a) 7 2 — — (a) 2022 Revenues from alternative revenue programs $ 17 $ 89 $ (19) $ (9) $ 78 Other revenues not from contracts with customers (103) (a)(b) 6 3 — (94) (a)(b) (a) Includes net realized gains and losses on derivative power contracts. (b) Includes $10 million for insurance recoveries related to lost sales associated with the Callaway Energy Center maintenance outage for the year ended December 31, 2022. Ameren Illinois Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Illinois Transmission Intersegment Eliminations Ameren Illinois 2024 Residential $ 1,254 $ 661 $ — $ — $ 1,915 Commercial 680 166 — — 846 Industrial 178 10 — — 188 Other (23) 101 564 (119) 523 Total revenues (a) $ 2,089 $ 938 $ 564 $ (119) $ 3,472 2023 Residential $ 1,344 $ 657 $ — $ — $ 2,001 Commercial 747 164 — — 911 Industrial 186 14 — — 200 Other (59) 62 480 (113) 370 Total revenues (a) $ 2,218 $ 897 $ 480 $ (113) $ 3,482 2022 Residential $ 1,325 $ 846 $ — $ — $ 2,171 Commercial 768 221 — — 989 Industrial 199 41 — — 240 Other (36) 72 424 (104) 356 Total revenues (a) $ 2,256 $ 1,180 $ 424 $ (104) $ 3,756 (a) The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the Ameren Illinois segments for the years ended December 31, 2024, 2023, and 2022: Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Illinois Transmission Ameren Illinois 2024 Revenues from alternative revenue programs $ (43) $ (3) $ 29 $ (17) Other revenues not from contracts with customers 10 2 — 12 2023 Revenues from alternative revenue programs $ 116 $ 49 $ 12 $ 177 Other revenues not from contracts with customers 7 2 — 9 2022 Revenues from alternative revenue programs $ 89 $ (19) $ (7) $ 63 Other revenues not from contracts with customers 6 3 — 9

Schedule I - Condensed Financia

Schedule I - Condensed Financial Information Of Parent	12 Months Ended
	Dec. 31, 2024
Condensed Financial Information Disclosure [Abstract]
Condensed Financial Information Of Parent	SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT AMEREN CORPORATION CONDENSED STATEMENT OF INCOME AND COMPREHENSIVE INCOME For the Years Ended December 31, 2024, 2023, and 2022 (In millions) 2024 2023 2022 Operating revenues $ — $ — $ — Operating expenses 17 22 15 Operating loss (17) (22) (15) Equity in earnings of subsidiaries 1,271 1,245 1,161 Interest income from affiliates 14 10 2 Total other income (expense), net 3 (11) (13) Interest charges (162) (119) (86) Income tax benefit 61 49 25 Net Income Attributable to Ameren Common Shareholders $ 1,170 $ 1,152 $ 1,074 Net Income Attributable to Ameren Common Shareholders $ 1,170 $ 1,152 $ 1,074 Other Comprehensive Income (Loss), Net of Taxes: Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $—, $(2), and $(4), respectively (3) (5) (14) Unrealized net gain on derivative hedging instruments, net of income taxes of $—, $—, and $—, respectively 3 — — Comprehensive Income Attributable to Ameren Common Shareholders $ 1,170 $ 1,147 $ 1,060 SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT (In millions, except per share amounts) December 31, 2024 December 31, 2023 Assets: Cash and cash equivalents $ — $ 16 Advances to money pool 103 598 Accounts receivable – affiliates 41 20 Miscellaneous accounts and notes receivable 35 31 Mark-to-market derivative assets 3 — Total current assets 182 665 Investments in subsidiaries 16,262 14,573 Investments in subsidiary debt securities 44 — Accumulated deferred income taxes, net 98 44 Other assets 155 149 Total assets $ 16,741 $ 15,431 Liabilities and Shareholders’ Equity: Current maturities of long-term debt $ — $ 450 Short-term debt 1,055 — Accounts payable — 2 Taxes accrued 7 10 Accounts payable – affiliates 49 100 Other current liabilities 54 45 Total current liabilities 1,165 607 Long-term debt, net 3,383 3,379 Pension and other postretirement benefits 18 19 Other deferred credits and liabilities 73 77 Total liabilities 4,639 4,082 Commitments and Contingencies (Note 4) Shareholders’ Equity: Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 269.9 and 266.3, respectively 3 3 Other paid-in capital, principally premium on common stock 7,513 7,216 Retained earnings 4,592 4,136 Accumulated other comprehensive loss (6) (6) Total shareholders’ equity 12,102 11,349 Total liabilities and shareholders’ equity $ 16,741 $ 15,431 SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT AMEREN CORPORATION CONDENSED STATEMENT OF CASH FLOWS For the Years Ended December 31, 2024, 2023, and 2022 (In millions) 2024 2023 2022 Net cash provided by (used in) operating activities $ (65) $ 171 $ 44 Cash flows from investing activities: Money pool advances, net 495 (530) 40 Notes receivable – ATXI — — 35 Investments in subsidiaries (557) (109) (30) Investments in subsidiary debt securities (44) — — Other 1 5 3 Net cash provided by (used in) investing activities (105) (634) 48 Cash flows from financing activities: Dividends on common stock (714) (662) (610) Short-term debt, net 1,054 (475) 198 Maturities of long-term debt (450) — — Issuances of long-term debt — 1,298 — Issuances of common stock 273 346 333 Employee payroll taxes related to stock-based compensation (8) (20) (16) Debt issuance costs (1) (8) (1) Net cash provided by (used in) financing activities 154 479 (96) Net change in cash, cash equivalents, and restricted cash $ (16) $ 16 $ (4) Cash, cash equivalents, and restricted cash at beginning of year 16 — 4 Cash, cash equivalents, and restricted cash at end of year $ — $ 16 $ — Supplemental information: Cash dividends received from consolidated subsidiaries $ 140 $ 173 $ 76 Noncash financing activity – Issuance of common stock for stock-based compensation 16 40 31 Noncash financing activity – Issuance of common stock under the DRPlus 7 7 8 AMEREN CORPORATION (parent company only) NOTES TO CONDENSED FINANCIAL STATEMENTS December 31, 2024 NOTE 1 – BASIS OF PRESENTATION Ameren Corporation (parent company only) is a public utility holding company that conducts substantially all of its business operations through its subsidiaries. Ameren Corporation (parent company only) has accounted for its subsidiaries using the equity method. These financial statements are presented on a condensed basis. See Note 1 – Summary of Significant Accounting Policies and Note 15 – Supplemental Information under Part II, Item 8, of this report for additional information. NOTE 2 – SHORT-TERM DEBT AND LIQUIDITY Ameren, Ameren Services, and other non-state-regulated Ameren subsidiaries have the ability, subject to Ameren parent company and applicable regulatory short-term borrowing authorizations, to access funding from the Credit Agreements and the commercial paper programs through a non-state-regulated subsidiary money pool agreement. All participants may borrow from or lend to the non-state-regulated money pool. The total amount available to pool participants from the non-state-regulated subsidiary money pool at any given time is reduced by the amount of borrowings made by participants, but is increased to the extent that the pool participants advance surplus funds to the non-state-regulated subsidiary money pool or remit funds from other external sources. The non-state-regulated subsidiary money pool was established to coordinate and to provide short-term cash and working capital for the participants. Participants receiving a loan under the non-state-regulated subsidiary money pool agreement must repay the principal amount of such loan, together with accrued interest. The rate of interest depends on the composition of internal and external funds in the non-state-regulated subsidiary money pool. Interest revenues related to non-state-regulated money pool advances were $14 million, $10 million, and immaterial in 2024, 2023 and 2022, respectively. Interest charges related to non-state-regulated money pool borrowings were immaterial in 2024, 2023, and 2022. See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of this report for a description and details of short-term debt and liquidity needs of Ameren Corporation (parent company only). NOTE 3 – LONG-TERM OBLIGATIONS See Note 5 – Long-term Debt and Equity Financings under Part II, Item 8, of this report for additional information on Ameren Corporation’s (parent company only) long-term debt, indenture provisions, forward sale agreements related to common stock, and ATM program. NOTE 4 – COMMITMENTS AND CONTINGENCIES See Note 14 – Commitments and Contingencies under Part II, Item 8, of this report for a description of all material contingencies of Ameren Corporation (parent company only). NOTE 5 – TOTAL OTHER EXPENSE, NET The following table presents the components of “Total Other Expense, Net” in the Condensed Statement of Income and Comprehensive Income for the years ended December 31, 2024, 2023, and 2022: (In millions) 2024 2023 2022 Total other (income) expense, net Non-service cost components of net periodic benefit income $ 4 $ 8 $ 3 Donations — (18) (15) Other expense, net (1) (1) (1) Total other (income) expense, net $ 3 $ (11) $ (13)
Other Income And Expenses	OTHER INCOME, NET The following table presents the components of “Other Income, Net” in the Ameren Companies’ statements of income for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren: Other Income, Net Allowance for equity funds used during construction $ 76 $ 54 $ 43 Interest income on industrial development revenue bonds — 1 24 Other interest income 41 32 11 Non-service cost components of net periodic benefit income (a) 304 295 184 Miscellaneous income 9 7 10 Gain on extinguishment of debt (b) 16 — — Earnings (losses) related to equity method investments (4) 1 2 Donations (5) (24) (26) Miscellaneous expense (20) (18) (22) Total Other Income, Net $ 417 $ 348 $ 226 Ameren Missouri: Other Income, Net Allowance for equity funds used during construction $ 58 $ 30 $ 24 Interest income on industrial development revenue bonds — 1 24 Other interest income 8 10 4 Non-service cost components of net periodic benefit income (a) 139 97 55 Miscellaneous income 4 3 4 Donations (2) (2) (3) Miscellaneous expense (11) (9) (9) Total Other Income, Net $ 196 $ 130 $ 99 Ameren Illinois: Other Income, Net Allowance for equity funds used during construction $ 17 $ 19 $ 18 Other Interest income 32 21 7 Non-service cost components of net periodic benefit income 105 124 84 Miscellaneous income 4 4 5 Donations (3) (4) (8) Miscellaneous expense (8) (8) (10) Total Other Income, Net $ 147 $ 156 $ 96 (a) For the years ended December 31, 2024, 2023, and 2022, the non-service cost components of net periodic benefit income were adjusted by amounts deferred of $(41) million, $27 million, and $22 million, respectively, due to a regulatory tracking mechanism for the difference between the level of such costs incurred by Ameren Missouri under GAAP and the level of such costs included in rates. See Note 10 – Retirement Benefits for additional information. (b) See Note 5 – Long-term Debt and Equity Financings for additional information on Ameren (parent)’s repurchase of Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were accounted for as a debt extinguishment. The following table presents the components of “Total Other Expense, Net” in the Condensed Statement of Income and Comprehensive Income for the years ended December 31, 2024, 2023, and 2022: (In millions) 2024 2023 2022 Total other (income) expense, net Non-service cost components of net periodic benefit income $ 4 $ 8 $ 3 Donations — (18) (15) Other expense, net (1) (1) (1) Total other (income) expense, net $ 3 $ (11) $ (13)

Schedule II - Valuation And Qua

Schedule II - Valuation And Qualifying Accounts	12 Months Ended
	Dec. 31, 2024
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Valuation And Qualifying Accounts	SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS FOR THE YEARS ENDED DECEMBER 31, 2024, 2023, AND 2022 (In millions) Column A Column B Column C Column D Column E Description Balance at (1) (2) Charged to Other Accounts (a) Deductions (b) Balance at End Ameren: Deducted from assets – allowance for doubtful accounts: 2024 $ 30 $ 39 $ 8 $ 47 $ 30 2023 31 51 5 57 30 2022 29 34 4 36 31 Ameren Missouri: Deducted from assets – allowance for doubtful accounts: 2024 $ 12 $ 11 $ — $ 11 $ 12 2023 13 11 — 12 12 2022 13 9 — 9 13 Ameren Illinois: Deducted from assets – allowance for doubtful accounts: 2024 $ 18 $ 28 $ 8 $ 36 $ 18 2023 18 40 5 45 18 2022 16 25 4 27 18 (a) Amounts associated with the allowance for doubtful accounts relate to the uncollectible account reserve associated with receivables purchased by Ameren Illinois from alternative retail electric suppliers, as required by the Illinois Public Utilities Act. (b) Uncollectible accounts charged off, less recoveries.

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Insider Trading Policies and Pr

Insider Trading Policies and Procedures	12 Months Ended
	Dec. 31, 2024
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

Cybersecurity Risk Management a

Cybersecurity Risk Management and Strategy Disclosure	12 Months Ended
	Dec. 31, 2024
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	The Ameren Companies have identified cybersecurity as an enterprise risk, which is managed through Ameren's integrated enterprise risk management program. The program is designed to continuously assess risk and evaluate the likelihood and probability of impact to determine the appropriate risk tolerance and risk management strategies that inform our cybersecurity policies, investments, practices, controls, and countermeasures. The program is a comprehensive, consistently applied management framework that is designed to ensure all forms of material risk and opportunity are identified, reported, and managed in an effective manner overseen by the risk management steering committee. The risk management steering committee, which is composed of executive management and senior-level Ameren officers, with Ameren board of directors’ oversight, oversees and governs Ameren's enterprise risk management processes, which include the identification, assessment, mitigation, and monitoring of risks including strategic, operational, and cybersecurity risks. Ameren's board of directors maintains a standing committee, the Cybersecurity and Digital Technology Committee, which is focused on the oversight of Ameren's cybersecurity and digital technology risks. The committee has primary responsibility for oversight of cybersecurity and digital technology risk management, including the programs, policies, procedures, processes, controls and safeguards for digital technology, information security, prevention and detection of cybersecurity incidents or data breaches, and cybersecurity and digital technology matters as they relate to crisis preparedness, incident response plans, and disaster recovery and business continuity capabilities. The committee receives regular updates from the Chief Information Security Officer, the Chief Information Officer, executive management, and other members of senior management who collectively maintain the responsibility for both the execution and ongoing management of Ameren’s cybersecurity program and respective initiatives. The Cybersecurity and Digital Technology Committee regularly reports on its activities to Ameren’s board of directors, including reviewing and advising Ameren’s board of directors of any developments it believes should be considered. Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who possesses over 25 years of critical infrastructure experience both managing and protecting information systems in concert with extensive cybersecurity operations and leadership roles. The Chief Information Security Officer regularly engages with senior-level Ameren officers, reports to the risk management steering committee, and has recurring meetings with the Cybersecurity and Digital Technology Committee as part of ongoing risk management and oversight of the cybersecurity program. In addition, Ameren’s board of directors participate in periodic cybersecurity drills to prepare for potential crisis scenarios. To manage against existing and emerging cybersecurity threats, we maintain enterprise-wide cybersecurity, crisis management, and information security policies and regular training and tests that reinforce the acceptable use of Ameren's information assets, protection of customer and employee data, and the role each employee plays in protecting Ameren against cybersecurity threats. Incident response plans and procedures are continuously tested through recurring companywide cybersecurity exercises to promote readiness across the organization. The plans and procedures are also designed to escalate incidents to appropriate members of management to guide the prevention, detection, response, recovery, and remediation from a material cybersecurity incident. These cybersecurity plans and procedures are positioned to promote the expedient identification, escalation, handling and reporting of a potentially material cybersecurity event or incident. To address cybersecurity threats, we work closely with law enforcement, cybersecurity consulting firms, and industry associations to enhance information sharing and guard against cybersecurity attacks. Ameren employs a third-party cybersecurity risk management program, which extends the governance elements of Ameren’s cybersecurity program, in addition to other diligence measures, to our critical third-party providers and suppliers. The supply chain and third-party risks introduced to Ameren are evaluated prior to the commencement of any new engagement or relationship, monitored closely throughout the lifecycle of the supplier and managed through privacy and cybersecurity provisions within the respective commercial contracts. Procedures have been established to address supplier incidents as well as supplier off-boarding at the expiration of the relationship. We leverage common and widely accepted external cybersecurity risk management frameworks, such as the National Institute of Standards and Technology Cybersecurity framework, to assess, guide, and enhance our cybersecurity posture. Our program effectiveness is measured through formal cybersecurity scorecards and metrics reported to senior-level Ameren officers, the risk management steering committee, and the Cybersecurity and Digital Technology Committee. These metrics include but are not limited to measures on the effectiveness of our cybersecurity controls across core National Institute of Standards and Technology Cybersecurity framework functions (Govern, Identify, Protect, Detect, Respond, and Recover), our ability to manage first- and third-party cybersecurity events and incidents, cybersecurity incident response exercises, results of our recurring internal assessments, vulnerability assessments, penetration tests, external assessments, and audits that Ameren regularly undergoes. Ameren regularly engages external cybersecurity experts to assist with evaluating our cybersecurity program. These engagements provide insights into control design and implementation, prioritized recommendations for enhancements to our cybersecurity strategy, and an overview of the cybersecurity threat landscape that collectively inform our investments and technical controls to protect Ameren's most critical assets. The results of these engagements are reviewed with senior-level Ameren officers, the risk management steering committee, and the Cybersecurity and Digital Technology Committee. We are not aware of any cybersecurity events that have materially affected or are reasonably likely to materially affect Ameren, including our business strategy, results of operations, financial position, or liquidity.
Cybersecurity Risk Management Processes Integrated [Flag]	true
Cybersecurity Risk Management Processes Integrated [Text Block]	The Ameren Companies have identified cybersecurity as an enterprise risk, which is managed through Ameren's integrated enterprise risk management program. The program is designed to continuously assess risk and evaluate the likelihood and probability of impact to determine the appropriate risk tolerance and risk management strategies that inform our cybersecurity policies, investments, practices, controls, and countermeasures. The program is a comprehensive, consistently applied management framework that is designed to ensure all forms of material risk and opportunity are identified, reported, and managed in an effective manner overseen by the risk management steering committee.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Board of Directors Oversight [Text Block]	Ameren's board of directors maintains a standing committee, the Cybersecurity and Digital Technology Committee, which is focused on the oversight of Ameren's cybersecurity and digital technology risks. The committee has primary responsibility for oversight of cybersecurity and digital technology risk management, including the programs, policies, procedures, processes, controls and safeguards for digital technology, information security, prevention and detection of cybersecurity incidents or data breaches, and cybersecurity and digital technology matters as they relate to crisis preparedness, incident response plans, and disaster recovery and business continuity capabilities. The committee receives regular updates from the Chief Information Security Officer, the Chief Information Officer, executive management, and other members of senior management who collectively maintain the responsibility for both the execution and ongoing management of Ameren’s cybersecurity program and respective initiatives. The Cybersecurity and Digital Technology Committee regularly reports on its activities to Ameren’s board of directors, including reviewing and advising Ameren’s board of directors of any developments it believes should be considered. Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who possesses over 25 years of critical infrastructure experience both managing and protecting information systems in concert with extensive cybersecurity operations and leadership roles. The Chief Information Security Officer regularly engages with senior-level Ameren officers, reports to the risk management steering committee, and has recurring meetings with the Cybersecurity and Digital Technology Committee as part of ongoing risk management and oversight of the cybersecurity program. In addition, Ameren’s board of directors participate in periodic cybersecurity drills to prepare for potential crisis scenarios. To manage against existing and emerging cybersecurity threats, we maintain enterprise-wide cybersecurity, crisis management, and information security policies and regular training and tests that reinforce the acceptable use of Ameren's information assets, protection of customer and employee data, and the role each employee plays in protecting Ameren against cybersecurity threats. Incident response plans and procedures are continuously tested through recurring companywide cybersecurity exercises to promote readiness across the organization. The plans and procedures are also designed to escalate incidents to appropriate members of management to guide the prevention, detection, response, recovery, and remediation from a material cybersecurity incident. These cybersecurity plans and procedures are positioned to promote the expedient identification, escalation, handling and reporting of a potentially material cybersecurity event or incident. To address cybersecurity threats, we work closely with law enforcement, cybersecurity consulting firms, and industry associations to enhance information sharing and guard against cybersecurity attacks. Ameren employs a third-party cybersecurity risk management program, which extends the governance elements of Ameren’s cybersecurity program, in addition to other diligence measures, to our critical third-party providers and suppliers. The supply chain and third-party risks introduced to Ameren are evaluated prior to the commencement of any new engagement or relationship, monitored closely throughout the lifecycle of the supplier and managed through privacy and cybersecurity provisions within the respective commercial contracts. Procedures have been established to address supplier incidents as well as supplier off-boarding at the expiration of the relationship. We leverage common and widely accepted external cybersecurity risk management frameworks, such as the National Institute of Standards and Technology Cybersecurity framework, to assess, guide, and enhance our cybersecurity posture. Our program effectiveness is measured through formal cybersecurity scorecards and metrics reported to senior-level Ameren officers, the risk management steering committee, and the Cybersecurity and Digital Technology Committee. These metrics include but are not limited to measures on the effectiveness of our cybersecurity controls across core National Institute of Standards and Technology Cybersecurity framework functions (Govern, Identify, Protect, Detect, Respond, and Recover), our ability to manage first- and third-party cybersecurity events and incidents, cybersecurity incident response exercises, results of our recurring internal assessments, vulnerability assessments, penetration tests, external assessments, and audits that Ameren regularly undergoes. Ameren regularly engages external cybersecurity experts to assist with evaluating our cybersecurity program. These engagements provide insights into control design and implementation, prioritized recommendations for enhancements to our cybersecurity strategy, and an overview of the cybersecurity threat landscape that collectively inform our investments and technical controls to protect Ameren's most critical assets. The results of these engagements are reviewed with senior-level Ameren officers, the risk management steering committee, and the Cybersecurity and Digital Technology Committee.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	Ameren's board of directors maintains a standing committee, the Cybersecurity and Digital Technology Committee, which is focused on the oversight of Ameren's cybersecurity and digital technology risks.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	The committee has primary responsibility for oversight of cybersecurity and digital technology risk management, including the programs, policies, procedures, processes, controls and safeguards for digital technology, information security, prevention and detection of cybersecurity incidents or data breaches, and cybersecurity and digital technology matters as they relate to crisis preparedness, incident response plans, and disaster recovery and business continuity capabilities.
Cybersecurity Risk Role of Management [Text Block]	Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who possesses over 25 years of critical infrastructure experience both managing and protecting information systems in concert with extensive cybersecurity operations and leadership roles. The Chief Information Security Officer regularly engages with senior-level Ameren officers, reports to the risk management steering committee, and has recurring meetings with the Cybersecurity and Digital Technology Committee as part of ongoing risk management and oversight of the cybersecurity program. In addition, Ameren’s board of directors participate in periodic cybersecurity drills to prepare for potential crisis scenarios.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who possesses over 25 years of critical infrastructure experience both managing and protecting information systems in concert with extensive cybersecurity operations and leadership roles.
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who possesses over 25 years of critical infrastructure experience both managing and protecting information systems in concert with extensive cybersecurity operations and leadership roles.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	The plans and procedures are also designed to escalate incidents to appropriate members of management to guide the prevention, detection, response, recovery, and remediation from a material cybersecurity incident. These cybersecurity plans and procedures are positioned to promote the expedient identification, escalation, handling and reporting of a potentially material cybersecurity event or incident.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag]	true

Summary Of Significant Accoun_2

Summary Of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2024
Accounting Policies [Abstract]
Nature of Operations	General Ameren, headquartered in St. Louis, Missouri, is a public utility holding company whose primary assets are its equity interests in its subsidiaries. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below. Ameren also has other subsidiaries that conduct other activities, such as providing shared services. • Union Electric Company, doing business as Ameren Missouri, operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri. Ameren Missouri was incorporated in Missouri in 1922 and is successor to a number of companies, the oldest of which was organized in 1881. It is the largest electric utility in the state of Missouri. It supplies electric and natural gas service to a 24,000-square-mile area in central and eastern Missouri, which includes the Greater St. Louis area. Ameren Missouri supplies electric service to 1.3 million customers and natural gas service to 0.1 million customers. • Ameren Illinois Company, doing business as Ameren Illinois, operates rate-regulated electric transmission, electric distribution, and natural gas distribution businesses in Illinois. Ameren Illinois was incorporated in Illinois in 1923 and is the successor to a number of companies, the oldest of which was organized in 1902. Ameren Illinois supplies electric and natural gas utility service to a 43,700 square mile area in central and southern Illinois. Ameren Illinois supplies electric service to 1.2 million customers and natural gas service to 0.8 million customers. • ATXI operates a FERC rate-regulated electric transmission business in the MISO. ATXI was incorporated in Illinois in 2006. ATXI operates, among other assets, the Spoon River, Mark Twain, and Illinois Rivers transmission lines.
Consolidation	Ameren’s and Ameren Missouri’s financial statements are prepared on a consolidated basis and therefore include the accounts of their majority-owned subsidiaries. All intercompany transactions have been eliminated. Ameren Illinois has no subsidiaries. All tabular dollar amounts are in millions, unless otherwise indicated. Our accounting policies conform to GAAP. Our financial statements reflect all adjustments (which include normal, recurring adjustments) that are necessary, in our opinion, for a fair presentation of our results. The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. Such estimates and assumptions affect reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of financial statements, and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates.
Public Utilities	Regulation Our customer rates are regulated by the MoPSC, the ICC, and the FERC. We defer certain costs as assets pursuant to actions of rate regulators or because of expectations that we will be able to recover such costs in future rates charged to customers. We also defer certain amounts as liabilities pursuant to actions of rate regulators or based on the expectation that such amounts will be refunded to customers in future rates. Regulatory assets and liabilities are amortized consistent with the period of expected regulatory treatment. See Note 2 – Rate and Regulatory Matters for additional information on our regulatory frameworks, regulatory recovery mechanisms, and regulatory assets and liabilities recorded at December 31, 2024 and 2023. We periodically assess the recoverability of our regulatory assets and probability of refund of our regulatory liabilities. Regulatory assets are charged to earnings when it is no longer probable that such amounts will be recovered through future revenues. To the extent that refunds to customers related to regulatory liabilities are eliminated by the regulator or are no longer probable, the amounts are credited to earnings. Environmental Costs Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are expensed or deferred as a regulatory asset when it is expected that the costs will be recovered from customers in future rates. See Note 14 – Commitments and Contingencies for additional information on liabilities for environmental costs.
Cash and Cash Equivalents	Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents include short-term, highly liquid investments purchased with an original maturity of three months or less. Cash and cash equivalents subject to legal or contractual restrictions and not readily available for use for general corporate purposes are classified as restricted cash. See Note 15 – Supplemental Information for a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets and the statements of cash flows.
Allowance for Doubtful Accounts Receivable	Allowance for Doubtful Accounts Receivable The allowance for doubtful accounts represents our estimate of existing accounts receivable that will ultimately be uncollectible. The allowance is calculated by applying estimated loss factors to various classes of outstanding receivables, including unbilled revenue. The loss factors used to estimate uncollectible accounts are based upon both historical collections experience and management’s estimate of future collections success given the existing and anticipated future collections environment. Ameren Illinois has bad debt riders that adjust rates for net write-offs of customer accounts receivable above or below those being collected in rates.
Inventories	Inventories Inventories are recorded at the lower of weighted-average cost or net realizable value. Inventories are charged to expense or capitalized to property, plant and equipment when issued, as appropriate, using the weighted-average cost method. See Note 15 – Supplemental Information for the components of inventories.
Property and Plant	Property, Plant, and Equipment, Net We capitalize the cost of additions to, and betterments of, units of property, plant, and equipment. The cost includes labor, material, applicable taxes, and overhead. An allowance for funds used during construction, as discussed below, is also capitalized as a cost of our rate-regulated assets. Maintenance expenses related to scheduled Callaway nuclear refueling and maintenance outages are deferred and amortized over the number of expected months until the completion of the next refueling outage, which historically has been approximately 18 months . Other maintenance expenditures are expensed as incurred. When units of depreciable property are retired, the original costs, and the associated removal cost, net of salvage, are charged to accumulated depreciation. If environmental expenditures are related to assets currently in use, as in the case of the installation of pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset. See Asset Retirement Obligations and Removal Costs section below and Note 3 – Property, Plant, and Equipment, Net for additional information. Ameren Missouri’s cost of nuclear fuel is capitalized as a part of “Property, Plant, and Equipment, Net” on Ameren and Ameren Missouri’s balance sheets and then amortized to “Operating Expenses – Fuel and purchased power” in their respective statements of income on a unit-of-production basis. Nuclear fuel amortization is reflected as a part of “Amortization of nuclear fuel” on their respective statements of cash flow. Plant to be Abandoned, Net When it becomes probable an asset will be retired significantly in advance of its previously expected useful life and in the near term, the Ameren Companies must assess the probability of recovery of the remaining net book value of the asset to be abandoned. We recognize a loss on abandonment when it becomes probable that all or part of the cost of an asset, including a return at the applicable WACC, will be disallowed from recovery either through customer rates or through the issuance of securitized utility tariff bonds and such amount is reasonably estimable. An abandonment loss, if any, would equal the difference between the remaining net book value of the asset and the present value of the expected future cash flows. If the asset is still in service, the net book value is classified as plant to be abandoned, net, within “Property, Plant, and Equipment, Net” on the balance sheet. The net book value will be classified as a regulatory asset on the balance sheet when the asset is no longer in service or as required by a rate order. In relation to the NSR and Clean Air Act litigation discussed in Note 14 – Commitments and Contingencies, Ameren Missouri retired the Rush Island Energy Center on October 15, 2024. In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance costs related to the accelerated retirement of the Rush Island Energy Center. In December 2024, AMF issued $476 million of securitized utility tariff bonds. As a result of the financing order and the issuance of the securitized utility tariff bonds, Ameren Missouri concluded no abandonment loss was required for the Rush Island Energy Center and classified the remaining net book value as a regulatory asset as of December 31, 2024. See Variable Interest Entities below, Note 2 – Rate and Regulatory Matters, and Note 5 – Long-term Debt and Equity Financings for additional information on Ameren Missouri's securitization of the Rush Island Energy Center's costs. As of December 31, 2023, Ameren and Ameren Missouri determined that the Rush Island Energy Center met the criteria to be considered probable of abandonment and classified its remaining net book value as plant to be abandoned, net, within “Property, Plant, and Equipment, Net” on Ameren’s and Ameren Missouri’s balance sheets. See Note 3 – Property, Plant, and Equipment, Net for our plant to be abandoned balance as of December 31, 2023. Depreciation Depreciation is provided over the estimated lives of the various classes of depreciable tangible property by applying composite rates on a straight-line basis to the cost basis of such property. The composite rates include a provision for the estimated removal cost of property, plant, and equipment retired from service, net of salvage. See Asset Retirement Obligation and Removal Costs section below for additional information. The provision for depreciation for the Ameren Companies in 2024, 2023, and 2022 ranged from 3% to 4% of the average depreciable cost. See Note 3 – Property, Plant, and Equipment, Net for additional information on estimated depreciable lives.
Allowance for Funds Used During Construction	Allowance for Funds Used During Construction As a part of “Property, Plant, and Equipment, Net” on the balance sheet, we capitalize allowance for funds used during construction, which is the cost of borrowed funds and the cost of equity funds (preferred and common shareholders’ equity) applicable to eligible rate-regulated construction work in progress, in accordance with the utility industry’s accounting practice and GAAP. The amount of allowance for funds used during construction is calculated using a FERC-prescribed formula based on a rate, which incorporates the average cost of short-term debt, the average cost of long-term debt, and the cost of equity funds. The portion attributable to borrowed funds is recorded as a reduction of “Interest Charges” on the statements of income. The portion attributable to equity funds is recorded within “Other Income, Net” on the statements of income. This accounting practice offsets the effect on earnings of the cost of financing during construction. See Note 15 – Supplemental Information for the amount of allowance for funds used during construction capitalized and the average rate applied to eligible construction work in progress. Allowance for funds used during construction does not represent a current source of cash funds. Under accepted ratemaking practice, cash recovery of allowance for funds used during construction and other construction costs occurs when completed projects are placed in service and reflected in customer rates.
Goodwill	Goodwill Goodwill represents the excess of the purchase price of an acquisition over the fair value of the net assets acquired. Ameren and Ameren Illinois had goodwill of $411 million at December 31, 2024 and 2023. Ameren has four reporting units: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission. Ameren Illinois has three reporting units: Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission. Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission had goodwill of $238 million, $80 million, and $93 million, respectively, at December 31, 2024 and 2023. The Ameren Transmission reporting unit had the same $93 million of goodwill as the Ameren Illinois Transmission reporting unit at December 31, 2024 and 2023. Ameren and Ameren Illinois evaluate goodwill for impairment in each of their reporting units as of October 31 each year, or more frequently if events occur or circumstances change that would more likely than not reduce the fair value of their reporting units below their carrying amounts. To determine whether the fair value of a reporting unit is more likely than not greater than its carrying amount, Ameren and Ameren Illinois can elect to perform either a qualitative assessment or to bypass the qualitative assessment and perform a quantitative test. Ameren and Ameren Illinois elected to perform a qualitative assessment for their annual goodwill impairment test conducted as of October 31, 2024. As part of this qualitative assessment, Ameren and Ameren Illinois evaluated, among other things, macroeconomic conditions, industry and market considerations such as observable industry market multiples, regulatory frameworks, cost factors, overall financial performance, and entity-specific events. The results of Ameren’s and Ameren Illinois’ qualitative assessment indicated that it was more likely than not that the fair value of each reporting unit exceeded its carrying value as of October 31, 2024, resulting in no impairment of Ameren’s or Ameren Illinois’ goodwill.
Impairment of Long-lived Assets	Impairment of Long-lived Assets We evaluate long-lived assets classified as held and used for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. Whether an impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets to the carrying value of the assets. If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount by which the carrying value exceeds the estimated fair value of the assets. In the period in which we determine that an asset meets held for sale criteria, we record an impairment charge to the extent the book value exceeds its estimated fair value less cost to sell. We did not identify any events or changes in circumstances that indicated that the carrying value of material long-lived assets may not be recoverable in 2024, 2023, or 2022.
Variable Interest Entities	Variable Interest Entities Variable Interest Entities that are Consolidated AMF was formed in 2024, for the purpose of issuing and servicing securitized utility tariff bonds related to costs for the accelerated retirement of the Rush Island Energy Center. Ameren Missouri is the primary beneficiary of this entity because it has the power to direct the activities that most significantly impact the economic performance of the company, as well as the obligation to absorb losses or the right to receive benefits from the company. The entity is considered a variable interest entity primarily because its equity capitalization is insufficient to support its operations. The entity’s primary assets and liabilities are comprised of regulatory assets related to the unrecovered net plant balance associated with the facility, among other costs, and long-term debt. Ameren and Ameren Missouri consolidate AMF, which Ameren Missouri wholly owns, and both manages and controls the entity’s operating activities. For additional information on the securitization of the Rush Island Energy Center costs, see Note 2 – Rate and Regulatory Matters. For additional information on the securitized tariff bond issuance, see Note 5 – Long-term Debt and Equity Financings. The following table presents the carrying values of AMF’s assets and liabilities included on Ameren’s and Ameren Missouri’s consolidated balance sheets as of December 31, 2024: 2024 Other current assets (a) $ 2 Noncurrent regulatory assets (a) 465 Current maturities of long term debt (b) 17 Interest accrued (b) 1 Long-term debt, net (b) 448 (a) Assets may be used only to meet AMF’s obligations and commitments. (b) The securitized tariff bondholders have no recourse to Ameren Missouri. Variable Interest Entities that are not Consolidated As of December 31, 2024 and 2023, Ameren had unconsolidated variable interests in various equity method investments, primarily to advance clean and resilient energy technologies, totaling $74 million and $73 million, respectively, included in “Other assets” on Ameren’s consolidated balance sheet. Any earnings or losses related to these investments are included in “Other Income, Net” on Ameren’s consolidated statement of income and comprehensive income. Ameren is not the primary beneficiary of these investments because it does not have the power to direct matters that most significantly affect the activities of these variable interest entities. As of December 31, 2024, the maximum exposure to loss related to these variable interest entities is limited to the investment in these partnerships of $74 million plus associated outstanding funding commitments of $35 million.
Asset Retirement Obligations	Asset Retirement Obligations and Removal Costs We record the estimated fair value of legal obligations associated with the retirement of tangible long-lived assets in the period in which the liabilities are incurred and capitalize a corresponding amount as part of the book value of the related long-lived asset. In subsequent periods, we adjust AROs for accretion and changes in the estimated fair values of the obligations, with a corresponding increase or decrease in the asset book value for the fair value changes. Asset book values, reflected within “Property, Plant, and Equipment, Net” on the balance sheet, are depreciated over the remaining useful life of the related asset. Depreciation is deferred as a regulatory balance. The depreciation of the asset book values at Ameren Missouri was $2 million , $9 million, and $7 million for the years ended December 31, 2024, 2023, and 2022, respectively, which was deferred as a reduction to the net regulatory liability. The net regulatory liability also reflects a deferral for the nuclear decommissioning trust fund balance for the Callaway Energy Center. The depreciation deferred to the regulatory asset at Ameren Illinois was immaterial in each respective period. Uncertainties as to the probability, timing, or amount of cash expenditures associated with AROs affect our estimates of fair value. Ameren and Ameren Missouri have recorded AROs for retirement costs associated with decommissioning of Ameren Missouri’s Callaway and wind renewable energy centers, certain Ameren Missouri solar energy centers, CCR facilities, and river structures at certain energy centers used for unloading coal and circulating water systems. Additionally, Ameren, Ameren Missouri, and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal and the disposal of certain transformers. See Note 15 – Supplemental Information for a reconciliation of the beginning and ending carrying amounts of AROs. Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment retired from service, net of salvage, represent a cost of removal regulatory liability. See the cost of removal regulatory liability balance in Note 2 – Rate and Regulatory Matters.
Company-owned Life Insurance	COLI Ameren (parent) and Ameren Illinois have COLI, which is recorded at the net cash surrender value. The net cash surrender value is the amount that can be realized under the insurance policies at the balance sheet date. As of December 31, 2024, the cash surrender value of COLI at Ameren and Ameren Illinois was $260 million (December 31, 2023 – $248 million) and $118 million (December 31, 2023 – $111 million), respectively, while total borrowings against the policies were $110 million (December 31, 2023 – $104 million) at both Ameren and Ameren Illinois. Ameren and Ameren Illinois have the right to offset the borrowings against the cash surrender value of the policies and, consequently, present the net asset in “Other assets” on their respective balance sheets. The net cash surrender value of Ameren’s COLI is affected by the investment performance of a separate account in which Ameren holds a beneficial interest.
Operating Revenues	Operating Revenues We record revenues from contracts with customers for various electric and natural gas services, which primarily consist of retail distribution, electric transmission, and off-system arrangements. When more than one performance obligation exists in a contract, the consideration under the contract is allocated to the performance obligations based on the relative standalone selling price. Electric and natural gas retail distribution revenues are earned when the commodity is delivered to our customers. We accrue an estimate of electric and natural gas retail distribution revenues for service provided but unbilled at the end of each accounting period. Electric transmission revenues are earned as electric transmission services are provided. Off-system revenues are primarily comprised of MISO revenues and wholesale bilateral revenues. MISO revenues include the sale of electricity, capacity, and ancillary services. Wholesale bilateral revenues include the sale of electricity and capacity. MISO-related electricity and wholesale bilateral electricity revenues are earned as electricity is delivered. Capacity and ancillary service revenues are earned as services are provided. Retail distribution, electric transmission, and off-system revenues, including the underlying components described above, represent a series of goods or services that are substantially the same and have the same pattern of transfer over time to our customers. Revenues from contracts with customers are equal to the amounts billed and our estimate of electric and natural gas retail distribution services provided but unbilled at the end of each accounting period. Customers are billed at least monthly, and payments are due less than one month after goods and/or services are provided. See Note 16 – Segment Information for disaggregated revenue information. For certain regulatory recovery mechanisms that are alternative revenue programs rather than revenues from contracts with customers, we recognize revenues that have been authorized for rate recovery, are objectively determinable and probable of recovery, and are expected to be collected from customers within two years from the end of the year. Our alternative revenue programs include revenue requirement reconciliations, the MEEIA, the RBA, the VBA, and the WNAR. These revenues are subsequently recognized as revenues from contracts with customers when billed, with an offset to alternative revenue program revenues. As of December 31, 2024 and 2023, our remaining performance obligations were immaterial. The Ameren Companies elected not to disclose the aggregate amount of the transaction price allocated to the performance obligations that are unsatisfied as of the end of the reporting period for contracts with an initial expected term of one year or less.
Cost Of Sales	Accounting for MISO Transactions MISO-related purchase and sale transactions are recorded by Ameren, Ameren Missouri, and Ameren Illinois using settlement information provided by the MISO. Ameren Missouri records these purchase and sale transactions on a net hourly position. Ameren Missouri records net purchases in a single hour in “Operating Expenses – Fuel and purchased power” and net sales in a single hour in “Operating Revenues – Electric” in its statement of income. Ameren Illinois records net purchases in “Operating Expenses – Fuel and purchased power” in its statement of income to reflect all of its MISO transactions relating to the procurement of power for its customers.
Stock-Based Compensation	Stock-based Compensation Stock-based compensation cost is measured at the grant date based on the fair value of the award, net of an assumed forfeiture rate. Ameren recognizes as compensation expense the estimated fair value of stock-based compensation on a straight-line basis over the requisite vesting period. To the extent that actual forfeitures differ from estimated forfeitures, such differences are accounted for as an adjustment to compensation expense and recorded in the period that estimates are revised. Compensation cost is ultimately recognized only for awards for which the requisite service was provided. See Note 11 – Stock-based Compensation for additional information.
Unamortized Debt Discount, Premium, And Expense	Unamortized Debt Discounts, Premiums, and Issuance Costs Long-term debt discounts, premiums, and issuance costs are amortized over the lives of the related issuances. Credit agreement fees are amortized over the term of the agreement.
Income Taxes	Income Taxes Ameren uses an asset and liability approach for its financial accounting and reporting of income taxes. Deferred tax assets and liabilities are recognized for transactions that are treated differently for financial reporting and income tax return purposes. These deferred tax assets and liabilities are based on statutory tax rates. We expect that regulators will reduce future revenues for deferred tax liabilities that were initially recorded at rates in excess of the current statutory rate. Therefore, reductions in certain excess deferred tax liabilities that were recorded because of decreases in the statutory rate have been credited to a regulatory liability. A regulatory asset has been established to recognize the probable recovery through future customer rates of tax benefits related to the equity component of allowance for funds used during construction, as well as the effects of tax rate increases. To the extent deferred tax balances are included in rate base, the revaluation of deferred taxes caused by a change in the statutory rate is recorded as a regulatory asset or liability on the balance sheet and will be collected from, or refunded to, customers. For deferred tax balances not included in rate base, the revaluation of deferred taxes caused by a change in the statutory rate is recorded as an adjustment to income tax expense on the income statement. Tax credits other than investment tax credits are recognized as a reduction to income tax expense when earned. The benefits for investment tax credits not transferred under the IRA are amortized over the book depreciable lives of the related property. For production and other tax credits otherwise eligible to be recognized when earned and for investment tax credits transferred under the IRA, Ameren considers the impact of rate regulation to determine if these credits and related adjustments should be deferred as regulatory liabilities. See Note 2 – Rate and Regulatory Matters for additional information on Ameren Missouri’s production and investment tax credit tracker and the RESRAM. Ameren Missouri, Ameren Illinois, and all the other Ameren subsidiary companies are parties to a tax allocation agreement with Ameren (parent) that provides for the allocation of consolidated tax liabilities. The tax allocation agreement specifies that each subsidiary be allocated an amount of tax using a stand-alone calculation ratio to the total amount of tax owed by the consolidated group. Any net benefit attributable to Ameren (parent) is reallocated to the other subsidiaries. This reallocation is treated as a capital contribution to the subsidiary receiving the benefit. See Note 13 – Related-party Transactions for information regarding capital contributions under the tax allocation agreement.
Noncontrolling Interests	The preferred stock of Ameren’s subsidiaries is included in “Noncontrolling Interests” on Ameren’s consolidated balance sheet
Derivatives, Policy	We use derivatives to manage the risk of changes in market prices for natural gas, power, uranium, and interest rates, as well as the risk of changes in rail transportation surcharges through fuel oil hedges. Such price fluctuations may cause the following: • an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices; • market values of natural gas and uranium inventories that differ from the cost of those commodities in inventory; • actual cash outlays for interest expense and the purchase of commodities that differ from anticipated cash outlays; and • actual off-system sales revenues that differ from anticipated revenues. The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty. The Ameren Companies elect to present the fair value amounts of derivative assets and derivative liabilities subject to an enforceable master netting arrangement or similar agreement at the gross amounts on the balance sheet. However, if the gross amounts recognized on the balance sheet were netted with derivative instruments and cash collateral received or posted, the net amounts would not be materially different from the gross amounts at December 31, 2024 and 2023.
Lessee, Leases	Leases Ameren and Ameren Missouri have lease agreements primarily relating to rail cars and land related to solar generation facilities. The land leases are related to the Cass County, Boomtown, and Huck Finn energy centers. See Note 2 – Rate and Regulatory Matters for additional information on the acquisitions. Rail cars are leased for the transportation of coal to its energy centers. For rail car leases, we account for the lease and non-lease components as a single lease component, and for the land leases related to solar generation projects, we account for the components separately for each agreement. Certain of the land leases related to the acquisitions of the Cass County, Boomtown, and Huck Finn energy centers have options to renew or terminate those leases. Termination and renewal options are not expected to be exercised and are not included in any of the lease measurements used to record the leased assets and liabilities in the tables below.
Excise Taxes	Excise Taxes
Earnings Per Share, Policy	Earnings per Share

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2024
Accounting Policies [Abstract]
Schedule of Other Assets and Other Liabilities	The following table presents the carrying values of AMF’s assets and liabilities included on Ameren’s and Ameren Missouri’s consolidated balance sheets as of December 31, 2024: 2024 Other current assets (a) $ 2 Noncurrent regulatory assets (a) 465 Current maturities of long term debt (b) 17 Interest accrued (b) 1 Long-term debt, net (b) 448 (a) Assets may be used only to meet AMF’s obligations and commitments. (b) The securitized tariff bondholders have no recourse to Ameren Missouri.

Rate And Regulatory Matters (Ta

Rate And Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2024
Public Utilities, General Disclosures [Abstract]
Schedule of Regulatory Frameworks and Significant Recovery Mechanisms	The following table presents the regulatory frameworks and significant regulatory recovery mechanisms for each of Ameren’s rate-regulated businesses, which are discussed in more detail below: Ameren Missouri Ameren Illinois’ electric distribution business Ameren Illinois’ natural gas delivery business Ameren Illinois’ and ATXI’s electric transmission businesses Regulatory framework • Historical test year ratemaking • Natural gas revenues for residential customers adjusted for sales volume deviations resulting from weather through the WNAR • MYRP • Initial rates based on future test years • Revenues decoupled from sales volumes and wholesale and miscellaneous revenues through the RBA • Future test year ratemaking • Revenues for residential and small nonresidential customers decoupled from sales volumes through the VBA • Formula ratemaking • Initial rates based on future test year • Revenues decoupled from sales volumes Regulatory mechanisms • PISA Riders: • RESRAM • FAC • Rush Island Securitization • MEEIA • PGA • WNAR Trackers: • Pension and postretirement benefit costs • Certain excess deferred income taxes • Renewable energy standard costs • Property taxes • Production and investment tax credits or proceeds from the sale of certain tax credits allowed under the IRA • Electric distribution service and energy-efficiency revenue requirement reconciliation adjustments (a) Riders: • RBA • Power procurement • Transmission services • Renewable energy credit compliance • Zero emission credits • Customer generation rebate program costs • Certain environmental costs • Bad debt write-offs • Costs of certain asbestos-related claims Riders: • PGA • VBA • Energy-efficiency program costs • Certain environmental costs • Bad debt write-offs • Invested capital taxes • Revenue requirement reconciliation adjustment (a)
Schedule of Solar Projects	The following table provides information with respect to each agreement: Agreement type Facility size Status of MoPSC CCN Status of FERC approval of acquisition In-service date (a) Huck Finn Solar Project (b)(c) Build-transfer 200-MW Approved February 2023 Received March 2023 December 2024 Boomtown Solar Project (c)(d) Build-transfer 150-MW Approved April 2023 Received October 2023 December 2024 Cass County Solar Project (c)(d) Development-transfer 150-MW Approved June 2024 Not applicable December 2024 Vandalia Solar Project (e)(f) Self-build 50-MW Approved March 2024 Not applicable Fourth quarter 2025 Bowling Green Solar Project (e)(f) Self-build 50-MW Approved March 2024 Not applicable First quarter 2026 Split Rail Solar Project (e)(f) Build-transfer 300-MW Approved March 2024 Received November 2024 Mid-2026 Castle Bluff Natural Gas Project (e) Self-build 800-MW Approved October 2024 (g) Not applicable Fourth quarter 2027 (a) In-service dates are dependent on the timing of construction completion, among other things. The assets of the Huck Finn, Boomtown, and Cass County solar projects were placed in service in December 2024. (b) The Huck Finn Solar Project is expected to support Ameren Missouri’s compliance with the state of Missouri’s renewable energy standard. Investments in the project are eligible for recovery under the RESRAM. (c) Ameren Missouri acquired the Cass County, Boomtown, and Huck Finn solar projects in June 2024, September 2024, and October 2024, respectively, and placed the assets of the projects, totaling $1 billion, in service in December 2024. (d) The Boomtown and Cass County solar projects are expected to support Ameren Missouri’s transition to renewable energy generation and serve customers under the Renewable Solutions Program, which allows certain commercial, industrial, and governmental customers who enroll in the program to receive up to 100% of their energy from renewable resources. (e) These projects collectively represent approximately $1.7 billion of expected capital expenditures. (f) These solar projects are expected to support Ameren Missouri’s transition to renewable energy generation. (g) For additional information see Castle Bluff Natural Gas Project CCN and Post-Construction Cost Deferral below.
Schedule of MYRP details	The following table presents the approved revenue requirements and average annual rate base in the ICC’s December 2024 MYRP order and the ICC’s June 2024 rehearing order: Year Revenue Requirement (in millions) Average Annual Rate Base (in billions) ICC’s December 2024 MYRP Order (a) : 2024 $1,206 $4.2 2025 $1,287 $4.4 2026 $1,367 $4.6 2027 $1,422 $4.8 ICC’s June 2024 Rehearing Order (a) : 2024 $1,196 $4.0 2025 $1,282 $4.3 2026 $1,350 $4.5 2027 $1,397 $4.7 (a) Based on an allowed ROE of 8.72% and a capital structure composed of 50% common equity. The ROE is under appeal, as discussed above. New rates became effective in December 2024.
Schedule Of Regulatory Assets And Liabilities	The following table presents our regulatory assets and regulatory liabilities at December 31, 2024 and 2023: 2024 2023 Ameren Ameren Ameren Ameren Ameren Ameren Regulatory assets: Under-recovered FAC (a) $ 41 $ — $ 41 $ 72 $ — $ 72 MTM derivative losses (b) 15 88 103 25 143 168 IEIMA revenue requirement reconciliation adjustment (c)(d) — 139 139 — 239 239 MYRP revenue requirement reconciliation adjustment (d)(e) — 24 24 — — — Under-recovered RBA (f) — 22 22 — — — FERC revenue requirement reconciliation adjustment (g) — 55 90 — 25 54 Under-recovered VBA (h) — 49 49 — 49 49 Income taxes (i) 237 81 322 126 78 207 Bad debt rider (j) — 25 25 — 43 43 Callaway refueling and maintenance outage costs (k) 13 — 13 37 — 37 Unamortized loss on reacquired debt (l) 42 5 47 45 5 50 Environmental cost riders (m) — 43 43 — 50 50 Storm costs (d)(n) — 18 18 — 27 27 Customer generation rebate program (d)(o) — 89 89 — 54 54 PISA (d)(p) 464 — 464 386 — 386 Rush Island Energy Center securitization (q) 465 — 465 — — — RESRAM (r) 51 — 51 48 — 48 Certain Meramec Energy Center costs (s) 26 — 26 39 — 39 Energy-efficiency rider (d)(t) — 576 576 — 500 500 Property tax tracker (u) 22 — 22 13 — 13 Other 56 78 134 65 74 139 Total regulatory assets $ 1,432 $ 1,292 $ 2,763 $ 856 $ 1,287 $ 2,175 Less: current regulatory assets (66) (281) (366) (101) (252) (365) Noncurrent regulatory assets $ 1,366 $ 1,011 $ 2,397 $ 755 $ 1,035 $ 1,810 Regulatory liabilities: Over-recovered Illinois electric power costs (v) — 34 34 — 36 36 Over-recovered PGA (v) 2 33 35 7 33 40 MTM derivative gains (b) 10 6 16 19 3 22 Income taxes (i) 1,040 679 1,804 999 724 1,809 Cost of removal (w) 1,118 1,115 2,294 1,098 1,038 2,186 AROs (x) 691 — 691 524 — 524 Pension and postretirement benefit costs (y) 202 156 358 202 144 346 Pension and postretirement benefit costs tracker (z) 70 — 70 111 — 111 Renewable energy credits and zero emission credits (aa) — 586 586 — 489 489 Certain Rush Island Energy Center costs (ab) 66 — 66 — — — Other 14 43 63 14 22 36 Total regulatory liabilities $ 3,213 $ 2,652 $ 6,017 $ 2,974 $ 2,489 $ 5,599 Less: current regulatory liabilities (37) (79) (120) (15) (71) (87) Noncurrent regulatory liabilities $ 3,176 $ 2,573 $ 5,897 $ 2,959 $ 2,418 $ 5,512 (a) Under-recovered fuel and purchased power costs to be recovered through the FAC. Specific accumulation periods aggregate the under-recovered costs over four months, any related adjustments that occur over the following four months, and the recovery from customers that occurs over the next eight months. (b) Deferral of commodity-related derivative MTM losses or gains. See Note 7 – Derivative Financial Instruments for additional information. (c) The difference between Ameren Illinois’ electric distribution service annual revenue requirement calculated under the IEIMA performance-based formula ratemaking framework and the revenue requirement included in customer rates for that year. The under-recovery will be recovered from customers with a return at the applicable WACC within two years. (d) These assets earn a return at the applicable WACC. (e) The difference between Ameren Illinois' actual electric distribution revenue requirement, as adjusted for certain cost variations, and the ICC-approved revenue requirement, subject to a reconciliation cap. The under-recovery will be recovered from customers with a return at the applicable WACC within two years. (f) Under-recovered electric distribution service revenue caused by sales volume and/or wholesale and miscellaneous revenue deviations from the related revenue requirement approved by the ICC for a given year. The under-recovery will be recovered from customers within two years. (g) Ameren Illinois’ and ATXI’s annual revenue requirement reconciliation calculated pursuant to the FERC’s electric transmission formula ratemaking framework. Any under-recovery or over-recovery will be recovered from, or refunded to, customers within two years. (h) Under-recovered natural gas revenue caused by sales volume deviations from weather normalized sales approved by the ICC in rate regulatory reviews. Each year’s amount will be recovered from customers from April through December of the following year. (i) The regulatory assets represent amounts that will be recovered from customers for deferred income taxes related to the equity component of allowance for funds used during construction, the securitization of the Rush Island Energy Center, and the effects of tax rate increases. The regulatory liabilities represent amounts that will be refunded to customers for excess deferred income taxes related to depreciation differences caused by a decrease in the statutory rates, other tax liabilities, and amounts related to the unamortized portion of investment tax credits. Amounts associated with the equity component of allowance for funds used during construction, the securitization of the Rush Island Energy Center, and amounts related to the unamortized portion of investment tax credits will be amortized over the expected life of the related assets. For net regulatory liabilities related to deferred income taxes recorded at rates other than the current statutory rate, the weighted-average remaining amortization periods at Ameren, Ameren Missouri, and Ameren Illinois are 39, 30, and 46 years. In addition, the regulatory liabilities for Ameren Missouri include a regulatory recovery mechanism for the difference between production and investment tax credits or proceeds from the sale of such tax credits allowed under the IRA and the level of such tax credits included in customer rates. The period of refund varies based on MoPSC approval in a regulatory rate review. The amortization period will be determined in a future regulatory rate review. (j) A rider for the difference between the level of bad debt write-offs, net of any subsequent recoveries, incurred by Ameren Illinois and the level of such costs included in electric distribution and natural gas delivery service rates. Under-recovered or over-recovered costs for each year are collected from, or refunded to, customers over a twelve-month period beginning in June of the following year. (k) Maintenance expenses related to scheduled refueling and maintenance outages at Ameren Missouri’s Callaway Energy Center. Amounts are amortized over the period between refueling and maintenance outages, which has historically been approximately 18 months. (l) Losses related to reacquired debt. These amounts are being amortized over the lives of the related new debt issuances or the original lives of the old debt issuances if no new debt was issued. (m) The recoverable portion of accrued environmental site liabilities that will be collected from electric and natural gas customers through ICC-approved cost recovery riders. The period of recovery will depend on the timing of remediation expenditures. See Note 14 – Commitments and Contingencies for additional information. (n) Storm costs from 2020 through 2023 deferred in accordance with the IEIMA and MYRP. These costs are being amortized over five-year periods beginning in the year the storm occurred. (o) Costs associated with Ameren Illinois’ customer generation rebate program. Costs are amortized over a 15-year period, beginning in the year rebates are paid. (p) Under the PISA, Ameren Missouri is permitted to defer and recover 85% of the depreciation expense and earn a return at the applicable WACC on 85% of investments in certain property, plant, and equipment placed in service and not included in base rates. Accumulated PISA deferrals, which also earn a return at the applicable WACC, are added to rate base prospectively and amortized over a period of 20 years following a regulatory rate review. (q) In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance costs related to the accelerated retirement of the Rush Island Energy Center, which includes the remaining unrecovered net plant balance associated with the facility, among other costs. Ameren Missouri will collect the amounts necessary to repay the securitized utility tariff bonds over approximately 15 years beginning in December 2024. (r) Under-recovered costs associated with Ameren Missouri’s compliance with the state of Missouri’s renewable energy standard. Under-recovered or over-recovered costs are aggregated over a twelve-month period beginning each August and are amortized over a twelve-month period beginning in February of the following year. (s) Certain costs associated with the Meramec Energy Center, which were authorized for recovery by a December 2021 MoPSC electric rate order. These costs are being collected over five years beginning in February 2022. (t) The electric energy-efficiency investments are being amortized over their weighted-average useful lives beginning in the period in which they were made, with current remaining amortization periods ranging from two (u) A regulatory recovery mechanism for the difference between actual property taxes incurred by Ameren Missouri and the related taxes included in customer rates. The period of recovery, or refund, varies based on MoPSC approval in a regulatory rate review. Amounts accumulated through 2022 are being collected over two years beginning July 2023. The amortization period for amounts accumulated after 2022 will be determined in a future regulatory rate review. (v) Over-recovered costs from utility customers. Amounts will be refunded to customers within one year of the deferral. (w) Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment when retired from service, net of salvage. (x) The ARO regulatory liability includes the nuclear decommissioning trust fund balance ($1,342 million and $1,150 million at December 31, 2024 and 2023, respectively), net of recoverable removal costs for AROs ($651 million and $626 million at December 31, 2024 and 2023, respectively). See Note 1 – Summary of Significant Accounting Policies – Asset Retirement Obligations and Removal Costs. (y) Over-recovered costs are being amortized in proportion to the recognition of prior service costs (credits) and actuarial losses (gains) attributable to Ameren’s pension plan and postretirement benefit plans. See Note 10 – Retirement Benefits for additional information. (z) A regulatory recovery mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri and the level of such costs included in customer rates. The period of refund varies based on MoPSC approval in a regulatory rate review. For electric and natural gas related costs incurred prior to 2023 and 2022, respectively, the weighted-average remaining amortization period is two years. For electric and natural gas related costs incurred after 2023 and 2022, respectively, the amortization period will be determined in a future regulatory rate review. (aa) Funds collected for the purchase of renewable energy credits and zero emission credits through IPA procurements. The balance will be amortized as the credits are purchased. Pursuant to the CEJA, if funds collected from customers are not used to procure renewable energy credits, they would be refunded to customers pursuant to an annual reconciliation proceeding, the latest of which was approved by the ICC in January 2025 and did not result in refunds to customers. (ab) Funds collected from the issuance of securitized utility tariff bonds by AMF primarily to pay for the decommissioning of the Rush Island Energy Center. The amortization period for the difference between the estimated costs and the actual costs incurred will be determined in a future regulatory rate review.

Property And Plant, Net (Tables

Property And Plant, Net (Tables)	12 Months Ended
	Dec. 31, 2024
Property, Plant and Equipment [Abstract]
Schedule Of Property And Plant, Net	The following table presents components of “Property, plant, and equipment, net” at December 31, 2024 and 2023: Ameren Ameren Other Ameren 2024 Property, plant, and equipment at original cost (a) : Electric generation: Coal (b) $ 3,556 $ — $ — $ 3,556 Natural gas 938 — — 938 Nuclear 5,931 — — 5,931 Renewable (c) 2,901 19 — 2,920 Electric distribution 9,469 8,160 — 17,629 Electric transmission 2,406 5,725 2,031 10,162 Natural gas 776 4,421 — 5,197 Other (d) 2,427 1,770 260 4,457 28,404 20,095 2,291 50,790 Less: Accumulated depreciation and amortization 10,875 5,184 436 16,495 17,529 14,911 1,855 34,295 Construction work in progress: Nuclear fuel in progress 268 — — 268 Other 991 619 131 1,741 Property, plant, and equipment, net $ 18,788 $ 15,530 $ 1,986 $ 36,304 2023 Property, plant, and equipment at original cost (a) : Electric generation: Coal (b) $ 3,452 $ — $ — $ 3,452 Natural gas 921 — — 921 Nuclear 5,879 — — 5,879 Renewable (c) 1,973 11 — 1,984 Electric distribution 8,638 7,820 — 16,458 Electric transmission 2,134 5,381 1,993 9,508 Natural gas 688 4,186 — 4,874 Other (d) 2,191 1,657 255 4,103 25,876 19,055 2,248 47,179 Less: Accumulated depreciation and amortization (f) 10,243 4,783 400 15,426 15,633 14,272 1,848 31,753 Construction work in progress: Nuclear fuel in progress 173 — — 173 Other 914 360 46 1,320 Plant to be abandoned, net (e) 530 — — 530 Property, plant, and equipment, net $ 17,250 $ 14,632 $ 1,894 $ 33,776 (a) The estimated lives for each asset group are as follows: 5 to 72 years for electric generation, excluding Ameren Missouri’s hydroelectric generating assets, which have useful lives of up to 150 years; 20 to 80 years for electric distribution; 50 to 75 years for electric transmission; 20 to 80 years for natural gas; and 2 to 55 years for other. (b) Includes $30 million and $29 million of oil-fired generation at December 31, 2024 and 2023, respectively. (c) Renewable includes hydroelectric, wind, solar, and methane gas generation facilities. (d) Other property, plant, and equipment includes assets used to support electric and natural gas services. (e) Represents the net book value of the Rush Island Energy Center as Ameren Missouri retired the energy center in October 2024, significantly in advance of its previously expected useful life. See Plant to be Abandoned, Net under Note 1 – Summary of Significant Accounting Policies, NSR and Clean Air Act Litigation under Note 14 – Commitments and Contingencies, and Securitization of Rush Island Energy Center Costs under Note 2 – Rate and Regulatory Matters for additional information on the accelerated retirement of the Rush Island Energy Center.
Schedule of Capitalized Software and Deferred Cloud Implementation Costs	Capitalized software costs are classified within “Property, Plant, and Equipment, Net” on the balance sheet and are amortized on a straight-line basis over the expected period of benefit, ranging from 2 to 15 years, with the amortization expense included in “Depreciation and amortization” on the statement of income. Deferred cloud implementation costs are classified within “Other Assets” on the balance sheet and are amortized on a straight-line basis over the term of the associated hosting arrangement, ranging from 5 to 15 years, with the amortization expense included in “Other operations and maintenance” on the statement of income. The following table presents the amortization expense, gross carrying value, and related accumulated amortization of capitalized software and deferred cloud implementation costs by year: Amortization Expense Gross Carrying Value Accumulated Amortization 2024 2023 2022 2024 2023 2024 2023 Capitalized software costs: Ameren $ 224 $ 212 $ 159 $ 1,996 $ 1,823 $ (1,348) $ (1,126) Ameren Missouri 118 114 85 881 795 (567) (453) Ameren Illinois 100 92 69 867 786 (552) (452) Deferred cloud implementation costs: Ameren $ 20 $ 17 $ 15 $ 157 $ 142 $ (71) $ (51) Ameren Missouri 9 8 7 71 63 (32) (23) Ameren Illinois 10 9 8 82 76 (36) (26)
Schedule of Capitalized Software, Future Amortization Expense	Annual amortization expense for capitalized software placed in service as of December 31, 2024, is estimated to be as follows: 2025 2026 2027 2028 2029 Ameren $ 190 $ 147 $ 110 $ 69 $ 38 Ameren Missouri 98 73 54 33 17 Ameren Illinois 85 70 53 34 20

Short-Term Debt And Liquidity (

Short-Term Debt And Liquidity (Tables)	12 Months Ended
	Dec. 31, 2024
Line of Credit Facility [Abstract]
Schedule Of Maximum Aggregate Amount Available On Credit Agreements	The following table presents the maximum aggregate amount available to each borrower under each facility: Missouri Illinois Ameren (parent) $ 1,000 $ 700 Ameren Missouri 1,000 (a) Ameren Illinois (a) 1,000 (a) Not applicable.
Schedule of Commercial Paper	The following table summarizes the activity and relevant interest rates for Ameren (parent)’s, Ameren Missouri’s, and Ameren Illinois’ commercial paper issuances under the Credit Agreements in the aggregate for the years ended December 31, 2024 and 2023: Ameren (parent) Ameren Missouri Ameren Illinois Ameren Consolidated 2024 Average daily amount outstanding $ 377 $ 192 $ 193 $ 762 Commercial paper issuances outstanding at period-end 1,055 — 88 1,143 Weighted-average interest rate 5.10 % 5.34 % 5.57 % 5.28 % Peak amount outstanding during period (a) $ 1,091 $ 595 $ 694 $ 1,569 Peak interest rate 5.60 % 5.68 % 5.68 % 5.68 % 2023 Average daily amount outstanding $ 726 $ 274 $ 166 $ 1,166 Commercial paper issuances outstanding at period-end — 170 366 536 Weighted-average interest rate 5.38 % 5.22 % 5.23 % 5.32 % Peak amount outstanding during period (a) $ 1,298 $ 592 $ 450 $ 1,526 Peak interest rate 5.65 % 5.68 % 5.68 % 5.68 % (a) The timing of peak outstanding commercial paper issuances and borrowings under the Credit Agreements varies by company. Therefore, the sum of individual company peak amounts may not equal the Ameren consolidated peak amount for the period.

Long-Term Debt And Equity Fin_2

Long-Term Debt And Equity Financings (Tables)	12 Months Ended
	Dec. 31, 2024
Long-Term Debt And Equity Financings [Abstract]
Schedule of Long-term Debt Instruments	The following table presents long-term debt outstanding, including maturities due within one year, as of December 31, 2024 and 2023: 2024 2023 Ameren (Parent): 2.50% Senior unsecured notes due 2024 $ — $ 450 3.65% Senior unsecured notes due 2026 350 350 5.70% Senior unsecured notes due 2026 600 600 1.95% Senior unsecured notes due 2027 500 500 1.75% Senior unsecured notes due 2028 450 450 5.00% Senior unsecured notes due 2029 700 700 3.50% Senior unsecured notes due 2031 800 800 Total long-term debt, gross 3,400 3,850 Less: Unamortized discount and premium (3) (4) Less: Unamortized debt issuance costs (14) (17) Less: Maturities due within one year — (450) Long-term debt, net $ 3,383 $ 3,379 Ameren Missouri: Bonds and notes: 3.50% Senior secured notes due 2024 (a) $ — $ 350 2.95% Senior secured notes due 2027 (a) 400 400 3.50% First mortgage bonds due 2029 (b) 450 450 2.95% First mortgage bonds due 2030 (b) 465 465 2.15% First mortgage bonds due 2032 (b) 525 525 2.90% 1998 Series A bonds due 2033 (c) 60 60 2.90% 1998 Series B bonds due 2033 (c) 50 50 2.75% 1998 Series C bonds due 2033 (c) 50 50 5.20% First mortgage bonds due 2034 (b) 500 — 5.50% Senior secured notes due 2034 (a) 184 184 5.30% Senior secured notes due 2037 (a) 300 300 8.45% Senior secured notes due 2039 (a)(d) 350 350 4.85% Securitized utility tariff bonds due 2039 (e) 476 — 3.90% Senior secured notes due 2042 (a)(d) 485 485 3.65% Senior secured notes due 2045 (a) 400 400 4.00% First mortgage bonds due 2048 (b) 425 425 3.25% First mortgage bonds due 2049 (b) 330 330 2.625% First mortgage bonds due 2051 (b) 550 550 3.90% First mortgage bonds due 2052 (b) 525 525 5.45% First mortgage bonds due 2053 (b) 500 500 5.25% First mortgage bonds due 2054 (b) 350 — 5.125% First mortgage bonds due 2055 (b) 450 — Total long-term debt, gross 7,825 6,399 Less: Long-term debt – related parties, gross (58) — Less: Unamortized discount and premium (17) (13) Less: Unamortized debt issuance costs (62) (45) Less: Maturities due within one year (17) (350) Long-term debt, net $ 7,671 $ 5,991 2024 2023 Ameren Illinois: Bonds and notes: 3.25% Senior secured notes due 2025 (f) $ 300 $ 300 6.125% Senior secured notes due 2028 (f) 60 60 3.80% First mortgage bonds due 2028 (g) 430 430 1.55% First mortgage bonds due 2030 (g) 375 375 3.85% First mortgage bonds due 2032 (g) 500 500 4.95% First mortgage bonds due 2033 (g) 500 500 6.70% Senior secured notes due 2036 (f) 61 61 6.70% Senior secured notes due 2036 (f) 42 42 4.80% Senior secured notes due 2043 (f) 280 280 4.30% Senior secured notes due 2044 (f) 250 250 4.15% Senior secured notes due 2046 (f) 490 490 3.70% First mortgage bonds due 2047 (g) 500 500 4.50% First mortgage bonds due 2049 (g) 500 500 3.25% First mortgage bonds due 2050 (g) 300 300 2.90% First mortgage bonds due 2051 (g) 350 350 5.90% First mortgage bonds due 2052 (g) 350 350 5.55% First mortgage bonds due 2054 (g) 625 — Total long-term debt, gross 5,913 5,288 Less: Long-term debt – related parties, gross (3) — Less: Unamortized discount and premium (10) (9) Less: Unamortized debt issuance costs (51) (47) Less: Maturities due within one year (300) — Long-term debt, net $ 5,549 $ 5,232 ATXI: 2.45% Senior unsecured notes due 2036 (h) $ 75 $ 75 5.17% Senior unsecured notes due 2039 70 — 3.43% Senior unsecured notes due 2050 (i) 351 400 2.96% Senior unsecured notes due 2052 (j) 95 95 5.42% Senior unsecured notes due 2053 70 — Total long-term debt, gross 661 570 Less: Unamortized debt issuance costs (2) (2) Less: Maturities due within one year — (49) Long-term debt, net $ 659 $ 519 Ameren consolidated long-term debt, net $ 17,262 $ 15,121 (a) These notes are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Missouri mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the 2055 maturity date of the 5.125% first mortgage bonds and the restrictions preventing a release date to occur that are attached to certain senior secured notes described in footnote (d) below, Ameren Missouri does not expect the first mortgage lien protection associated with these notes to fall away. (b) These bonds are first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. They are secured by substantially all Ameren Missouri property and franchises. (c) These bonds are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture and have a fall-away lien provision similar to that of Ameren Missouri’s senior secured notes. (d) Ameren Missouri has agreed that so long as any of the 3.90% senior secured notes due 2042 are outstanding, Ameren Missouri will not permit a release date to occur, and so long as any of the 8.45% senior secured notes due 2039 are outstanding, Ameren Missouri will not optionally redeem, purchase, or otherwise retire in full the outstanding first mortgage bonds not subject to release provisions. (e) These bonds were issued by AMF. The bondholders of AMF have no recourse to Ameren Missouri’s assets. Ameren Missouri collects securitization surcharges to cover the principal and interest on the bonds as well as certain other qualified costs. The surcharges collected by Ameren Missouri on behalf of AMF are remitted to AMF and are not available to creditors of Ameren Missouri. Principal and interest payments on these bonds are payable semiannually on April 1 and October 1 of each year, beginning October 1, 2025, with final principal and interest payment due October 1, 2039. (f) These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Illinois mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the 2054 maturity date of the 5.55% first mortgage bonds, Ameren Illinois does not expect the first mortgage lien protection associated with these notes to fall away. (g) These bonds are first mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. They are secured by substantially all Ameren Illinois property and franchises. The following table presents Ameren Missouri’s and Ameren Illinois’ “Long-term Debt, Net - Related Parties” as of December 31, 2024 and 2023: 2024 2023 Ameren Missouri: 3.65% Senior secured notes due 2045 $ 7 $ — 3.25% First mortgage bonds due 2049 33 — 2.625% First mortgage bonds due 2051 4 — 3.90% First mortgage bonds due 2052 14 — Total long-term debt - related parties, gross 58 — Less: Unamortized debt issuance costs (1) — Long-term debt - related parties, net $ 57 $ — Ameren Illinois: 3.70% First mortgage bonds due 2047 $ 1 $ — 3.25% First mortgage bonds due 2050 2 — Long-term debt - related parties, net $ 3 $ —
Schedule Of Maturities Of Long-Term Debt	The following table presents the principal maturities schedule for the 2.45% senior unsecured notes due 2036: Payment Date Principal Payment November 2029 $ 30 November 2036 45 Total $ 75 (i) The following table presents the principal maturities schedule for the 3.43% senior unsecured notes due 2050: Payment Date Principal Payment August 2027 $ 50 August 2030 49 August 2032 50 August 2038 49 August 2043 77 August 2050 76 Total $ 351 (j) The following table presents the principal maturities schedule for the 2.96% senior unsecured notes due 2052: Payment Date Principal Payment August 2040 $ 45 August 2052 50 Total $ 95 The following table presents the aggregate maturities of long-term debt, including current maturities, at December 31, 2024: Ameren (parent) (a) Ameren Missouri (a) Ameren Illinois (a) ATXI (a) Ameren Consolidated (a) 2025 $ — $ 17 $ 300 $ — $ 317 2026 950 24 — — 974 2027 500 424 — 50 974 2028 450 26 490 — 966 2029 700 477 — 30 1,207 Thereafter 800 6,857 5,123 581 13,361 Total $ 3,400 $ 7,825 $ 5,913 $ 661 $ 17,799 (a) Excludes unamortized discount, premium, and debt issuance costs of $17 million, $79 million, $61 million, and $2 million at Ameren (parent), Ameren Missouri, Ameren Illinois, and ATXI, respectively.
Schedule Of Outstanding Preferred Stock	The following table presents the outstanding preferred stock of Ameren Missouri and Ameren Illinois, which is redeemable at the option of the issuer, at the prices shown below as of December 31, 2024 and 2023: Shares Outstanding Redemption Price (per share) 2024 2023 Ameren Missouri: Without par value and stated value of $100 per share, 25 million shares authorized $3.50 Series 130,000 shares $ 110.00 $ 13 $ 13 $3.70 Series 40,000 shares 104.75 4 4 $4.00 Series 150,000 shares 105.625 15 15 $4.30 Series 40,000 shares 105.00 4 4 $4.50 Series 213,595 shares 110.00 (a) 21 21 $4.56 Series 200,000 shares 102.47 20 20 $4.75 Series 20,000 shares 102.176 2 2 $5.50 Series A 14,000 shares 110.00 1 1 Total $ 80 $ 80 Ameren Illinois: With par value of $100 per share, 2 million shares authorized 4.00% Series 144,275 shares $ 101.00 $ 14 $ 14 4.08% Series 45,224 shares 103.00 5 5 4.20% Series 23,655 shares 104.00 2 2 4.25% Series 50,000 shares 102.00 5 5 4.26% Series 16,621 shares 103.00 2 2 4.42% Series 16,190 shares 103.00 2 2 4.70% Series 18,429 shares 104.30 2 2 4.90% Series 73,825 shares 102.00 7 7 4.92% Series 49,289 shares 103.50 5 5 5.16% Series 50,000 shares 102.00 5 5 Total $ 49 $ 49 Total Ameren $ 129 $ 129 (a) In the event of voluntary liquidation, $105.50.
Schedule of Required and Actual Debt Ratios	The following table summarizes the required and actual interest coverage ratios for interest charges, dividend coverage ratios, and bonds and preferred stock issuable as of December 31, 2024, at an assumed interest rate of 7% and dividend rate of 8%. Required Interest Coverage Ratio (a) Actual Interest Bonds Issuable (b) Required Dividend Coverage Ratio (c) Actual Dividend Preferred Stock Ameren Missouri > 2.0 2.4 $2,283 > 2.5 164.4 $2,769 Ameren Illinois > 2.0 6.8 9,225 > 1.5 3.5 203 (d) (a) Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds. (b) Amount of bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include bonds issuable based on retired bond capacity of $1,509 million and $1,143 million at Ameren Missouri and Ameren Illinois, respectively. (c) Coverage required on the annual dividend on preferred stock outstanding and to be issued, as required in the respective company’s articles of incorporation. (d) Preferred stock issuable is restricted by the amount of preferred stock that is currently authorized by Ameren Illinois’ articles of incorporation.

Other Income, Net (Tables)

Other Income, Net (Tables)	12 Months Ended
	Dec. 31, 2024
Other Nonoperating Income (Expense) [Abstract]
Other Income And Expenses	OTHER INCOME, NET The following table presents the components of “Other Income, Net” in the Ameren Companies’ statements of income for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren: Other Income, Net Allowance for equity funds used during construction $ 76 $ 54 $ 43 Interest income on industrial development revenue bonds — 1 24 Other interest income 41 32 11 Non-service cost components of net periodic benefit income (a) 304 295 184 Miscellaneous income 9 7 10 Gain on extinguishment of debt (b) 16 — — Earnings (losses) related to equity method investments (4) 1 2 Donations (5) (24) (26) Miscellaneous expense (20) (18) (22) Total Other Income, Net $ 417 $ 348 $ 226 Ameren Missouri: Other Income, Net Allowance for equity funds used during construction $ 58 $ 30 $ 24 Interest income on industrial development revenue bonds — 1 24 Other interest income 8 10 4 Non-service cost components of net periodic benefit income (a) 139 97 55 Miscellaneous income 4 3 4 Donations (2) (2) (3) Miscellaneous expense (11) (9) (9) Total Other Income, Net $ 196 $ 130 $ 99 Ameren Illinois: Other Income, Net Allowance for equity funds used during construction $ 17 $ 19 $ 18 Other Interest income 32 21 7 Non-service cost components of net periodic benefit income 105 124 84 Miscellaneous income 4 4 5 Donations (3) (4) (8) Miscellaneous expense (8) (8) (10) Total Other Income, Net $ 147 $ 156 $ 96 (a) For the years ended December 31, 2024, 2023, and 2022, the non-service cost components of net periodic benefit income were adjusted by amounts deferred of $(41) million, $27 million, and $22 million, respectively, due to a regulatory tracking mechanism for the difference between the level of such costs incurred by Ameren Missouri under GAAP and the level of such costs included in rates. See Note 10 – Retirement Benefits for additional information. (b) See Note 5 – Long-term Debt and Equity Financings for additional information on Ameren (parent)’s repurchase of Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were accounted for as a debt extinguishment. The following table presents the components of “Total Other Expense, Net” in the Condensed Statement of Income and Comprehensive Income for the years ended December 31, 2024, 2023, and 2022: (In millions) 2024 2023 2022 Total other (income) expense, net Non-service cost components of net periodic benefit income $ 4 $ 8 $ 3 Donations — (18) (15) Other expense, net (1) (1) (1) Total other (income) expense, net $ 3 $ (11) $ (13)

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Open Gross Derivative Volumes By Commodity Type	The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of December 31, 2024 and 2023. As of December 31, 2024, these contracts extended through October 2028, October 2029, and May 2032 for fuel oils, natural gas, and power, respectively. Quantity (in millions, except as indicated) 2024 2023 Commodity Ameren Missouri Ameren Ameren Ameren Missouri Ameren Ameren Fuel oils (in gallons) 23 — 23 17 — 17 Natural gas (in mmbtu) 45 213 258 53 218 271 Power (in MWhs) — 4 4 — 5 5 Uranium (pounds in thousands) — — — 186 — 186
Derivative Instruments Carrying Value	The following table presents the carrying value and balance sheet location of all derivative commodity contracts, none of which were designated as hedging instruments, as of December 31, 2024 and 2023: 2024 2023 Commodity Balance Sheet Location Ameren Ameren Ameren Ameren Ameren Ameren Fuel oils Other current assets $ — $ — $ — $ 2 $ — $ 2 Other assets — — — — — — Natural gas Other current assets 2 2 4 — — — Other assets 2 4 6 3 3 6 Power Other current assets 6 — 6 5 — 5 Other assets — — — — — — Uranium Other current assets — — — 9 — 9 Other assets — — — — — — Total assets $ 10 $ 6 $ 16 $ 19 $ 3 $ 22 Fuel oils Other current liabilities $ 2 $ — $ 2 $ 1 $ — $ 1 Other deferred credits and liabilities 2 — 2 1 — 1 Natural gas Other current liabilities 5 22 27 12 45 57 Other deferred credits and liabilities 6 13 19 10 30 40 Power Other current liabilities — 10 10 1 12 13 Other deferred credits and liabilities — 43 43 — 56 56 Total liabilities $ 15 $ 88 $ 103 $ 25 $ 143 $ 168

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Schedule Of Fair Value Hierarchy Of Assets And Liabilities Measured At Fair Value On Recurring Basis	The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Ameren Missouri Derivative assets – commodity contracts: Fuel oils $ — $ — $ — $ — $ 2 $ — $ — $ 2 Natural gas — 4 — 4 — 3 — 3 Power — — 6 6 — — 5 5 Uranium — — — — — — 9 9 Total derivative assets – commodity contracts $ — $ 4 $ 6 $ 10 $ 2 $ 3 $ 14 $ 19 Nuclear decommissioning trust fund: Equity securities: U.S. large capitalization $ 911 $ — $ — $ 911 $ 787 $ — $ — $ 787 Debt securities: U.S. Treasury and agency securities — 191 — 191 — 150 — 150 Corporate bonds — 145 — 145 — 136 — 136 Other — 86 — 86 — 68 — 68 Total nuclear decommissioning trust fund $ 911 $ 422 $ — $ 1,333 (a) $ 787 $ 354 $ — $ 1,141 (a) Total Ameren Missouri $ 911 $ 426 $ 6 $ 1,343 $ 789 $ 357 $ 14 $ 1,160 Ameren Illinois Derivative assets – commodity contracts: Natural gas $ — $ 3 $ 3 $ 6 $ — $ 1 $ 2 $ 3 Total Ameren Illinois $ — $ 3 $ 3 $ 6 $ — $ 1 $ 2 $ 3 Ameren Derivative assets – commodity contracts (b) $ — $ 7 $ 9 $ 16 $ 2 $ 4 $ 16 $ 22 Nuclear decommissioning trust fund (c) 911 422 — 1,333 (a) 787 354 — 1,141 (a) Total Ameren $ 911 $ 429 $ 9 $ 1,349 $ 789 $ 358 $ 16 $ 1,163 Liabilities: Ameren Missouri Derivative liabilities – commodity contracts: Fuel oils $ 4 $ — $ — $ 4 $ 2 $ — $ — $ 2 Natural gas $ — $ 11 $ — $ 11 $ — $ 19 $ 3 $ 22 Power — — — — — — 1 1 Total Ameren Missouri $ 4 $ 11 $ — $ 15 $ 2 $ 19 $ 4 $ 25 Ameren Illinois Derivative liabilities – commodity contracts: Natural gas $ 1 $ 28 $ 6 $ 35 $ 4 $ 60 $ 11 $ 75 Power — — 53 53 — — 68 68 Total Ameren Illinois $ 1 $ 28 $ 59 $ 88 $ 4 $ 60 $ 79 $ 143 Ameren Derivative liabilities – commodity contracts (b) $ 5 $ 39 $ 59 $ 103 $ 6 $ 79 $ 83 $ 168 (a) Balance excludes $9 million and $9 million of cash and cash equivalents, receivables, payables, and accrued income, net for December 31, 2024 and 2023, respectively. (b) See the Ameren Missouri and Ameren Illinois sections of the table for the fair value of Ameren’s derivative assets and liabilities by type of commodity. (c) See the Ameren Missouri section of the table for Ameren’s nuclear decommissioning trust fund by investment type.
Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level 3 In The Fair Value Hierarchy	The following table presents the fair value reconciliation of Level 3 power derivative contract assets and liabilities measured at fair value on a recurring basis for the years ended December 31, 2024 and 2023: 2024 2023 Ameren Ameren Ameren Ameren Ameren Ameren Beginning balance at January 1 $ 4 $ (68) $ (64) $ 12 $ (33) $ (21) Realized and unrealized gains (losses) included in regulatory assets/liabilities 12 (1) 11 1 (48) (47) Settlements (10) 16 6 (9) 13 4 Ending balance at December 31 $ 6 $ (53) $ (47) $ 4 $ (68) $ (64) Change in unrealized gains (losses) related to assets/liabilities held at December 31 $ 6 $ 3 $ 9 $ 4 $ (36) $ (32)
Fair Value Inputs, Assets and Liabilities, Quantitative Information	The following table describes the valuation techniques and significant unobservable inputs utilized for the fair value of our Level 3 power derivative contract assets and liabilities as of December 31, 2024 and 2023: Fair Value Weighted Average (b) Commodity Assets Liabilities Valuation Technique(s) Unobservable Input (a) Range 2024 Power (c) $ 6 $ (53) Discounted cash flow Average forward peak and off-peak pricing – forwards/swaps ($/MWh) 32 – 69 45 Nodal basis ($/MWh) (8) – (2) (5) 2023 Power (c) $ 5 $ (69) Discounted cash flow Average forward peak and off-peak pricing – forwards/swaps ($/MWh) 31 – 65 43 Nodal basis ($/MWh) (8) – (1) (5) (a) Generally, significant increases (decreases) in these inputs in isolation would result in a significantly higher (lower) fair value measurement. (b) Unobservable inputs were weighted by relative fair value. (c) Valuations use visible forward prices adjusted for nodal-to-hub basis differentials.
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]	The following table sets forth the carrying amount and, by level within the fair value hierarchy, the fair value of long-term debt (including current portion), disclosed, but not recorded, at at fair value as of December 31, 2024 and 2023: Carrying Amount (a) Fair Value Long-Term Debt (Including Current Portion): Level 2 Level 3 Total December 31, 2024 Ameren (b) 17,579 15,395 538 (c) 15,933 Ameren Missouri (d) 7,745 6,926 — 6,926 Ameren Illinois (d) 5,852 5,243 — 5,243 December 31, 2023 Ameren 15,970 14,366 467 (c) 14,833 Ameren Missouri 6,341 5,800 — 5,800 Ameren Illinois 5,232 4,867 — 4,867 (a) Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $129 million, $62 million, and $51 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2024. Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $111 million, $45 million, and $47 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2023. (b) Amount excludes Ameren (parent)’s repurchase of Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds in 2024 that were accounted for as a debt extinguishment. See Note 5 – Long-term Debt and Equity Financings for additional information. (c) The Level 3 fair value amount consists of ATXI’s senior unsecured notes. (d) Amount includes Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were repurchased by Ameren (parent) in 2024.

Callaway Energy Center (Tables)

Callaway Energy Center (Tables)	12 Months Ended
	Dec. 31, 2024
Nuclear Waste Matters [Abstract]
Proceeds From Sale Of Investments In Nuclear Decommissioning Trust Fund And Gross Realized Gains And Losses	The following table presents proceeds from the sales and maturities of investments in Ameren Missouri’s nuclear decommissioning trust fund and the gross realized gains and losses resulting from those sales for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Proceeds from sales and maturities $ 564 $ 240 $ 216 Gross realized gains 44 6 40 Gross realized losses 28 11 10
Fair Value Of Securities In Nuclear Decommissioning Trust Fund	The following table presents the cost and fair value of investments in debt and equity securities in Ameren’s and Ameren Missouri’s nuclear decommissioning trust fund at December 31, 2024 and 2023: Security Type Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value 2024 Debt securities $ 437 $ 2 $ 17 $ 422 Equity securities 179 740 8 911 Cash and cash equivalents 10 — — 10 Other (a) (1) — — (1) Total $ 625 $ 742 $ 25 $ 1,342 2023 Debt securities $ 382 $ 3 $ 31 $ 354 Equity securities 191 603 7 787 Cash and cash equivalents 5 — — 5 Other (a) 4 — — 4 Total $ 582 $ 606 $ 38 $ 1,150 (a) Represents net receivables and payables relating to pending securities sales, interest, and securities purchases.
Fair Value Of Securities In Nuclear Decommissioning Trust Fund Classified by Contractual Maturity Date	The following table presents the costs and fair values of investments in debt securities in Ameren’s and Ameren Missouri’s nuclear decommissioning trust fund according to their contractual maturities at December 31, 2024: Cost Fair Value Less than 5 years $ 186 $ 184 5 years to 10 years 117 112 Due after 10 years 134 126 Total $ 437 $ 422
Schedule of Insurance Coverage	The following table presents insurance coverage at Ameren Missouri’s Callaway Energy Center at January 1, 2025: Type and Source of Coverage Most Recent Maximum Coverages Maximum Assessments Public liability and nuclear worker liability: American Nuclear Insurers January 1, 2025 $ 500 $ — Pool participation (a) 15,763 (a) 166 (b) $ 16,263 (c) $ 166 Property damage: NEIL and EMANI April 1, 2024 $ 3,200 (d) $ 28 (e) Accidental outage: NEIL April 1, 2024 $ 490 (f) $ 11 (e) (a) Provided through mandatory participation in an industrywide retrospective premium assessment program. The maximum coverage available is dependent on the number of United States commercial reactors participating in the program. (b) Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $500 million in the event of an incident at any licensed United States commercial reactor, payable at $25 million per year. (c) Limit of liability for each incident under the Price-Anderson liability provisions of the Atomic Energy Act of 1954, as amended. This limit is subject to change to account for the effects of inflation and changes in the number of licensed power reactors. (d) NEIL provides $2.7 billion in property damage, stabilization, decontamination, and premature decommissioning insurance for radiation events and $0.7 billion in property damage insurance for nonradiation events. EMANI provides $490 million in property damage insurance for both radiation and nonradiation events. (e) All NEIL-insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL. (f) Accidental outage insurance provides for lost sales in the event of a prolonged accidental outage. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first 12 weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter for a total not exceeding the policy limit of $490 million. Nonradiation events are limited to $291 million.

Retirement Benefits (Tables)

Retirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2024
Summary Of Benefit Liability Recorded	The following table presents the net benefit liability/(asset) recorded on the balance sheets as of December 31, 2024 and 2023: 2024 2023 Ameren (a) $ (734) $ (551) Ameren Missouri (a) (201) (142) Ameren Illinois (a) (438) (351) (a) Liabilities associated with pension and other postretirement benefits are recorded in “Other current liabilities” and “Other deferred credits and liabilities” on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets.
Funded Status Of Benefit Plans and Amounts Included In Regulatory Assets and AOCI	The following table presents the funded status of Ameren’s pension and postretirement benefit plans as of December 31, 2024 and 2023. It also provides the amounts included in regulatory assets or liabilities and accumulated OCI at December 31, 2024 and 2023, that have not been recognized in net periodic benefit costs. 2024 2023 Pension Postretirement Pension Postretirement Accumulated benefit obligation at end of year $ 3,962 $ (a) $ 4,102 $ (a) Change in benefit obligation: Net benefit obligation at beginning of year $ 4,258 $ 856 $ 4,061 $ 838 Service cost 88 12 79 12 Interest cost 222 44 221 45 Participant contributions — 7 — 7 Actuarial (gain) loss (143) (51) 170 17 Benefits paid (291) (61) (273) (63) Net benefit obligation at end of year 4,134 807 4,258 856 Change in plan assets: Fair value of plan assets at beginning of year 4,272 1,393 4,027 1,249 Actual return on plan assets 193 150 514 197 Employer contributions 8 4 4 3 Participant contributions — 7 — 7 Benefits paid (291) (61) (273) (63) Fair value of plan assets at end of year 4,182 1,493 4,272 1,393 Funded status – surplus (48) (686) (14) (537) Accrued benefit asset at December 31 $ (48) $ (686) $ (14) $ (537) Amounts recognized in the balance sheet consist of: Noncurrent asset $ (71) $ (686) $ (44) $ (537) Current liability (b) 2 — 2 — Noncurrent liability (c) 21 — 28 — Net asset recognized $ (48) $ (686) $ (14) $ (537) Amounts recognized in regulatory assets or liabilities consist of: Net actuarial (gain) loss $ 42 $ (379) $ (10) $ (311) Prior service credit — (21) — (25) Amounts recognized in accumulated OCI (pretax) consist of: Net actuarial (gain) loss 26 (7) 22 (4) Total $ 68 $ (407) $ 12 $ (340) (a) Not applicable. (b) Included in “Other current liabilities” on Ameren’s consolidated balance sheet. (c) Included in “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet.
Assumptions Used To Determine Benefit Obligations	The following table presents the assumptions used to determine our benefit obligations at December 31, 2024 and 2023: Pension Benefits Postretirement Benefits 2024 2023 2024 2023 Discount rate at measurement date 5.70 % 5.25 % 5.70 % 5.25 % Increase in future compensation 4.00 3.50 (a) 4.00 3.50 (a) Cash balance pension plan interest crediting rate 5.50 5.50 (b) (b) Medical cost trend rate (initial) (c) (b) (b) (d) (d) Medical cost trend rate (ultimate) (c) (b) (b) 5.00 5.00 (a) As of December 31, 2023, increase in future compensation was 4.00% in 2024, and 3.50% thereafter. (b) Not applicable. (c) Initial and ultimate medical cost trend rate for certain Medicare-eligible participants was 2.50% at December 31, 2024 and 2023. (d) Initial medical cost trend rates of 7.00% and 6.93% for pre-Medicare plan participants and 7.00% and 6.50% for post-Medicare plan participants at December 31, 2024 and 2023, respectively, trend down to the ultimate rate by 2033 and 2030, respectively, with a 3.00% upward adjustment to the post-Medicare trend rate in 2025.
Schedule Of Cash Contributions Made To Benefit Plans	The following table presents the cash contributions made to our defined benefit retirement plans and to our postretirement plan during 2024, 2023, and 2022: Pension Benefits Postretirement Benefits 2024 2023 2022 2024 2023 2022 Ameren Missouri $ 1 $ 1 $ 1 $ 2 $ 2 $ 1 Ameren Illinois 1 2 3 1 1 1 Ameren Services 6 1 1 1 — — Ameren $ 8 $ 4 $ 5 $ 4 $ 3 $ 2
Target Allocation Of The Plans' Asset Categories	The following table presents our target allocations and our pension and postretirement plans’ asset categories as of December 31, 2024 and 2023: Asset Target Allocation 2024 Percentage of Plan Assets at December 31, 2024 2023 Pension Plan: Cash and cash equivalents 0% – 5% 3 % 1 % Equity securities: U.S. large-capitalization 10% – 20% 16 % 15 % U.S. small- and mid-capitalization 3% – 13% 9 % 8 % Global 10% – 20% 15 % 16 % International 4% – 14% 9 % 12 % Total equity 42% – 52% 49 % 51 % Debt securities 32% – 42% 35 % (a) 35 % (a) Diversified credit 6% – 16% 8 % 7 % Real estate 0% – 10% 5 % 6 % Private equity 0% – 5% (b) (b) Total 100 % 100 % Postretirement Plans: Cash and cash equivalents 0% – 7% 2 % 1 % Equity securities: U.S. large-capitalization 23% – 33% 33 % 32 % U.S. small- and mid-capitalization 3% – 13% 8 % 8 % Global 9% – 19% 13 % 15 % International 5% – 15% 8 % 8 % Total equity 55% – 65% 62 % 63 % Debt securities 33% – 43% 36 % 36 % Total 100 % 100 % (a) Includes interest rate futures derivative instruments. (b) Less than 1% of plan assets.
Components Of Net Periodic Benefit Cost	The following table presents the components of the net periodic benefit cost (income) of Ameren’s pension and postretirement benefit plans during 2024, 2023, and 2022: Pension Benefits Postretirement Benefits 2024 2023 2022 2024 2023 2022 Service cost (a) $ 88 $ 79 $ 128 $ 12 $ 12 $ 20 Non-service cost components: Interest cost 222 221 163 44 45 34 Expected return on plan assets (b) (327) (333) (320) (93) (91) (85) Amortization of (b) : Prior service cost (credit) — — — (4) (4) (4) Actuarial (gain) loss (67) (115) 25 (38) (45) (19) Total non-service cost components (c) $ (172) $ (227) $ (132) $ (91) $ (95) $ (74) Net periodic benefit cost (income) (d) $ (84) $ (148) $ (4) $ (79) $ (83) $ (54) (a) Service cost, net of capitalization, is reflected in “Operating Expenses - Other operations and maintenance” on Ameren’s statement of income. (b) Prior service cost (credit) is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment. Net actuarial gains or losses related to the net benefit obligation subject to amortization are amortized on a straight-line basis over 10 years. The difference between the actual and expected return on plan assets is amortized over 4 years. (c) Non-service cost components are reflected in “Other Income, Net” on Ameren’s consolidated statement of income. See Note 6 – Other Income, Net for additional information. (d) Does not include the impact of the tracker for the difference between the level of pension and postretirement benefit costs (income) incurred by Ameren Missouri under GAAP and the level of such costs included in rates.
Summary Of Benefit Plan Costs Incurred	The Ameren Companies are responsible for their share of the pension and postretirement benefit costs (income). The following table presents the pension and postretirement benefit costs (income) incurred for the years ended December 31, 2024, 2023, and 2022: Pension Costs Postretirement Costs 2024 2023 2022 2024 2023 2022 Ameren Missouri (a) $ (44) $ (76) $ (3) $ (27) $ (30) $ (14) Ameren Illinois (34) (62) 3 (52) (54) (41) Other (6) (10) (4) — 1 1 Ameren $ (84) $ (148) $ (4) $ (79) $ (83) $ (54) (a) Does not include the impact of the tracker for the difference between the level of pension and postretirement benefit costs (income) incurred by Ameren Missouri under GAAP and the level of such costs included in customer rates.
Schedule Of Expected Payments From Qualified Trust And Company Funds	The expected pension and postretirement benefit payments from qualified trust and company funds, which reflect expected future service, as of December 31, 2024, are as follows: Pension Benefits Postretirement Benefits Paid from Paid from Paid from Paid from 2025 $ 284 $ 2 $ 56 $ 3 2026 289 2 57 3 2027 292 2 57 4 2028 295 2 57 4 2029 297 2 57 4 2030 – 2034 1,504 13 284 18
Assumptions Used To Determine Net Periodic Benefit Cost	The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2024, 2023, and 2022: Pension Benefits Postretirement Benefits 2024 2023 2022 2024 2023 2022 Discount rate at measurement date 5.25 % 5.55 % 3.00 % 5.25 % 5.55 % 3.00 % Expected return on plan assets 6.75 6.75 6.50 6.75 6.75 6.50 Increase in future compensation (a) 3.50 3.50 3.50 3.50 3.50 3.50 Cash balance pension plan interest crediting rate (b) 5.50 5.00 5.00 (c) (c) (c) Medical cost trend rate (initial) (d) (c) (c) (c) (e) (f) 5.00 Medical cost trend rate (ultimate) (d) (c) (c) (c) 5.00 5.00 5.00 (a) Increase in future compensation is 4.00% for 2024 and 3.50% thereafter for the year ended December 31, 2024, and was 4.50% for 2023, 4.00% for 2024, and 3.50% thereafter for the year ended December 31, 2023. (b) Cash balance pension plan interest crediting rate is 6.42% for 2024 and 5.50% thereafter for the year ended December 31, 2024, and was 5.50% for 2023 and 2024, and 5.00% thereafter for the year ended December 31, 2023. (c) Not applicable. (d) Initial and ultimate medical cost trend rate for certain Medicare-eligible participants is 2.50% for the years ended December 31, 2024 and 2023, and 3.00% for the year ended December 31, 2022. (e) Initial medical cost trend rates of 6.93% for pre-Medicare plan participants and 6.50% for post-Medicare plan participants trend down to the ultimate rate by 2030, with a 3.00% upward adjustment to the post-Medicare trend rate in 2025. (f) Initial medical cost trend rates of 7.25% for pre-Medicare plan participants and 6.75% for post-Medicare plan participants trend down to the ultimate rate by 2030, with a 3.00% upward adjustment to the post-Medicare trend rate in 2025.
Schedule Of Matching Contributions	The following table presents the portion of the matching contribution to the Ameren 401(k) plan attributable to each of the Ameren Companies for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren Missouri $ 26 $ 27 $ 23 Ameren Illinois 22 21 19 Other 1 1 1 Ameren $ 49 $ 49 $ 43
Pension Benefits
Target Allocation Of The Plans' Asset Categories	The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plans’ assets measured at fair value and NAV as of December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Level 1 Level 2 NAV Total Level 1 Level 2 NAV Total Cash and cash equivalents $ — $ — $ 75 $ 75 $ — $ — $ 90 $ 90 Equity securities: U.S. large-capitalization — — 689 689 — — 663 663 U.S. small- and mid-capitalization 375 — — 375 353 — — 353 International 182 — 226 408 316 — 229 545 Global — — 680 680 — — 721 721 Debt securities: Corporate bonds — 463 — 463 — 479 — 479 Municipal bonds — 36 — 36 — 43 — 43 U.S. Treasury and agency securities — 1,032 — 1,032 — 994 — 994 Diversified credit — — 344 344 — — 305 305 Other (17) 11 — (6) 49 13 — 62 Real estate — — 233 233 — — 248 248 Total $ 540 $ 1,542 $ 2,247 $ 4,329 $ 718 $ 1,529 $ 2,256 $ 4,503 Less: Medical benefit assets (a) (200) (196) Plus: Net receivables (payables) (b) 53 (35) Fair value of pension plans’ assets $ 4,182 $ 4,272 (a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation. (b) Net of receivables related to pending securities sales and payables related to pending securities purchases.
Postretirement Benefits
Target Allocation Of The Plans' Asset Categories	The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans’ assets measured at fair value and NAV as of December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Level 1 Level 2 NAV Total Level 1 Level 2 NAV Total Cash and cash equivalents $ 25 $ — $ — $ 25 $ 10 $ — $ — $ 10 Equity securities: U.S. large-capitalization 332 — 91 423 302 — 81 383 U.S. small- and mid-capitalization 106 — — 106 96 — — 96 International 54 — 52 106 51 — 49 100 Global — — 165 165 — — 174 174 Debt securities: Municipal bonds — 173 — 173 — 161 — 161 Other — — 293 293 — — 271 271 Total $ 517 $ 173 $ 601 $ 1,291 $ 459 $ 161 $ 575 $ 1,195 Plus: Medical benefit assets (a) 200 196 Plus: Net receivables (b) 2 2 Fair value of postretirement benefit plans’ assets $ 1,493 $ 1,393 (a) Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above. (b) Net of receivables related to pending securities sales and payables related to pending securities purchases.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2024
Share-Based Payment Arrangement [Abstract]
Summary Of Nonvested Shares Related To Long-Term Incentive Plan	The following table summarizes Ameren’s outstanding performance share unit and restricted stock unit activity for the year ended December 31, 2024: Performance Share Units – Market Condition (a) Performance Share Units – Performance Condition (b) Restricted Stock Units Share Weighted-average Fair Value per Share Unit Share Weighted-average Fair Value per Share Unit Stock Weighted-average Fair Value per Stock Unit Outstanding at January 1, 2024 (c) 761,712 $ 89.22 112,391 $ 83.36 377,864 $ 83.82 Granted 314,456 56.73 51,938 68.83 159,050 69.09 Forfeitures (46,636) 73.97 (7,691) 77.22 (29,330) 79.59 Dividend equivalents (d) 27,508 77.74 4,127 79.03 13,580 79.59 Vested and distributed (248,090) 87.10 (39,768) 78.11 (125,644) 78.58 Outstanding at December 31, 2024 (c) 808,950 $ 77.73 120,997 $ 79.09 395,520 $ 79.73 (a) The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the specified market conditions. Compensation cost on nonforfeited awards is recognized regardless of whether Ameren achieves the specified market conditions. (b) The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the performance goals. Compensation cost is recognized ratably over the requisite service period only for awards for which it is probable that the performance condition will be satisfied. (c) Outstanding awards include awards that vest on a pro-rata basis due to attainment of retirement eligibility by employees, but have not yet been distributed. In these cases, the pro-rata basis awards have not yet been distributed as the entire performance period has not been completed. The number of shares issued for retirement-eligible employees will vary depending on actual performance over the three-year performance period. (d) Dividend equivalents represent the right to receive shares measured by the dividend payable with respect to the corresponding number of outstanding share units. Dividend equivalents will accrue and be reinvested in additional share units throughout the performance period.
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award	The following table presents the fair value of each share unit along with the significant assumptions used to calculate the fair value of each share unit for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Fair value of share units awarded $56.73 $91.07 $92.75 Three-year risk-free rate 4.25% 4.19% 1.80% Ameren’s common stock volatility (a) 21% 26% 29% Volatility range for the peer group (a) 19% – 23% 24% – 32% 26% – 35% (a) Based on a historical period that is equal to the remaining term of the performance period as of the grant date. The following table presents the stock-based compensation expense for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren Missouri $ 8 $ 6 $ 4 Ameren Illinois 4 4 2 Other (a) 16 16 18 Ameren 28 26 24 Less: Income tax benefit 7 7 6 Stock-based compensation expense, net $ 21 $ 19 $ 18 (a) Represents compensation expense for employees of Ameren Services. These amounts are not included in the Ameren Missouri and Ameren Illinois amounts above.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Schedule Of Effective Income Tax Rate Reconciliation	The following table presents the principal reasons for the difference between the effective income tax rate and the federal statutory corporate income tax rate for the years ended December 31, 2024, 2023, and 2022: Ameren Missouri Ameren Illinois Ameren 2024 Federal statutory corporate income tax rate 21 % 21 % 21 % Increases (decreases) from: Amortization of excess deferred income taxes (a) (17) (4) (9) Amortization of deferred investment tax credit (1) — — Renewable and other tax credits (b) (24) — (9) State tax 3 7 5 Depreciation differences — — (1) Effective income tax rate (18) % 24 % 7 % 2023 Federal statutory corporate income tax rate 21 % 21 % 21 % Increases (decreases) from: Amortization of excess deferred income taxes (a) (15) (2) (8) Amortization of deferred investment tax credit (1) — — Renewable and other tax credits (b) (10) — (4) State tax 3 7 5 Effective income tax rate (2) % 26 % 14 % 2022 Federal statutory corporate income tax rate 21 % 21 % 21 % Increases (decreases) from: Amortization of excess deferred income taxes (a) (15) (2) (8) Amortization of deferred investment tax credit (1) — — Renewable and other tax credits (b) (10) — (4) State tax 3 7 5 Effective income tax rate (2) % 26 % 14 % (a) Reflects the amortization of a regulatory liability resulting from the revaluation of accumulated deferred income taxes subject to regulatory ratemaking, which are being refunded to customers. (b) The benefit of the credits associated with Missouri renewable energy standard compliance is refunded to customers through the RESRAM. The benefit of the credits associated with the production and investment tax credit tracker will be refunded to customers based on MoPSC approval in a regulatory rate review.
Schedule Of Components Of Income Tax Expense (Benefit)	The following table presents the components of income tax expense (benefit) for the years ended December 31, 2024, 2023, and 2022: Ameren Missouri Ameren Illinois Other Ameren 2024 Current taxes: Federal $ (55) $ 5 $ 7 $ (43) State (3) — 2 (1) Deferred taxes: Federal 45 144 (12) 177 State 8 76 (19) 65 Amortization of excess deferred income taxes (79) (32) (1) (112) Amortization of deferred investment tax credits (3) — — (3) Total income tax expense (benefit) $ (87) $ 193 $ (23) $ 83 2023 Current taxes: Federal $ (37) $ 27 $ (37) $ (47) State 1 5 (5) 1 Deferred taxes: Federal 102 123 35 260 State 9 71 (10) 70 Amortization of excess deferred income taxes (80) (17) (1) (98) Amortization of deferred investment tax credits (3) — — (3) Total income tax expense (benefit) $ (8) $ 209 $ (18) $ 183 2022 Current taxes: Federal $ (26) $ 46 $ (15) $ 5 State (5) 16 (10) 1 Deferred taxes: Federal 93 82 19 194 State 18 48 14 80 Amortization of excess deferred income taxes (86) (13) (1) (100) Amortization of deferred investment tax credits (4) — — (4) Total income tax expense (benefit) $ (10) $ 179 $ 7 $ 176
Schedule Of Deferred Tax Assets And Liabilities Resulting From Temporary Differences	The following table presents the accumulated deferred income tax assets and liabilities recorded as a result of temporary differences and accumulated deferred production and investment tax credits at December 31, 2024 and 2023: Ameren Missouri Ameren Illinois Other Ameren 2024 Accumulated deferred income taxes, net liability (asset): Plant-related $ 2,429 $ 2,250 $ 261 $ 4,940 Regulatory assets and liabilities, net (193) (170) (22) (385) Deferred employee benefit costs (25) 77 (25) 27 Tax carryforwards (355) (45) (103) (503) Other 131 28 3 162 Total net accumulated deferred income tax liabilities (assets) 1,987 2,140 114 4,241 Accumulated deferred investment tax credits 230 3 — 233 Accumulated deferred income taxes and investment tax credits $ 2,217 $ 2,143 $ 114 $ 4,474 2023 Accumulated deferred income taxes, net liability (asset): Plant-related $ 2,370 $ 2,030 $ 246 $ 4,646 Regulatory assets and liabilities, net (206) (184) (23) (413) Deferred employee benefit costs (48) 55 (33) (26) Tax carryforwards (124) (33) (61) (218) Other 104 38 19 161 Total net accumulated deferred income tax liabilities (assets) 2,096 1,906 148 4,150 Accumulated deferred investment tax credits 26 — — 26 Accumulated deferred income taxes and investment tax credits $ 2,122 $ 1,906 $ 148 $ 4,176
Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards	The following table presents the components of accumulated deferred income tax assets relating to net operating loss carryforwards and tax credit carryforwards at December 31, 2024 and 2023: Ameren Missouri Ameren Illinois Other Ameren 2024 Net operating loss carryforwards: Federal (a) $ — $ — $ 30 $ 30 State (b) — 34 29 63 Total net operating loss carryforwards $ — $ 34 $ 59 $ 93 Tax credit carryforwards: Federal (c) $ 355 $ 9 $ 44 $ 408 State (d) — 2 — 2 Total tax credit carryforwards $ 355 $ 11 $ 44 $ 410 2023 Net operating loss carryforwards: Federal $ — $ — $ — $ — State — 26 16 42 Total net operating loss carryforwards $ — $ 26 $ 16 $ 42 Tax credit carryforwards: Federal $ 124 $ 5 $ 45 $ 174 State — 2 — 2 Total tax credit carryforwards $ 124 $ 7 $ 45 $ 176 (a) No expiration date. (b) Will expire between 2032 and 2044. (c) Will expire between 2031 and 2044. (d) Will expire between 2025 and 2028.

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2024
Related Party Transactions [Abstract]
Schedule of Related Party Electric Power Supply Agreements	The following table presents the specified performance period, amount of MWhs, and average price per MWh included in the agreements: IPA Procurement Event Performance Period MWhs Average Price per MWh September 2020 September 2021 – November 2022 204,800 31 April 2021 July 2022 – November 2022 33,600 34 September 2021 January 2022 – September 2023 136,000 37
Schedule of Affiliate Receivables and Payables	The following table presents the affiliate balances related to income taxes for Ameren Missouri and Ameren Illinois as of December 31, 2024 and 2023: 2024 2023 Ameren Missouri Ameren Illinois Ameren Missouri Ameren Illinois Income taxes payable to parent (a) $ — $ 32 $ — $ 2 Income taxes receivable from parent (b) 28 — 56 22 (a) Included in “Accounts payable – affiliates” on the balance sheet. (b)
Schedule of Capital Contributions	The following table presents cash capital contributions received from Ameren (parent) by Ameren Missouri and Ameren Illinois for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren Missouri (a) $ 476 $ — $ — Ameren Illinois (a) 36 91 15 (a) Includes capital contributions made as a result of the tax allocation agreement.
Schedule of Related Party Transactions	The following table presents the impact on Ameren Missouri and Ameren Illinois of related-party transactions for the years ended December 31, 2024, 2023, and 2022. It is based primarily on the agreements discussed above and the money pool arrangements discussed in Note 4 – Short-term Debt and Liquidity. Agreement Income Statement Line Item Ameren Ameren Ameren Missouri power supply agreements Operating Revenues 2024 $ — $ (a) with Ameren Illinois 2023 2 (a) 2022 9 (a) Ameren Missouri and Ameren Illinois Operating Revenues 2024 31 1 rent and facility services 2023 32 (b) 2022 25 (b) Ameren Missouri and Ameren Illinois Operating Revenues 2024 2 2 miscellaneous support services 2023 (b) 2 2022 (b) 2 Total Operating Revenues 2024 $ 33 $ 3 2023 34 2 2022 34 2 Ameren Illinois power supply Purchased Power 2024 $ (a) $ — agreements with Ameren Missouri 2023 (a) 2 2022 (a) 9 Ameren Missouri and Ameren Illinois Purchased Power 2024 9 2 transmission services from ATXI 2023 2 1 2022 1 (b) Total Purchased Power 2024 $ 9 $ 2 2023 2 3 2022 1 9 Ameren Missouri and Ameren Illinois Other Operations and 2024 $ 1 $ 1 rent and facility services Maintenance 2023 (b) 3 2022 (b) 3 Ameren Services support services Other Operations and 2024 169 158 agreement Maintenance 2023 148 138 2022 150 141 Total Other Operations and 2024 $ 170 $ 159 Maintenance Expenses 2023 148 141 2022 150 144 Money pool borrowings (advances) (Interest Charges) 2024 $ (4) $ (b) Other Income, Net 2023 (b) (b) 2022 (b) (b) Long-term debt, net - related parties (Interest Charges) 2024 (b) (b) 2023 (a) (a) 2022 (a) (a) (a) Not applicable. (b) Amount less than $1 million.

Supplemental Information (Table

Supplemental Information (Tables)	12 Months Ended
	Dec. 31, 2024
Supplemental Information [Abstract]
Schedule of Cash and Cash Equivalents Including Restricted Cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets and the statements of cash flows as of December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Ameren Ameren Ameren Ameren Ameren Ameren “Cash and cash equivalents” $ 7 $ — $ — $ 25 $ — $ — Restricted cash included in “Other current assets” 15 7 6 13 5 5 Restricted cash included in “Other assets” 296 — 296 229 — 229 Restricted cash included in “Nuclear decommissioning trust fund” 10 10 — 5 5 — Total cash, cash equivalents, and restricted cash $ 328 $ 17 $ 302 $ 272 $ 10 $ 234
Schedule of Accounts, Notes, Loans and Financing Receivable	The following table provides a reconciliation of the beginning and ending amount of the allowance for doubtful accounts for the years ended December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Ameren Missouri Ameren Illinois (a) Ameren Ameren Missouri Ameren Illinois (a) Ameren Beginning balance at January 1 $ 12 $ 18 $ 30 $ 13 $ 18 $ 31 Bad debt expense 11 28 39 11 40 51 Charged to other accounts (b) — 8 8 — 5 5 Net write-offs (11) (36) (47) (12) (45) (57) Ending balance at December 31 $ 12 $ 18 $ 30 $ 12 $ 18 $ 30 (a) Ameren Illinois has rate-adjustment mechanisms that allow it to recover the difference between its actual net bad debt write-offs under GAAP, including those associated with receivables purchased from alternative retail electric suppliers, and the amount of net bad debt write-offs included in its base rates. (b) Amounts associated with the allowance for doubtful accounts related to receivables purchased by Ameren Illinois from alternative retail electric suppliers, as required by the Illinois Public Utilities Act.
Schedule of Supplemental Balance Sheet Information Related to Operating Leases	The following table provides supplemental balance sheet information related to operating leases as of December 31, 2024: Ameren Ameren Missouri Other assets $ 72 $ 69 Other current liabilities 5 4 Other deferred credits and liabilities 67 65 Weighted average remaining operating lease term 29 years 30 years Weighted average discount rate (a) 5.3 % 5.3 % (a) As an implicit rate is not readily determinable under most of our lease agreements, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We use an implicit rate when readily determinable.
Schedule of Maturity of Operating Lease Liabilities	The following table presents Ameren’s and Ameren Missouri’s remaining maturities of operating lease liabilities as of December 31, 2024: Ameren Ameren Missouri 2025 $ 8 $ 7 2026 5 4 2027 4 3 2028 4 4 2029 4 4 Thereafter 131 131 Total lease payments $ 156 $ 153 Less imputed interest 84 84 Total $ 72 $ 69
Schedule of Inventories	The following table presents the components of inventories for each of the Ameren Companies at December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Ameren Ameren Ameren Ameren Ameren Ameren Fuel (a) $ 113 $ — $ 113 $ 109 $ — $ 109 Natural gas stored underground 9 82 91 8 87 95 Materials, supplies, and other 392 162 558 391 138 529 Total inventories $ 514 $ 244 $ 762 $ 508 $ 225 $ 733 (a) Consists of coal, oil, and propane.
Schedule of Asset Retirement Obligations	The following table provides a reconciliation of the beginning and ending carrying amount of AROs for the years ended December 31, 2024 and 2023: December 31, 2024 December 31, 2023 Ameren Ameren Ameren Ameren Ameren Ameren Beginning balance at January 1 $ 787 (a) $ 4 (b) $ 791 (a) $ 782 $ 4 $ 786 Liabilities incurred 21 (c) — 21 (c) — — — Liabilities settled (13) — (13) (10) — (10) Accretion (d) 35 (d) — 35 (d) 33 — 33 Change in estimates (7) — (7) (18) — (18) Ending balance at December 31 $ 823 (a)(e) $ 4 (b) $ 827 (a)(e) $ 787 (a) $ 4 (b) $ 791 (a) (a) Balance included $5 million and $19 million in “Other current liabilities” on the balance sheet as of December 31, 2024 and 2023, respectively. (b) Included in “Other deferred credits and liabilities” on the balance sheet. (c) In 2024, Ameren and Ameren Missouri recorded an ARO related to decommissioning for the Cass County, Boomtown, and Huck Finn energy centers. In addition, as a result of the 2024 CCR Rule, Ameren and Ameren Missouri recorded an increase to their AROs associated with CCR storage facilities. See Note 14 – Commitments and Contingencies for additional information. (d) Accretion expense attributable to Ameren Missouri was recorded as a decrease to regulatory liabilities. (e) The balance as of December 31, 2024, included an ARO related to the decommissioning of the Callaway Enter Center of $648 million.
Schedule of Excise Taxes	The following table presents the excise taxes recorded on a gross basis in “Operating Revenues – Electric,” “Operating Revenues – Natural gas” and “Operating Expenses – Taxes other than income taxes” on the statements of income for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Ameren Missouri $ 169 $ 166 $ 162 Ameren Illinois 130 121 133 Ameren $ 299 $ 287 $ 295
Schedule of Rates and Amounts For Allowance for Funds Used During Construction	The following table presents the average rate that was applied to eligible construction work in progress and the amounts of allowance for funds used during construction capitalized in 2024, 2023, and 2022: 2024 2023 2022 Average rate: Ameren Missouri 6 % 6 % 5 % Ameren Illinois 6 % 6 % 5 % Ameren: Allowance for equity funds used during construction $ 76 $ 54 $ 43 Allowance for borrowed funds used during construction 56 48 26 Total Ameren $ 132 $ 102 $ 69 Ameren Missouri: Allowance for equity funds used during construction $ 58 $ 30 $ 24 Allowance for borrowed funds used during construction 39 27 13 Total Ameren Missouri $ 97 $ 57 $ 37 Ameren Illinois: Allowance for equity funds used during construction $ 17 $ 19 $ 18 Allowance for borrowed funds used during construction 15 17 12 Total Ameren Illinois $ 32 $ 36 $ 30
Schedule of Earnings Per Share, Basic and Diluted	The following table reconciles the weighted-average number of common shares outstanding to the diluted weighted-average number of common shares outstanding for the years ended December 31, 2024, 2023, and 2022: 2024 2023 2022 Weighted-average Common Shares Outstanding – Basic 266.8 262.8 258.4 Assumed settlement of performance share units and restricted stock units 0.5 0.6 1.0 Dilutive effect of forward sale agreements 0.1 — 0.1 Weighted-average Common Shares Outstanding – Diluted (a) 267.4 263.4 259.5 (a) There was an immaterial number of anti-dilutive securities excluded from the earnings per diluted share calculations for the years ended December 31, 2024, 2023, and 2022 related to performance share units and restricted stock units. Outstanding forward sale agreements as of December 31, 2024 that were anti-dilutive for the year ended December 31, 2024 were excluded from the earnings per diluted share calculation as calculated using the treasury stock method. The outstanding forward sale agreements as of December 31, 2023, were anti-dilutive for the year ended December 31, 2023, and excluded from the earnings per diluted share calculation as calculated using the treasury stock method. For additional information about the outstanding forward sale agreements, see Note 5 – Long-term Debt and Equity Financings.
Schedule of Cash Flow, Supplemental Disclosures	The following table provides noncash financing and investing activity excluded from the statements of cash flows for the years ended December 31, 2024, 2023, and 2022: December 31, 2024 December 31, 2023 December 31, 2022 Ameren Ameren Ameren Ameren Ameren Ameren Ameren Ameren Ameren Investing Accrued capital expenditures, including nuclear fuel expenditures $ 480 $ 303 $ 157 $ 518 $ 270 $ 212 $ 441 $ 243 $ 181 Net realized and unrealized gain (loss) – nuclear decommissioning trust fund 165 165 — 167 167 — (218) (218) — Return of investment in industrial development revenue bonds (a) — — — 240 240 — — — — Financing Issuance of common stock for stock-based compensation $ 16 $ — $ — $ 40 $ — $ — $ 31 $ — $ — Issuance of common stock under the DRPlus 7 — — 7 — — 8 — — Termination of a financing agreement (a) — — — 240 240 — — — — (a)

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2024
Segment Reporting [Abstract]
Schedule Of Segment Reporting Information, By Segment	The following tables present information about the reported revenue and specified items reflected in net income attributable to common shareholders and capital expenditures by segment at Ameren and Ameren Illinois for the years ended December 31, 2024, 2023, and 2022. Ameren, Ameren Missouri, and Ameren Illinois management review segment capital expenditure information rather than any individual or total asset amount. Ameren Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Other Intersegment Eliminations Ameren 2024 External revenues $ 3,960 $ 2,088 $ 938 $ 637 $ — $ — $ 7,623 Intersegment revenues 33 1 — 144 — (178) — Revenue 3,993 2,089 938 781 — (178) 7,623 Fuel and purchased power (a) (1,071) (740) — — — 130 (1,681) Natural gas purchased for resale (a) (60) — (260) — — — (320) Other operations and maintenance expenses (a) (1,050) (619) (230) (70) (48) 48 (1,969) Other segment items Depreciation and amortization (917) (369) (129) (167) (8) — (1,590) Taxes other than income taxes (372) (75) (78) (9) (13) — (547) Other income, net 196 97 27 26 83 (12) 417 Interest charges (244) (98) (63) (117) (b) (153) 12 (663) Income taxes (benefit) 87 (50) (56) (120) 56 — (83) Noncontrolling interests – preferred stock dividends (3) (1) — (1) — — (5) Net income (loss) attributable to Ameren common shareholders 559 234 149 323 (83) — 1,182 Interest income 8 28 1 6 10 (12) 41 Capital expenditures 2,712 579 264 758 7 (1) 4,319 Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Other Intersegment Eliminations Ameren 2023 External revenues $ 3,825 $ 2,217 $ 897 $ 561 $ — $ — $ 7,500 Intersegment revenues 34 1 — 116 — (151) — Revenue 3,859 2,218 897 677 — (151) 7,500 Fuel and purchased power (a) (997) (933) — — — 118 (1,812) Natural gas purchased for resale (a) (79) — (276) — — — (355) Other operations and maintenance expenses (a) (1,003) (532) (237) (60) (67) 33 (1,866) Other segment items Depreciation and amortization (783) (351) (108) (138) (7) — (1,387) Taxes other than income taxes (360) (75) (67) (8) (12) — (522) Other income, net 130 103 30 28 62 (5) 348 Interest charges (227) (89) (55) (96) (b) (104) 5 (566) Income taxes (benefit) 8 (82) (50) (106) 47 — (183) Noncontrolling interests – preferred stock dividends (3) (1) — (1) — — (5) Net income (loss) attributable to Ameren common shareholders 545 258 134 296 (81) — 1,152 Interest income 11 19 1 2 5 (5) 33 Capital expenditures 1,760 752 299 804 9 (27) 3,597 2022 External revenues $ 4,012 $ 2,255 $ 1,180 $ 510 $ — $ — $ 7,957 Intersegment revenues 34 1 — 105 — (140) — Revenue 4,046 2,256 1,180 615 — (140) 7,957 Fuel and purchased power (a) (1,150) (984) — — — 114 (2,020) Natural gas purchased for resale (a) (104) — (553) — — — (657) Other operations and maintenance expenses (a) (1,028) (580) (253) (60) (42) 26 (1,937) Other segment items Depreciation and amortization (732) (332) (98) (123) (4) — (1,289) Taxes other than income taxes (363) (75) (82) (9) (10) — (539) Other income, net 99 60 19 17 32 (1) 226 Interest charges (213) (74) (44) (84) (b) (72) 1 (486) Income taxes (benefit) 10 (68) (46) (92) 20 — (176) Noncontrolling interests – preferred stock dividends (3) (1) — (1) — — (5) Net income (loss) attributable to Ameren common shareholders 562 202 123 263 (76) — 1,074 Interest income 28 7 — — 1 (1) 35 Capital expenditures 1,690 621 308 741 7 (16) 3,351 (a) Significant segment expense that is regularly provided to the CODMs. Intersegment expenses are included within the amounts shown. (b) Ameren Transmission interest charges include an allocation of financing costs from Ameren (parent). Ameren Illinois Ameren Illinois Electric Distribution Ameren Illinois Ameren Illinois Transmission Intersegment Eliminations Ameren Illinois 2024 External revenues $ 2,089 $ 938 $ 445 $ — $ 3,472 Intersegment revenues — — 119 (119) — Revenue 2,089 938 564 (119) 3,472 Purchased power (a) (740) — — 119 (621) Natural gas purchased for resale (a) — (260) — — (260) Other operations and maintenance expenses (a) (619) (230) (57) — (906) Other segment items Depreciation and amortization (369) (129) (121) — (619) Taxes other than income taxes (75) (78) (4) — (157) Other income, net 97 27 23 — 147 Interest charges (98) (63) (80) — (241) Income taxes (50) (56) (87) — (193) Noncontrolling interests – preferred stock dividends (1) — (1) — (2) Net income available to common shareholder 234 149 237 — 620 Interest income 28 1 3 — 32 Capital expenditures 579 264 624 — 1,467 2023 External revenues $ 2,218 $ 897 $ 367 $ — $ 3,482 Intersegment revenues — — 113 (113) — Revenue 2,218 897 480 (113) 3,482 Purchased power (a) (933) — — 113 (820) Natural gas purchased for resale (a) — (276) — — (276) Other operations and maintenance expenses (a) (532) (237) (49) — (818) Other segment items Depreciation and amortization (351) (108) (97) — (556) Taxes other than income taxes (75) (67) (4) — (146) Other income, net 103 30 23 — 156 Interest charges (89) (55) (60) — (204) Income taxes (82) (50) (77) — (209) Noncontrolling interests – preferred stock dividends (1) — (1) — (2) Net income available to common shareholder 258 134 215 — 607 Interest income 19 1 1 — 21 Capital expenditures 752 299 680 — 1,731 Ameren Illinois Electric Distribution Ameren Illinois Ameren Illinois Transmission Intersegment Eliminations Ameren Illinois 2022 External revenues $ 2,256 $ 1,180 $ 320 $ — $ 3,756 Intersegment revenues — — 104 (104) — Revenue 2,256 1,180 424 (104) 3,756 Purchased power (a) (984) — — 104 (880) Natural gas purchased for resale (a) — (553) — — (553) Other operations and maintenance expenses (a) (580) (253) (49) — (882) Other segment items Depreciation and amortization (332) (98) (84) — (514) Taxes other than income taxes (75) (82) (4) — (161) Other income, net 60 19 17 — 96 Interest charges (74) (44) (50) — (168) Income taxes (68) (46) (65) — (179) Noncontrolling interests – preferred stock dividends (1) — (1) — (2) Net income available to common shareholder 202 123 188 — 513 Interest income 7 — — — 7 Capital expenditures 621 308 672 — 1,601 (a) Significant segment expense that is regularly provided to the CODMs. Intersegment expenses are included within the amounts shown.
Disaggregation of Revenue	The following tables present disaggregated revenues by segment at Ameren and Ameren Illinois for the years ended December 31, 2024, 2023, and 2022. Economic factors affect the nature, timing, amount, and uncertainty of revenues and cash flows in a similar manner across customer classes. Revenues from alternative revenue programs have a similar distribution among customer classes as revenues from contracts with customers. Other revenues not associated with contracts with customers are presented in the Other customer classification, along with electric transmission and off-system sales and capacity revenues. Ameren Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Intersegment Eliminations Ameren 2024 Residential $ 1,638 $ 1,254 $ — $ — $ — $ 2,892 Commercial 1,313 680 — — — 1,993 Industrial 311 178 — — — 489 Other 585 (23) — 781 (177) 1,166 Total electric revenues $ 3,847 $ 2,089 $ — $ 781 $ (177) $ 6,540 Residential $ 90 $ — $ 661 $ — $ — $ 751 Commercial 37 — 166 — — 203 Industrial 4 — 10 — — 14 Other 15 — 101 — (1) 115 Total gas revenues $ 146 $ — $ 938 $ — $ (1) $ 1,083 Total revenues (a) $ 3,993 $ 2,089 $ 938 $ 781 $ (178) $ 7,623 2023 Residential $ 1,577 $ 1,344 $ — $ — $ — $ 2,921 Commercial 1,280 747 — — — 2,027 Industrial 306 186 — — — 492 Other 531 (59) — 677 (150) 999 Total electric revenues $ 3,694 $ 2,218 $ — $ 677 $ (150) $ 6,439 Residential $ 100 $ — $ 657 $ — $ — $ 757 Commercial 46 — 164 — — 210 Industrial 5 — 14 — — 19 Other 14 — 62 — (1) 75 Total gas revenues $ 165 $ — $ 897 $ — $ (1) $ 1,061 Total revenues (a) $ 3,859 $ 2,218 $ 897 $ 677 $ (151) $ 7,500 2022 Residential $ 1,578 $ 1,325 $ — $ — $ — $ 2,903 Commercial 1,219 768 — — — 1,987 Industrial 290 199 — — — 489 Other 762 (36) — 615 (139) 1,202 Total electric revenues $ 3,849 $ 2,256 $ — $ 615 $ (139) $ 6,581 Residential $ 119 $ — $ 846 $ — $ — $ 965 Commercial 56 — 221 — — 277 Industrial 7 — 41 — — 48 Other 15 — 72 — (1) 86 Total gas revenues $ 197 $ — $ 1,180 $ — $ (1) $ 1,376 Total revenues (a) $ 4,046 $ 2,256 $ 1,180 $ 615 $ (140) $ 7,957 (a) The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the years ended December 31, 2024, 2023, and 2022: Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Ameren 2024 Revenues from alternative revenue programs $ 4 $ (43) $ (3) $ 33 $ (9) Other revenues not from contracts with customers 7 (a) 10 2 — 19 (a) 2023 Revenues from alternative revenue programs $ (5) $ 116 $ 49 $ 19 $ 179 Other revenues not from contracts with customers (9) (a) 7 2 — — (a) 2022 Revenues from alternative revenue programs $ 17 $ 89 $ (19) $ (9) $ 78 Other revenues not from contracts with customers (103) (a)(b) 6 3 — (94) (a)(b) (a) Includes net realized gains and losses on derivative power contracts. (b) Includes $10 million for insurance recoveries related to lost sales associated with the Callaway Energy Center maintenance outage for the year ended December 31, 2022. Ameren Illinois Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Illinois Transmission Intersegment Eliminations Ameren Illinois 2024 Residential $ 1,254 $ 661 $ — $ — $ 1,915 Commercial 680 166 — — 846 Industrial 178 10 — — 188 Other (23) 101 564 (119) 523 Total revenues (a) $ 2,089 $ 938 $ 564 $ (119) $ 3,472 2023 Residential $ 1,344 $ 657 $ — $ — $ 2,001 Commercial 747 164 — — 911 Industrial 186 14 — — 200 Other (59) 62 480 (113) 370 Total revenues (a) $ 2,218 $ 897 $ 480 $ (113) $ 3,482 2022 Residential $ 1,325 $ 846 $ — $ — $ 2,171 Commercial 768 221 — — 989 Industrial 199 41 — — 240 Other (36) 72 424 (104) 356 Total revenues (a) $ 2,256 $ 1,180 $ 424 $ (104) $ 3,756 (a) The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the Ameren Illinois segments for the years ended December 31, 2024, 2023, and 2022: Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Illinois Transmission Ameren Illinois 2024 Revenues from alternative revenue programs $ (43) $ (3) $ 29 $ (17) Other revenues not from contracts with customers 10 2 — 12 2023 Revenues from alternative revenue programs $ 116 $ 49 $ 12 $ 177 Other revenues not from contracts with customers 7 2 — 9 2022 Revenues from alternative revenue programs $ 89 $ (19) $ (7) $ 63 Other revenues not from contracts with customers 6 3 — 9

Summary Of Significant Accoun_3

Summary Of Significant Accounting Policies - Schedule of Other Assets and Other Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Accounting Policies [Line Items]
Other current assets	$ 162	$ 139
Regulatory Asset, Noncurrent	2,397	1,810
Long-Term Debt, Current Maturities	317	849
Interest accrued	196	147
Long-Term Debt, Excluding Current Maturities	17,262	$ 15,121
Ameren Missouri Securitization Funding I, LLC
Accounting Policies [Line Items]
Other current assets	2
Regulatory Asset, Noncurrent	465
Long-Term Debt, Current Maturities	17
Interest accrued	1
Long-Term Debt, Excluding Current Maturities	$ 448

Summary Of Significant Accoun_4

Summary Of Significant Accounting Policies (Narrative) (Details) customer in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) mi² segment customer	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Accounting Policies [Line Items]
Goodwill	$ 411,000,000	$ 411,000,000
Number of reportable segments | segment	4
Goodwill, Impairment Loss	$ 0
Noncontrolling Interest in Variable Interest Entity	74,000,000	73,000,000
Cash Surrender Value of Life Insurance	260,000,000	248,000,000
Loans, Gross, Insurance Policy	$ 110,000,000	104,000,000
Ameren Missouri
Accounting Policies [Line Items]
Public Utilities, Area Serviced | mi²	24,000
Number of Months Between Callaway Maintenance Outages	18 months
Ameren Missouri | 4.85% Securitized Utility Tariff Bonds Due 2039 | Secured Debt
Accounting Policies [Line Items]
Debt instrument face amount	$ 476,000,000	0
Ameren Illinois
Accounting Policies [Line Items]
Public Utilities, Area Serviced | mi²	43,700
Goodwill	$ 411,000,000	411,000,000
Number of reportable segments | segment	3
Goodwill, Impairment Loss	$ 0
Cash Surrender Value of Life Insurance	118,000,000	111,000,000
Loans, Gross, Insurance Policy	$ 110,000,000	$ 104,000,000
Minimum
Accounting Policies [Line Items]
Percent of average depreciable cost	3%	3%	3%
Maximum
Accounting Policies [Line Items]
Percent of average depreciable cost	4%	4%	4%
Electric | Ameren Missouri
Accounting Policies [Line Items]
Public Utilities, Number of Customers | customer	1.3
Power | Ameren Illinois
Accounting Policies [Line Items]
Public Utilities, Number of Customers | customer	1.2
Natural gas | Ameren Missouri
Accounting Policies [Line Items]
Public Utilities, Number of Customers | customer	0.1
Natural gas | Ameren Illinois
Accounting Policies [Line Items]
Public Utilities, Number of Customers | customer	0.8
Ameren Illinois Electric Distribution
Accounting Policies [Line Items]
Goodwill	$ 238,000,000
Ameren Illinois Gas
Accounting Policies [Line Items]
Goodwill	80,000,000
Ameren Illinois Transmission
Accounting Policies [Line Items]
Goodwill	93,000,000
Ameren Transmission
Accounting Policies [Line Items]
Goodwill	93,000,000
AROs | Ameren Missouri
Accounting Policies [Line Items]
Noncash Depreciation related to ARO	2,000,000	$ 9,000,000	$ 7,000,000
Partnership Funding Commitment [Member]
Accounting Policies [Line Items]
Unrecorded Unconditional Purchase Obligation	$ 35,000,000

Rate and Regulatory Matters (Re

Rate and Regulatory Matters (Regulatory Framework-Missouri) (Details) - Ameren Missouri	12 Months Ended
	Dec. 31, 2024 MWh
Public Utilities, General Disclosures [Line Items]
Number of months to complete a regulatory rate review	11 months
PISA deferral percentage	85%
Depreciation percentage not included in PISA deferral	15%
Amount of Megawatts	102
Sharing Level For Fac	95%
Percentage of variance not covered by FAC	5%
Base rate reset period	4 years
Maximum
Public Utilities, General Disclosures [Line Items]
Public utilities, approved rate increase (decrease), percentage	2.50%
PISA
Public Utilities, General Disclosures [Line Items]
Regulatory asset, amortization period	20 years

Rate and Regulatory Matters (_2

Rate and Regulatory Matters (Regulatory Framework-Illinois) (Details) - Ameren Illinois	12 Months Ended
	Dec. 31, 2024 numberOfProposedPerformanceMetrics
FEJA
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Return on Equity, Percentage	5.80%
Return on equity adjustment	2%
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%

Rate and Regulatory Matters (_3

Rate and Regulatory Matters (Regulatory Framework-Federal) (Details)	12 Months Ended
	Dec. 31, 2024
Midwest Independent Transmission System Operator, Inc
Public Utilities, General Disclosures [Line Items]
Incentive adder to FERC allowed base return on common equity	0.50%
FERC revenue requirement reconciliation adjustment
Public Utilities, General Disclosures [Line Items]
Regulatory asset, amortization period	2 years

Rate and Regulatory Matters (Na

Rate and Regulatory Matters (Narrative-Missouri) (Details)

1 Months Ended

3 Months Ended

12 Months Ended

Nov. 30, 2023 USD ($)

Sep. 30, 2024 MWh

Dec. 31, 2023 MWh

Mar. 31, 2023 MWh

Dec. 31, 2022 MWh

Sep. 30, 2022 MWh

Dec. 31, 2027 USD ($)

Dec. 31, 2026 USD ($)

Dec. 31, 2025 USD ($)

Dec. 31, 2024 USD ($) MWh

Dec. 31, 2023 USD ($)

Dec. 31, 2022 USD ($)

Public Utilities, General Disclosures [Line Items]

Capital expenditures

$ 4,319,000,000

$ 3,597,000,000

$ 3,351,000,000

Revenues

$ 7,623,000,000

7,500,000,000

7,957,000,000

Natural gas

Public Utilities, General Disclosures [Line Items]

Percentage of energy sourced from renewable resources

100%

Ameren Missouri

Public Utilities, General Disclosures [Line Items]

Amount of Megawatts | MWh

102

Cass County, Boomtown, and Huck Finn Solar Project Purchase Price

$ 1,000,000,000

Capital expenditures

$ 2,712,000,000

1,760,000,000

1,690,000,000

Ameren Missouri | Rush Island Energy Center

Public Utilities, General Disclosures [Line Items]

Costs to be securitized

$ 476,000,000

Amortization of regulatory asset

$ 15

Ameren Missouri | Solar generation facility

Public Utilities, General Disclosures [Line Items]

Amount of Megawatts | MWh

500

Ameren Missouri | Generation Facilities

Public Utilities, General Disclosures [Line Items]

Capital expenditures

$ 1,700,000,000

Ameren Missouri | Maximum

Public Utilities, General Disclosures [Line Items]

Percentage of energy sourced from renewable resources

100%

Ameren Missouri | Electric | Pending Rate Case

Public Utilities, General Disclosures [Line Items]

Cumulative rate increase

$ 446,000,000

Percent of requested return on equity

10.25%

Percentage of requested equity capital structure

52%

American Missouri Proposed Average Annual Rate Base

$ 13,900,000,000

MoPSC Staff recommended rate increase (decrease)

$ 384,000,000

MoPSC Staff's recommended ROE

9.74%

MoPSC Staff's recommended capital structure

52%

MoPSC Staff's recommended rate base

$ 13,900,000,000

Months to complete a rate proceeding

11 months

Ameren Missouri | Electric | Minimum | Pending Rate Case

Public Utilities, General Disclosures [Line Items]

Percentage of High Prairie costs challenged by the MoOPC

25%

Ameren Missouri | Electric | Maximum | Pending Rate Case

Public Utilities, General Disclosures [Line Items]

Percentage of High Prairie costs challenged by the MoOPC

45%

Ameren Missouri | Build-transfer | Solar generation facility

Public Utilities, General Disclosures [Line Items]

Amount of Megawatts | MWh

300

200

150

Ameren Missouri | Development-transfer | Solar generation facility

Public Utilities, General Disclosures [Line Items]

Amount of Megawatts | MWh

150

Ameren Missouri | Self-build | Solar generation facility

Public Utilities, General Disclosures [Line Items]

Amount of Megawatts | MWh

50

50

Ameren Missouri | Self-build | Natural Gas Generation Facility

Public Utilities, General Disclosures [Line Items]

Amount of Megawatts | MWh

800

Ameren Missouri | Natural gas | Pending Rate Case

Public Utilities, General Disclosures [Line Items]

Cumulative rate increase

$ 40,000,000

Percent of requested return on equity

10.25%

Percentage of requested equity capital structure

52%

American Missouri Proposed Average Annual Rate Base

$ 531,000,000

Months to complete a rate proceeding

11 months

Ameren Missouri | MEEIA 2019 | Electric

Public Utilities, General Disclosures [Line Items]

Revenues

$ 13,000,000

$ 12,000,000

$ 22,000,000

Ameren Missouri | MEEIA 2024 | Electric | Forecast

Public Utilities, General Disclosures [Line Items]

Energy efficiency investments in MEEIA 2019 programs

$ 22,000,000

$ 51,000,000

Percentage of MEEIA energy efficiency goals achieved

100%

Incentive award if energy efficiency goals are achieved

$ 2,000,000

$ 5,000,000

$ 5,000,000

Rate And Regulatory Matters (_4

Rate And Regulatory Matters (Narrative-Illinois) (Details) - USD ($) $ in Millions

1 Months Ended

12 Months Ended

Jan. 31, 2025

Dec. 31, 2024

Nov. 30, 2024

Dec. 31, 2023

Nov. 30, 2023

Oct. 31, 2023

Dec. 31, 2027

Dec. 31, 2026

Dec. 31, 2025

Dec. 31, 2024

Dec. 31, 2023

Dec. 31, 2022

Public Utilities, General Disclosures [Line Items]

Capital expenditures

$ 4,319

$ 3,597

$ 3,351

Ameren Illinois

Public Utilities, General Disclosures [Line Items]

Capital expenditures

1,467

$ 1,731

$ 1,601

Natural gas

Public Utilities, General Disclosures [Line Items]

Percentage of energy sourced from renewable resources

100%

Natural gas | Ameren Illinois

Public Utilities, General Disclosures [Line Items]

Percent of requested return on equity

9.89%

Percentage of requested equity capital structure

52%

IETL | Electric Distribution | Ameren Illinois

Public Utilities, General Disclosures [Line Items]

Multi-year rate plan approved revenue requirement

$ 1,206

Public Utilities, Approved Return on Equity, Percentage

8.72%

Public Utilities, Approved Equity Capital Structure, Percentage

50%

Approved rate base

$ 4,200

$ 4,200

Multi-year rate plan requested revenue requirement

1,196

American Illinois Proposed Average Annual Rate Base (in Billions)

4,000

Approved rate increase (decrease), amount

$ 309

IETL | Electric Distribution | Ameren Illinois | Forecast

Public Utilities, General Disclosures [Line Items]

Multi-year rate plan approved revenue requirement

$ 1,422

$ 1,367

$ 1,287

Approved rate base

4,800

4,600

4,400

Multi-year rate plan requested revenue requirement

1,397

1,350

1,282

American Illinois Proposed Average Annual Rate Base (in Billions)

$ 4,700

$ 4,500

$ 4,300

Pending Rate Case | Electric Distribution | Ameren Illinois

Public Utilities, General Disclosures [Line Items]

Cumulative rate increase

$ 158

Percentage of requested equity capital structure

50%

Pending Rate Case | Natural gas | Ameren Illinois

Public Utilities, General Disclosures [Line Items]

Capital expenditures

$ 30

Pending Rate Case | Electric Energy-Efficiency | Ameren Illinois

Public Utilities, General Disclosures [Line Items]

Approved rate base

$ 434

Cumulative rate increase

$ 126

Pending Rate Case | Electric Energy-Efficiency | Ameren Illinois | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Cumulative rate increase

$ 26

Delivery Service Rate Order | Natural gas | Ameren Illinois

Public Utilities, General Disclosures [Line Items]

Cumulative rate increase

$ 140

Delivery Service Rate Order | Natural gas | Ameren Illinois | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Public Utilities, Approved Return on Equity, Percentage

10.70%

Public Utilities, Approved Equity Capital Structure, Percentage

52%

Approved rate base

$ 3,300

Final Rate Order | Natural gas | Ameren Illinois

Public Utilities, General Disclosures [Line Items]

Public Utilities, Approved Return on Equity, Percentage

9.44%

Public Utilities, Approved Equity Capital Structure, Percentage

50%

Approved rate base

$ 2,850

Cumulative rate increase

112

Capital expenditures

$ 93

$ 93

Final Rate Order | Natural gas | Ameren Illinois | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Public Utilities, Approved Return on Equity, Percentage

9.44%

Capital expenditures

$ 48

Rate and Regulatory Matters (_5

Rate and Regulatory Matters (Narrative-Federal) (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended
	Oct. 31, 2024	May 31, 2020	Dec. 31, 2024	Dec. 31, 2023
Ameren Illinois
Public Utilities, General Disclosures [Line Items]
Current regulatory liabilities			$ 79	$ 71
Final Rate Order | Midwest Independent Transmission System Operator, Inc
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Return on Equity, Percentage	9.98%	10.02%
Expense recognized due to lower FERC-allowed base ROE			2
Current regulatory liabilities			12
Final Rate Order | Midwest Independent Transmission System Operator, Inc | Electric
Public Utilities, General Disclosures [Line Items]
Revenue reduction due to lower FERC-allowed base ROE			10
Final Rate Order | Midwest Independent Transmission System Operator, Inc | Ameren Illinois
Public Utilities, General Disclosures [Line Items]
Expense recognized due to lower FERC-allowed base ROE			1
Current regulatory liabilities			8
Final Rate Order | Midwest Independent Transmission System Operator, Inc | Ameren Illinois | Electric
Public Utilities, General Disclosures [Line Items]
Revenue reduction due to lower FERC-allowed base ROE			$ 7

Rate And Regulatory Matters (Sc

Rate And Regulatory Matters (Schedule Of Regulatory Assets And Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Regulatory assets:
Less: current regulatory assets	$ (366)	$ (365)
Noncurrent regulatory assets	2,397	1,810
Regulatory liabilities:
Noncurrent regulatory liabilities	5,897	5,512
Ameren Missouri
Regulatory assets:
Total regulatory assets	1,432	856
Less: current regulatory assets	(66)	(101)
Noncurrent regulatory assets	1,366	755
Regulatory liabilities:
Total regulatory liabilities	3,213	2,974
Less: current regulatory liabilities	(37)	(15)
Noncurrent regulatory liabilities	$ 3,176	2,959
PISA deferral percentage	85%
Ameren Illinois
Regulatory assets:
Total regulatory assets	$ 1,292	1,287
Less: current regulatory assets	(281)	(252)
Noncurrent regulatory assets	1,011	1,035
Regulatory liabilities:
Total regulatory liabilities	2,652	2,489
Less: current regulatory liabilities	(79)	(71)
Noncurrent regulatory liabilities	2,573	2,418
Ameren (parent)
Regulatory assets:
Total regulatory assets	2,763	2,175
Less: current regulatory assets	(366)	(365)
Noncurrent regulatory assets	2,397	1,810
Regulatory liabilities:
Total regulatory liabilities	6,017	5,599
Less: current regulatory liabilities	(120)	(87)
Noncurrent regulatory liabilities	5,897	5,512
Under-recovered FAC
Regulatory assets:
Total regulatory assets	41	72
Under-recovered FAC | Ameren Missouri
Regulatory assets:
Total regulatory assets	41	72
Under-recovered FAC | Ameren Illinois
Regulatory assets:
Total regulatory assets	0	0
MTM derivative losses
Regulatory assets:
Total regulatory assets	103	168
MTM derivative losses | Ameren Missouri
Regulatory assets:
Total regulatory assets	15	25
MTM derivative losses | Ameren Illinois
Regulatory assets:
Total regulatory assets	88	143
IEIMA revenue requirement reconciliation adjustment
Regulatory assets:
Total regulatory assets	139	239
IEIMA revenue requirement reconciliation adjustment | Ameren Missouri
Regulatory assets:
Total regulatory assets	0	0
IEIMA revenue requirement reconciliation adjustment | Ameren Illinois
Regulatory assets:
Total regulatory assets	$ 139	239
Regulatory liabilities:
Regulatory asset, amortization period	2 years
MYRP revenue requirement reconciliation adjustment
Regulatory assets:
Total regulatory assets	$ 24	0
MYRP revenue requirement reconciliation adjustment | Ameren Missouri
Regulatory assets:
Total regulatory assets	0	0
MYRP revenue requirement reconciliation adjustment | Ameren Illinois
Regulatory assets:
Total regulatory assets	24	0
Under-recovered RBA
Regulatory assets:
Total regulatory assets	22	0
Under-recovered RBA | Ameren Missouri
Regulatory assets:
Total regulatory assets	0	0
Under-recovered RBA | Ameren Illinois
Regulatory assets:
Total regulatory assets	22	0
FERC revenue requirement reconciliation adjustment
Regulatory assets:
Total regulatory assets	$ 90	54
Regulatory liabilities:
Regulatory asset, amortization period	2 years
FERC revenue requirement reconciliation adjustment | Ameren Missouri
Regulatory assets:
Total regulatory assets	$ 0	0
FERC revenue requirement reconciliation adjustment | Ameren Illinois
Regulatory assets:
Total regulatory assets	55	25
Under-recovered VBA
Regulatory assets:
Total regulatory assets	49	49
Under-recovered VBA | Ameren Missouri
Regulatory assets:
Total regulatory assets	0	0
Under-recovered VBA | Ameren Illinois
Regulatory assets:
Total regulatory assets	49	49
Income taxes
Regulatory assets:
Total regulatory assets	322	207
Regulatory liabilities:
Total regulatory liabilities	$ 1,804	1,809
Weighted-average amortization period	39 years
Income taxes | Ameren Missouri
Regulatory assets:
Total regulatory assets	$ 237	126
Regulatory liabilities:
Total regulatory liabilities	$ 1,040	999
Weighted-average amortization period	30 years
Income taxes | Ameren Illinois
Regulatory assets:
Total regulatory assets	$ 81	78
Regulatory liabilities:
Total regulatory liabilities	$ 679	724
Weighted-average amortization period	46 years
Bad debt rider
Regulatory assets:
Total regulatory assets	$ 25	43
Bad debt rider | Ameren Missouri
Regulatory assets:
Total regulatory assets	0	0
Bad debt rider | Ameren Illinois
Regulatory assets:
Total regulatory assets	25	43
Callaway refueling and maintenance outage costs
Regulatory assets:
Total regulatory assets	13	37
Callaway refueling and maintenance outage costs | Ameren Missouri
Regulatory assets:
Total regulatory assets	$ 13	37
Regulatory liabilities:
Regulatory asset, amortization period	18 months
Callaway refueling and maintenance outage costs | Ameren Illinois
Regulatory assets:
Total regulatory assets	$ 0	0
Unamortized loss on reacquired debt
Regulatory assets:
Total regulatory assets	47	50
Unamortized loss on reacquired debt | Ameren Missouri
Regulatory assets:
Total regulatory assets	42	45
Unamortized loss on reacquired debt | Ameren Illinois
Regulatory assets:
Total regulatory assets	5	5
Environmental cost riders
Regulatory assets:
Total regulatory assets	43	50
Environmental cost riders | Ameren Missouri
Regulatory assets:
Total regulatory assets	0	0
Environmental cost riders | Ameren Illinois
Regulatory assets:
Total regulatory assets	43	50
Storm costs
Regulatory assets:
Total regulatory assets	18	27
Storm costs | Ameren Missouri
Regulatory assets:
Total regulatory assets	0	0
Storm costs | Ameren Illinois
Regulatory assets:
Total regulatory assets	18	27
Customer generation rebate program
Regulatory assets:
Total regulatory assets	89	54
Customer generation rebate program | Ameren Missouri
Regulatory assets:
Total regulatory assets	0	0
Customer generation rebate program | Ameren Illinois
Regulatory assets:
Total regulatory assets	89	54
PISA
Regulatory assets:
Total regulatory assets	464	386
PISA | Ameren Missouri
Regulatory assets:
Total regulatory assets	$ 464	386
Regulatory liabilities:
Regulatory asset, amortization period	20 years
PISA | Ameren Illinois
Regulatory assets:
Total regulatory assets	$ 0	0
Rush Island Energy Center securitization
Regulatory assets:
Total regulatory assets	465	0
Rush Island Energy Center securitization | Ameren Missouri
Regulatory assets:
Total regulatory assets	465	0
Rush Island Energy Center securitization | Ameren Illinois
Regulatory assets:
Total regulatory assets	0	0
RESRAM
Regulatory assets:
Total regulatory assets	51	48
RESRAM | Ameren Missouri
Regulatory assets:
Total regulatory assets	51	48
RESRAM | Ameren Illinois
Regulatory assets:
Total regulatory assets	0	0
Certain Meramec Energy Center costs
Regulatory assets:
Total regulatory assets	26	39
Certain Meramec Energy Center costs | Ameren Missouri
Regulatory assets:
Total regulatory assets	$ 26	39
Regulatory liabilities:
Regulatory asset, amortization period	5 years
Certain Meramec Energy Center costs | Ameren Illinois
Regulatory assets:
Total regulatory assets	$ 0	0
FEJA energy-efficiency rider
Regulatory assets:
Total regulatory assets	576	500
FEJA energy-efficiency rider | Ameren Missouri
Regulatory assets:
Total regulatory assets	0	0
FEJA energy-efficiency rider | Ameren Illinois
Regulatory assets:
Total regulatory assets	576	500
Property Tax Tracker
Regulatory assets:
Total regulatory assets	$ 22	13
Regulatory liabilities:
Regulatory asset, amortization period	2 years
Property Tax Tracker | Ameren Missouri
Regulatory assets:
Total regulatory assets	$ 22	13
Property Tax Tracker | Ameren Illinois
Regulatory assets:
Total regulatory assets	0	0
Other regulatory assets
Regulatory assets:
Total regulatory assets	134	139
Other regulatory assets | Ameren Missouri
Regulatory assets:
Total regulatory assets	56	65
Other regulatory assets | Ameren Illinois
Regulatory assets:
Total regulatory assets	78	74
Over-recovered Illinois electric power costs
Regulatory liabilities:
Total regulatory liabilities	34	36
Over-recovered Illinois electric power costs | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	0	0
Over-recovered Illinois electric power costs | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	$ 34	36
Amortization period	1 year
Over-recovered PGA
Regulatory liabilities:
Total regulatory liabilities	$ 35	40
Over-recovered PGA | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	2	7
Over-recovered PGA | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	33	33
MTM derivative gains
Regulatory liabilities:
Total regulatory liabilities	16	22
MTM derivative gains | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	10	19
MTM derivative gains | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	6	3
Cost of removal
Regulatory liabilities:
Total regulatory liabilities	2,294	2,186
Cost of removal | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	1,118	1,098
Cost of removal | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	1,115	1,038
AROs
Regulatory liabilities:
Total regulatory liabilities	691	524
AROs | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	691	524
AROs | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	0	0
Pension and postretirement benefit costs
Regulatory liabilities:
Total regulatory liabilities	358	346
Pension and postretirement benefit costs | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	202	202
Pension and postretirement benefit costs | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	156	144
Pension and postretirement benefit costs tracker
Regulatory liabilities:
Total regulatory liabilities	70	111
Pension and postretirement benefit costs tracker | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	$ 70	111
Regulatory liability, amortization period	2 years
Pension and postretirement benefit costs tracker | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	$ 0	0
Renewable energy credits and zero emission credits
Regulatory liabilities:
Total regulatory liabilities	586	489
Renewable energy credits and zero emission credits | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	0	0
Renewable energy credits and zero emission credits | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	586	489
Certain Rush Island Energy Center Costs
Regulatory liabilities:
Total regulatory liabilities	66	0
Certain Rush Island Energy Center Costs | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	66	0
Certain Rush Island Energy Center Costs | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	0	0
Other regulatory liabilities
Regulatory liabilities:
Total regulatory liabilities	63	36
Other regulatory liabilities | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	14	14
Other regulatory liabilities | Ameren Illinois
Regulatory liabilities:
Total regulatory liabilities	$ 43	22
FAC adjustments | Ameren Missouri
Regulatory liabilities:
Accumulation period	4 months
Regulatory asset, amortization period	8 months
Asset Retirement Obligation - Nuclear decommissioning trust fund balance | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	$ 1,342	1,150
Asset Retirement Obligation - removal costs | Ameren Missouri
Regulatory liabilities:
Total regulatory liabilities	$ 651	$ 626
Minimum | FEJA energy-efficiency rider | Ameren Illinois
Regulatory liabilities:
Regulatory asset, amortization period	2 years
Maximum | FEJA energy-efficiency rider | Ameren Illinois
Regulatory liabilities:
Regulatory asset, amortization period	12 years

Property And Plant, Net (Schedu

Property And Plant, Net (Schedule Of Property And Plant, Net) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ 16,495	$ 15,426
Property, plant, and equipment, net	36,304	33,776
Depreciable Property, Plant And Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	50,790	47,179
Property, plant, and equipment, net	34,295	31,753
Coal Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	3,556	3,452
Natural Gas and Oil Fired Electric Generation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	938	921
Nuclear
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	5,931	5,879
Renewable Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	2,920	1,984
Electric distribution
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	17,629	16,458
Electric transmission
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	10,162	9,508
Natural gas
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	5,197	4,874
Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	4,457	4,103
Nuclear fuel in progress
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	268	173
Oil Fired Electric Generation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	30	29
Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	1,741	1,320
Plant To Be Abandoned, Net
Property, Plant and Equipment [Line Items]
Property and plant, at original cost		530
Ameren Missouri
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	10,875	10,243
Property, plant, and equipment, net	18,788	17,250
Ameren Missouri | Depreciable Property, Plant And Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	28,404	25,876
Property, plant, and equipment, net	17,529	15,633
Ameren Missouri | Coal Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	3,556	3,452
Ameren Missouri | Natural Gas and Oil Fired Electric Generation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	938	921
Ameren Missouri | Nuclear
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	5,931	5,879
Ameren Missouri | Renewable Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	2,901	1,973
Ameren Missouri | Electric distribution
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	9,469	8,638
Ameren Missouri | Electric transmission
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	2,406	2,134
Ameren Missouri | Natural gas
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	776	688
Ameren Missouri | Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	2,427	2,191
Ameren Missouri | Nuclear fuel in progress
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	268	173
Ameren Missouri | Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	991	914
Ameren Missouri | Plant To Be Abandoned, Net
Property, Plant and Equipment [Line Items]
Property and plant, at original cost		530
Ameren Illinois
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	5,184	4,783
Property, plant, and equipment, net	15,530	14,632
Ameren Illinois | Depreciable Property, Plant And Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	20,095	19,055
Property, plant, and equipment, net	14,911	14,272
Ameren Illinois | Coal Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Ameren Illinois | Natural Gas and Oil Fired Electric Generation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Ameren Illinois | Nuclear
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Ameren Illinois | Renewable Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	19	11
Ameren Illinois | Electric distribution
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	8,160	7,820
Ameren Illinois | Electric transmission
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	5,725	5,381
Ameren Illinois | Natural gas
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	4,421	4,186
Ameren Illinois | Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	1,770	1,657
Ameren Illinois | Nuclear fuel in progress
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Ameren Illinois | Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	619	360
Ameren Illinois | Plant To Be Abandoned, Net
Property, Plant and Equipment [Line Items]
Property and plant, at original cost		0
Other
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	436	400
Property, plant, and equipment, net	1,986	1,894
Other | Depreciable Property, Plant And Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	2,291	2,248
Property, plant, and equipment, net	1,855	1,848
Other | Coal Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Natural Gas and Oil Fired Electric Generation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Nuclear
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Renewable Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Electric distribution
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Electric transmission
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	2,031	1,993
Other | Natural gas
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	260	255
Other | Nuclear fuel in progress
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	$ 131	46
Other | Plant To Be Abandoned, Net
Property, Plant and Equipment [Line Items]
Property and plant, at original cost		$ 0
Minimum | Electric distribution
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Minimum | Electric transmission
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	50 years
Minimum | Natural gas
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Minimum | Other
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Minimum | Electric generation
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Maximum | Electric distribution
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	80 years
Maximum | Electric transmission
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	75 years
Maximum | Natural gas
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	80 years
Maximum | Other
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	55 years
Maximum | Electric generation
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	72 years
Maximum | Ameren Missouri | Electric generation
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	150 years

Property and Plant, Net (Sche_2

Property and Plant, Net (Schedule of Capitalized Software and Deferred Cloud Implementation Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Capitalized Computer Software, Amortization	$ 224	$ 212	$ 159
Capitalized Computer Software, Gross	1,996	1,823
Capitalized Computer Software, Accumulated Amortization	(1,348)	(1,126)
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization	20	17	15
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization	157	142
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization	(71)	(51)
Ameren Missouri | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Capitalized Computer Software, Amortization	118	114	85
Capitalized Computer Software, Gross	881	795
Capitalized Computer Software, Accumulated Amortization	(567)	(453)
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization	9	8	7
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization	71	63
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization	(32)	(23)
Ameren Illinois | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Capitalized Computer Software, Amortization	100	92	69
Capitalized Computer Software, Gross	867	786
Capitalized Computer Software, Accumulated Amortization	(552)	(452)
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization	10	9	$ 8
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization	82	76
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization	$ (36)	$ (26)
Minimum | Software and Software Development Costs
Finite-Lived Intangible Assets [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Minimum | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Maximum | Software and Software Development Costs
Finite-Lived Intangible Assets [Line Items]
Property, Plant and Equipment, Useful Life	15 years
Maximum | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years

Property and Plant, Net (Sche_3

Property and Plant, Net (Schedule of Capitalized Software, Future Amortization Expense) (Details) - Capitalized software costs $ in Millions	Dec. 31, 2024 USD ($)
Finite-Lived Intangible Assets [Line Items]
2025	$ 190
2026	147
2027	110
2028	69
2029	38
Ameren Missouri
Finite-Lived Intangible Assets [Line Items]
2025	98
2026	73
2027	54
2028	33
2029	17
Ameren Illinois
Finite-Lived Intangible Assets [Line Items]
2025	85
2026	70
2027	53
2028	34
2029	$ 20

Short-Term Debt And Liquidity_2

Short-Term Debt And Liquidity (Narrative) (Details)	12 Months Ended
	Dec. 31, 2024 USD ($) lender	Dec. 31, 2023
Utilities
Short-term Debt [Line Items]
Average interest rate	5.19%	5.29%
Multiyear Credit Facility
Short-term Debt [Line Items]
Number of lenders | lender	20
Line of credit facility, maximum borrowing capacity, per lender	$ 156,000,000
Multiyear Credit Facility
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	2,600,000,000
Commitment fee amount	$ 100,000,000
Actual debt-to-capital ratio	0.60
Multiyear Credit Facility | Maximum
Short-term Debt [Line Items]
Actual debt-to-capital ratio	0.65
Missouri Credit Agreement
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,400,000,000
Missouri Credit Agreement | Ameren Missouri
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,000,000,000
Actual debt-to-capital ratio	0.48
Missouri Credit Agreement | Multiyear Credit Facility
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,700,000,000
Illinois Credit Agreement
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	1,200,000,000
Illinois Credit Agreement | Ameren Illinois
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,000,000,000
Actual debt-to-capital ratio	0.45
Illinois Credit Agreement | Multiyear Credit Facility
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,500,000,000
Credit Agreements
Short-term Debt [Line Items]
Net liquidity available	1,400,000,000
Covenant terms, default provisions, maximum indebtedness	$ 100,000,000

Short-Term Debt And Liquidity_3

Short-Term Debt And Liquidity (Schedule Of Maximum Aggregate Amount Available On Credit Agreements) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Missouri Credit Agreement
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,400
Missouri Credit Agreement | Ameren (parent)
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,000
Missouri Credit Agreement | Ameren Missouri
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,000
Illinois Credit Agreement
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,200
Illinois Credit Agreement | Ameren (parent)
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	700
Illinois Credit Agreement | Ameren Illinois
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,000

Short-Term Debt And Liquidity_4

Short-Term Debt And Liquidity (Commercial Paper) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Short-term Debt [Line Items]
Average daily amount outstanding	$ 762	$ 1,166
Commercial paper issuances outstanding at period-end	$ 1,143	$ 536
Weighted-average interest rate	5.28%	5.32%
Peak amount outstanding during period	$ 1,569	$ 1,526
Peak interest rate	5.68%	5.68%
Ameren (parent)
Short-term Debt [Line Items]
Average daily amount outstanding	$ 377	$ 726
Commercial paper issuances outstanding at period-end	$ 1,055	$ 0
Weighted-average interest rate	5.10%	5.38%
Peak amount outstanding during period	$ 1,091	$ 1,298
Peak interest rate	5.60%	5.65%
Ameren Missouri
Short-term Debt [Line Items]
Average daily amount outstanding	$ 192	$ 274
Commercial paper issuances outstanding at period-end	$ 0	$ 170
Weighted-average interest rate	5.34%	5.22%
Peak amount outstanding during period	$ 595	$ 592
Peak interest rate	5.68%	5.68%
Ameren Illinois
Short-term Debt [Line Items]
Average daily amount outstanding	$ 193	$ 166
Commercial paper issuances outstanding at period-end	$ 88	$ 366
Weighted-average interest rate	5.57%	5.23%
Peak amount outstanding during period	$ 694	$ 450
Peak interest rate	5.68%	5.68%

Long-Term Debt And Equity Fin_3

Long-Term Debt And Equity Financings (Schedule Of Long-Term Debt Outstanding) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Oct. 31, 2024	Sep. 30, 2024	Aug. 31, 2024	Jun. 30, 2024	Apr. 30, 2024	Jan. 31, 2024	Dec. 31, 2023	Nov. 30, 2023	May 31, 2023	Mar. 31, 2023
Debt Instrument [Line Items]
Less: Maturities due within one year	$ (317)							$ (849)
Long-Term Debt, Excluding Current Maturities	17,262							15,121
Thereafter	13,361
Ameren (parent)
Debt Instrument [Line Items]
Total long-term debt, gross	3,400							3,850
Less: Unamortized discount and premium	(3)							(4)
Less: Unamortized debt issuance costs	(14)							(17)
Long-Term Debt, Excluding Current Maturities	3,383							3,379
Thereafter	800
Ameren Missouri
Debt Instrument [Line Items]
Total long-term debt, gross	7,825							6,399
Less: Unamortized discount and premium	(17)							(13)
Less: Unamortized debt issuance costs	(62)							(45)
Less: Maturities due within one year	(17)							(350)
Long-Term Debt, Excluding Current Maturities	7,671							5,991
Thereafter	6,857
Ameren Missouri | Related Party
Debt Instrument [Line Items]
Less: Unamortized debt issuance costs	(1)							0
Long-Term Debt, Excluding Current Maturities	57							0
Ameren Illinois
Debt Instrument [Line Items]
Total long-term debt, gross	5,913							5,288
Less: Unamortized discount and premium	(10)							(9)
Less: Unamortized debt issuance costs	(51)							(47)
Less: Maturities due within one year	(300)							0
Long-Term Debt, Excluding Current Maturities	5,549							5,232
Thereafter	5,123
Ameren Illinois | Related Party
Debt Instrument [Line Items]
Long-Term Debt, Excluding Current Maturities	3							0
Ameren Transmission Company of Illinois
Debt Instrument [Line Items]
Total long-term debt, gross	661							570
Less: Unamortized debt issuance costs	(2)							(2)
Less: Maturities due within one year	0							(49)
Long-Term Debt, Excluding Current Maturities	659							519
Thereafter	$ 581
Unsecured Debt | Ameren (parent) | 2.50% Senior unsecured notes due 2024
Debt Instrument [Line Items]
Long-term debt interest rate	2.50%		2.50%
Debt instrument face amount	$ 0		$ (450)					(450)
Unsecured Debt | Ameren (parent) | 3.65% Senior unsecured notes due 2026
Debt Instrument [Line Items]
Long-term debt interest rate	3.65%
Debt instrument face amount	$ (350)							(350)
Unsecured Debt | Ameren (parent) | 5.70% Senior unsecured notes due 2026
Debt Instrument [Line Items]
Long-term debt interest rate	5.70%								5.70%
Debt instrument face amount	$ (600)							(600)	$ (600)
Unsecured Debt | Ameren (parent) | 1.95% Senior unsecured notes due 2027
Debt Instrument [Line Items]
Long-term debt interest rate	1.95%
Debt instrument face amount	$ (500)							(500)
Unsecured Debt | Ameren (parent) | 1.75% Senior unsecured notes due 2028
Debt Instrument [Line Items]
Long-term debt interest rate	1.75%
Debt instrument face amount	$ (450)							(450)
Unsecured Debt | Ameren (parent) | 5.00% Senior unsecured notes due 2029
Debt Instrument [Line Items]
Long-term debt interest rate	5%
Debt instrument face amount	$ (700)							(700)
Unsecured Debt | Ameren (parent) | 3.50% Senior unsecured notes due 2031
Debt Instrument [Line Items]
Long-term debt interest rate	3.50%
Debt instrument face amount	$ (800)							(800)
Unsecured Debt | Ameren Illinois | 4.95% First mortgage bonds due 2033
Debt Instrument [Line Items]
Long-term debt interest rate										4.95%
Unsecured Debt | Ameren Transmission Company of Illinois | 2.45% Senior unsecured notes due 2036
Debt Instrument [Line Items]
Long-term debt interest rate	2.45%
Debt instrument face amount	$ (75)							(75)
Unsecured Debt | Ameren Transmission Company of Illinois | 2.45% Senior unsecured notes due 2036 | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Thereafter	30
Unsecured Debt | Ameren Transmission Company of Illinois | 2.45% Senior unsecured notes due 2036 | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Thereafter	$ 45
Unsecured Debt | Ameren Transmission Company of Illinois | Senior Unsecured Notes, 5.17%, Due 2039
Debt Instrument [Line Items]
Long-term debt interest rate	5.17%			5.17%
Debt instrument face amount	$ (70)			$ (70)				0
Unsecured Debt | Ameren Transmission Company of Illinois | 3.43% Senior unsecured notes due 2050
Debt Instrument [Line Items]
Long-term debt interest rate	3.43%			3.43%
Debt instrument face amount	$ (351)							(400)
Unsecured Debt | Ameren Transmission Company of Illinois | 2.96% Senior unsecured notes due 2052
Debt Instrument [Line Items]
Long-term debt interest rate	2.96%
Debt instrument face amount	$ (95)							(95)
Unsecured Debt | Ameren Transmission Company of Illinois | 2.96% Senior unsecured notes due 2052 | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Thereafter	45
Unsecured Debt | Ameren Transmission Company of Illinois | 2.96% Senior unsecured notes due 2052 | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Thereafter	$ 50
Unsecured Debt | Ameren Transmission Company of Illinois | Senior Unsecured Notes, 5.42%, Due 2053
Debt Instrument [Line Items]
Long-term debt interest rate	5.42%			5.42%
Debt instrument face amount	$ (70)			$ (70)				0
Secured Debt | Ameren Missouri | Related Party
Debt Instrument [Line Items]
Debt instrument face amount	$ (58)							0
Secured Debt | Ameren Missouri | 3.50% senior secured notes due 2024
Debt Instrument [Line Items]
Long-term debt interest rate	3.50%					3.50%
Debt instrument face amount	$ 0					$ (350)		(350)
Secured Debt | Ameren Missouri | 2.95% senior secured notes due 2027
Debt Instrument [Line Items]
Long-term debt interest rate	2.95%
Debt instrument face amount	$ (400)							(400)
Secured Debt | Ameren Missouri | 3.50% First mortgage bonds due 2029
Debt Instrument [Line Items]
Long-term debt interest rate	3.50%
Debt instrument face amount	$ (450)							(450)
Secured Debt | Ameren Missouri | 2.95% First mortgage bonds due 2030
Debt Instrument [Line Items]
Long-term debt interest rate	2.95%
Debt instrument face amount	$ (465)							(465)
Secured Debt | Ameren Missouri | 2.15% First mortgage bonds due 2032
Debt Instrument [Line Items]
Long-term debt interest rate	2.15%
Debt instrument face amount	$ (525)							(525)
Secured Debt | Ameren Missouri | First Mortgage Bonds 5.20% Due 2034
Debt Instrument [Line Items]
Long-term debt interest rate	5.20%
Debt instrument face amount	$ (500)							0
Secured Debt | Ameren Missouri | 5.50% Senior secured notes due 2034
Debt Instrument [Line Items]
Long-term debt interest rate	5.50%
Debt instrument face amount	$ (184)							(184)
Secured Debt | Ameren Missouri | 5.30% Senior secured notes due 2037
Debt Instrument [Line Items]
Long-term debt interest rate	5.30%
Debt instrument face amount	$ (300)							(300)
Secured Debt | Ameren Missouri | 8.45% Senior secured notes due 2039
Debt Instrument [Line Items]
Long-term debt interest rate	8.45%
Debt instrument face amount	$ (350)							(350)
Secured Debt | Ameren Missouri | 4.85% Securitized Utility Tariff Bonds Due 2039
Debt Instrument [Line Items]
Long-term debt interest rate	4.85%
Debt instrument face amount	$ (476)							0
Secured Debt | Ameren Missouri | 3.90% Senior secured notes due 2042
Debt Instrument [Line Items]
Long-term debt interest rate	3.90%
Debt instrument face amount	$ (485)							(485)
Secured Debt | Ameren Missouri | 3.65% Senior secured notes due 2045
Debt Instrument [Line Items]
Long-term debt interest rate	3.65%
Debt instrument face amount	$ (400)							(400)
Secured Debt | Ameren Missouri | 3.65% Senior secured notes due 2045 | Related Party
Debt Instrument [Line Items]
Long-term debt interest rate	3.65%
Debt instrument face amount	$ (7)							0
Secured Debt | Ameren Missouri | 4.00% First mortgage bonds due 2048
Debt Instrument [Line Items]
Long-term debt interest rate	4%
Debt instrument face amount	$ (425)							(425)
Secured Debt | Ameren Missouri | 3.25% First Mortgage bonds due 2049
Debt Instrument [Line Items]
Long-term debt interest rate	3.25%
Debt instrument face amount	$ (330)							(330)
Secured Debt | Ameren Missouri | 3.25% First Mortgage bonds due 2049 | Related Party
Debt Instrument [Line Items]
Long-term debt interest rate	3.25%
Debt instrument face amount	$ (33)							0
Secured Debt | Ameren Missouri | 2.625% First Mortgage bonds due 2051
Debt Instrument [Line Items]
Long-term debt interest rate	2.625%
Debt instrument face amount	$ (550)							(550)
Secured Debt | Ameren Missouri | 2.625% First Mortgage bonds due 2051 | Related Party
Debt Instrument [Line Items]
Long-term debt interest rate	2.625%
Debt instrument face amount	$ (4)							0
Secured Debt | Ameren Missouri | First Mortgage Bonds, 3.90%, Due 2052 - $525 Issuance
Debt Instrument [Line Items]
Long-term debt interest rate	3.90%
Debt instrument face amount	$ (525)							(525)
Secured Debt | Ameren Missouri | First Mortgage Bonds, 3.90%, Due 2052 - $525 Issuance | Related Party
Debt Instrument [Line Items]
Long-term debt interest rate	3.90%
Debt instrument face amount	$ (14)							0
Secured Debt | Ameren Missouri | 5.45% First mortgage bonds due 2053
Debt Instrument [Line Items]
Long-term debt interest rate	5.45%										5.45%
Debt instrument face amount	$ (500)							(500)			$ (500)
Secured Debt | Ameren Missouri | First Mortgage Bonds, 5.25%, Due 2054 - $350 Issuance
Debt Instrument [Line Items]
Long-term debt interest rate	5.25%						5.25%
Debt instrument face amount	$ (350)						$ (350)	0
Secured Debt | Ameren Missouri | First Mortgage Bonds, 5.125%, Due 2055 - $450 Issuance
Debt Instrument [Line Items]
Long-term debt interest rate	5.125%	5.125%
Debt instrument face amount	$ (450)	$ (450)						0
Secured Debt | Ameren Illinois | Related Party
Debt Instrument [Line Items]
Debt instrument face amount	$ (3)							0
Secured Debt | Ameren Illinois | 3.25% First Mortgage bonds due 2025
Debt Instrument [Line Items]
Long-term debt interest rate	3.25%
Debt instrument face amount	$ (300)							(300)
Secured Debt | Ameren Illinois | 6.125% First Mortgage bonds due 2028
Debt Instrument [Line Items]
Long-term debt interest rate	6.125%
Debt instrument face amount	$ (60)							(60)
Secured Debt | Ameren Illinois | 3.80% First Mortgage bonds due 2028
Debt Instrument [Line Items]
Long-term debt interest rate	3.80%
Debt instrument face amount	$ (430)							(430)
Secured Debt | Ameren Illinois | 1.55% First Mortgage bonds due 2030
Debt Instrument [Line Items]
Long-term debt interest rate	1.55%
Debt instrument face amount	$ (375)							(375)
Secured Debt | Ameren Illinois | 3.85% First mortgage bonds due 2032
Debt Instrument [Line Items]
Long-term debt interest rate	3.85%
Debt instrument face amount	$ (500)							(500)
Secured Debt | Ameren Illinois | 4.95% First mortgage bonds due 2033
Debt Instrument [Line Items]
Long-term debt interest rate	4.95%
Debt instrument face amount	$ (500)							(500)		$ (500)
Secured Debt | Ameren Illinois | 6.70% First Mortgage bonds due 2036
Debt Instrument [Line Items]
Long-term debt interest rate	6.70%
Debt instrument face amount	$ (61)							(61)
Secured Debt | Ameren Illinois | 6.70% First Mortgage bonds due 2036
Debt Instrument [Line Items]
Long-term debt interest rate	6.70%
Debt instrument face amount	$ (42)							(42)
Secured Debt | Ameren Illinois | 4.80% First Mortgage bonds due 2043
Debt Instrument [Line Items]
Long-term debt interest rate	4.80%
Debt instrument face amount	$ (280)							(280)
Secured Debt | Ameren Illinois | 4.30% First Mortgage bonds due 2044
Debt Instrument [Line Items]
Long-term debt interest rate	4.30%
Debt instrument face amount	$ (250)							(250)
Secured Debt | Ameren Illinois | 4.15% First Mortgage bonds due 2046
Debt Instrument [Line Items]
Long-term debt interest rate	4.15%
Debt instrument face amount	$ (490)							(490)
Secured Debt | Ameren Illinois | 3.70% First Mortgage bonds due 2047
Debt Instrument [Line Items]
Long-term debt interest rate	3.70%
Debt instrument face amount	$ (500)							(500)
Secured Debt | Ameren Illinois | 3.70% First Mortgage bonds due 2047 | Related Party
Debt Instrument [Line Items]
Long-term debt interest rate	3.70%
Debt instrument face amount	$ (1)							0
Secured Debt | Ameren Illinois | 4.50% First Mortgage bonds due 2049
Debt Instrument [Line Items]
Long-term debt interest rate	4.50%
Debt instrument face amount	$ (500)							(500)
Secured Debt | Ameren Illinois | 3.25% First Mortgage bonds due 2050
Debt Instrument [Line Items]
Long-term debt interest rate	3.25%
Debt instrument face amount	$ (300)							(300)
Secured Debt | Ameren Illinois | 3.25% First Mortgage bonds due 2050 | Related Party
Debt Instrument [Line Items]
Long-term debt interest rate	3.25%
Debt instrument face amount	$ (2)							0
Secured Debt | Ameren Illinois | 2.90% First Mortgage bonds due 2051
Debt Instrument [Line Items]
Long-term debt interest rate	2.90%
Debt instrument face amount	$ (350)							(350)
Secured Debt | Ameren Illinois | 5.90% First mortgage bonds due 2052
Debt Instrument [Line Items]
Long-term debt interest rate	5.90%
Debt instrument face amount	$ (350)							(350)
Secured Debt | Ameren Illinois | 5.55% First mortgage bonds due 2054
Debt Instrument [Line Items]
Long-term debt interest rate	5.55%				5.55%
Debt instrument face amount	$ (625)				$ (625)			0
Environmental Improvement And Pollution Control Revenue Bonds | Ameren Missouri | 2.90% 1998 Series A due 2033
Debt Instrument [Line Items]
Long-term debt interest rate	2.90%
Debt instrument face amount	$ (60)							(60)
Environmental Improvement And Pollution Control Revenue Bonds | Ameren Missouri | 2.90% 1998 Series B due 2033
Debt Instrument [Line Items]
Long-term debt interest rate	2.90%
Debt instrument face amount	$ (50)							(50)
Environmental Improvement And Pollution Control Revenue Bonds | Ameren Missouri | 2.75% 1998 Series C due 2033
Debt Instrument [Line Items]
Long-term debt interest rate	2.75%
Debt instrument face amount	$ (50)							$ (50)

Long-Term Debt And Equity Fin_4

Long-Term Debt And Equity Financings (Schedule Of Maturities Of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
2025	$ 317
2026	974
2027	974
2028	966
2029	1,207
Thereafter	13,361
Total	17,799
Ameren (parent)
Debt Instrument [Line Items]
2025	0
2026	950
2027	500
2028	450
2029	700
Thereafter	800
Total	3,400
Unamortized discount, premium, and debt issuance costs	17
Ameren Missouri
Debt Instrument [Line Items]
2025	17
2026	24
2027	424
2028	26
2029	477
Thereafter	6,857
Total	7,825
Unamortized discount, premium, and debt issuance costs	79
Ameren Illinois
Debt Instrument [Line Items]
2025	300
2026	0
2027	0
2028	490
2029	0
Thereafter	5,123
Total	5,913
Unamortized discount, premium, and debt issuance costs	61
Ameren Transmission Company of Illinois
Debt Instrument [Line Items]
2025	0
2026	0
2027	50
2028	0
2029	30
Thereafter	581
Total	661
Unamortized discount, premium, and debt issuance costs	2
Unsecured Debt | Ameren Transmission Company of Illinois | 2.45% Senior unsecured notes due 2036
Debt Instrument [Line Items]
Debt instrument face amount	75	$ 75
Unsecured Debt | Ameren Transmission Company of Illinois | 2.45% Senior unsecured notes due 2036 | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Thereafter	30
Unsecured Debt | Ameren Transmission Company of Illinois | 2.45% Senior unsecured notes due 2036 | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Thereafter	45
Unsecured Debt | Ameren Transmission Company of Illinois | 3.43% Senior unsecured notes due 2050
Debt Instrument [Line Items]
Debt instrument face amount	351	$ 400
Unsecured Debt | Ameren Transmission Company of Illinois | 3.43% Senior unsecured notes due 2050 | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Thereafter	50
Unsecured Debt | Ameren Transmission Company of Illinois | 3.43% Senior unsecured notes due 2050 | Debt Instrument, Redemption, Period Four
Debt Instrument [Line Items]
Thereafter	49
Unsecured Debt | Ameren Transmission Company of Illinois | 3.43% Senior unsecured notes due 2050 | Debt Instrument, Redemption, Period Five
Debt Instrument [Line Items]
Thereafter	50
Unsecured Debt | Ameren Transmission Company of Illinois | 3.43% Senior unsecured notes due 2050 | Debt Instrument, Redemption, Period Six
Debt Instrument [Line Items]
Thereafter	49
Unsecured Debt | Ameren Transmission Company of Illinois | 3.43% Senior unsecured notes due 2050 | Debt Instrument, Redemption, Period Seven
Debt Instrument [Line Items]
Thereafter	77
Unsecured Debt | Ameren Transmission Company of Illinois | 3.43% Senior unsecured notes due 2050 | Debt Instrument, Redemption, Period Eight
Debt Instrument [Line Items]
Thereafter	$ 76

Long-Term Debt And Equity Fin_5

Long-Term Debt And Equity Financings (Schedule Of Outstanding Preferred Stock) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	0
Preferred stock, voluntary liquidation (in dollars per share)	$ 105.50
Preferred stock, par value (in dollars per share)	$ 0.01
Preferred stock, authorized (in shares)	100,000,000
Union Electric Company and Ameren Illinois
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, issued (in shares)	$ 129	$ 129
Ameren Missouri
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	0
Preferred stock, issued (in shares)	$ 80	80
Preferred stock, par value (in dollars per share)	$ 1
Preferred stock, authorized (in shares)	7,500,000
Ameren Missouri | Par Value $100
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, par value (in dollars per share)	$ 100
Preferred stock, authorized (in shares)	25,000,000
Ameren Missouri | $3.50 Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	130,000
Preferred stock, redemption price per share (in dollars per share)	$ 110
Preferred stock, issued (in shares)	$ 13	13
Dividend rate on preferred shares, per-dollar amount (in dollars per share)	$ 3.50
Ameren Missouri | $3.70 Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	40,000
Preferred stock, redemption price per share (in dollars per share)	$ 104.75
Preferred stock, issued (in shares)	$ 4	4
Dividend rate on preferred shares, per-dollar amount (in dollars per share)	$ 3.70
Ameren Missouri | $4.00 Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	150,000
Preferred stock, redemption price per share (in dollars per share)	$ 105.625
Preferred stock, issued (in shares)	$ 15	15
Dividend rate on preferred shares, per-dollar amount (in dollars per share)	$ 4
Ameren Missouri | $4.30 Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	40,000
Preferred stock, redemption price per share (in dollars per share)	$ 105
Preferred stock, issued (in shares)	$ 4	4
Dividend rate on preferred shares, per-dollar amount (in dollars per share)	$ 4.30
Ameren Missouri | $4.50 Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	213,595
Preferred stock, redemption price per share (in dollars per share)	$ 110
Preferred stock, issued (in shares)	$ 21	21
Dividend rate on preferred shares, per-dollar amount (in dollars per share)	$ 4.50
Ameren Missouri | $4.56 Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	200,000
Preferred stock, redemption price per share (in dollars per share)	$ 102.47
Preferred stock, issued (in shares)	$ 20	20
Dividend rate on preferred shares, per-dollar amount (in dollars per share)	$ 4.56
Ameren Missouri | $4.75 Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	20,000
Preferred stock, redemption price per share (in dollars per share)	$ 102.176
Preferred stock, issued (in shares)	$ 2	2
Dividend rate on preferred shares, per-dollar amount (in dollars per share)	$ 4.75
Ameren Missouri | $5.50 Series A
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	14,000
Preferred stock, redemption price per share (in dollars per share)	$ 110
Preferred stock, issued (in shares)	$ 1	1
Dividend rate on preferred shares, per-dollar amount (in dollars per share)	$ 5.50
Ameren Illinois
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	0
Preferred stock, issued (in shares)	$ 49	49
Preferred stock, par value (in dollars per share)	$ 0
Preferred stock, authorized (in shares)	2,600,000
Ameren Illinois | Par Value $100
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, par value (in dollars per share)	$ 100
Preferred stock, authorized (in shares)	2,000,000
Ameren Illinois | 4.00% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	144,275
Preferred stock, redemption price per share (in dollars per share)	$ 101
Preferred stock, issued (in shares)	$ 14	14
Dividend rate on preferred shares, percentage	4%
Ameren Illinois | 4.08% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	45,224
Preferred stock, redemption price per share (in dollars per share)	$ 103
Preferred stock, issued (in shares)	$ 5	5
Dividend rate on preferred shares, percentage	4.08%
Ameren Illinois | 4.20% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	23,655
Preferred stock, redemption price per share (in dollars per share)	$ 104
Preferred stock, issued (in shares)	$ 2	2
Dividend rate on preferred shares, percentage	4.20%
Ameren Illinois | 4.25% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	50,000
Preferred stock, redemption price per share (in dollars per share)	$ 102
Preferred stock, issued (in shares)	$ 5	5
Dividend rate on preferred shares, percentage	4.25%
Ameren Illinois | 4.26% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	16,621
Preferred stock, redemption price per share (in dollars per share)	$ 103
Preferred stock, issued (in shares)	$ 2	2
Dividend rate on preferred shares, percentage	4.26%
Ameren Illinois | 4.42% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	16,190
Preferred stock, redemption price per share (in dollars per share)	$ 103
Preferred stock, issued (in shares)	$ 2	2
Dividend rate on preferred shares, percentage	4.42%
Ameren Illinois | 4.70% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	18,429
Preferred stock, redemption price per share (in dollars per share)	$ 104.30
Preferred stock, issued (in shares)	$ 2	2
Dividend rate on preferred shares, percentage	4.70%
Ameren Illinois | 4.90% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	73,825
Preferred stock, redemption price per share (in dollars per share)	$ 102
Preferred stock, issued (in shares)	$ 7	7
Dividend rate on preferred shares, percentage	4.90%
Ameren Illinois | 4.92% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	49,289
Preferred stock, redemption price per share (in dollars per share)	$ 103.50
Preferred stock, issued (in shares)	$ 5	5
Dividend rate on preferred shares, percentage	4.92%
Ameren Illinois | 5.16% Series
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, shares outstanding (in shares)	50,000
Preferred stock, redemption price per share (in dollars per share)	$ 102
Preferred stock, issued (in shares)	$ 5	$ 5
Dividend rate on preferred shares, percentage	5.16%

Long-Term Debt And Equity Fin_6

Long-Term Debt And Equity Financings (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Jan. 31, 2025	Jan. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Oct. 31, 2024	Sep. 30, 2024	Aug. 31, 2024	Jun. 30, 2024	Apr. 30, 2024	Jan. 31, 2024	Nov. 30, 2023	Jun. 30, 2023	May 31, 2023	Mar. 31, 2023	May 31, 2022	May 31, 2021
Long-Term Debt And Equity Financings [Line Items]
Gain (Loss) on Extinguishment of Debt			$ 16	$ 0	$ 0
Preferred stock, authorized (in shares)			100,000,000
Preferred stock, par value (in dollars per share)			$ 0.01
Preferred stock, shares outstanding (in shares)			0
Shares issued under the DRPlus and 401(k) plan			500,000	600,000	500,000
Issuances of common stock			$ 273	$ 346	$ 333
Accrued Proceeds from Issuance of Common Stock			$ 7	$ 7
Shares issued (in shares)			200,000	500,000	400,000
Value of stock issued				$ 40
Common stock, shares authorized under DRPlus plan (in shares)														3,000,000
Common stock, shares authorized under 401(k) Plan (in shares)																7,500,000
Maximum value of shares to be issued under ATM Program			$ 550														$ 1,750
Number of shares issued under ATM Program (in shares)			2,900,000	3,200,000	3,400,000
Value of shares issued under ATM program			$ 233	$ 299	$ 292
Payments of stock issuance costs			$ 2	3	3
Initial forward sale price, basis spread			0.0075
Termination of a financing obligation			$ 0	240	0
Debt default provision excess			$ 25
Forward Sale Agreements Outstanding
Long-Term Debt And Equity Financings [Line Items]
Number of shares to settle forward sale agreements (in shares)			2,500,000
Cash settlement of forward sale agreements			$ 213
Period End Net Cash Settlement Price			13
Period end net share settlement price			0.1
Forward sale agreement equity offering shares (in shares)			2.5
Forward Sale Agreement Gross Sales Price			215
Dividend reinvestment and 401 (k) plans
Long-Term Debt And Equity Financings [Line Items]
Issuances of common stock			$ 33	39	41
Ameren Missouri
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, authorized (in shares)			7,500,000
Preferred stock, par value (in dollars per share)			$ 1
Preferred stock, shares outstanding (in shares)			0
Termination of a financing obligation		$ 240	$ 0	240	0
Ameren Missouri | Secured Debt | Related Party
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 58	0
Ameren Illinois
Long-Term Debt And Equity Financings [Line Items]
Preferred stock, authorized (in shares)			2,600,000
Preferred stock, par value (in dollars per share)			$ 0
Preferred stock, shares outstanding (in shares)			0
Termination of a financing obligation			$ 0	0	$ 0
Common stock equity to capitalization ratio			54%
Ameren Illinois | Secured Debt | Related Party
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 3	0
Ameren Missouri and Ameren Illinois
Long-Term Debt And Equity Financings [Line Items]
Bonds interest rate assumption			7%
Dividend rate on preferred shares, percentage			8%
Senior Secured Notes and First Mortgage Bonds | Secured Debt | Related Party
Long-Term Debt And Equity Financings [Line Items]
Gain (Loss) on Extinguishment of Debt			$ 16
Interest Expense, Debt			1
Senior Secured Notes and First Mortgage Bonds | Ameren (parent) | Secured Debt | Related Party
Long-Term Debt And Equity Financings [Line Items]
Repayments of Senior Secured Notes and First Mortgage Bonds			44
2.50% Senior unsecured notes due 2024 | Ameren (parent) | Unsecured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 0	450			$ 450
Long-term debt interest rate			2.50%				2.50%
5.70% Senior unsecured notes due 2026 | Ameren (parent) | Unsecured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 600	600								$ 600
Long-term debt interest rate			5.70%									5.70%
5.00% Senior unsecured notes due 2029 | Ameren (parent) | Unsecured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 700
Long-term debt interest rate			5%
First Mortgage Bonds, 5.25%, Due 2054 - $350 Issuance | Ameren Missouri | Secured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 350	0							$ 350
Long-term debt interest rate			5.25%								5.25%
Senior Secured Notes 5.20% Due 2034 | Ameren Missouri | Secured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount										$ 500
Long-term debt interest rate										5.20%
3.50% senior secured notes due 2024 | Ameren Missouri | Secured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 0	350						$ 350
Long-term debt interest rate			3.50%							3.50%
First Mortgage Bonds, 5.125%, Due 2055 - $450 Issuance | Ameren Missouri | Secured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 450	0		$ 450
Long-term debt interest rate			5.125%			5.125%
4.85% Securitized Utility Tariff Bonds Due 2039 | Ameren Missouri | Secured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 476	0
Long-term debt interest rate			4.85%
5.45% First mortgage bonds due 2053 | Ameren Missouri | Secured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 500	500											$ 500
Long-term debt interest rate			5.45%												5.45%
5.55% First mortgage bonds due 2054 | Ameren Illinois | Secured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 625	0					$ 625
Long-term debt interest rate			5.55%						5.55%
4.95% First mortgage bonds due 2033 | Ameren Illinois | Secured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 500	500										$ 500
Long-term debt interest rate			4.95%
4.95% First mortgage bonds due 2033 | Ameren Illinois | Unsecured Debt
Long-Term Debt And Equity Financings [Line Items]
Long-term debt interest rate														4.95%
0.375% First Mortgage bonds due 2023 | Ameren Illinois | Debt securities
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount													$ 100
Long-term debt interest rate													0.375%
Senior Unsecured Notes, 5.17%, Due 2039 | Ameren Transmission Company of Illinois | Unsecured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 70	0				$ 70
Long-term debt interest rate			5.17%					5.17%
Senior Unsecured Notes, 5.42%, Due 2053 | Ameren Transmission Company of Illinois | Unsecured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 70	0				$ 70
Long-term debt interest rate			5.42%					5.42%
3.43% Senior unsecured notes due 2050 | Ameren Transmission Company of Illinois | Unsecured Debt
Long-Term Debt And Equity Financings [Line Items]
Debt instrument face amount			$ 351	$ 400
Long-term debt interest rate			3.43%					3.43%
Long-Term Debt, Maturity, Remainder of Fiscal Year								$ 49
Ratio of Indebtedness to Net Capital			0.70
Ratio of Indebtedness to Total Assets			0.10
Minimum
Long-Term Debt And Equity Financings [Line Items]
Forward contract indexed to issuer's equity, forward rate per share (in dollars per share)			$ 81
Minimum | Ameren Illinois
Long-Term Debt And Equity Financings [Line Items]
Common stock equity to capitalization ratio			30%
Maximum
Long-Term Debt And Equity Financings [Line Items]
Forward contract indexed to issuer's equity, forward rate per share (in dollars per share)			$ 93.06
Weighted Average
Long-Term Debt And Equity Financings [Line Items]
Forward contract indexed to issuer's equity, forward rate per share (in dollars per share)			$ 84.14
Subsequent Event | Forward Sale Agreements Outstanding
Long-Term Debt And Equity Financings [Line Items]
Number of shares to settle forward sale agreements (in shares)	600,000
Subsequent Event | Weighted Average
Long-Term Debt And Equity Financings [Line Items]
Forward contract indexed to issuer's equity, forward rate per share (in dollars per share)	$ 87.43

Long-Term Debt and Equity Fin_7

Long-Term Debt and Equity Financings (Schedule of Required and Actual Debt Ratios) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($)
Ameren Missouri
Debt Instrument [Line Items]
Bonds Issuable	$ 2,283
Preferred Stock Issuable Based On Coverage Ratio	2,769
Retired Bond Capacity	$ 1,509
Ameren Missouri | Actual Interest Coverage Ratio
Debt Instrument [Line Items]
Interest Coverage Ratio	2.4
Dividend Coverage Ratio	164.4
Ameren Illinois
Debt Instrument [Line Items]
Bonds Issuable	$ 9,225
Preferred Stock Issuable Based On Coverage Ratio	203
Retired Bond Capacity	$ 1,143
Ameren Illinois | Actual Interest Coverage Ratio
Debt Instrument [Line Items]
Interest Coverage Ratio	6.8
Dividend Coverage Ratio	3.5
Minimum | Ameren Missouri | Required Dividend Coverage Ratio
Debt Instrument [Line Items]
Interest Coverage Ratio	2
Dividend Coverage Ratio	2.5
Minimum | Ameren Illinois | Required Dividend Coverage Ratio
Debt Instrument [Line Items]
Interest Coverage Ratio	2
Dividend Coverage Ratio	1.5

Other Income, Net (Other Income

Other Income, Net (Other Income And Expenses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	$ 76	$ 54	$ 43
Interest income on industrial development revenue bonds	0	1	24
Other interest income	41	32	11
Non-service cost components of net periodic benefit income	304	295	184
Miscellaneous income	9	7	10
Gain (Loss) on Extinguishment of Debt	16	0	0
Equity in earnings of subsidiaries	(4)	1	2
Donations	(5)	(24)	(26)
Miscellaneous expense	(20)	(18)	(22)
Total other income, net	417	348	226
Ameren Missouri
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	58	30	24
Interest income on industrial development revenue bonds	0	1	24
Other interest income	8	10	4
Non-service cost components of net periodic benefit income	139	97	55
Miscellaneous income	4	3	4
Donations	(2)	(2)	(3)
Miscellaneous expense	(11)	(9)	(9)
Total other income, net	196	130	99
Defined Benefit Plan, Non-service Cost or Income Components - Tracker	(41)	27	22
Ameren Illinois
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	17	19	18
Other interest income	32	21	7
Non-service cost components of net periodic benefit income	105	124	84
Miscellaneous income	4	4	5
Donations	(3)	(4)	(8)
Miscellaneous expense	(8)	(8)	(10)
Total other income, net	$ 147	$ 156	$ 96

Derivative Financial Instrume_3

Derivative Financial Instruments (Narrative) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Interest Rate Swap
Derivative [Line Items]
Derivative, Notional Amount	$ 140

Derivative Financial Instrume_4

Derivative Financial Instruments (Open Gross Derivative Volumes By Commodity Type) (Details) lb in Thousands, gal in Millions, MWh in Millions, MMBTU in Millions	12 Months Ended
	Dec. 31, 2024 MMBTU MWh lb gal	Dec. 31, 2023 MMBTU MWh lb gal
Fuel oils
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | gal	23	17
Natural gas
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	258	271
Power
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MWh	4	5
Uranium
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	0	186
Ameren Missouri | Fuel oils
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | gal	23	17
Ameren Missouri | Natural gas
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	45	53
Ameren Missouri | Power
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MWh	0	0
Ameren Missouri | Uranium
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	0	186
Ameren Illinois | Fuel oils
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | gal	0	0
Ameren Illinois | Natural gas
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	213	218
Ameren Illinois | Power
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MWh	4	5
Ameren Illinois | Uranium
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	0	0

Derivative Financial Instrume_5

Derivative Financial Instruments (Derivative Instruments Carrying Value) (Details) - Not Designated As Hedging Instrument - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Derivative [Line Items]
Derivative assets	$ 16	$ 22
Derivative liabilities	103	168
Fuel oils | Other current assets
Derivative [Line Items]
Derivative assets	0	2
Fuel oils | Other assets
Derivative [Line Items]
Derivative assets	0	0
Fuel oils | Other current liabilities
Derivative [Line Items]
Derivative liabilities	2	1
Fuel oils | Other deferred credits and liabilities
Derivative [Line Items]
Derivative liabilities	2	1
Natural gas | Other current assets
Derivative [Line Items]
Derivative assets	4	0
Natural gas | Other assets
Derivative [Line Items]
Derivative assets	6	6
Natural gas | Other current liabilities
Derivative [Line Items]
Derivative liabilities	27	57
Natural gas | Other deferred credits and liabilities
Derivative [Line Items]
Derivative liabilities	19	40
Power | Other current assets
Derivative [Line Items]
Derivative assets	6	5
Power | Other assets
Derivative [Line Items]
Derivative assets	0	0
Power | Other current liabilities
Derivative [Line Items]
Derivative liabilities	10	13
Power | Other deferred credits and liabilities
Derivative [Line Items]
Derivative liabilities	43	56
Uranium | Other current assets
Derivative [Line Items]
Derivative assets	0	9
Uranium | Other assets
Derivative [Line Items]
Derivative assets	0	0
Ameren Missouri
Derivative [Line Items]
Derivative assets	10	19
Derivative liabilities	15	25
Ameren Missouri | Fuel oils | Other current assets
Derivative [Line Items]
Derivative assets	0	2
Ameren Missouri | Fuel oils | Other assets
Derivative [Line Items]
Derivative assets	0	0
Ameren Missouri | Fuel oils | Other current liabilities
Derivative [Line Items]
Derivative liabilities	2	1
Ameren Missouri | Fuel oils | Other deferred credits and liabilities
Derivative [Line Items]
Derivative liabilities	2	1
Ameren Missouri | Natural gas | Other current assets
Derivative [Line Items]
Derivative assets	2	0
Ameren Missouri | Natural gas | Other assets
Derivative [Line Items]
Derivative assets	2	3
Ameren Missouri | Natural gas | Other current liabilities
Derivative [Line Items]
Derivative liabilities	5	12
Ameren Missouri | Natural gas | Other deferred credits and liabilities
Derivative [Line Items]
Derivative liabilities	6	10
Ameren Missouri | Power | Other current assets
Derivative [Line Items]
Derivative assets	6	5
Ameren Missouri | Power | Other assets
Derivative [Line Items]
Derivative assets	0	0
Ameren Missouri | Power | Other current liabilities
Derivative [Line Items]
Derivative liabilities	0	1
Ameren Missouri | Power | Other deferred credits and liabilities
Derivative [Line Items]
Derivative liabilities	0	0
Ameren Missouri | Uranium | Other current assets
Derivative [Line Items]
Derivative assets	0	9
Ameren Missouri | Uranium | Other assets
Derivative [Line Items]
Derivative assets	0	0
Ameren Illinois
Derivative [Line Items]
Derivative assets	6	3
Derivative liabilities	88	143
Ameren Illinois | Fuel oils | Other current assets
Derivative [Line Items]
Derivative assets	0	0
Ameren Illinois | Fuel oils | Other assets
Derivative [Line Items]
Derivative assets	0	0
Ameren Illinois | Fuel oils | Other current liabilities
Derivative [Line Items]
Derivative liabilities	0	0
Ameren Illinois | Fuel oils | Other deferred credits and liabilities
Derivative [Line Items]
Derivative liabilities	0	0
Ameren Illinois | Natural gas | Other current assets
Derivative [Line Items]
Derivative assets	2	0
Ameren Illinois | Natural gas | Other assets
Derivative [Line Items]
Derivative assets	4	3
Ameren Illinois | Natural gas | Other current liabilities
Derivative [Line Items]
Derivative liabilities	22	45
Ameren Illinois | Natural gas | Other deferred credits and liabilities
Derivative [Line Items]
Derivative liabilities	13	30
Ameren Illinois | Power | Other current assets
Derivative [Line Items]
Derivative assets	0	0
Ameren Illinois | Power | Other assets
Derivative [Line Items]
Derivative assets	0	0
Ameren Illinois | Power | Other current liabilities
Derivative [Line Items]
Derivative liabilities	10	12
Ameren Illinois | Power | Other deferred credits and liabilities
Derivative [Line Items]
Derivative liabilities	43	56
Ameren Illinois | Uranium | Other current assets
Derivative [Line Items]
Derivative assets	0	0
Ameren Illinois | Uranium | Other assets
Derivative [Line Items]
Derivative assets	$ 0	$ 0

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule Of Fair Value Hierarchy Of Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	$ 1,333	$ 1,141
Excluded receivables, payables, and accrued income, net	9	9
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	911	787
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	422	354
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	0	0
Power | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	6	5
Commodity Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	16	22
Nuclear Decommissioning Trust Fund	1,333	1,141
Assets	1,349	1,163
Derivative liabilities	103	168
Commodity Contract | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	2
Nuclear Decommissioning Trust Fund	911	787
Assets	911	789
Derivative liabilities	5	6
Commodity Contract | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7	4
Nuclear Decommissioning Trust Fund	422	354
Assets	429	358
Derivative liabilities	39	79
Commodity Contract | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	9	16
Nuclear Decommissioning Trust Fund	0	0
Assets	9	16
Derivative liabilities	59	83
Ameren Missouri
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	1,343	1,160
Ameren Missouri | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	911	789
Ameren Missouri | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	426	357
Ameren Missouri | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	6	14
Ameren Missouri | Fuel oils
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	2
Derivative liabilities	4	2
Ameren Missouri | Fuel oils | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	2
Derivative liabilities	4	2
Ameren Missouri | Fuel oils | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Ameren Missouri | Fuel oils | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Ameren Missouri | Natural gas
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	4	3
Derivative liabilities	11	22
Ameren Missouri | Natural gas | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Ameren Missouri | Natural gas | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	4	3
Derivative liabilities	11	19
Ameren Missouri | Natural gas | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	3
Ameren Missouri | Power
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	6	5
Derivative liabilities	0	1
Ameren Missouri | Power | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Ameren Missouri | Power | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Ameren Missouri | Power | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	6	5
Derivative liabilities	0	1
Ameren Missouri | Uranium
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	9
Ameren Missouri | Uranium | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Ameren Missouri | Uranium | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Ameren Missouri | Uranium | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	9
Ameren Missouri | Commodity Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	10	19
Derivative liabilities	15	25
Ameren Missouri | Commodity Contract | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	2
Derivative liabilities	4	2
Ameren Missouri | Commodity Contract | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	4	3
Derivative liabilities	11	19
Ameren Missouri | Commodity Contract | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	6	14
Derivative liabilities	0	4
Ameren Missouri | Equity securities | U.S. large capitalization
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	911	787
Ameren Missouri | Equity securities | U.S. large capitalization | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	911	787
Ameren Missouri | Equity securities | U.S. large capitalization | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	0	0
Ameren Missouri | Equity securities | U.S. large capitalization | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	0	0
Ameren Missouri | Debt securities | U.S. Treasury and agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	191	150
Ameren Missouri | Debt securities | U.S. Treasury and agency securities | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	0	0
Ameren Missouri | Debt securities | U.S. Treasury and agency securities | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	191	150
Ameren Missouri | Debt securities | U.S. Treasury and agency securities | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	0	0
Ameren Missouri | Debt securities | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	145	136
Ameren Missouri | Debt securities | Corporate bonds | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	0	0
Ameren Missouri | Debt securities | Corporate bonds | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	145	136
Ameren Missouri | Debt securities | Corporate bonds | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	0	0
Ameren Missouri | Debt securities | Diversified credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	86	68
Ameren Missouri | Debt securities | Diversified credit | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	0	0
Ameren Missouri | Debt securities | Diversified credit | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	86	68
Ameren Missouri | Debt securities | Diversified credit | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nuclear Decommissioning Trust Fund	0	0
Ameren Illinois | Natural gas
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	6	3
Derivative liabilities	35	75
Ameren Illinois | Natural gas | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	1	4
Ameren Illinois | Natural gas | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	3	1
Derivative liabilities	28	60
Ameren Illinois | Natural gas | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	3	2
Derivative liabilities	6	11
Ameren Illinois | Power
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	53	68
Ameren Illinois | Power | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	0	0
Ameren Illinois | Power | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	0	0
Ameren Illinois | Power | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	53	68
Ameren Illinois | Commodity Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	6	3
Derivative liabilities	88	143
Ameren Illinois | Commodity Contract | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	1	4
Ameren Illinois | Commodity Contract | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	3	1
Derivative liabilities	28	60
Ameren Illinois | Commodity Contract | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	3	2
Derivative liabilities	$ 59	$ 79

Fair Value Measurements (Sche_2

Fair Value Measurements (Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level 3 In The Fair Value Hierarchy) (Details) - Power - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ (47)	$ (64)	$ (21)
Included in regulatory assets/liabilities	11	(47)
Settlements	6	4
Change in unrealized gains (losses) related to assets/liabilities held at December 31	9	(32)
Ameren Missouri
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	6	4	12
Included in regulatory assets/liabilities	12	1
Settlements	(10)	(9)
Change in unrealized gains (losses) related to assets/liabilities held at December 31	6	4
Ameren Illinois
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(53)	(68)	$ (33)
Included in regulatory assets/liabilities	(1)	(48)
Settlements	16	13
Change in unrealized gains (losses) related to assets/liabilities held at December 31	$ 3	$ (36)

Fair Value Measurements (Sche_3

Fair Value Measurements (Schedule of Valuation Process and Unobservable Inputs) (Details) - Power $ in Millions	Dec. 31, 2024 USD ($) $ / MWh	Dec. 31, 2023 USD ($) $ / MWh
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative assets | $	$ 6	$ 5
Derivative Liability | $	$ (53)	$ (69)
Measurement Input, Commodity Forward Price | Minimum | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	32	31
Measurement Input, Commodity Forward Price | Maximum | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	69	65
Measurement Input, Commodity Forward Price | Weighted Average | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	45	43
Measurement Input, Nodal Basis | Minimum | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	(8)	(8)
Measurement Input, Nodal Basis | Maximum | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	(2)	(1)
Measurement Input, Nodal Basis | Weighted Average | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	(5)	(5)

Fair Value Measurements (Sche_4

Fair Value Measurements (Schedule Of Carrying Amounts And Estimated Fair Values Of Financial Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Ameren Missouri
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Issuance Costs, Net	$ 62	$ 45
Ameren Illinois
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Issuance Costs, Net	51	47
Carrying Amount(a)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt (including current portion)	17,579	15,970
Debt Issuance Costs, Net	129	111
Carrying Amount(a) | Ameren Missouri
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt (including current portion)	7,745	6,341
Debt Issuance Costs, Net	62	45
Carrying Amount(a) | Ameren Illinois
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt (including current portion)	5,852	5,232
Debt Issuance Costs, Net	51	47
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	15,933	14,833
Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	15,395	14,366
Fair Value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	538	467
Fair Value | Ameren Missouri
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	6,926	5,800
Fair Value | Ameren Missouri | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	6,926	5,800
Fair Value | Ameren Missouri | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	0	0
Fair Value | Ameren Illinois
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	5,243	4,867
Fair Value | Ameren Illinois | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	5,243	4,867
Fair Value | Ameren Illinois | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 0	$ 0

Callaway Energy Center (Narrati

Callaway Energy Center (Narrative) (Details) - Ameren Missouri $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($)
Nuclear Waste Matters [Line Items]
Frequency of Decommissioning Cost Study	3 years
Minimum | Nuclear Decommissioning Trust Fund
Nuclear Waste Matters [Line Items]
Trust Fund Investments, Target Allocation Percentage	60%
Maximum | Nuclear Decommissioning Trust Fund
Nuclear Waste Matters [Line Items]
Trust Fund Investments, Target Allocation Percentage	70%
Nuclear Plant
Nuclear Waste Matters [Line Items]
Annual decommissioning costs included in costs of service	$ 7

Callaway Energy Center (Proceed

Callaway Energy Center (Proceeds From The Sale Of Investments And Related Gross Realized Gains And Losses In Nuclear Decommissioning Trust Fund) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Nuclear Waste Matters [Line Items]
Proceeds from sales and maturities	$ 564	$ 240	$ 216
Ameren Missouri
Nuclear Waste Matters [Line Items]
Proceeds from sales and maturities	564	240	216
Gross realized gains	44	6	40
Gross realized losses	$ 28	$ 11	$ 10

Callaway Energy Center (Fair Va

Callaway Energy Center (Fair Values Of Investments In Debt And Equity Securities In Nuclear Decommissioning Trust Fund) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Nuclear Waste Matters [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 437
Cash and cash equivalents	328	$ 272	$ 216	$ 155
Fair Value	1,342	1,150
Cash and cash equivalents	7	25
Ameren Missouri
Nuclear Waste Matters [Line Items]
Debt, Equity, Marketable, And Other Securities, Available-For-Sale, Amortized Cost	625	582
Cash and cash equivalents	17	10	$ 13	$ 8
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	742	606
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	25	38
Fair Value	1,342	1,150
Cash and cash equivalents	0	0
Debt, Equity, Marketable, And Other Securities, Available-For-Sale	1,342	1,150
Ameren Missouri | Debt securities
Nuclear Waste Matters [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	437	382
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2	3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	17	31
Fair Value	422	354
Ameren Missouri | Equity securities
Nuclear Waste Matters [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis	179	191
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	740	603
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	8	7
Equity Securities, FV-NI	911	787
Ameren Missouri | Cash and cash equivalents
Nuclear Waste Matters [Line Items]
Marketable Securities	10	5
Cash and cash equivalents	0	0
Cash and Cash Equivalents and Restricted Cash and Cash Equivalents	0	0
Cash and cash equivalents	10	5
Ameren Missouri | Other Debt And Equity Securities
Nuclear Waste Matters [Line Items]
Net Receivables (Payables) From Pending Securities Sales, Interest, and Securities Purchases, Cost Basis	(1)	4
Net Receivables (Payables) From Pending Securities Sales, Interest, And Securities Purchases, Available-For-sale Securities, Accumulated Gross Unrealized Gain, Before Tax	0	0
Net Receivables (Payables) From Pending Securities Sales, Interest, And Securities Purchases, Available-For-sale Securities, Accumulated Gross Unrealized Loss, Before Tax	0	0
Net Receivables (Payables) From Pending Securities Sales, Interest, and Securities Purchases, Fair Value	$ (1)	$ 4

Callaway Energy Center (Cost an

Callaway Energy Center (Cost and Fair Values of Investments In Debt Securities in Nuclear Decommissioning Trust Fund According to Contractual Maturities) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Nuclear Waste Matters [Abstract]
Cost, Less than 5 years	$ 186
Cost, 5 years to 10 years	117
Cost, Due after 10 years	134
Cost, Total	437
Fair Value, Less than 5 years	184
Fair Value, 5 years to 10 years	112
Fair Value, Due after 10 years	126
Fair Value, Total	$ 422

Callaway Energy Center (Insuran

Callaway Energy Center (Insurance Disclosure) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($)
Nuclear Waste Matters [Line Items]
Number Of Years The Limit Of Liability And The Maximum Potential Annual Payments Are Adjusted	five years
Number of weeks of coverage after the first twelve weeks of an outage	1
Number Of Additional Weeks After Initial Indemnity Coverage For Power Outage	1.365
Public Liability And Nuclear Worker Liability - American Nuclear Insurers
Nuclear Waste Matters [Line Items]
Maximum Coverages	$ 500
Maximum Assessments for Single Incidents	0
Public Liability And Nuclear Worker Liability - Pool Participation
Nuclear Waste Matters [Line Items]
Maximum Coverages	15,763
Maximum Assessments for Single Incidents	166
Threshold Amount For which a Retrospective Assessment For a Covered loss is necessary	500
Maximum Annual Payment Per Incident At Licensed Commercial Nuclear Reactor	25
Public Liability And Nuclear Worker Liability
Nuclear Waste Matters [Line Items]
Maximum Coverages	16,263
Maximum Assessments for Single Incidents	166
Property Damage - Nuclear Electric Insurance Ltd
Nuclear Waste Matters [Line Items]
Maximum Coverages	3,200
Maximum Assessments for Single Incidents	28
Replacement Power - Nuclear Electric Insurance Ltd
Nuclear Waste Matters [Line Items]
Maximum Coverages	490
Maximum Assessments for Single Incidents	11
Amount of Weekly Indemnity Coverage Commencing Twelve Weeks After Power Outage	4.5
Amount of additional weekly indemnity coverage commencing after initial indemnity coverage	3.6
Amount Of Weekly Indemnity Coverage Thereafter Not Exceeding Policy Limit	490
Sub-limit of for Non-Nuclear Events	291
Radiation Event
Nuclear Waste Matters [Line Items]
Maximum Coverages	2,700
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period	3,200
Non-radiation event
Nuclear Waste Matters [Line Items]
Maximum Coverages	700
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period	1,800
Property Damage European Mutual Association for Nuclear Insurance
Nuclear Waste Matters [Line Items]
Maximum Coverages	$ 490

Retirement Benefits (Narrative)

Retirement Benefits (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024 USD ($) bond	Dec. 31, 2023 USD ($)	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded (Unfunded) Status of Plan		$ 734	$ 551
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation, Change in Discount Rate		0.45%
Number of high-quality corporate bonds | bond		860
Defined benefit plan estimated future employer contributions over next five years		$ 170
Collateralized loan percentage compared to asset's market value		102%
Securities Loaned		$ 454	234
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded (Unfunded) Status of Plan		$ 48	$ 14
Expected return on plan assets		6.75%	6.75%	6.50%
Pension Benefits | Forecast
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	6.75%
Ameren Missouri | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Future funding requirement, percentage		40%
Ameren Illinois | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Future funding requirement, percentage		50%

Retirement Benefits (Summary Of

Retirement Benefits (Summary Of Benefit Liability Recorded) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	$ (734)	$ (551)
Ameren Missouri
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	(201)	(142)
Ameren Illinois
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	$ (438)	$ (351)

Retirement Benefits (Funded Sta

Retirement Benefits (Funded Status Of Benefit Plans And Amounts Included In Regulatory Assets And OCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Change in plan assets:
Funded status – surplus	$ (734)	$ (551)
Accrued benefit asset at December 31	(734)	(551)
Amounts recognized in the balance sheet consist of:
Noncurrent asset	(757)	(581)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation at end of year	3,962	4,102
Change in benefit obligation:
Net benefit obligation at beginning of year	4,258	4,061
Service cost	88	79	$ 128
Interest cost	222	221	163
Participant contributions	0	0
Actuarial (gain) loss	(143)	170
Benefits paid	(291)	(273)
Net benefit obligation at end of year	4,134	4,258	4,061
Change in plan assets:
Fair value of plan assets at beginning of year	4,272	4,027
Actual return on plan assets	193	514
Employer contributions	8	4	5
Participant contributions	0	0
Benefits paid	(291)	(273)
Fair value of plan assets at end of year	4,182	4,272	4,027
Funded status – surplus	(48)	(14)
Accrued benefit asset at December 31	(48)	(14)
Amounts recognized in the balance sheet consist of:
Noncurrent asset	(71)	(44)
Liability, Defined Benefit Plan, Current	2	2
Liability, Defined Benefit Plan, Noncurrent	21	28
Amounts recognized in regulatory assets or liabilities consist of:
Net actuarial (gain) loss	42	(10)
Prior service credit	0	0
Amounts recognized in accumulated OCI (pretax) consist of:
Net actuarial (gain) loss	26	22
Total	68	12
Postretirement Benefits
Change in benefit obligation:
Net benefit obligation at beginning of year	856	838
Service cost	12	12	20
Interest cost	44	45	34
Participant contributions	7	7
Actuarial (gain) loss	(51)	17
Benefits paid	(61)	(63)
Net benefit obligation at end of year	807	856	838
Change in plan assets:
Fair value of plan assets at beginning of year	1,393	1,249
Actual return on plan assets	150	197
Employer contributions	4	3	2
Participant contributions	7	7
Benefits paid	(61)	(63)
Fair value of plan assets at end of year	1,493	1,393	$ 1,249
Funded status – surplus	(686)	(537)
Accrued benefit asset at December 31	(686)	(537)
Amounts recognized in the balance sheet consist of:
Noncurrent asset	(686)	(537)
Liability, Defined Benefit Plan, Current	0	0
Liability, Defined Benefit Plan, Noncurrent	0	0
Amounts recognized in regulatory assets or liabilities consist of:
Net actuarial (gain) loss	(379)	(311)
Prior service credit	(21)	(25)
Amounts recognized in accumulated OCI (pretax) consist of:
Net actuarial (gain) loss	(7)	(4)
Total	$ (407)	$ (340)

Retirement Benefits (Assumption

Retirement Benefits (Assumptions Used To Determine Benefit Obligations) (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate at measurement date	5.70%	5.25%
Increase in future compensation	4%	3.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate	5.50%	5.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase for 2024		4%
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate at measurement date	5.70%	5.25%
Increase in future compensation	4%	3.50%
Medical cost trend rate (ultimate)	5%	5%	5%
Medical cost trend rate (initial)			5%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase for 2024		4%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year, Pre-Medicare Plan Participantes	7%	6.93%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year, Post-Medicare Plan Participants	7%	6.50%
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2033	2030
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year, Post-Medicare Plan Participants Adjustment	3%	3%
Postretirement Health Coverage
Defined Benefit Plan Disclosure [Line Items]
Medical cost trend rate (ultimate)	2.50%	2.50%	3%
Medical cost trend rate (initial)	2.50%	2.50%

Retirement Benefits (Cash Contr

Retirement Benefits (Cash Contributions Made To Benefit Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to benefit plans	$ 8	$ 4	$ 5
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to benefit plans	4	3	2
Ameren Missouri | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to benefit plans	1	1	1
Ameren Missouri | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to benefit plans	2	2	1
Ameren Illinois | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to benefit plans	1	2	3
Ameren Illinois | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to benefit plans	1	1	1
Other | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to benefit plans	6	1	1
Other | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to benefit plans	$ 1	$ 0	$ 0

Retirement Benefits (Target All

Retirement Benefits (Target Allocation Of The Plans' Asset Categories) (Details)	Dec. 31, 2024	Dec. 31, 2023
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	100%	100%
Pension Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	3%	1%
Pension Benefits | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	49%	51%
Pension Benefits | U.S. large-capitalization
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	16%	15%
Pension Benefits | U.S. small- and mid-capitalization
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	9%	8%
Pension Benefits | Global
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	15%	16%
Pension Benefits | International
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	9%	12%
Pension Benefits | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	35%	35%
Pension Benefits | Diversified credit
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	8%	7%
Pension Benefits | Real estate
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	5%	6%
Pension Benefits | Private equity
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	1%	1%
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	100%	100%
Postretirement Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	2%	1%
Postretirement Benefits | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	62%	63%
Postretirement Benefits | U.S. large-capitalization
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	33%	32%
Postretirement Benefits | U.S. small- and mid-capitalization
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	8%	8%
Postretirement Benefits | Global
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	13%	15%
Postretirement Benefits | International
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	8%	8%
Postretirement Benefits | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at December 31,	36%	36%
Minimum | Pension Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%
Minimum | Pension Benefits | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	42%
Minimum | Pension Benefits | U.S. large-capitalization
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10%
Minimum | Pension Benefits | U.S. small- and mid-capitalization
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3%
Minimum | Pension Benefits | Global
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10%
Minimum | Pension Benefits | International
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	4%
Minimum | Pension Benefits | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	32%
Minimum | Pension Benefits | Diversified credit
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	6%
Minimum | Pension Benefits | Real estate
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%
Minimum | Pension Benefits | Private equity
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%
Minimum | Postretirement Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%
Minimum | Postretirement Benefits | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	55%
Minimum | Postretirement Benefits | U.S. large-capitalization
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	23%
Minimum | Postretirement Benefits | U.S. small- and mid-capitalization
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3%
Minimum | Postretirement Benefits | Global
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	9%
Minimum | Postretirement Benefits | International
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	5%
Minimum | Postretirement Benefits | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	33%
Maximum | Pension Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	5%
Maximum | Pension Benefits | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	52%
Maximum | Pension Benefits | U.S. large-capitalization
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	20%
Maximum | Pension Benefits | U.S. small- and mid-capitalization
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	13%
Maximum | Pension Benefits | Global
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	20%
Maximum | Pension Benefits | International
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	14%
Maximum | Pension Benefits | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	42%
Maximum | Pension Benefits | Diversified credit
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	16%
Maximum | Pension Benefits | Real estate
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10%
Maximum | Pension Benefits | Private equity
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	5%
Maximum | Postretirement Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	7%
Maximum | Postretirement Benefits | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	65%
Maximum | Postretirement Benefits | U.S. large-capitalization
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	33%
Maximum | Postretirement Benefits | U.S. small- and mid-capitalization
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	13%
Maximum | Postretirement Benefits | Global
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	19%
Maximum | Postretirement Benefits | International
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	15%
Maximum | Postretirement Benefits | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	43%

Retirement Benefits (Fair Value

Retirement Benefits (Fair Value Of Plan Assets Utilizing Fair Value Hierarchy) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 4,182	$ 4,272	$ 4,027
Pension Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	540	718
Pension Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,542	1,529
Pension Benefits | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,247	2,256
Pension Benefits | Includes Medical Benefit Component Under Section401 H And Excludes Receivables Related To Pending Security Sales [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,329	4,503
Pension Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	75	90
Pension Benefits | Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Cash and cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Cash and cash equivalents | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	75	90
Pension Benefits | U.S. large-capitalization
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	689	663
Pension Benefits | U.S. large-capitalization | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | U.S. large-capitalization | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | U.S. large-capitalization | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	689	663
Pension Benefits | U.S. small- and mid-capitalization
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	375	353
Pension Benefits | U.S. small- and mid-capitalization | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	375	353
Pension Benefits | U.S. small- and mid-capitalization | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | U.S. small- and mid-capitalization | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	408	545
Pension Benefits | International | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	182	316
Pension Benefits | International | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | International | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	226	229
Pension Benefits | Global
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	680	721
Pension Benefits | Global | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Global | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Global | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	680	721
Pension Benefits | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	463	479
Pension Benefits | Corporate bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	463	479
Pension Benefits | Corporate bonds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36	43
Pension Benefits | Municipal bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Municipal bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36	43
Pension Benefits | Municipal bonds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | U.S. Treasury and agency securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,032	994
Pension Benefits | U.S. Treasury and agency securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | U.S. Treasury and agency securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,032	994
Pension Benefits | U.S. Treasury and agency securities | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Diversified Credit
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	344
Pension Benefits | Diversified Credit | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Diversified Credit | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Diversified Credit | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	344	305
Pension Benefits | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(6)	62
Pension Benefits | Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(17)	49
Pension Benefits | Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	13
Pension Benefits | Other | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	233	248
Pension Benefits | Real estate | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Real estate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Real estate | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	233	248
Pension Benefits | Medical benefit assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(200)	(196)
Pension Benefits | Net receivables
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	53	(35)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,493	1,393	$ 1,249
Postretirement Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	517	459
Postretirement Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	173	161
Postretirement Benefits | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	601	575
Postretirement Benefits | Includes Medical Benefit Component Under Section401 H And Excludes Receivables Related To Pending Security Sales [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,291	1,195
Postretirement Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25	10
Postretirement Benefits | Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25	10
Postretirement Benefits | Cash and cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | Cash and cash equivalents | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | U.S. large-capitalization
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	423	383
Postretirement Benefits | U.S. large-capitalization | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	332	302
Postretirement Benefits | U.S. large-capitalization | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | U.S. large-capitalization | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	91	81
Postretirement Benefits | U.S. small- and mid-capitalization
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	106	96
Postretirement Benefits | U.S. small- and mid-capitalization | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	106	96
Postretirement Benefits | U.S. small- and mid-capitalization | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | U.S. small- and mid-capitalization | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	106	100
Postretirement Benefits | International | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54	51
Postretirement Benefits | International | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | International | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	52	49
Postretirement Benefits | Global
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	165	174
Postretirement Benefits | Global | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | Global | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | Global | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	165	174
Postretirement Benefits | Municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	173	161
Postretirement Benefits | Municipal bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | Municipal bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	173	161
Postretirement Benefits | Municipal bonds | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	293	271
Postretirement Benefits | Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Postretirement Benefits | Other | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	293	271
Postretirement Benefits | Medical benefit assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	200	196
Postretirement Benefits | Net receivables
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 2	$ 2

Retirement Benefits (Components

Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Non-service Cost or Income Components	$ 304	$ 295	$ 184
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	88	79	128
Interest cost	222	221	163
Expected return on plan assets(b)	(327)	(333)	(320)
Prior service cost (credit)	0	0	0
Actuarial (gain) loss	(67)	(115)	25
Defined Benefit Plan, Non-service Cost or Income Components	(172)	(227)	(132)
Net periodic benefit cost (income)(d)	$ (84)	(148)	(4)
Defined Benefit Plan, Amortization of Gain (Loss)	10 years
Defined Benefit Plan, Difference Between Actual and Expected Return (Loss) on Plan Assets Amortization Period	4 years
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 12	12	20
Interest cost	44	45	34
Expected return on plan assets(b)	(93)	(91)	(85)
Prior service cost (credit)	(4)	(4)	(4)
Actuarial (gain) loss	(38)	(45)	(19)
Defined Benefit Plan, Non-service Cost or Income Components	(91)	(95)	(74)
Net periodic benefit cost (income)(d)	$ (79)	$ (83)	$ (54)
Defined Benefit Plan, Amortization of Gain (Loss)	10 years
Defined Benefit Plan, Difference Between Actual and Expected Return (Loss) on Plan Assets Amortization Period	4 years

Retirement Benefits (Summary _2

Retirement Benefits (Summary Of Benefit Plan Costs Incurred) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ (84)	$ (148)	$ (4)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	(79)	(83)	(54)
Ameren Missouri | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	(44)	(76)	(3)
Ameren Missouri | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	(27)	(30)	(14)
Ameren Illinois | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	(34)	(62)	3
Ameren Illinois | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	(52)	(54)	(41)
Other | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	(6)	(10)	(4)
Other | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 0	$ 1	$ 1

Retirement Benefits (Schedule O

Retirement Benefits (Schedule Of Expected Payments From Qualified Trust And Company Funds) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Pension Benefits | Paid from Qualified Trust Funds
Defined Benefit Plan Disclosure [Line Items]
2025	$ 284
2026	289
2027	292
2028	295
2029	297
2030 – 2034	1,504
Pension Benefits | Paid from Company Funds
Defined Benefit Plan Disclosure [Line Items]
2025	2
2026	2
2027	2
2028	2
2029	2
2030 – 2034	13
Postretirement Benefits | Paid from Qualified Trust Funds
Defined Benefit Plan Disclosure [Line Items]
2025	56
2026	57
2027	57
2028	57
2029	57
2030 – 2034	284
Postretirement Benefits | Paid from Company Funds
Defined Benefit Plan Disclosure [Line Items]
2025	3
2026	3
2027	4
2028	4
2029	4
2030 – 2034	$ 18

Retirement Benefits (Assumpti_2

Retirement Benefits (Assumptions Used To Determine Net Periodic Benefit Cost) (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate at measurement date	5.25%	5.55%	3%
Expected return on plan assets	6.75%	6.75%	6.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	3.50%	3.50%	3.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate	5.50%	5%	5%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase for 2024	4%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase for 2023	4.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate for 2024	6.42%	5.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate for 2023		5.50%
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate at measurement date	5.25%	5.55%	3%
Expected return on plan assets	6.75%	6.75%	6.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	3.50%	3.50%	3.50%
Medical cost trend rate (initial)			5%
Medical cost trend rate (ultimate)	5%	5%	5%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase for 2024	4%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase for 2023	4.50%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate, Pre-Medicare Plan Participants	6.93%	7.25%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate, Post-Medicare Plan Participants	6.50%	6.75%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year, Post-Medicare Plan Participants Adjustment	3%	3%
Postretirement Health Coverage
Defined Benefit Plan Disclosure [Line Items]
Medical cost trend rate (initial)	2.50%	2.50%
Medical cost trend rate (ultimate)	2.50%	2.50%	3%

Retirement Benefits (Schedule_2

Retirement Benefits (Schedule Of Matching Contributions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 49	$ 49	$ 43
Ameren Missouri
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	26	27	23
Ameren Illinois
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	22	21	19
Other
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 1	$ 1	$ 1

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	8.8
Maximum shares available for grants (in shares)	7.7
Settled performance share units and restricted stock units	$ 24	$ 60	$ 47
Compensation cost not yet recognized	$ 39
Expected weighted average recognition period for share-based compensation expense, in months	23 months
Income taxes
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	$ (1)	$ 6	$ 5
Performance Share Units | Market Condition PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares issued per share unit, minimum	0%
Percentage of shares issued per share unit, maximum	200%
Performance Share Units | Performance Condition PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Share-Based Compensation Arrangement By Share-Based Payment Award, Extended Award Vesting Period	38 months
Award Requisite Service Period	5 years
Percentage of shares issued per share unit, minimum	0%
Percentage of shares issued per share unit, maximum	200%
Performance Share Units | Market Condition PSUs February Grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Share-Based Compensation Arrangement By Share-Based Payment Award, Extended Award Vesting Period	38 months
Award Requisite Service Period	5 years
Percentage of shares issued per share unit, minimum	0%
Percentage of shares issued per share unit, maximum	200%
Stock Issued During Period Percentage Conversion Of Units, Mid-point	100%
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	38 months
Award Requisite Service Period	5 years

Stock-Based Compensation (Summa

Stock-Based Compensation (Summary Of Nonvested Shares) (Details)	12 Months Ended
	Dec. 31, 2024 $ / shares shares
Performance Share Units | Market Condition PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares issued per share unit, minimum	0%
Percentage of shares issued per share unit, maximum	200%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at January 1, 2024(c) | shares	761,712
Granted | shares	314,456
Forfeitures | shares	(46,636)
Dividend equivalents | shares	27,508
Vested and distributed | shares	(248,090)
Outstanding at December 31, 2024(c) | shares	808,950
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted-average Fair Value per Unit, Nonvested at beginning of year (in dollars per share) | $ / shares	$ 89.22
Fair value of share units awarded | $ / shares	56.73
Weighted-average Fair Value per Unit, Unearned or forfeited (in dollars per share) | $ / shares	73.97
Weighted-average Fair Value per Unit, Dividend Equivalent (in dollars per share) | $ / shares	77.74
Weighted-average Fair Value per Unit, Vested and distributed (in dollars per share) | $ / shares	87.10
Weighted-average Fair Value per Unit, Nonvested at end of year (in dollars per share) | $ / shares	$ 77.73
Performance Share Units | Performance Condition PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares issued per share unit, minimum	0%
Percentage of shares issued per share unit, maximum	200%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at January 1, 2024(c) | shares	112,391
Granted | shares	51,938
Forfeitures | shares	(7,691)
Dividend equivalents | shares	4,127
Vested and distributed | shares	(39,768)
Outstanding at December 31, 2024(c) | shares	120,997
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted-average Fair Value per Unit, Nonvested at beginning of year (in dollars per share) | $ / shares	$ 83.36
Fair value of share units awarded | $ / shares	68.83
Weighted-average Fair Value per Unit, Unearned or forfeited (in dollars per share) | $ / shares	77.22
Weighted-average Fair Value per Unit, Dividend Equivalent (in dollars per share) | $ / shares	79.03
Weighted-average Fair Value per Unit, Vested and distributed (in dollars per share) | $ / shares	78.11
Weighted-average Fair Value per Unit, Nonvested at end of year (in dollars per share) | $ / shares	$ 79.09
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at January 1, 2024(c) | shares	377,864
Granted | shares	159,050
Forfeitures | shares	(29,330)
Dividend equivalents | shares	13,580
Vested and distributed | shares	(125,644)
Outstanding at December 31, 2024(c) | shares	395,520
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted-average Fair Value per Unit, Nonvested at beginning of year (in dollars per share) | $ / shares	$ 83.82
Fair value of share units awarded | $ / shares	69.09
Weighted-average Fair Value per Unit, Unearned or forfeited (in dollars per share) | $ / shares	79.59
Weighted-average Fair Value per Unit, Dividend Equivalent (in dollars per share) | $ / shares	79.59
Weighted-average Fair Value per Unit, Vested and distributed (in dollars per share) | $ / shares	78.58
Weighted-average Fair Value per Unit, Nonvested at end of year (in dollars per share) | $ / shares	$ 79.73

Stock-Based Compensation (Sum_2

Stock-Based Compensation (Summary of Expense) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 28	$ 26	$ 24
Employee service share-based compensation, tax benefit from compensation expense	7	7	6
Share-based Compensation Expense, Net of Tax	21	19	18
Ameren Missouri
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	8	6	4
Ameren Illinois
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	4	4	2
Other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 16	$ 16	$ 18
Performance Share Units | Market Condition PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share units awarded	$ 56.73
Performance Share Units | Market Condition PSUs February Grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share units awarded	$ 56.73	$ 91.07	$ 92.75
Three-year risk-free rate	4.25%	4.19%	1.80%
Ameren’s common stock volatility	21%	26%	29%
Volatility range for peer group, minimum	19%	24%	26%
Volatility range for peer group, maximum	23%	32%	35%

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Aug. 16, 2022
Income Taxes [Line Items]
Increase (Decrease) In Deferred Tax Liabilities	$ 123
Ameren Missouri
Income Taxes [Line Items]
Increase (Decrease) In Deferred Tax Liabilities	12
Ameren Illinois
Income Taxes [Line Items]
Increase (Decrease) In Deferred Tax Liabilities	$ 111
Federal
Income Taxes [Line Items]
Production and Investment Tax Credit Adder		10%
Greenhouse Emissions Reduction Target, Inflation Reduction Act		75%
Eligible Transfer of Tax Credits, Inflation Reduction Act		100%
Minimum Tax on Book Income, Inflation Reduction Act, Percent		15%
Minimum Adjusted Financial Statement Income Subject to Inflation Reduction Act Tax		$ 1,000

Income Taxes (Schedule Of Effec

Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Federal statutory corporate income tax rate	21%	21%	21%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amortization of Excess Deferred Taxes, Percent	(9.00%)	(8.00%)	(8.00%)
Amortization of deferred investment tax credit	0%	0%	0%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent	(9.00%)	(4.00%)	(4.00%)
State tax	5%	5%	5%
Depreciation differences	(1.00%)
Effective income tax rate	7%	14%	14%
Ameren Missouri
Income Taxes [Line Items]
Federal statutory corporate income tax rate	21%	21%	21%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amortization of Excess Deferred Taxes, Percent	(17.00%)	(15.00%)	(15.00%)
Amortization of deferred investment tax credit	(1.00%)	(1.00%)	(1.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Percent	(24.00%)	(10.00%)	(10.00%)
State tax	3%	3%	3%
Depreciation differences	0%
Effective income tax rate	(18.00%)	(2.00%)	(2.00%)
Ameren Illinois
Income Taxes [Line Items]
Federal statutory corporate income tax rate	21%	21%	21%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amortization of Excess Deferred Taxes, Percent	(4.00%)	(2.00%)	(2.00%)
Amortization of deferred investment tax credit	0%	0%	0%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent	0%	0%	0%
State tax	7%	7%	7%
Depreciation differences	0%
Effective income tax rate	24%	26%	26%

Income Taxes (Schedule Of Compo

Income Taxes (Schedule Of Components Of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Current Federal taxes	$ (43)	$ (47)	$ 5
Current State taxes	(1)	1	1
Deferred Federal Income Tax Expense (Benefit)	177	260	194
Deferred State taxes	65	70	80
Amortization of excess deferred income taxes	(112)	(98)	(100)
Amortization of deferred investment tax credits	(3)	(3)	(4)
Income tax benefit	83	183	176
Ameren Missouri
Income Taxes [Line Items]
Current Federal taxes	(55)	(37)	(26)
Current State taxes	(3)	1	(5)
Deferred Federal Income Tax Expense (Benefit)	45	102	93
Deferred State taxes	8	9	18
Amortization of excess deferred income taxes	(79)	(80)	(86)
Amortization of deferred investment tax credits	(3)	(3)	(4)
Income tax benefit	(87)	(8)	(10)
Ameren Illinois
Income Taxes [Line Items]
Current Federal taxes	5	27	46
Current State taxes	0	5	16
Deferred Federal Income Tax Expense (Benefit)	144	123	82
Deferred State taxes	76	71	48
Amortization of excess deferred income taxes	(32)	(17)	(13)
Amortization of deferred investment tax credits	0	0	0
Income tax benefit	193	209	179
Other
Income Taxes [Line Items]
Current Federal taxes	7	(37)	(15)
Current State taxes	2	(5)	(10)
Deferred Federal Income Tax Expense (Benefit)	(12)	35	19
Deferred State taxes	(19)	(10)	14
Amortization of excess deferred income taxes	(1)	(1)	(1)
Amortization of deferred investment tax credits	0	0	0
Income tax benefit	$ (23)	$ (18)	$ 7

Income Taxes (Schedule Of Defer

Income Taxes (Schedule Of Deferred Tax Assets And Liabilities Resulting From Temporary Differences) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Income Taxes [Line Items]
Plant-related	$ 4,940	$ 4,646
Regulatory assets and liabilities, net	(385)	(413)
Deferred employee benefit costs - asset	27
Deferred employee benefit costs - liability		26
Tax carryforwards	(503)	(218)
Other - liabilities	162	161
Total net accumulated deferred income tax liabilities (assets)	4,241	4,150
Accumulated deferred investment tax credits	233	26
Accumulated deferred income taxes and investment tax credits	4,474	4,176
Ameren Missouri
Income Taxes [Line Items]
Plant-related	2,429	2,370
Regulatory assets and liabilities, net	(193)	(206)
Deferred employee benefit costs - liability	25	48
Tax carryforwards	(355)	(124)
Other - liabilities	131	104
Total net accumulated deferred income tax liabilities (assets)	1,987	2,096
Accumulated deferred investment tax credits	230	26
Accumulated deferred income taxes and investment tax credits	2,217	2,122
Ameren Illinois
Income Taxes [Line Items]
Plant-related	2,250	2,030
Regulatory assets and liabilities, net	(170)	(184)
Deferred employee benefit costs - asset	77	55
Tax carryforwards	(45)	(33)
Other - liabilities	28	38
Total net accumulated deferred income tax liabilities (assets)	2,140	1,906
Accumulated deferred investment tax credits	3	0
Accumulated deferred income taxes and investment tax credits	2,143	1,906
Other
Income Taxes [Line Items]
Plant-related	261	246
Regulatory assets and liabilities, net	(22)	(23)
Deferred employee benefit costs - liability	25	33
Tax carryforwards	(103)	(61)
Other - liabilities	3	19
Total net accumulated deferred income tax liabilities (assets)	114	148
Accumulated deferred investment tax credits	0	0
Accumulated deferred income taxes and investment tax credits	$ 114	$ 148

Income Taxes (Schedule Of Net O

Income Taxes (Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Net operating loss carryforwards:
Net operating loss carryforwards:	$ 93	$ 42
Tax credit carryforwards:	410	176
Federal
Net operating loss carryforwards:
Net operating loss carryforwards:	30	0
Tax credit carryforwards:	408	174
State
Net operating loss carryforwards:
Net operating loss carryforwards:	63	42
Tax credit carryforwards:	2	2
Ameren Missouri
Net operating loss carryforwards:
Net operating loss carryforwards:	0	0
Tax credit carryforwards:	355	124
Ameren Missouri | Federal
Net operating loss carryforwards:
Net operating loss carryforwards:	0	0
Tax credit carryforwards:	355	124
Ameren Missouri | State
Net operating loss carryforwards:
Net operating loss carryforwards:	0	0
Tax credit carryforwards:	0	0
Ameren Illinois
Net operating loss carryforwards:
Net operating loss carryforwards:	34	26
Tax credit carryforwards:	11	7
Ameren Illinois | Federal
Net operating loss carryforwards:
Net operating loss carryforwards:	0	0
Tax credit carryforwards:	9	5
Ameren Illinois | State
Net operating loss carryforwards:
Net operating loss carryforwards:	34	26
Tax credit carryforwards:	2	2
Other
Net operating loss carryforwards:
Net operating loss carryforwards:	59	16
Tax credit carryforwards:	44	45
Other | Federal
Net operating loss carryforwards:
Net operating loss carryforwards:	30	0
Tax credit carryforwards:	44	45
Other | State
Net operating loss carryforwards:
Net operating loss carryforwards:	29	16
Tax credit carryforwards:	$ 0	$ 0

Related Party Transactions (Nar

Related Party Transactions (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Related Party Transaction [Line Items]
Interconnection agreement, optional termination period	3 years
Other assets	$ 1,123	$ 921
Ameren Illinois
Related Party Transaction [Line Items]
Other assets	697	603
Ameren Missouri
Related Party Transaction [Line Items]
Other assets	254	152
Ameren Illinois Capacity Supply Agreements with Ameren Missouri | Ameren Illinois | 2021 Procurements
Related Party Transaction [Line Items]
Energy supply agreements amount	$ 2
Ameren Services Support Services Agreement
Related Party Transaction [Line Items]
Support services agreement, optional termination period	60 days
Ameren Services Support Services Agreement | Ameren Illinois
Related Party Transaction [Line Items]
Other assets	$ 32	34
Ameren Services Support Services Agreement | Ameren Missouri
Related Party Transaction [Line Items]
Other assets	$ 29	$ 31

Related Party Transactions (Sch

Related Party Transactions (Schedule of Related Party Electric Power Supply Agreements) (Details) - Ameren Illinois - Ameren Illinois Power Supply Agreements with Ameren Missouri	12 Months Ended
	Dec. 31, 2024 MWh $ / MWh
September 2020
Schedule of Related Party Electric Power Supply Agreements [Line Items]
MWhs | MWh	204,800
Average Price per MWh | $ / MWh	31
April 2021
Schedule of Related Party Electric Power Supply Agreements [Line Items]
MWhs | MWh	33,600
Average Price per MWh | $ / MWh	34
September 2021
Schedule of Related Party Electric Power Supply Agreements [Line Items]
MWhs | MWh	136,000
Average Price per MWh | $ / MWh	37

Related Party Transactions (S_2

Related Party Transactions (Schedule of Affiliate Receivables and Payables) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Related Party Transaction [Line Items]
Accounts receivable - affiliates	$ 525	$ 494
Ameren Missouri | Related Party
Related Party Transaction [Line Items]
Accounts receivable - affiliates	40	72
Ameren Missouri | Income taxes payable to parent | Related Party
Related Party Transaction [Line Items]
Income taxes payable to parent	0	0
Ameren Missouri | Income taxes receivable from parent | Related Party
Related Party Transaction [Line Items]
Accounts receivable - affiliates	28	56
Ameren Illinois | Related Party
Related Party Transaction [Line Items]
Accounts receivable - affiliates	15	35
Ameren Illinois | Income taxes payable to parent | Related Party
Related Party Transaction [Line Items]
Income taxes payable to parent	32	2
Ameren Illinois | Income taxes receivable from parent | Related Party
Related Party Transaction [Line Items]
Accounts receivable - affiliates	$ 0	$ 22

Related Party Transactions (S_3

Related Party Transactions (Schedule of Capital Contributions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Ameren Missouri
Related Party Transaction [Line Items]
Capital contribution from parent	$ 476	$ 0	$ 0
Ameren Illinois
Related Party Transaction [Line Items]
Capital contribution from parent	$ 36	$ 91	$ 15

Related Party Transactions (Eff

Related Party Transactions (Effects of Related-party Transactions on the Statement of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Operating Revenues	$ 7,623	$ 7,500	$ 7,957
Other operations and maintenance	1,969	1,866	1,937
Interest Charges	663	566	486
Ameren Missouri
Related Party Transaction [Line Items]
Operating Revenues	3,993	3,859	4,046
Other operations and maintenance	1,050	1,003	1,028
Interest Charges	244	227	213
Ameren Missouri | Ameren Missouri Power Supply Agreements with Ameren Illinois | Related Party
Related Party Transaction [Line Items]
Operating Revenues	0	2	9
Ameren Missouri | Ameren Missouri and Ameren Illinois Rent and Facility Services | Related Party
Related Party Transaction [Line Items]
Operating Revenues	31	32	25
Other operations and maintenance	1	1	1
Ameren Missouri | Ameren Missouri and Ameren Illinois miscellaneous support services and services provided to ATXI | Related Party
Related Party Transaction [Line Items]
Operating Revenues	2	1	1
Ameren Missouri | Total Operating Revenues | Related Party
Related Party Transaction [Line Items]
Operating Revenues	33	34	34
Ameren Missouri | Ameren Illinois Transmission Services From ATXI | Related Party
Related Party Transaction [Line Items]
Purchased power	9	2	1
Ameren Missouri | Total Purchased Power | Related Party
Related Party Transaction [Line Items]
Purchased power	9	2	1
Ameren Missouri | Ameren Services Support Services Agreement | Related Party
Related Party Transaction [Line Items]
Other operations and maintenance	169	148	150
Ameren Missouri | Total Related Party Other Operations and Maintenance | Related Party
Related Party Transaction [Line Items]
Other operations and maintenance	170	148	150
Ameren Missouri | Money Pool Borrowings (Advances) | Related Party
Related Party Transaction [Line Items]
Interest Charges	(4)	1	1
Ameren Missouri | Long-Term Debt | Related Party
Related Party Transaction [Line Items]
Interest Charges	1
Ameren Illinois
Related Party Transaction [Line Items]
Operating Revenues	3,472	3,482	3,756
Purchased power	621	820	880
Other operations and maintenance	906	818	882
Interest Charges	241	204	168
Ameren Illinois | Ameren Missouri and Ameren Illinois Rent and Facility Services | Related Party
Related Party Transaction [Line Items]
Operating Revenues	1	1	1
Other operations and maintenance	1	3	3
Ameren Illinois | Ameren Missouri and Ameren Illinois miscellaneous support services and services provided to ATXI | Related Party
Related Party Transaction [Line Items]
Operating Revenues	2	2	2
Ameren Illinois | Total Operating Revenues | Related Party
Related Party Transaction [Line Items]
Operating Revenues	3	2	2
Ameren Illinois | Ameren Illinois Power Supply Agreements with Ameren Missouri | Related Party
Related Party Transaction [Line Items]
Purchased power	0	2	9
Ameren Illinois | Ameren Illinois Transmission Services From ATXI | Related Party
Related Party Transaction [Line Items]
Purchased power	2	1
Ameren Illinois | Total Purchased Power | Related Party
Related Party Transaction [Line Items]
Purchased power	2	3	9
Ameren Illinois | Ameren Services Support Services Agreement | Related Party
Related Party Transaction [Line Items]
Other operations and maintenance	158	138	141
Ameren Illinois | Total Related Party Other Operations and Maintenance | Related Party
Related Party Transaction [Line Items]
Other operations and maintenance	159	141	144
Ameren Illinois | Money Pool Borrowings (Advances) | Related Party
Related Party Transaction [Line Items]
Interest Charges	1	$ 1	$ 1
Ameren Illinois | Long-Term Debt | Related Party
Related Party Transaction [Line Items]
Interest Charges	$ 1

Commitments And Contingencies (

Commitments And Contingencies (Environmental Matters) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) energyCenter scrubber site	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Estimated capital costs to comply with existing and known federal CO2 emissions regulations	$ 580
Estimated capital costs to comply with existing and known federal MATS regulations	320
Other current liabilities	475	$ 501
Other deferred credits and liabilities	487	426
Other operations and maintenance	1,969	1,866	$ 1,937
Asset Retirement Obligation	$ 827	791	786
Environmental Loss Contingency Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	false
Rush Island Energy Center Additional Mitigation Relief Ordered
Other current liabilities	$ 40
Other deferred credits and liabilities	24
Other operations and maintenance	$ 59
Ameren Missouri
Number of Energy Center Scrubbers | scrubber	2
Number of days of the EPA's requested appellate court suspension	60 days
Estimated capital costs to comply with existing and known federal CO2 emissions regulations	$ 580
Estimated capital costs to comply with existing and known federal MATS regulations	320
Cost of additional mitigation ordered for the Rush Island Energy Center	64
Other current liabilities	235	181
Other deferred credits and liabilities	150	56
Other operations and maintenance	1,050	1,003	1,028
Asset Retirement Obligation	$ 823	787	782
Number of Ameren Missouri Natural Gas Energy Centers Subject To IETL | energyCenter	4
Ameren Missouri | Rush Island Energy Center Additional Mitigation Relief Ordered
Other current liabilities	$ 40
Other deferred credits and liabilities	24
Other operations and maintenance	59
Ameren Illinois
Other current liabilities	231	298
Other deferred credits and liabilities	273	308
Other operations and maintenance	906	818	882
Asset Retirement Obligation	$ 4	$ 4	$ 4
Number of remediation sites | site	3
Manufactured Gas Plant
Accrual for environmental loss contingencies	$ 44
Manufactured Gas Plant | Ameren Illinois
Number of remediation sites | site	44
Accrual for environmental loss contingencies	$ 44
Minimum
Estimated capital costs to comply with existing and known federal and state air emissions regulations	900
Minimum | Ameren Missouri
Estimated capital costs to comply with existing and known federal and state air emissions regulations	900
Minimum | Manufactured Gas Plant | Ameren Illinois
Estimate of possible loss	44
Maximum
Estimated capital costs to comply with existing and known federal and state air emissions regulations	1,000
Maximum | Ameren Missouri
Estimated capital costs to comply with existing and known federal and state air emissions regulations	1,000
Maximum | Manufactured Gas Plant | Ameren Illinois
Estimate of possible loss	91
New CCR Rules Estimate
Asset Retirement Obligation	46
New CCR Rules Estimate | Ameren Missouri
Asset Retirement Obligation	$ 46

Supplemental Information (Narra

Supplemental Information (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Supplemental Information [Line Items]
Deferred Compensation Liability, Classified, Noncurrent	$ 79	$ 85
Ameren Illinois
Supplemental Information [Line Items]
Payables for purchased receivables	$ 43	$ 42

Supplemental Information (Cash

Supplemental Information (Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Cash and Cash Equivalents Including Restricted Cash [Line Items]
Cash and cash equivalents	$ 7	$ 25
Restricted cash included in “Other current assets”	15	13
Restricted Cash and Cash Equivalents, Noncurrent	296	229
Restricted cash included in “Nuclear decommissioning trust fund”	10	5
Cash and cash equivalents	328	272	$ 216	$ 155
Ameren Missouri
Schedule of Cash and Cash Equivalents Including Restricted Cash [Line Items]
Cash and cash equivalents	0	0
Restricted cash included in “Other current assets”	7	5
Restricted Cash and Cash Equivalents, Noncurrent	0	0
Restricted cash included in “Nuclear decommissioning trust fund”	10	5
Cash and cash equivalents	17	10	13	8
Ameren Illinois
Schedule of Cash and Cash Equivalents Including Restricted Cash [Line Items]
Cash and cash equivalents	0	0
Restricted cash included in “Other current assets”	6	5
Restricted Cash and Cash Equivalents, Noncurrent	296	229
Restricted cash included in “Nuclear decommissioning trust fund”	0	0
Cash and cash equivalents	$ 302	$ 234	$ 191	$ 133

Supplemental Information (Allow

Supplemental Information (Allowance for Doubtful Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance at January 1	$ 30	$ 31
Bad debt expense	39	51
Accounts Receivable, Credit Loss charged to other accounts	8	5
Net write-offs	(47)	(57)
Ending balance at December 31	30	30
Ameren Missouri
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance at January 1	12	13
Bad debt expense	11	11
Accounts Receivable, Credit Loss charged to other accounts	0	0
Net write-offs	(11)	(12)
Ending balance at December 31	12	12
Ameren Illinois
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance at January 1	18	18
Bad debt expense	28	40
Accounts Receivable, Credit Loss charged to other accounts	8	5
Net write-offs	(36)	(45)
Ending balance at December 31	$ 18	$ 18

Supplemental Information (Lease

Supplemental Information (Leases) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Schedule of Supplemental Balance Sheet Information Related to Operating Leases [Line Items]
Operating Lease, Right-of-Use Asset	$ 72
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets
Operating Lease, Liability, Current	$ 5
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other current liabilities
Operating Lease, Liability, Noncurrent	$ 67
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other deferred credits and liabilities
Operating Lease, Weighted Average Remaining Lease Term	29 years
Operating Lease, Weighted Average Discount Rate, Percent	5.30%
Lessee, Operating Lease, Liability, to be Paid, Maturity [Line Items]
2025	$ 8
2026	5
2027	4
2028	4
2029	4
Thereafter	131
Total lease payments	156
Less imputed interest	84
Total	72
Ameren Missouri
Schedule of Supplemental Balance Sheet Information Related to Operating Leases [Line Items]
Operating Lease, Right-of-Use Asset	69
Operating Lease, Liability, Current	4
Operating Lease, Liability, Noncurrent	$ 65
Operating Lease, Weighted Average Remaining Lease Term	30 years
Operating Lease, Weighted Average Discount Rate, Percent	5.30%
Lessee, Operating Lease, Liability, to be Paid, Maturity [Line Items]
2025	$ 7
2026	4
2027	3
2028	4
2029	4
Thereafter	131
Total lease payments	153
Less imputed interest	84
Total	$ 69

Supplemental Information (Inven

Supplemental Information (Inventories) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Public Utilities, Inventory [Line Items]
Fuel	$ 113	$ 109
Natural gas stored underground	91	95
Materials, supplies, and other	558	529
Total inventories	762	733
Ameren Missouri
Public Utilities, Inventory [Line Items]
Fuel	113	109
Natural gas stored underground	9	8
Materials, supplies, and other	392	391
Total inventories	514	508
Ameren Illinois
Public Utilities, Inventory [Line Items]
Fuel	0	0
Natural gas stored underground	82	87
Materials, supplies, and other	162	138
Total inventories	$ 244	$ 225

Supplemental Information (Sched

Supplemental Information (Schedule of Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	$ 827	$ 791	$ 786
Liabilities incurred	21	0
Liabilities settled	(13)	(10)
Accretion	35	33
Change in estimates	(7)	(18)
Current asset retirement obligations	5	19
Nuclear Plant
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	648
Ameren Missouri
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	823	787	782
Liabilities incurred	21	0
Liabilities settled	(13)	(10)
Accretion	35	33
Change in estimates	(7)	(18)
Ameren Illinois
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	4	4	$ 4
Liabilities incurred	0	0
Liabilities settled	0	0
Accretion	0	0
Change in estimates	$ 0	$ 0

Supplemental Information (Sch_2

Supplemental Information (Schedule of Excise Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Line Items]
Excise Tax Expense	$ 299	$ 287	$ 295
Ameren Missouri
Accounting Policies [Line Items]
Excise Tax Expense	169	166	162
Ameren Illinois
Accounting Policies [Line Items]
Excise Tax Expense	$ 130	$ 121	$ 133

Supplemental Information (All_2

Supplemental Information (Allowance For Funds Used During Construction) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Allowance for Funds Used During Construction, Rate [Line Items]
Allowance for equity funds used during construction	$ 76	$ 54	$ 43
Allowance for borrowed funds used during construction	56	48	26
Allowance for equity funds used during construction	$ 132	$ 102	$ 69
Ameren Missouri
Allowance for Funds Used During Construction, Rate [Line Items]
Public Utilities, Allowance for Funds Used During Construction, Rate	6%	6%	5%
Allowance for equity funds used during construction	$ 58	$ 30	$ 24
Allowance for borrowed funds used during construction	39	27	13
Allowance for equity funds used during construction	$ 97	$ 57	$ 37
Ameren Illinois
Allowance for Funds Used During Construction, Rate [Line Items]
Public Utilities, Allowance for Funds Used During Construction, Rate	6%	6%	5%
Allowance for equity funds used during construction	$ 17	$ 19	$ 18
Allowance for borrowed funds used during construction	15	17	12
Allowance for equity funds used during construction	$ 32	$ 36	$ 30

Supplemental Information (Earni

Supplemental Information (Earnings Per Share) (Details) - shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share Reconciliation [Abstract]
Weighted-average Common Shares Outstanding – Basic	266,800,000	262,800,000	258,400,000
Assumed settlement of performance share units and restricted stock units	500,000	600,000	1,000,000
Dilutive effect of forward sale agreements	100,000	0	100,000
Weighted Average Number of Shares Outstanding, Diluted (in shares)	267,400,000	263,400,000	259,500,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	0	0	0

Supplemental Information (Suppl

Supplemental Information (Supplemental Cash Flow Information) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Supplemental Cash Flow Information [Line Items]
Accrued capital expenditures		$ 480	$ 518	$ 441
Net realized and unrealized gain (loss) – nuclear decommissioning trust fund		165	167	(218)
Return on investment in industrial development revenue bonds		0	240	0
Stock Issued			40
Termination of a financing obligation		0	240	0
Issuance of common stock for stock-based compensation
Supplemental Cash Flow Information [Line Items]
Stock Issued		16	40	31
Issuance of common stock under the DRPlus
Supplemental Cash Flow Information [Line Items]
Stock Issued		7	7	8
Ameren Missouri
Supplemental Cash Flow Information [Line Items]
Accrued capital expenditures		303	270	243
Net realized and unrealized gain (loss) – nuclear decommissioning trust fund		165	167	(218)
Return on investment in industrial development revenue bonds		0	240	0
Termination of a financing obligation	$ 240	0	240	0
Ameren Missouri | Issuance of common stock for stock-based compensation
Supplemental Cash Flow Information [Line Items]
Stock Issued		0	0	0
Ameren Missouri | Issuance of common stock under the DRPlus
Supplemental Cash Flow Information [Line Items]
Stock Issued		0	0	0
Ameren Illinois
Supplemental Cash Flow Information [Line Items]
Accrued capital expenditures		157	212	181
Net realized and unrealized gain (loss) – nuclear decommissioning trust fund		0	0	0
Return on investment in industrial development revenue bonds		0	0	0
Termination of a financing obligation		0	0	0
Ameren Illinois | Issuance of common stock for stock-based compensation
Supplemental Cash Flow Information [Line Items]
Stock Issued		0	0	0
Ameren Illinois | Issuance of common stock under the DRPlus
Supplemental Cash Flow Information [Line Items]
Stock Issued		$ 0	$ 0	$ 0

Segment Information (Schedule O

Segment Information (Schedule Of Segment Reporting Information By Segment) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) segment	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	4
External revenues	$ 7,623	$ 7,500	$ 7,957
Revenues	7,623	7,500	7,957
Fuel and purchased power	(1,681)	(1,812)	(2,020)
Natural gas purchased for resale	(320)	(355)	(657)
Other operations and maintenance	(1,969)	(1,866)	(1,937)
Depreciation and amortization	(1,590)	(1,387)	(1,289)
Taxes other than income taxes	(547)	(522)	(539)
Other Income, Net	417	348	226
Interest Charges	(663)	(566)	(486)
Income tax benefit	(83)	(183)	(176)
Preferred Stock Dividends	(5)	(5)	(5)
Net Income (Loss) Available to Common Stockholders, Basic	1,182	1,152	1,074
Interest income	41	33	35
Capital expenditures	$ 4,319	3,597	3,351
Ameren Missouri
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Ameren Illinois
Segment Reporting Information [Line Items]
Number of reportable segments | segment	3
External revenues	$ 3,472	3,482	3,756
Revenues	3,472	3,482	3,756
Purchased power	621	820	880
Natural gas purchased for resale	(260)	(276)	(553)
Other operations and maintenance	(906)	(818)	(882)
Depreciation and amortization	(619)	(556)	(514)
Taxes other than income taxes	(157)	(146)	(161)
Other Income, Net	147	156	96
Interest Charges	(241)	(204)	(168)
Income tax benefit	(193)	(209)	(179)
Preferred Stock Dividends	(2)	(2)	(2)
Net Income (Loss) Available to Common Stockholders, Basic	620	607	513
Interest income	32	21	7
Capital expenditures	1,467	1,731	1,601
Operating Segments | Ameren Missouri
Segment Reporting Information [Line Items]
External revenues	3,960	3,825	4,012
Revenues	3,993	3,859	4,046
Fuel and purchased power	(1,071)	(997)	(1,150)
Natural gas purchased for resale	(60)	(79)	(104)
Other operations and maintenance	(1,050)	(1,003)	(1,028)
Depreciation and amortization	(917)	(783)	(732)
Taxes other than income taxes	(372)	(360)	(363)
Other Income, Net	196	130	99
Interest Charges	(244)	(227)	(213)
Income tax benefit	87	8	10
Preferred Stock Dividends	(3)	(3)	(3)
Net Income (Loss) Available to Common Stockholders, Basic	559	545	562
Interest income	8	11	28
Capital expenditures	2,712	1,760	1,690
Operating Segments | Ameren Illinois Electric Distribution
Segment Reporting Information [Line Items]
External revenues	2,088	2,217	2,255
Revenues	2,089	2,218	2,256
Fuel and purchased power	(740)	(933)	(984)
Natural gas purchased for resale	0	0	0
Other operations and maintenance	(619)	(532)	(580)
Depreciation and amortization	(369)	(351)	(332)
Taxes other than income taxes	(75)	(75)	(75)
Other Income, Net	97	103	60
Interest Charges	(98)	(89)	(74)
Income tax benefit	(50)	(82)	(68)
Preferred Stock Dividends	(1)	(1)	(1)
Net Income (Loss) Available to Common Stockholders, Basic	234	258	202
Interest income	28	19	7
Capital expenditures	579	752	621
Operating Segments | Ameren Illinois Gas
Segment Reporting Information [Line Items]
External revenues	938	897	1,180
Revenues	938	897	1,180
Fuel and purchased power	0	0	0
Natural gas purchased for resale	(260)	(276)	(553)
Other operations and maintenance	(230)	(237)	(253)
Depreciation and amortization	(129)	(108)	(98)
Taxes other than income taxes	(78)	(67)	(82)
Other Income, Net	27	30	19
Interest Charges	(63)	(55)	(44)
Income tax benefit	(56)	(50)	(46)
Preferred Stock Dividends	0	0	0
Net Income (Loss) Available to Common Stockholders, Basic	149	134	123
Interest income	1	1	0
Capital expenditures	264	299	308
Operating Segments | Ameren Transmission
Segment Reporting Information [Line Items]
External revenues	637	561	510
Revenues	781	677	615
Fuel and purchased power	0	0	0
Natural gas purchased for resale	0	0	0
Other operations and maintenance	(70)	(60)	(60)
Depreciation and amortization	(167)	(138)	(123)
Taxes other than income taxes	(9)	(8)	(9)
Other Income, Net	26	28	17
Interest Charges	(117)	(96)	(84)
Income tax benefit	(120)	(106)	(92)
Preferred Stock Dividends	(1)	(1)	(1)
Net Income (Loss) Available to Common Stockholders, Basic	323	296	263
Interest income	6	2	0
Capital expenditures	758	804	741
Operating Segments | Ameren Illinois | Ameren Illinois Electric Distribution
Segment Reporting Information [Line Items]
External revenues	2,089	2,218	2,256
Revenues	2,089	2,218	2,256
Purchased power	740	933	984
Other operations and maintenance	(619)	(532)	(580)
Depreciation and amortization	(369)	(351)	(332)
Taxes other than income taxes	(75)	(75)	(75)
Other Income, Net	97	103	60
Interest Charges	(98)	(89)	(74)
Income tax benefit	(50)	(82)	(68)
Preferred Stock Dividends	(1)	(1)	(1)
Net Income (Loss) Available to Common Stockholders, Basic	234	258	202
Interest income	28	19	7
Capital expenditures	579	752	621
Operating Segments | Ameren Illinois | Ameren Illinois Gas
Segment Reporting Information [Line Items]
External revenues	938	897	1,180
Revenues	938	897	1,180
Natural gas purchased for resale	(260)	(276)	(553)
Other operations and maintenance	(230)	(237)	(253)
Depreciation and amortization	(129)	(108)	(98)
Taxes other than income taxes	(78)	(67)	(82)
Other Income, Net	27	30	19
Interest Charges	(63)	(55)	(44)
Income tax benefit	(56)	(50)	(46)
Net Income (Loss) Available to Common Stockholders, Basic	149	134	123
Interest income	1	1	0
Capital expenditures	264	299	308
Operating Segments | Ameren Illinois | Ameren Illinois Transmission
Segment Reporting Information [Line Items]
External revenues	445	367	320
Revenues	564	480	424
Other operations and maintenance	(57)	(49)	(49)
Depreciation and amortization	(121)	(97)	(84)
Taxes other than income taxes	(4)	(4)	(4)
Other Income, Net	23	23	17
Interest Charges	(80)	(60)	(50)
Income tax benefit	(87)	(77)	(65)
Preferred Stock Dividends	(1)	(1)	(1)
Net Income (Loss) Available to Common Stockholders, Basic	237	215	188
Interest income	3	1	0
Capital expenditures	624	680	672
Segment Reconciling Items
Segment Reporting Information [Line Items]
Other operations and maintenance	(48)	(67)	(42)
Depreciation and amortization	(8)	(7)	(4)
Taxes other than income taxes	(13)	(12)	(10)
Other Income, Net	83	62	32
Interest Charges	(153)	(104)	(72)
Income tax benefit	56	47	20
Net Income (Loss) Available to Common Stockholders, Basic	(83)	(81)	(76)
Interest income	10	5	1
Capital expenditures	7	9	7
Intersegment Elimination
Segment Reporting Information [Line Items]
Intersegment revenues	178	151	140
Revenues	(178)	(151)	(140)
Fuel and purchased power	130	118	114
Natural gas purchased for resale	0	0	0
Other operations and maintenance	48	33	26
Depreciation and amortization	0	0	0
Taxes other than income taxes	0	0	0
Other Income, Net	(12)	(5)	(1)
Interest Charges	12	5	1
Income tax benefit	0	0	0
Preferred Stock Dividends	0	0	0
Interest income	(12)	(5)	(1)
Capital expenditures	(1)	(27)	(16)
Intersegment Elimination | Ameren Missouri
Segment Reporting Information [Line Items]
Intersegment revenues	33	34	34
Intersegment Elimination | Ameren Illinois Electric Distribution
Segment Reporting Information [Line Items]
Intersegment revenues	1	1	1
Intersegment Elimination | Ameren Illinois Gas
Segment Reporting Information [Line Items]
Intersegment revenues	0	0	0
Intersegment Elimination | Ameren Transmission
Segment Reporting Information [Line Items]
Intersegment revenues	144	116	105
Intersegment Elimination | Ameren Illinois
Segment Reporting Information [Line Items]
Intersegment revenues	119	113	104
Revenues	(119)	(113)	(104)
Purchased power	119	113	104
Intersegment Elimination | Ameren Illinois | Ameren Illinois Electric Distribution
Segment Reporting Information [Line Items]
Intersegment revenues	0	0	0
Intersegment Elimination | Ameren Illinois | Ameren Illinois Gas
Segment Reporting Information [Line Items]
Intersegment revenues	0	0	0
Intersegment Elimination | Ameren Illinois | Ameren Illinois Transmission
Segment Reporting Information [Line Items]
Intersegment revenues	$ 119	$ 113	$ 104

Segment Information (Disaggrega

Segment Information (Disaggregation of Revenues) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
External revenues	$ 7,623	$ 7,500	$ 7,957
Revenues	7,623	7,500	7,957
Revenues from alternative revenue programs	(9)	179	78
Revenue Not from Contract with Customer, Other	19	0	(94)
Insurance recoveries related to lost sales			10
Ameren Missouri
Disaggregation of Revenue [Line Items]
Revenues from alternative revenue programs	4	(5)	17
Revenue Not from Contract with Customer, Other	7	(9)	(103)
Insurance recoveries related to lost sales			10
Ameren Illinois Electric Distribution
Disaggregation of Revenue [Line Items]
Revenues from alternative revenue programs	(43)	116	89
Revenue Not from Contract with Customer, Other	10	7	6
Ameren Illinois Gas
Disaggregation of Revenue [Line Items]
Revenues from alternative revenue programs	(3)	49	(19)
Revenue Not from Contract with Customer, Other	2	2	3
Ameren Transmission
Disaggregation of Revenue [Line Items]
Revenues from alternative revenue programs	33	19	(9)
Revenue Not from Contract with Customer, Other	0	0	0
Electric
Disaggregation of Revenue [Line Items]
External revenues	6,540	6,439	6,581
Revenues	6,540	6,439	6,581
Electric | Residential
Disaggregation of Revenue [Line Items]
External revenues	2,892	2,921	2,903
Electric | Commercial
Disaggregation of Revenue [Line Items]
External revenues	1,993	2,027	1,987
Electric | Industrial
Disaggregation of Revenue [Line Items]
External revenues	489	492	489
Electric | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	1,166	999	1,202
Natural gas
Disaggregation of Revenue [Line Items]
External revenues	1,083	1,061	1,376
Revenues	1,083	1,061	1,376
Natural gas | Residential
Disaggregation of Revenue [Line Items]
External revenues	751	757	965
Natural gas | Commercial
Disaggregation of Revenue [Line Items]
External revenues	203	210	277
Natural gas | Industrial
Disaggregation of Revenue [Line Items]
External revenues	14	19	48
Natural gas | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	115	75	86
Ameren Illinois
Disaggregation of Revenue [Line Items]
External revenues	3,472	3,482	3,756
Revenues	3,472	3,482	3,756
Revenues from alternative revenue programs	(17)	177	63
Revenue Not from Contract with Customer, Other	12	9	9
Ameren Illinois | Residential
Disaggregation of Revenue [Line Items]
External revenues	1,915	2,001	2,171
Ameren Illinois | Commercial
Disaggregation of Revenue [Line Items]
External revenues	846	911	989
Ameren Illinois | Industrial
Disaggregation of Revenue [Line Items]
External revenues	188	200	240
Ameren Illinois | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	523	370	356
Ameren Illinois | Ameren Illinois Electric Distribution
Disaggregation of Revenue [Line Items]
Revenues from alternative revenue programs	(43)	116	89
Revenue Not from Contract with Customer, Other	10	7	6
Ameren Illinois | Ameren Illinois Gas
Disaggregation of Revenue [Line Items]
Revenues from alternative revenue programs	(3)	49	(19)
Revenue Not from Contract with Customer, Other	2	2	3
Ameren Illinois | Ameren Illinois Transmission
Disaggregation of Revenue [Line Items]
Revenues from alternative revenue programs	29	12	(7)
Revenue Not from Contract with Customer, Other	0	0	0
Ameren Illinois | Electric
Disaggregation of Revenue [Line Items]
External revenues	2,534	2,585	2,576
Ameren Illinois | Natural gas
Disaggregation of Revenue [Line Items]
External revenues	938	897	1,180
Operating Segments | Ameren Missouri
Disaggregation of Revenue [Line Items]
External revenues	3,960	3,825	4,012
Revenues	3,993	3,859	4,046
Operating Segments | Ameren Illinois Electric Distribution
Disaggregation of Revenue [Line Items]
External revenues	2,088	2,217	2,255
Revenues	2,089	2,218	2,256
Operating Segments | Ameren Illinois Gas
Disaggregation of Revenue [Line Items]
External revenues	938	897	1,180
Revenues	938	897	1,180
Operating Segments | Ameren Transmission
Disaggregation of Revenue [Line Items]
External revenues	637	561	510
Revenues	781	677	615
Operating Segments | Electric | Ameren Missouri
Disaggregation of Revenue [Line Items]
Revenues	3,847	3,694	3,849
Operating Segments | Electric | Ameren Missouri | Residential
Disaggregation of Revenue [Line Items]
External revenues	1,638	1,577	1,578
Operating Segments | Electric | Ameren Missouri | Commercial
Disaggregation of Revenue [Line Items]
External revenues	1,313	1,280	1,219
Operating Segments | Electric | Ameren Missouri | Industrial
Disaggregation of Revenue [Line Items]
External revenues	311	306	290
Operating Segments | Electric | Ameren Missouri | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	585	531	762
Operating Segments | Electric | Ameren Illinois Electric Distribution
Disaggregation of Revenue [Line Items]
Revenues	2,089	2,218	2,256
Operating Segments | Electric | Ameren Illinois Electric Distribution | Residential
Disaggregation of Revenue [Line Items]
External revenues	1,254	1,344	1,325
Operating Segments | Electric | Ameren Illinois Electric Distribution | Commercial
Disaggregation of Revenue [Line Items]
External revenues	680	747	768
Operating Segments | Electric | Ameren Illinois Electric Distribution | Industrial
Disaggregation of Revenue [Line Items]
External revenues	178	186	199
Operating Segments | Electric | Ameren Illinois Electric Distribution | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(23)	(59)	(36)
Operating Segments | Electric | Ameren Illinois Gas
Disaggregation of Revenue [Line Items]
Revenues	0	0	0
Operating Segments | Electric | Ameren Illinois Gas | Residential
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Electric | Ameren Illinois Gas | Commercial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Electric | Ameren Illinois Gas | Industrial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Electric | Ameren Illinois Gas | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	0	0	0
Operating Segments | Electric | Ameren Transmission
Disaggregation of Revenue [Line Items]
Revenues	781	677	615
Operating Segments | Electric | Ameren Transmission | Residential
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Electric | Ameren Transmission | Commercial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Electric | Ameren Transmission | Industrial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Electric | Ameren Transmission | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	781	677	615
Operating Segments | Natural gas | Ameren Missouri
Disaggregation of Revenue [Line Items]
Revenues	146	165	197
Operating Segments | Natural gas | Ameren Missouri | Residential
Disaggregation of Revenue [Line Items]
External revenues	90	100	119
Operating Segments | Natural gas | Ameren Missouri | Commercial
Disaggregation of Revenue [Line Items]
External revenues	37	46	56
Operating Segments | Natural gas | Ameren Missouri | Industrial
Disaggregation of Revenue [Line Items]
External revenues	4	5	7
Operating Segments | Natural gas | Ameren Missouri | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	15	14	15
Operating Segments | Natural gas | Ameren Illinois Electric Distribution
Disaggregation of Revenue [Line Items]
Revenues	0	0	0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Residential
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Commercial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Industrial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	0	0	0
Operating Segments | Natural gas | Ameren Illinois Gas
Disaggregation of Revenue [Line Items]
Revenues	938	897	1,180
Operating Segments | Natural gas | Ameren Illinois Gas | Residential
Disaggregation of Revenue [Line Items]
External revenues	661	657	846
Operating Segments | Natural gas | Ameren Illinois Gas | Commercial
Disaggregation of Revenue [Line Items]
External revenues	166	164	221
Operating Segments | Natural gas | Ameren Illinois Gas | Industrial
Disaggregation of Revenue [Line Items]
External revenues	10	14	41
Operating Segments | Natural gas | Ameren Illinois Gas | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	101	62	72
Operating Segments | Natural gas | Ameren Transmission
Disaggregation of Revenue [Line Items]
Revenues	0	0	0
Operating Segments | Natural gas | Ameren Transmission | Residential
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Natural gas | Ameren Transmission | Commercial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Natural gas | Ameren Transmission | Industrial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Natural gas | Ameren Transmission | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	0	0	0
Operating Segments | Ameren Illinois | Ameren Illinois Electric Distribution
Disaggregation of Revenue [Line Items]
External revenues	2,089	2,218	2,256
Revenues	2,089	2,218	2,256
Operating Segments | Ameren Illinois | Ameren Illinois Gas
Disaggregation of Revenue [Line Items]
External revenues	938	897	1,180
Revenues	938	897	1,180
Operating Segments | Ameren Illinois | Ameren Illinois Transmission
Disaggregation of Revenue [Line Items]
External revenues	445	367	320
Revenues	564	480	424
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Electric Distribution
Disaggregation of Revenue [Line Items]
Revenues	2,089	2,218	2,256
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Electric Distribution | Residential
Disaggregation of Revenue [Line Items]
External revenues	1,254	1,344	1,325
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Electric Distribution | Commercial
Disaggregation of Revenue [Line Items]
External revenues	680	747	768
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Electric Distribution | Industrial
Disaggregation of Revenue [Line Items]
External revenues	178	186	199
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Electric Distribution | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(23)	(59)	(36)
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Transmission
Disaggregation of Revenue [Line Items]
Revenues	564	480	424
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Transmission | Residential
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Transmission | Commercial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Transmission | Industrial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Operating Segments | Ameren Illinois | Electric | Ameren Illinois Transmission | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	564	480	424
Operating Segments | Ameren Illinois | Natural gas | Ameren Illinois Gas
Disaggregation of Revenue [Line Items]
Revenues	938	897	1,180
Operating Segments | Ameren Illinois | Natural gas | Ameren Illinois Gas | Residential
Disaggregation of Revenue [Line Items]
External revenues	661	657	846
Operating Segments | Ameren Illinois | Natural gas | Ameren Illinois Gas | Commercial
Disaggregation of Revenue [Line Items]
External revenues	166	164	221
Operating Segments | Ameren Illinois | Natural gas | Ameren Illinois Gas | Industrial
Disaggregation of Revenue [Line Items]
External revenues	10	14	41
Operating Segments | Ameren Illinois | Natural gas | Ameren Illinois Gas | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	101	62	72
Intersegment Elimination
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(178)	(151)	(140)
Revenues	(178)	(151)	(140)
Intersegment Elimination | Ameren Missouri
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(33)	(34)	(34)
Intersegment Elimination | Ameren Illinois Electric Distribution
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(1)	(1)	(1)
Intersegment Elimination | Ameren Illinois Gas
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	0	0	0
Intersegment Elimination | Ameren Transmission
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(144)	(116)	(105)
Intersegment Elimination | Electric
Disaggregation of Revenue [Line Items]
Revenues	(177)	(150)	(139)
Intersegment Elimination | Electric | Residential
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Intersegment Elimination | Electric | Commercial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Intersegment Elimination | Electric | Industrial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Intersegment Elimination | Electric | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(177)	(150)	(139)
Intersegment Elimination | Natural gas
Disaggregation of Revenue [Line Items]
Revenues	(1)	(1)	(1)
Intersegment Elimination | Natural gas | Residential
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Intersegment Elimination | Natural gas | Commercial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Intersegment Elimination | Natural gas | Industrial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Intersegment Elimination | Natural gas | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(1)	(1)	(1)
Intersegment Elimination | Ameren Illinois
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(119)	(113)	(104)
Revenues	(119)	(113)	(104)
Intersegment Elimination | Ameren Illinois | Residential
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Intersegment Elimination | Ameren Illinois | Commercial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Intersegment Elimination | Ameren Illinois | Industrial
Disaggregation of Revenue [Line Items]
External revenues	0	0	0
Intersegment Elimination | Ameren Illinois | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	(119)	(113)	(104)
Intersegment Elimination | Ameren Illinois | Ameren Illinois Electric Distribution
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	0	0	0
Intersegment Elimination | Ameren Illinois | Ameren Illinois Gas
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	0	0	0
Intersegment Elimination | Ameren Illinois | Ameren Illinois Transmission
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	$ (119)	$ (113)	$ (104)

Schedule I - Condensed Financ_2

Schedule I - Condensed Financial Information Of Parent (Statement of Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Financial Statements, Captions [Line Items]
Operating revenues	$ 7,623	$ 7,500	$ 7,957
Operating expenses	6,107	5,942	6,442
Operating loss	1,516	1,558	1,515
Equity in earnings of subsidiaries	(4)	1	2
Interest income from affiliates	41	32	11
Total other income (expense), net	417	348	226
Interest Charges	(663)	(566)	(486)
Income tax benefit	83	183	176
Comprehensive Income from Continuing Operations
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $—, $(2), and $(4), respectively	(3)	(5)	(14)
Unrealized net gain on derivative hedging instruments, net of income taxes of $—, $—, and $—, respectively	3	0	0
Comprehensive Income Attributable to Ameren Common Shareholders	1,182	1,147	1,060
Other Comprehensive Income (Loss), Taxes:
Pension and other postretirement benefit plan activity, tax (benefit)	0	(2)	(4)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	0	0	0
Ameren (parent)
Condensed Financial Statements, Captions [Line Items]
Operating revenues	0	0	0
Operating expenses	17	22	15
Operating loss	(17)	(22)	(15)
Equity in earnings of subsidiaries	1,271	1,245	1,161
Interest income from affiliates	14	10	2
Total other income (expense), net	3	(11)	(13)
Interest Charges	(162)	(119)	(86)
Income tax benefit	61	49	25
Net Income Attributable to Ameren Common Shareholders	1,170	1,152	1,074
Comprehensive Income from Continuing Operations
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $—, $(2), and $(4), respectively	(3)	(5)	(14)
Unrealized net gain on derivative hedging instruments, net of income taxes of $—, $—, and $—, respectively	(3)	0	0
Comprehensive Income Attributable to Ameren Common Shareholders	1,170	1,147	1,060
Other Comprehensive Income (Loss), Taxes:
Pension and other postretirement benefit plan activity, tax (benefit)	$ 0	$ (2)	$ (4)

Schedule I - Condensed Financ_3

Schedule I - Condensed Financial Information Of Parent (Balance Sheet) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets:
Cash and cash equivalents	$ 7	$ 25
Advances to money pool	96	106
Accounts receivable - affiliates	525	494
Miscellaneous accounts and notes receivable	96	106
Total current assets	2,264	2,181
Other assets	1,123	921
Total assets	44,598	40,830
Liabilities and Shareholders' Equity:
Long-Term Debt, Current Maturities	317	849
Short-term debt	1,143	536
Accounts and wages payable	1,059	1,136
Other current liabilities	475	501
Total current liabilities	3,413	3,345
Long-term debt, net	17,262	15,121
Other deferred credits and liabilities	487	426
Commitments and Contingencies (Note 4)
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 269.9 and 266.3, respectively	3	3
Other paid-in capital, principally premium on common stock	7,513	7,216
Retained earnings	4,604	4,136
Accumulated other comprehensive loss	(6)	(6)
Total shareholders’ equity	12,243	11,478	$ 10,637
TOTAL LIABILITIES AND EQUITY	$ 44,598	$ 40,830
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000	400,000,000
Common Stock, Shares, Outstanding	269,900,000	266,300,000	262,000,000	257,700,000
Ameren (parent)
Assets:
Cash and cash equivalents	$ 0	$ 16
Derivative Asset, Current	3	0
Total current assets	182	665
Investments in subsidiaries	16,262	14,573
Debt Securities, Noncurrent	44	0
Accumulated deferred income taxes, net	98	44
Other assets	155	149
Total assets	16,741	15,431
Liabilities and Shareholders' Equity:
Long-Term Debt, Current Maturities	0	450
Short-term debt	1,055	0
Taxes accrued	7	10
Other current liabilities	54	45
Total current liabilities	1,165	607
Long-term debt, net	3,383	3,379
Pension and other postretirement benefits	18	19
Other deferred credits and liabilities	73	77
Total liabilities	4,639	4,082
Commitments and Contingencies (Note 4)
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 269.9 and 266.3, respectively	3	3
Other paid-in capital, principally premium on common stock	7,513	7,216
Retained earnings	4,592	4,136
Accumulated other comprehensive loss	(6)	(6)
Total shareholders’ equity	12,102	11,349
TOTAL LIABILITIES AND EQUITY	$ 16,741	$ 15,431
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000	400,000,000
Common Stock, Shares, Outstanding	269,900,000	266,300,000
Ameren (parent) | Related Party
Assets:
Advances to money pool	$ 103	$ 598
Accounts receivable - affiliates	41	20
Miscellaneous accounts and notes receivable	103	598
Liabilities and Shareholders' Equity:
Accounts and wages payable	49	100
Ameren (parent) | Nonrelated Party
Assets:
Advances to money pool	35	31
Miscellaneous accounts and notes receivable	35	31
Liabilities and Shareholders' Equity:
Accounts and wages payable	$ 0	$ 2

Schedule I - Condensed Financ_4

Schedule I - Condensed Financial Information Of Parent (Statement of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	$ 2,763	$ 2,564	$ 2,263
Cash Flows From Investing Activities:
Other	(26)	(1)	23
Net cash provided by (used in) investing activities	(4,456)	(3,798)	(3,370)
Cash flows from financing activities:
Dividends on common stock	(714)	(662)	(610)
Short-term debt, net	607	(533)	522
Maturities and extinguishment of long-term debt	(893)	(100)	(505)
Issuances of long-term debt	2,535	2,295	1,467
Issuances of common stock	273	346	333
Employee payroll taxes related to stock-based compensation	(8)	(20)	(16)
Debt issuance costs	(31)	(21)	(18)
Net cash provided by (used in) financing activities	1,749	1,290	1,168
Cash, cash equivalents, and restricted cash at beginning of year	272	216	155
Cash, cash equivalents, and restricted cash at end of year	328	272	216
Noncash Investing and Financing Items [Abstract]
Stock Issued		40
Ameren (parent)
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(65)	171	44
Cash Flows From Investing Activities:
Money pool advances, net	495		40
Money pool advances, net		(530)
Notes receivable – ATXI	0	0	35
Investments in subsidiaries	(557)	(109)	(30)
Investments in subsidiary debt securities	44	0	0
Other	1	5	3
Net cash provided by (used in) investing activities	(105)	(634)	48
Cash flows from financing activities:
Dividends on common stock	(714)	(662)	(610)
Short-term debt, net	1,054	(475)	198
Maturities and extinguishment of long-term debt	(450)	0	0
Issuances of long-term debt	0	1,298	0
Issuances of common stock	273	346	333
Employee payroll taxes related to stock-based compensation	(8)	(20)	(16)
Debt issuance costs	(1)	(8)	(1)
Net cash provided by (used in) financing activities	154	479	(96)
Net change in cash, cash equivalents, and restricted cash	(16)	16	(4)
Cash, cash equivalents, and restricted cash at beginning of year	16	0	4
Cash, cash equivalents, and restricted cash at end of year	0	16	0
Cash dividends received from consolidated subsidiaries	140	173	76
Noncash Investing and Financing Items [Abstract]
Stock Issued	$ 16	$ 40	$ 31

Schedule I - Condensed Financ_5

Schedule I - Condensed Financial Information Of Parent Other Income (Expense), Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Nonoperating Income (Expense) [Line Items]
Non-service cost components of net periodic benefit income	$ 304	$ 295	$ 184
Donations	(5)	(24)	(26)
Total other income (expense), net	417	348	226
Ameren (parent)
Other Nonoperating Income (Expense) [Line Items]
Non-state-regulated money pool advances	14	10
Non-service cost components of net periodic benefit income	4	8	3
Donations	0	(18)	(15)
Other expense, net	(1)	(1)	(1)
Total other income (expense), net	$ 3	$ (11)	$ (13)

Schedule II - Valuation And Q_2

Schedule II - Valuation And Qualifying Accounts (Details) - Allowance For Doubtful Accounts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 30	$ 31	$ 29
Charged to Costs and Expenses	39	51	34
Charged to Other Accounts	8	5	4
Deductions	47	57	36
Balance at End of Period	30	30	31
Ameren Missouri
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	12	13	13
Charged to Costs and Expenses	11	11	9
Charged to Other Accounts	0	0	0
Deductions	11	12	9
Balance at End of Period	12	12	13
Ameren Illinois
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	18	18	16
Charged to Costs and Expenses	28	40	25
Charged to Other Accounts	8	5	4
Deductions	36	45	27
Balance at End of Period	$ 18	$ 18	$ 18