Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2024	Oct. 31, 2024
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Emerging growth company	false
Entity Shell Company	false
Shares outstanding		266,927,767
Entity Central Index Key	0001002910
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false
Union Electric Company
Entity Information [Line Items]
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
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Emerging growth company	false
Entity Shell Company	false
Shares outstanding		102,123,834
Entity Central Index Key	0000100826
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false
Ameren Illinois Company
Entity Information [Line Items]
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
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Emerging growth company	false
Entity Shell Company	false
Shares outstanding		25,452,373
Entity Central Index Key	0000018654
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false

Consolidated Statement of Income (Loss) and Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating Revenues:
Total operating revenues	$ 2,173	$ 2,060	$ 5,682	$ 5,882
Operating Expenses:
Fuel and purchased power	499	430	1,154	1,518
Natural gas purchased for resale	30	30	214	280
Other operations and maintenance	520	470	1,455	1,368
Depreciation and amortization	388	369	1,125	1,024
Taxes other than income taxes	150	147	416	398
Total operating expenses	1,587	1,446	4,364	4,588
Operating Income	586	614	1,318	1,294
Other Income, Net	101	101	293	261
Interest Charges	173	152	492	413
Income Before Income Taxes	514	563	1,119	1,142
Income Taxes	57	69	140	144
Net Income	457	494	979	998
Less: Net Income Attributable to Noncontrolling Interests	1	1	4	4
Net Income Attributable to Ameren Common Shareholders	456	493	975	994
Pension and other postretirement benefit plan activity, net of income taxes (benefit)	(1)	(1)	(4)	(3)
Comprehensive Income	456	493	975	995
Less: Comprehensive Income Attributable to Noncontrolling Interests	1	1	4	4
Comprehensive Income Attributable to Ameren Common Shareholders	$ 455	$ 492	$ 971	$ 991
Earnings Per Share, Basic [Abstract]
Earnings per Common Share – Basic	$ 1.71	$ 1.88	$ 3.66	$ 3.79
Earnings Per Share, Diluted [Abstract]
Earnings per Common Share – Diluted	$ 1.70	$ 1.87	$ 3.65	$ 3.78
Weighted-average Common Shares Outstanding – Basic	266.8	262.8	266.6	262.5
Weighted-average Common Shares Outstanding – Diluted	267.3	263.4	266.9	263.2
Electric
Operating Revenues:
Total operating revenues	$ 2,035	$ 1,921	$ 4,920	$ 5,096
Natural gas
Operating Revenues:
Total operating revenues	138	139	762	786
Union Electric Company
Operating Revenues:
Total operating revenues	1,342	1,237	3,005	3,101
Operating Expenses:
Fuel and purchased power	334	233	689	843
Natural gas purchased for resale	4	4	41	60
Other operations and maintenance	288	256	789	732
Depreciation and amortization	220	217	623	579
Taxes other than income taxes	109	108	287	276
Total operating expenses	955	818	2,429	2,490
Operating Income	387	419	576	611
Other Income, Net	51	44	144	85
Interest Charges	62	63	187	166
Income Before Income Taxes	376	400	533	530
Income Taxes	(6)	(12)	(4)	(14)
Net Income	382	412	537	544
Preferred Stock Dividends	1	1	3	3
Net Income Available to Common Shareholder	381	411	534	541
Union Electric Company \| Electric
Operating Revenues:
Total operating revenues	1,324	1,219	2,902	2,978
Union Electric Company \| Natural gas
Operating Revenues:
Total operating revenues	18	18	103	123
Ameren Illinois Company
Operating Revenues:
Total operating revenues	793	783	2,559	2,663
Operating Expenses:
Purchased Power	169	200	474	679
Natural gas purchased for resale	26	26	173	220
Other operations and maintenance	229	200	663	603
Depreciation and amortization	155	139	462	410
Taxes other than income taxes	37	34	116	108
Total operating expenses	616	599	1,888	2,020
Operating Income	177	184	671	643
Other Income, Net	37	37	105	115
Interest Charges	63	54	178	151
Income Before Income Taxes	151	167	598	607
Income Taxes	37	42	144	154
Net Income	114	125	454	453
Preferred Stock Dividends	0	0	1	1
Net Income Available to Common Shareholder	114	125	453	452
Ameren Illinois Company \| Electric
Operating Revenues:
Total operating revenues	672	661	1,899	1,998
Ameren Illinois Company \| Natural gas
Operating Revenues:
Total operating revenues	$ 121	$ 122	$ 660	$ 665

Consolidated Statement of Income (Loss) and Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Statement [Abstract]
Pension and other postretirement benefit plan activity, tax	$ 0	$ (1)	$ (1)	$ (1)

Consolidated Balance Sheet - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Current Assets:
Cash and cash equivalents	$ 17	$ 25
Accounts receivable - trade (less allowance for doubtful accounts)	651	494
Unbilled revenue	348	319
Miscellaneous accounts receivable	70	106
Inventories	792	733
Current regulatory assets	226	365
Other current assets	153	139
Total current assets	2,257	2,181
Property, Plant, and Equipment, Net	35,720	33,776
Investments and Other Assets:
Nuclear decommissioning trust fund	1,333	1,150
Goodwill	411	411
Regulatory assets	1,915	1,810
Pension and other postretirement benefits	581	581
Other assets	1,081	921
Total investments and other assets	5,321	4,873
TOTAL ASSETS	43,298	40,830
Current Liabilities:
Current maturities of long-term debt	300	849
Short-term debt	1,539	536
Accounts and wages payable	717	1,136
Customer deposits	205	176
Taxes accrued	206	54
Other current liabilities	600	594
Total current liabilities	3,567	3,345
Long-term Debt, Net	16,422	15,121
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and tax credits, net	4,477	4,176
Regulatory liabilities	5,562	5,512
Asset retirement obligations	798	772
Other deferred credits and liabilities	510	426
Total deferred credits and other liabilities	11,347	10,886
Commitments and Contingencies
Shareholders’ Equity:
Common Stock	3	3
Other paid-in capital, principally premium on common stock	7,264	7,216
Retained earnings	4,576	4,136
Accumulated other comprehensive loss	(10)	(6)
Total shareholders’ equity	11,833	11,349
Noncontrolling Interests	129	129
Total equity	11,962	11,478
TOTAL LIABILITIES AND EQUITY	43,298	40,830
Union Electric Company
Current Assets:
Cash and cash equivalents	0	0
Advances to money pool	9	0
Unbilled revenue	229	163
Miscellaneous accounts receivable	28	26
Inventories	529	508
Current regulatory assets	84	101
Other current assets	65	68
Total current assets	1,266	1,142
Property, Plant, and Equipment, Net	18,518	17,250
Investments and Other Assets:
Nuclear decommissioning trust fund	1,333	1,150
Regulatory assets	746	755
Pension and other postretirement benefits	142	157
Other assets	204	152
Total investments and other assets	2,425	2,214
TOTAL ASSETS	22,209	20,606
Current Liabilities:
Current maturities of long-term debt	0	350
Short-term debt	576	170
Borrowings from money pool	17	306
Taxes accrued	184	28
Other current liabilities	322	222
Total current liabilities	1,489	1,747
Long-term Debt, Net	6,830	5,991
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and tax credits, net	2,208	2,122
Regulatory liabilities	2,914	2,959
Asset retirement obligations	795	768
Other deferred credits and liabilities	126	56
Total deferred credits and other liabilities	6,043	5,905
Commitments and Contingencies
Shareholders’ Equity:
Common Stock	511	511
Other paid-in capital, principally premium on common stock	3,075	2,725
Preferred stock	80	80
Retained earnings	4,181	3,647
Total shareholders’ equity	7,847	6,963
TOTAL LIABILITIES AND EQUITY	22,209	20,606
Union Electric Company \| Nonrelated Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	300	204
Current Liabilities:
Accounts and wages payable	327	618
Union Electric Company \| Related Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	22	72
Current Liabilities:
Accounts and wages payable	63	53
Ameren Illinois Company
Current Assets:
Cash and cash equivalents	0	0
Unbilled revenue	119	156
Miscellaneous accounts receivable	7	44
Inventories	260	225
Current regulatory assets	139	252
Other current assets	66	62
Total current assets	944	1,047
Property, Plant, and Equipment, Net	15,247	14,632
Investments and Other Assets:
Goodwill	411	411
Regulatory assets	1,135	1,035
Pension and other postretirement benefits	419	394
Other assets	679	603
Total investments and other assets	2,644	2,443
TOTAL ASSETS	18,835	18,122
Current Liabilities:
Current maturities of long-term debt	300	0
Short-term debt	17	366
Borrowings from money pool	0	135
Customer deposits	166	141
Current regulatory liabilities	50	71
Other current liabilities	230	298
Total current liabilities	1,193	1,433
Long-term Debt, Net	5,552	5,232
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and tax credits, net	2,012	1,906
Regulatory liabilities	2,504	2,418
Other deferred credits and liabilities	346	308
Total deferred credits and other liabilities	4,862	4,632
Commitments and Contingencies
Shareholders’ Equity:
Common Stock	0	0
Other paid-in capital, principally premium on common stock	3,020	3,020
Preferred stock	49	49
Retained earnings	4,159	3,756
Total shareholders’ equity	7,228	6,825
TOTAL LIABILITIES AND EQUITY	18,835	18,122
Ameren Illinois Company \| Nonrelated Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	336	273
Current Liabilities:
Accounts and wages payable	283	370
Ameren Illinois Company \| Related Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	17	35
Current Liabilities:
Accounts and wages payable	$ 147	$ 52

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Accounts Receivable, Allowance for Credit Loss, Current	$ 31	$ 30
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	400,000,000.0	400,000,000.0
Common Stock, Shares, Outstanding	266,900,000	266,300,000
Union Electric Company
Accounts Receivable, Allowance for Credit Loss, Current	$ 12	$ 12
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares authorized (in shares)	150,000,000.0	150,000,000.0
Common Stock, Shares, Outstanding	102,100,000	102,100,000
Ameren Illinois Company
Accounts Receivable, Allowance for Credit Loss, Current	$ 19	$ 18
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	45,000,000.0	45,000,000.0
Common Stock, Shares, Outstanding	25,500,000	25,500,000

Consolidated Statement of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash Flows From Operating Activities:
Net income	$ 979	$ 998
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,142	1,063
Amortization of nuclear fuel	59	56
Amortization of debt issuance costs and premium/discounts	14	12
Deferred income taxes and investment tax credits, net	145	128
Allowance for equity funds used during construction	(48)	(39)
Stock-based compensation costs	22	21
Other	84	12
Changes in assets and liabilities:
Receivables	(183)	54
Inventories	(60)	(93)
Accounts and wages payable	(239)	(287)
Taxes accrued	176	156
Regulatory assets and liabilities	86	15
Assets, other	(53)	(78)
Liabilities, other	(11)	51
Pension and other postretirement benefits	(168)	(182)
Counterparty collateral, net	1	144
Net cash provided by operating activities	1,946	2,031
Cash Flows From Investing Activities:
Capital expenditures	(3,029)	(2,571)
Nuclear fuel expenditures	(57)	(63)
Purchases of securities – nuclear decommissioning trust fund	(499)	(156)
Sales and maturities of securities – nuclear decommissioning trust fund	480	136
Other	(1)	(2)
Net cash used in investing activities	(3,106)	(2,656)
Cash Flows From Financing Activities:
Dividends on common stock	(535)	(496)
Dividends paid to noncontrolling interest holders	(4)	(4)
Short-term debt, net	1,002	272
Maturities of long-term debt	(849)	(100)
Issuances of long-term debt	1,610	997
Issuances of common stock	30	28
Employee payroll taxes related to stock-based compensation	(8)	(20)
Debt issuance costs	(19)	(12)
Other	(15)	(10)
Net cash provided by financing activities	1,212	655
Net change in cash, cash equivalents, and restricted cash	52	30
Cash, cash equivalents, and restricted cash at beginning of year	272	216
Cash, cash equivalents, and restricted cash at end of period	324	246
Union Electric Company
Cash Flows From Operating Activities:
Net income	537	544
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	641	618
Amortization of nuclear fuel	59	56
Amortization of debt issuance costs and premium/discounts	5	5
Deferred income taxes and investment tax credits, net	2	(73)
Allowance for equity funds used during construction	(38)	(20)
Other	69	(12)
Changes in assets and liabilities:
Receivables	(178)	(119)
Inventories	(21)	(78)
Accounts and wages payable	(223)	(206)
Taxes accrued	218	222
Regulatory assets and liabilities	(5)	65
Assets, other	(17)	12
Liabilities, other	10	(5)
Pension and other postretirement benefits	(59)	(67)
Counterparty collateral, net	(3)	89
Net cash provided by operating activities	997	1,031
Cash Flows From Investing Activities:
Capital expenditures	(1,839)	(1,255)
Nuclear fuel expenditures	(57)	(63)
Purchases of securities – nuclear decommissioning trust fund	(499)	(156)
Sales and maturities of securities – nuclear decommissioning trust fund	480	136
Money pool advances, net	(9)	0
Other	(8)	0
Net cash used in investing activities	(1,932)	(1,338)
Cash Flows From Financing Activities:
Dividends on preferred stock	(3)	(3)
Short-term debt, net	406	(172)
Money pool borrowings, net	(289)	0
Maturities of long-term debt	(350)	0
Issuances of long-term debt	846	499
Capital contributions from parent	350	0
Debt issuance costs	(10)	(7)
Other	(15)	(10)
Net cash provided by financing activities	935	307
Net change in cash, cash equivalents, and restricted cash	0	0
Cash, cash equivalents, and restricted cash at beginning of year	10	13
Cash, cash equivalents, and restricted cash at end of period	10	13
Ameren Illinois Company
Cash Flows From Operating Activities:
Net income	454	453
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	461	410
Amortization of debt issuance costs and premium/discounts	3	3
Deferred income taxes and investment tax credits, net	72	123
Allowance for equity funds used during construction	(10)	(15)
Other	32	31
Changes in assets and liabilities:
Receivables	(23)	164
Inventories	(35)	(15)
Accounts and wages payable	(8)	(77)
Taxes accrued	118	19
Regulatory assets and liabilities	96	(45)
Assets, other	(38)	(80)
Liabilities, other	(2)	74
Pension and other postretirement benefits	(66)	(74)
Counterparty collateral, net	13	55
Net cash provided by operating activities	1,067	1,026
Cash Flows From Investing Activities:
Capital expenditures	(1,091)	(1,226)
Other	1	(3)
Net cash used in investing activities	(1,090)	(1,229)
Cash Flows From Financing Activities:
Dividends on common stock	(50)	0
Dividends on preferred stock	(1)	(1)
Short-term debt, net	(349)	(205)
Money pool borrowings, net	(135)	0
Maturities of long-term debt	0	(100)
Issuances of long-term debt	624	498
Capital contributions from parent	0	50
Debt issuance costs	(7)	(5)
Net cash provided by financing activities	82	237
Net change in cash, cash equivalents, and restricted cash	59	34
Cash, cash equivalents, and restricted cash at beginning of year	234	191
Cash, cash equivalents, and restricted cash at end of period	$ 293	$ 225

Consolidated Statement of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Other Paid-in Capital:	Retained Earnings:	Deferred Retirement Benefit Costs	Accumulated Other Comprehensive Loss:	Total Shareholders’ Equity	Noncontrolling Interests:	Union Electric Company	Union Electric Company Common Stock	Union Electric Company Other Paid-in Capital:	Union Electric Company Preferred Stock	Union Electric Company Retained Earnings:	Ameren Illinois Company	Ameren Illinois Company Common Stock	Ameren Illinois Company Other Paid-in Capital:	Ameren Illinois Company Preferred Stock	Ameren Illinois Company Retained Earnings:
Beginning of period at Dec. 31, 2022			$ 6,860	$ 3,646	$ (1)			$ 129			$ 2,725		$ 3,111			$ 2,929		$ 3,190
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the DRPlus and 401(k) plan			35
Stock-based compensation activity			5
Net income	$ 998								$ 544					$ 453
Net income attributable to Ameren common shareholders	994			994
Dividends on common stock				(496)														0
Dividends on preferred stock													(3)					(1)
Change in deferred retirement benefit costs	(3)				(3)
Net income attributable to noncontrolling interest holders	$ (4)							4
Dividends paid to noncontrolling interest holders								(4)
Common stock shares outstanding at beginning of period at Dec. 31, 2022	262,000,000.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the DRPlus and 401(k) plan	400,000
Shares issued for stock-based compensation	500,000
Common stock shares outstanding at end of period at Sep. 30, 2023	262,900,000
End of period at Sep. 30, 2023	$ 11,172	$ 3	6,900	4,144	(4)	$ (4)		129		$ 511	2,725	$ 80	3,652		$ 0	2,979	$ 49	3,642
Shareholders' equity, end of year at Sep. 30, 2023							$ 11,043		6,968					6,670
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per common share	$ 1.89
Beginning of period at Jun. 30, 2023			6,880	3,817	(3)			129			2,725		3,241			2,929		3,517
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the DRPlus and 401(k) plan			12
Stock-based compensation activity			8
Net income	$ 494								412					125
Net income attributable to Ameren common shareholders	493			493
Dividends on common stock				(166)														0
Dividends on preferred stock													(1)					0
Change in deferred retirement benefit costs	(1)				(1)
Net income attributable to noncontrolling interest holders	$ (1)							1
Dividends paid to noncontrolling interest holders								(1)
Common stock shares outstanding at beginning of period at Jun. 30, 2023	262,700,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the DRPlus and 401(k) plan	200,000
Shares issued for stock-based compensation	0
Common stock shares outstanding at end of period at Sep. 30, 2023	262,900,000
End of period at Sep. 30, 2023	$ 11,172	3	6,900	4,144	(4)	(4)		129		511	2,725	80	3,652		0	2,979	49	3,642
Shareholders' equity, end of year at Sep. 30, 2023							11,043		6,968					6,670
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per common share	$ 0.63
Beginning of period at Dec. 31, 2023	$ 11,478		7,216	4,136	(6)			129			2,725		3,647			3,020		3,756
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the DRPlus and 401(k) plan			30
Stock-based compensation activity			18
Net income	979								$ 537					$ 454
Net income attributable to Ameren common shareholders	975			975
Dividends on common stock				(535)														(50)
Dividends on preferred stock													(3)					(1)
Change in deferred retirement benefit costs	(4)				(4)
Net income attributable to noncontrolling interest holders	$ (4)							4
Dividends paid to noncontrolling interest holders								(4)
Common stock shares outstanding at beginning of period at Dec. 31, 2023	266,300,000								102,100,000					25,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the DRPlus and 401(k) plan	400,000
Shares issued for stock-based compensation	200,000
Common stock shares outstanding at end of period at Sep. 30, 2024	266,900,000								102,100,000					25,500,000
End of period at Sep. 30, 2024	$ 11,962	3	7,264	4,576	(10)	(10)		129		511	3,075	80	4,181		0	3,020	49	4,159
Shareholders' equity, end of year at Sep. 30, 2024	$ 11,833						11,833		$ 7,847					$ 7,228
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per common share	$ 2.01
Beginning of period at Jun. 30, 2024			7,246	4,299	(9)			129			3,075		3,800			3,020		4,070
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the DRPlus and 401(k) plan			9
Stock-based compensation activity			9
Net income	$ 457								$ 382					$ 114
Net income attributable to Ameren common shareholders	456			456
Dividends on common stock				(179)														(25)
Dividends on preferred stock													(1)					0
Change in deferred retirement benefit costs	(1)				(1)
Net income attributable to noncontrolling interest holders	$ (1)							1
Dividends paid to noncontrolling interest holders								(1)
Common stock shares outstanding at beginning of period at Jun. 30, 2024	266,800,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the DRPlus and 401(k) plan	100,000
Shares issued for stock-based compensation	0
Common stock shares outstanding at end of period at Sep. 30, 2024	266,900,000								102,100,000					25,500,000
End of period at Sep. 30, 2024	$ 11,962	$ 3	$ 7,264	$ 4,576	$ (10)	$ (10)		$ 129		$ 511	$ 3,075	$ 80	$ 4,181		$ 0	$ 3,020	$ 49	$ 4,159
Shareholders' equity, end of year at Sep. 30, 2024	$ 11,833						$ 11,833		$ 7,847					$ 7,228
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per common share	$ 0.67

Summary Of Significant Accounting Policies	9 Months Ended
Summary Of Significant Accounting Policies	Sep. 30, 2024
Accounting Policies [Abstract]
SUMMARY OF 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 Illinois Company, doing business as Ameren Illinois, operates rate-regulated electric transmission, electric distribution, and natural gas distribution businesses in Illinois. •ATXI operates a FERC rate-regulated electric transmission business within the MISO. 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 Missouri’s subsidiaries were created for the ownership of renewable generation projects. 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 statement 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 reporting periods. Actual results could differ from those estimates. The results of operations for an interim period may not give a true indication of results that may be expected for a full year. These financial statements should be read in conjunction with the financial statements and accompanying notes included in the Form 10-K. Variable Interest Entities As of September 30, 2024, and December 31, 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 September 30, 2024, Ameren’s maximum exposure to loss related to these variable interests is limited to its investment of $74 million plus associated outstanding funding commitments of $12 million. COLI Ameren 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 September 30, 2024, the cash surrender value of COLI at Ameren and Ameren Illinois was $263 million (December 31, 2023 – $248 million) and $116 million (December 31, 2023 – $111 million), respectively, while total borrowings against the policies were $108 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.

Rate And Regulatory Matters

9 Months Ended

Sep. 30, 2024

Public Utilities, General Disclosures [Abstract]

RATE AND REGULATORY MATTERS

Below is a summary of updates to significant regulatory proceedings and related legal proceedings. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of the Form 10-K for additional information and a summary of our regulatory frameworks. We are unable to predict the ultimate outcome of these matters, the timing of final decisions of the various agencies and courts, or the impact on our results of operations, financial position, or liquidity.

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 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 $14 billion, and a test year ended March 31, 2024, with certain pro-forma adjustments expected through an anticipated true-up date of December 31, 2024. Ameren Missouri also requested the continued use of the FAC and trackers for pension and postretirement benefits, uncertain income tax positions, certain excess deferred income taxes, and the utilization of production and investment tax credits or proceeds from the sale of tax credits allowed under the IRA, which the MoPSC previously authorized in earlier electric rate orders. 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 solar 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, consistent with Ameren Missouri’s 2023 IRP, to ensure reliability.

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 the PGA, WNAR, and trackers for pension and other postretirement benefits and certain excess deferred taxes that the MoPSC previously authorized in earlier natural gas rate orders. 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 would be eligible for recovery under the post-construction cost deferral discussed below, if approved by the MoPSC. The following table provides information with respect to each agreement:

Agreement type

Facility size

Status of MoPSC CCN

Status of FERC approval of acquisition

Anticipated in-service date(a)

Huck Finn Solar Project(b)(c)

Build-transfer

200-MW

Approved February 2023

Received March 2023

Fourth quarter 2024

Boomtown Solar Project(c)(d)

Build-transfer

150-MW

Approved April 2023

Received October 2023

Fourth quarter 2024

Cass County Solar Project(c)(d)

Development-transfer(e)

150-MW

Approved June 2024

Not applicable

Fourth quarter 2024

Vandalia Solar Project(f)(g)

Self-build

50-MW

Approved March 2024

Not applicable

Fourth quarter 2025

Bowling Green Solar Project(f)(g)

Self-build

50-MW

Approved March 2024

Not applicable

First quarter 2026

Split Rail Solar Project(f)(g)

Build-transfer

300-MW

Approved March 2024

Received November 2024

Mid-2026

Castle Bluff Natural Gas Project(f)

Self-build

800-MW

Approved October 2024(h)

Not applicable

Fourth quarter 2027

(a)Anticipated in-service dates are dependent on the timing of construction completion, among other things.

(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. These three acquisitions collectively represent a purchase price of approximately $0.9 billion.

(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.

(e)The development-transfer agreement included solar panels, project design, land rights, and engineering, procurement, and construction agreements. Ameren Missouri took over construction management of the project when it was acquired in June 2024.

(f)These projects collectively represent approximately $1.7 billion of expected capital expenditures.

(g)These solar projects are expected to support Ameren Missouri’s transition to renewable energy generation.

(h)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 a wholly owned, special purpose subsidiary of Ameren Missouri to finance approximately $470 million of costs related to the planned accelerated retirement of the Rush Island Energy Center, which includes the expected 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 financing order also includes 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 9 – Commitments and Contingencies. However, claims regarding such actions could be considered in future regulatory proceedings. If future regulatory proceedings result in revenue reductions based on Ameren Missouri’s prior actions that resulted in the adverse ruling in the NSR and Clean Air Act litigation, it could have a material adverse effect on the results of operations, financial position, and liquidity of Ameren and Ameren Missouri. In September 2024, the financing order became final and unappealable.

MEEIA

In January 2024, Ameren Missouri filed a proposed customer energy-efficiency plan with the MoPSC under the MEEIA. In October 2024, Ameren Missouri, the MoOPC, and other intervenors filed a nonunanimous stipulation and agreement with the MoPSC for a three-year plan, which includes a portfolio of customer energy-efficiency and demand response programs, along with the continued use of the MEEIA rider,

which allows Ameren Missouri to collect from customers its actual MEEIA program costs and related lost electric revenues. If the agreement is approved, Ameren Missouri intends to invest $51 million annually in 2025 and 2026 and $22 million in 2027 in the proposed customer energy-efficiency and demand response programs. In addition, the agreement requested performance incentives applicable to each plan year to earn revenues by achieving certain spending and demand response goals. If 100% of the goals are achieved in 2025, 2026, and 2027, Ameren Missouri would earn performance incentive revenues of $5 million, $5 million, and $2 million, respectively. Ameren Missouri expects a decision by the MoPSC in the fourth quarter of 2024, but cannot predict the ultimate outcome of this regulatory proceeding.

MISO Long-Range Transmission Projects CCN

In July 2022, the MISO approved the first tranche of projects related to a preliminary long-range transmission planning roadmap of projects through 2039. A portion of these projects were assigned or awarded via a competitive bid process to various utilities, including Ameren. In July 2024, ATXI filed a request for a CCN, among other things, with the MoPSC related to a portion of the MISO long-range transmission projects that it expects to construct within the MoPSC’s jurisdiction. A decision by the MoPSC is expected by mid-2025.

Illinois

MYRP

In December 2023, the ICC issued an order in Ameren Illinois' MYRP proceeding approving base rates for electric distribution services for 2024 through 2027 and rejecting Ameren Illinois' Grid Plan, which was addressed as part of the MYRP proceeding. Rate changes consistent with the December 2023 order became effective in January 2024 and remained effective through late June 2024, when new rates became effective pursuant to the June 2024 ICC rehearing order discussed below. The December 2023 order adopted an alternative methodology to establish a rate base and revenue requirements for the years 2024 through 2027 using Ameren Illinois’ previously approved 2022 year-end rate base. In January 2024, the ICC partially denied a rehearing requested by Ameren Illinois to revise the allowed ROE in the December 2023 order and granted Ameren Illinois’ rehearing request to reconsider the rate base for each year of the MYRP and to include a base level of investments to maintain grid reliability in each year of the MYRP. In June 2024, the ICC issued an order on Ameren Illinois’ rehearing request, which revised the rate bases for Ameren Illinois’ MYRP test years to include investments for 2023 through 2027, among other things. New rates became effective in late June 2024. For additional information on the ICC’s June 2024 rehearing order, see the table below. In July 2024, Ameren Illinois filed a request for rehearing of the ICC’s June 2024 rehearing order to include an asset associated with other postretirement benefits in the rate base. Subsequently, in August 2024, the ICC denied the rehearing request. Also, in January 2024, Ameren Illinois filed an appeal of the December 2023 ICC order, including the 8.72% ROE, and subsequently updated the appeal filing in September 2024 to include the June 2024 rehearing order regarding the inclusion of an asset associated with other postretirement benefits in the rate base to the Illinois Appellate Court for the Fifth Judicial District. The court is under no deadline to address the appeal.

In September 2024, Ameren Illinois filed an update to its revised Grid Plan and revised MYRP to update the requested revenue requirements for 2024 through 2027. Related to this MYRP filing, the ICC staff submitted its recommendation, and the administrative law judges issued a proposed order in August 2024 and October 2024, respectively, each recommending ICC approval of the Grid Plan and MYRP, with various adjustments as outlined in the table below. An ICC decision on the revised Grid Plan and updated revenue requirements is expected in December 2024 with rates effective in January 2025.

The following table presents the approved revenue requirements and average annual rate base in the ICC’s June 2024 rehearing order, as well as the proposed revenue requirements and average annual rate base in Ameren Illinois’ September 2024 revised MYRP, the ICC staff’s August 2024 revised MYRP recommendation, and the October 2024 administrative law judges’ proposed order:


Year	Revenue Requirement (in millions)	Average Annual Rate Base (in billions)
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
Ameren Illinois’ September 2024 Revised MYRP(a):
2024	$1,215	$4.3
2025	$1,299	$4.5
2026	$1,385	$4.8
2027	$1,444	$5.0
ICC Staff’s August 2024 Revised MYRP(a):
2024	$1,206	$4.2
2025	$1,288	$4.4
2026	$1,369	$4.6
2027	$1,424	$4.8
Administrative Law Judges’ October 2024 Proposed Order(a):
2024	$1,206	$4.2
2025	$1,287	$4.4
2026	$1,370	$4.6
2027	$1,427	$4.9

(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.

Using the 2023 revenue requirement as a starting point, the approved revenue requirements in the ICC’s June 2024 rehearing order represent a cumulative four-year increase of $285 million compared to a cumulative increase of $332 million in Ameren Illinois’ September 2024 revised MYRP, a cumulative increase of $311 million in the ICC staff’s August 2024 revised MYRP recommendation, and a cumulative increase of $315 million in the administrative law judges’ October 2024 proposed order.

Ameren Illinois cannot predict the ultimate outcome of the appeal to the Illinois Appellate Court for the Fifth Judicial District, its revised Grid Plan filing, or its request to update the associated MYRP revenue requirements for 2024 through 2027.

2023 Electric Distribution Revenue Requirement Reconciliation Adjustment Request

In April 2024, Ameren Illinois filed for a reconciliation adjustment to its 2023 electric distribution service revenue requirement with the ICC. In July 2024, Ameren Illinois filed a revised reconciliation adjustment, requesting recovery of $158 million. The reconciliation adjustment reflects a capital structure composed of 50% common equity and Ameren Illinois’ actual 2023 recoverable costs and year-end rate base. In August 2024, the ICC staff submitted its calculation of the reconciliation adjustment, recommending approval of Ameren Illinois’ request. An ICC decision in this proceeding is required by December 2024, and any approved adjustment would be collected from customers in 2025. This is the final revenue requirement reconciliation under the IEIMA formula framework.

Electric Customer Energy-Efficiency Investments

In May 2024, Ameren Illinois filed its annual electric energy-efficiency formula rate update to increase its rates by $26 million with the ICC. In September 2024, the ICC staff filed a recommendation supporting Ameren Illinois’ requested increase. An ICC decision in this proceeding is required by December 2024, with new rates effective January 2025.

2023 Natural Gas Delivery Service Rate Order

In November 2023, the ICC issued an order in Ameren Illinois’ January 2023 natural gas delivery service regulatory rate review, which resulted in an increase to its annual revenues for natural gas delivery service of $112 million based on a 9.44% allowed ROE, a capital structure composed of 50% common equity, and a rate base of approximately $2.85 billion. The order reflected a reduction of approximately

$93 million of planned distribution and transmission capital investments included in Ameren Illinois’ requested revenue increase, which used a 2024 future test year. The new rates became effective on November 28, 2023.

In December 2023, Ameren Illinois filed a request for rehearing of the ICC’s November 2023 order. The filing requested the ICC revise the order to include an allowed ROE of at least 9.89%, a capital structure composed of 52% common equity, and the reversal of the approximately $93 million reduction of planned distribution and transmission capital investments included in the order, among other things. In January 2024, the ICC denied Ameren Illinois’ rehearing request. Subsequently, in January 2024, Ameren Illinois filed an appeal of the November 2023 ICC order to the Illinois Appellate Court for the Fifth Judicial District. The court is under no deadline to address the appeal. Ameren Illinois cannot predict the ultimate outcome of this appeal.

QIP Reconciliation Hearing

In March 2021, Ameren Illinois filed a request with the ICC to initiate a reconciliation proceeding to determine the accuracy and prudence of natural gas capital investments recovered under the QIP rider during 2020. In September 2024, the Illinois Attorney General’s office challenged the recovery of capital investments that were made during 2020, alleging that the ICC should disallow approximately $30 million in natural gas capital investments as improper and imprudent, and resulting in a potential over-recovery of approximately $1 million by Ameren Illinois in 2020. In October 2023, and again in September 2024, the ICC staff filed testimony that supports the prudence and reasonableness of the capital investments made during 2020. Ameren Illinois’ 2020 QIP rate recovery request under review by the ICC was within the rate increase limitations allowed by law. The ICC is under no deadline to issue an order in this proceeding. Ameren Illinois cannot predict the ultimate outcome of this regulatory proceeding.

MISO Long-Range Transmission Projects CCN

In July 2022, the MISO approved the first tranche of projects related to a preliminary long-range transmission planning roadmap of projects through 2039. A portion of these projects were assigned or awarded via a competitive bidding process to various utilities, including Ameren. In February 2024, Ameren Illinois and ATXI filed a request for a CCN, among other things, with the ICC related to the portion of the MISO long-range transmission projects they will construct within the ICC’s jurisdiction. A decision by the ICC is expected by mid-2025.

Federal

FERC Complaint Cases

Since November 2013, the allowed base ROE for FERC-regulated transmission rate base under the MISO tariff has been subject to customer complaint cases and has been changed by various FERC orders. In May 2020, the FERC issued an order, which set the allowed base ROE to 10.02% and required refunds, with interest, for the periods from November 2013 to February 2015 and from late September 2016 forward. Ameren and Ameren Illinois paid these refunds, including interest, by March 31, 2022. In June and July 2020, Ameren Missouri, Ameren Illinois, and ATXI, as well as various customers, petitioned the United States Court of Appeals for the District of Columbia Circuit for review of the May 2020 order, challenging certain aspects of the new ROE methodology established. The petition filed by Ameren Missouri, Ameren Illinois, and ATXI challenged the refunds required for the period from September 2016 to May 2020. In August 2022, the court issued a ruling that granted the customers’ petition for review, vacated the FERC’s previous MISO ROE-determining orders, and remanded the proceedings to the FERC. The court elected not to rule on the issues raised by Ameren Missouri, Ameren Illinois, and ATXI. In October 2024, the FERC issued an order, which decreased the allowed base ROE from 10.02% to 9.98% and required refunds, with interest, for the same periods covered by the May 2020 order.

As a result of the October 2024 order, Ameren and Ameren Illinois recognized reductions to "Operating Revenues – Electric" on their statements of income of $10 million and $7 million, respectively, and recognized expense of $2 million and $1 million, respectively, in “Interest charges” on their statements of income during the third quarter of 2024. As of September 30, 2024, Ameren and Ameren Illinois had recorded liabilities in "Current regulatory liabilities" on their balance sheets of $12 million and $8 million, respectively, to reflect the expected refunds, including interest, associated with the allowed base ROE set by the October 2024 order. The decrease in the FERC-allowed base ROE resulting from the October 2024 order is not material to Ameren Missouri’s results of operations, financial position, or liquidity.

Short-Term Debt And Liquidity

9 Months Ended

Sep. 30, 2024

Debt Disclosure [Abstract]

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, in the case of Ameren Missouri and Ameren Illinois, short-term affiliate borrowings. See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of the Form 10-K for a description of our indebtedness provisions and other covenants as well as a description of money pool agreements.

Short-term Borrowings

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, and the issuance of letters of credit. As of September 30, 2024, based on commercial paper outstanding and letters of credit issued under the Credit Agreements, along with cash and cash equivalents, the net liquidity available to Ameren (parent), Ameren Missouri, and Ameren Illinois, collectively, was $1.1 billion. The Ameren Companies were in compliance with the covenants in their Credit Agreements as of September 30, 2024. As of September 30, 2024, the ratios of consolidated indebtedness to consolidated total capitalization, calculated in accordance with the provisions of the Credit Agreements, were 61%, 49%, and 45% for Ameren, Ameren Missouri, and Ameren Illinois, respectively.

The following table presents commercial paper outstanding, net of issuance discounts, as of September 30, 2024, and December 31, 2023. There were no borrowings outstanding under the Credit Agreements as of September 30, 2024, or December 31, 2023.


	September 30, 2024		December 31, 2023
Ameren (parent)	$	946	$	—
Ameren Missouri	576		170
Ameren Illinois	17		366
Ameren consolidated	$	1,539	$	536

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 for the nine months ended September 30, 2024 and 2023:


	Ameren (parent)			Ameren Missouri			Ameren Illinois			Ameren Consolidated
2024
Average daily amount outstanding	$	177		$	187		$	256		$	620

Weighted-average interest rate	5.46		%	5.52		%	5.57		%	5.53		%
Peak amount outstanding during period(a)	$	948		$	576		$	694		$	1,542
Peak interest rate	5.60		%	5.68		%	5.68		%	5.68		%
2023
Average daily amount outstanding	$	687		$	306		$	181		$	1,174

Weighted-average interest rate	5.29		%	5.15		%	5.15		%	5.24		%
Peak amount outstanding during period(a)	$	1,127		$	592		$	450		$	1,381
Peak interest rate	5.60		%	5.60		%	5.60		%	5.60		%

(a)The timing of peak outstanding commercial paper issuances 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.

Money Pools

Ameren has money pool agreements with and among its subsidiaries to coordinate and provide for certain short-term cash and working capital requirements. The average interest rate for borrowings under the utility money pool for the three and nine months ended September 30, 2024, was 5.29% and 5.37%, respectively (2023 – 5.50% and 5.20%, respectively). See Note 8 – Related-party Transactions for the amount of interest income and expense from the utility money pool agreements recorded by Ameren Missouri and Ameren Illinois for the three and nine months ended September 30, 2024 and 2023.

Long-Term Debt And Equity Financings	9 Months Ended
Long-Term Debt And Equity Financings	Sep. 30, 2024
Long-Term Debt And Equity Financings [Abstract]
LONG-TERM DEBT AND EQUITY FINANCINGS	LONG-TERM DEBT AND EQUITY FINANCINGS Ameren For the three and nine months ended September 30, 2024, Ameren issued a total of 0.1 million and 0.4 million shares of common stock, under its DRPlus and 401(k) plan, and received proceeds of $2 million and $23 million, respectively. As of September 30, 2024, Ameren had a receivable of $7 million related to issuances of common stock under its DRPlus. In addition, in the first quarter of 2024, Ameren issued 0.2 million shares of common stock valued at $16 million upon the settlement of stock-based compensation awards. There were no shares issued under the ATM program for the three and nine months ended September 30, 2024. As of September 30, 2024, Ameren had approximately $615 million of common stock available for sale under the ATM program, which takes into account the forward sale agreements in effect as of September 30, 2024, discussed below. The forward sale agreements outstanding as of September 30, 2024, can be settled at Ameren’s discretion on or prior to dates ranging from January 14, 2025 to February 10, 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 $76.69 to $89.31, with an average initial forward sale price of $80.96. Each initial 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 the spread on any day, the interest rate factor will result in a reduction 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 September 30, 2024, Ameren could have settled the forward sale agreements with physical delivery of 4.7 million shares of common stock to the respective counterparties in exchange for cash of $386 million. Alternatively, the forward sale agreements could have also been settled at September 30, 2024, with delivery of approximately $29 million of cash or approximately 0.3 million shares of common stock to the counterparties. In connection with the forward sale agreements outstanding at September 30, 2024, the various counterparties, or their affiliates, borrowed from third parties and sold 4.7 million shares of common stock. The gross sales price of these shares totaled $388 million. Ameren has not received any proceeds from such sales of borrowed shares. The forward sale agreements have been classified as equity transactions. In September 2024, $450 million principal amount of Ameren (parent)’s 2.50% senior unsecured notes matured and was repaid with commercial paper borrowings. 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. Ameren Missouri received capital contributions totaling $350 million from Ameren (parent) during the nine months ended September 30, 2024. 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. 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 See Note 5 – Long-term Debt and Equity Financings under Part II, Item 8, of the Form 10-K for a description of our indenture provisions and other covenants, as well as restrictions on the payment of dividends. At September 30, 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. Off-balance-sheet Arrangements At September 30, 2024, none of the Ameren Companies had any material off-balance-sheet financing arrangements, other than their investment in variable interest entities 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

9 Months Ended

Sep. 30, 2024

Other Nonoperating Income (Expense) [Abstract]

OTHER INCOME, NET

The following table presents the components of “Other Income, Net” in the Ameren Companies’ statements of income for the three and nine months ended September 30, 2024 and 2023:


	Three Months				Nine Months
	2024		2023		2024		2023
Ameren:

Allowance for equity funds used during construction	$	23	$	16	$	48	$	39
Interest income on industrial development revenue bonds	—		—		—		1
Other interest income	8		6		29		23

Non-service cost components of net periodic benefit income(a)	76		84		228		211
Miscellaneous income	—		1		6		4
Earnings (losses) related to equity method investments	(2)		—		(1)		2
Donations	(1)		(1)		(5)		(5)
Miscellaneous expense	(3)		(5)		(12)		(14)
Total Other Income, Net	$	101	$	101	$	293	$	261
Ameren Missouri:

Allowance for equity funds used during construction	$	15	$	8	$	38	$	20
Interest income on industrial development revenue bonds	—		—		—		1
Other interest income	2		3		7		8
Non-service cost components of net periodic benefit income(a)	35		34		104		62
Miscellaneous income	1		1		3		3
Donations	—		—		(2)		(2)
Miscellaneous expense	(2)		(2)		(6)		(7)
Total Other Income, Net	$	51	$	44	$	144	$	85
Ameren Illinois:

Allowance for equity funds used during construction	$	8	$	5	$	10	$	15
Other interest income	7		4		22		14

Non-service cost components of net periodic benefit income	25		31		78		93
Miscellaneous income	—		—		3		2
Donations	—		(1)		(2)		(3)
Miscellaneous expense	(3)		(2)		(6)		(6)
Total Other Income, Net	$	37	$	37	$	105	$	115

(a)For the three and nine months ended September 30, 2024, the non-service cost components of net periodic benefit income were adjusted by amounts deferred of $(11) million and $(31) 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. The deferral was $(2) million and $32 million, respectively, for the three and nine months ended September 30, 2023. See Note 11 – Retirement Benefits for additional information.

Derivative Financial Instruments

9 Months Ended

Sep. 30, 2024

Derivative Instruments and Hedging Activities Disclosure [Abstract]

DERIVATIVE FINANCIAL INSTRUMENTS

We use derivatives to manage the risk of changes in market prices for natural gas, power, and uranium, 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 the purchase of these 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. 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 September 30, 2024, and December 31, 2023, all contracts that met the definition of a derivative and were not eligible for the NPNS exception received regulatory deferral. The cash flows from our derivative financial instruments follow the cash flow classification of the hedged item.

The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of September 30, 2024, and December 31, 2023. As of September 30, 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)
	September 30, 2024			December 31, 2023
Commodity	Ameren Missouri	Ameren Illinois	Ameren	Ameren Missouri	Ameren Illinois	Ameren
Fuel oils (in gallons)	25	—	25	17	—	17
Natural gas (in mmbtu)	49	204	253	53	218	271
Power (in MWhs)	—	5	5	—	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 September 30, 2024, and December 31, 2023:


		September 30, 2024						December 31, 2023
	Balance Sheet Location	Ameren Missouri		Ameren Illinois		Ameren			Ameren Missouri		Ameren Illinois		Ameren







Fuel oils	Other current assets	$	—	$	—	$	—		$	2	$	—	$	2



Natural gas	Other current assets	1		2		3			—		—		—
	Other assets	2		1		3			3		3		6


Power	Other current assets	10		—		10			5		—		5



Uranium	Other current assets	—		—		—			9		—		9

	Total assets	$	13	$	3	$	16		$	19	$	3	$	22


Fuel oils	Other current liabilities	$	3	$	—	$	3		$	1	$	—	$	1
	Other deferred credits and liabilities	2		—		2			1		—		1


Natural gas	Other current liabilities	7		28		35			12		45		57
	Other deferred credits and liabilities	9		29		38			10		30		40


Power	Other current liabilities	—		11		11			1		12		13
	Other deferred credits and liabilities	—		67		67			—		56		56




	Total liabilities	$	21	$	135	$	156		$	25	$	143	$	168

We believe that entering into master netting arrangements or similar agreements mitigates the level of financial loss that could result from default by allowing net settlement of derivative assets and liabilities. These master netting arrangements allow the counterparties to net settle sale and purchase transactions. Further, collateral requirements are calculated at the master netting arrangement or similar agreement level by counterparty.

The following table provides the recognized gross derivative balances and the net amounts of those derivatives subject to an enforceable master netting arrangement or similar agreement as of September 30, 2024, and December 31, 2023:


			Gross Amounts Not Offset in the Balance Sheet
Commodity Contracts Eligible to be Offset	Gross Amounts Recognized in the Balance Sheet		Derivative Instruments		Cash Collateral Received/Posted(a)		Net Amount
September 30, 2024
Assets:
Ameren Missouri	$	13	$	3	$	—	$	10
Ameren Illinois	3		2		—		1
Ameren	$	16	$	5	$	—	$	11
Liabilities:
Ameren Missouri	$	21	$	3	$	—	$	18
Ameren Illinois	135		2		—		133
Ameren	$	156	$	5	$	—	$	151
December 31, 2023
Assets:
Ameren Missouri	$	19	$	6	$	—	$	13
Ameren Illinois	3		1		—		2
Ameren	$	22	$	7	$	—	$	15
Liabilities:
Ameren Missouri	$	25	$	6	$	—	$	19
Ameren Illinois	143		1		6		136
Ameren	$	168	$	7	$	6	$	155

(a)Cash collateral received reduces gross asset balances and is included in “Other current liabilities” and “Other deferred credits and liabilities” on the balance sheet. Cash collateral posted reduces gross liability balances and is included in “Other current assets” and “Other assets” on the balance sheet.

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 September 30, 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.

Certain of our derivative instruments contain collateral provisions tied to the Ameren Companies’ credit ratings. If our credit ratings were downgraded below investment grade, or if a counterparty with reasonable grounds for uncertainty regarding our ability to satisfy an obligation requested adequate assurance of performance, additional collateral postings might be required. The additional collateral required is the net liability position allowed under master netting arrangements or similar agreements, assuming (1) the credit risk-related contingent features underlying these arrangements were triggered and (2) those counterparties with rights to do so requested collateral. The following table presents, as of September 30, 2024, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a gross liability position, the cash collateral posted, and the aggregate amount of additional collateral that counterparties could require:



	Aggregate Fair Value of Derivative Liabilities(a)		Cash Collateral Posted		Potential Aggregate Amount of Additional Collateral Required(b)
Ameren Missouri	$	21	$	—	$	18
Ameren Illinois	57		—		55
Ameren	$	78	$	—	$	73

(a)Before consideration of master netting arrangements or similar agreements.

(b)As collateral requirements with certain counterparties are based on master netting arrangements or similar agreements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such arrangements

Fair Value Measurements

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value Disclosures

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. Fair value measurements are classified in three levels based on the fair value hierarchy as defined by GAAP. See Note 8 – Fair Value Measurements under Part II, Item 8, of the Form 10-K for information related to hierarchy levels and valuation techniques.

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 the three and nine months ended September 30, 2024 or 2023. At September 30, 2024, and December 31, 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 September 30, 2024, and December 31, 2023:


		September 30, 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	—		3		—		3			—		3		—		3
	Power	—		—		10		10			—		—		5		5
	Uranium	—		—		—		—			—		—		9		9
	Total derivative assets – commodity contracts	$	—	$	3	$	10	$	13		$	2	$	3	$	14	$	19
	Nuclear decommissioning trust fund:

	Equity securities:
	U.S. large capitalization	$	888	$	—	$	—	$	888		$	787	$	—	$	—	$	787
	Debt securities:
	U.S. Treasury and agency securities	—		212		—		212			—		150		—		150
	Corporate bonds	—		147		—		147			—		136		—		136


	Other	—		78		—		78			—		68		—		68
	Total nuclear decommissioning trust fund	$	888	$	437	$	—	$	1,325	(a)	$	787	$	354	$	—	$	1,141	(a)
	Total Ameren Missouri	$	888	$	440	$	10	$	1,338		$	789	$	357	$	14	$	1,160
Ameren Illinois
	Derivative assets – commodity contracts:
	Natural gas	$	1	$	1	$	1	$	3		$	—	$	1	$	2	$	3

	Total Ameren Illinois	$	1	$	1	$	1	$	3		$	—	$	1	$	2	$	3
Ameren
	Derivative assets – commodity contracts(b)	$	1	$	4	$	11	$	16		$	2	$	4	$	16	$	22
	Nuclear decommissioning trust fund(c)	888		437		—		1,325		(a)	787		354		—		1,141		(a)
	Total Ameren	$	889	$	441	$	11	$	1,341		$	789	$	358	$	16	$	1,163
Liabilities:
Ameren Missouri
	Derivative liabilities – commodity contracts:
	Fuel oils	$	4	$	—	$	1	$	5		$	2	$	—	$	—	$	2
	Natural gas	—		15		1		16			—		19		3		22
	Power	—		—		—		—			—		—		1		1

	Total Ameren Missouri	$	4	$	15	$	2	$	21		$	2	$	19	$	4	$	25
Ameren Illinois
	Derivative liabilities – commodity contracts:
	Natural gas	$	3	$	48	$	6	$	57		$	4	$	60	$	11	$	75
	Power	—		—		78		78			—		—		68		68
	Total Ameren Illinois	$	3	$	48	$	84	$	135		$	4	$	60	$	79	$	143
Ameren
	Derivative liabilities – commodity contracts(b)	$	7	$	63	$	86	$	156		$	6	$	79	$	83	$	168

(a)Balance excludes $8 million and $9 million of cash and cash equivalents, receivables, payables, and accrued income, net, for September 30, 2024, and December 31, 2023, respectively.

(b)See the Ameren Missouri and Ameren Illinois sections of the table for a breakout of the fair value of Ameren’s derivative assets and liabilities by type of commodity.

(c)See the Ameren Missouri section of the table for a breakout of the fair value of Ameren’s nuclear decommissioning trust fund by investment type.

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 three and nine months ended September 30, 2024 and 2023:


	2024						2023
	Ameren Missouri		Ameren Illinois		Ameren			Ameren Missouri		Ameren Illinois		Ameren
For the three months ended September 30:
Beginning balance at July 1	$	14	$	(61)	$	(47)		$	14	$	(68)	$	(54)
Realized and unrealized gains/(losses) included in regulatory assets/liabilities	(1)		(21)		(22)			(5)		1		(4)


Settlements	(3)		4		1			(3)		3		—


Ending balance at September 30	$	10	$	(78)	$	(68)		$	6	$	(64)	$	(58)
Change in unrealized gains/(losses) related to assets/liabilities held at September 30	$	(1)	$	(19)	$	(20)		$	(5)	$	1	$	(4)
For the nine months ended September 30:
Beginning balance at January 1	$	4	$	(68)	$	(64)		$	12	$	(33)	$	(21)
Realized and unrealized gains/(losses) included in regulatory assets/liabilities	13		(23)		(10)			3		(40)		(37)


Settlements	(7)		13		6			(9)		9		—


Ending balance at September 30	$	10	$	(78)	$	(68)		$	6	$	(64)	$	(58)
Change in unrealized gains/(losses) related to assets/liabilities held at September 30	$	10	$	(18)	$	(8)		$	6	$	(31)	$	(25)

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 other comprehensive income 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 September 30, 2024, and December 31, 2023:


			Fair Value						Weighted Average(b)
	Commodity		Assets		Liabilities	Valuation Technique(s)	Unobservable Input(a)	Range
2024	Power(c)	$	10	$	(78)	Discounted cash flow	Average forward peak and off-peak pricing – forwards/swaps ($/MWh)	31 – 59	40

							Nodal basis ($/MWh)	(8) – 1	(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 fair value as of September 30, 2024, and December 31, 2023:


Long-Term Debt (Including Current Portion):	Carrying Amount(a)		Fair Value
			Level 2		Level 3			Total
	September 30, 2024




Ameren	$	16,722	$	15,303	$	570	(b)	$	15,873






Ameren Missouri	6,830		6,409		—			6,409





Ameren Illinois	5,852		5,560		—			5,560
	December 31, 2023



Ameren	$	15,970	$	14,366	$	467	(b)	$	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 $123 million, $53 million, and $52 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of September 30, 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)The Level 3 fair value amount consists of ATXI’s senior unsecured notes.

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.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

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+ Details

Related Party Transactions

9 Months Ended

Sep. 30, 2024

RELATED PARTY TRANSACTIONS

RELATED-PARTY TRANSACTIONS

In the ordinary course of business, Ameren Missouri and Ameren Illinois have engaged in, and may in the future 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. For a discussion of material related-party agreements and money pool agreements, see Note 13 – Related-party Transactions and Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of the Form 10-K.

Support Services Agreements

Ameren Missouri and Ameren Illinois had long-term receivables included in “Other assets” from Ameren Services of $19 million and $22 million, respectively, as of September 30, 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.

In December 2023, ATXI placed in service a transmission operations control center. Rental revenues received by ATXI from Ameren Services associated with this facility are affiliate transactions and are eliminated in consolidation for Ameren’s consolidated financial statements. Ameren Services’ rental expenses incurred are subsequently allocated to Ameren Missouri and Ameren Illinois as part of the Ameren Services support agreement.

Tax Allocation Agreement

See Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of the Form 10-K 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 September 30, 2024, and December 31, 2023:


	September 30, 2024				December 31, 2023
	Ameren Missouri		Ameren Illinois		Ameren Missouri		Ameren Illinois
Income taxes payable to parent(a)	$	20	$	105	$	—	$	2
Income taxes receivable from parent(b)	—		—		56		22

(a)Included in “Accounts payable – affiliates” on the balance sheet.

(b)Included in “Accounts receivable – affiliates” on the balance sheet.

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 three and nine months ended September 30, 2024 and 2023:


				Three Months				Nine Months
Agreement	Income Statement Line Item			Ameren Missouri		Ameren Illinois		Ameren Missouri		Ameren Illinois
Ameren Missouri power supply	Operating Revenues	2024	$	(b)	$	(a)	$	(b)	$	(a)
agreements with Ameren Illinois		2023		2		(a)		2		(a)
Ameren Missouri and Ameren Illinois	Operating Revenues	2024	$	8	$	(b)	$	23	$	(b)
rent and facility services		2023		7		(b)		25		(b)
Ameren Missouri and Ameren Illinois miscellaneous	Operating Revenues	2024	$	1	$	(b)	$	2	$	1
support services		2023		(b)		2		(b)		2
Total Operating Revenues		2024	$	9	$	(b)	$	25	$	1
		2023		9		2		27		2
Ameren Illinois power supply	Purchased Power	2024	$	(a)	$	(b)	$	(a)	$	(b)
agreements with Ameren Missouri		2023		(a)		2		(a)		2
Ameren Missouri and Ameren Illinois	Purchased Power	2024	$	3	$	1	$	7	$	2
transmission services from ATXI		2023		(b)		1		1		1
Total Purchased Power		2024	$	3	$	1	$	7	$	2
		2023		(b)		3		1		3
Ameren Missouri and Ameren Illinois	Other Operations and Maintenance	2024	$	(b)	$	(b)	$	(b)	$	(b)
rent and facility services		2023		(b)		(b)		(b)		2
Ameren Services support services	Other Operations and Maintenance	2024	$	41	$	38	$	122	$	115
agreement		2023		36		33		106		101
Total Other Operations and		2024	$	41	$	38	$	122	$	115
Maintenance		2023		36		33		106		103
Money pool interest	(Interest Charges)/Other Income, Net	2024	$	(b)	$	(b)	$	(3)	$	(2)
		2023		(b)		(b)		(b)		(b)

(a)Not applicable.

(b)Amount less than $1 million.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
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-Paragraph 2
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

+ Details

Commitments And Contingencies	9 Months Ended
Commitments And Contingencies	Sep. 30, 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 in this report and in the Form 10-K, will not have a material adverse effect on our results of operations, financial position, or liquidity. Reference is made to 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 14 – Commitments and Contingencies under Part II, Item 8, of the Form 10-K. See also Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 8 – Related-party Transactions, and Note 10 – Callaway Energy Center of 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 address air emissions; discharges to water bodies; the storage, 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. We employ dedicated personnel knowledgeable in environmental matters to oversee our business activities’ compliance with requirements of environmental laws. 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 power plants. Regulations under the Clean Air Act that apply to the electric utility industry include the NSPS, the CSAPR, the MATS, 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 SO2, particulate matter, NOx, mercury, toxic metals and acid gases, and CO2 emissions. Regulations implementing the Clean Water Act govern both intake and discharges of water, as well as evaluation of the ecological and biological impact of those operations, and could require modifications to water intake structures or more stringent limitations on wastewater discharges. Depending upon the scope of modifications ultimately required by state regulators, capital expenditures associated with these modifications could be significant. The management and disposal of coal ash is regulated under the Resource Conservation and Recovery Act and the CCR Rule, which require the closure of surface impoundments at Ameren Missouri’s coal-fired energy centers. 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 Renewable 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. Ameren Missouri does not anticipate these operating curtailments will have a material impact on its results of operations, financial position, or liquidity. Ameren and Ameren Missouri estimate that they will need to make capital expenditures of $90 million to $120 million from 2024 through 2028 to comply with environmental regulations. These estimates exclude capital expenditures that may be necessary to comply with regulations issued by the EPA in 2024 relating to CO2 emissions, MATS, effluent limitations guidelines, and CCR, which Ameren and Ameren Missouri are assessing and are discussed below. Additional capital expenditures for environmental controls beyond 2028 could be required. This estimate of capital expenditures 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. In addition to planned retirements of coal-fired energy centers identified in the 2023 IRP filed with the MoPSC in September 2023 and as noted below with respect to the NSR and Clean Air Act litigation and Illinois emissions standards discussed in Note 14 – Commitments and Contingencies under Part II, Item 8, of the Form 10-K, 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. 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 SO2 and NOx 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 NOx 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 allows the EPA to implement revisions to the CSAPR through a federal implementation plan. In March 2023, the EPA announced federal implementation plan requirements, which were subsequently published to the Federal Register in June 2023, reducing the amount of NOx allowances available for state budgets and imposing NOx 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 and sought a stay of the EPA’s disapproval of the Missouri state plan. Both the United States Court of Appeals for the Eighth Circuit and the United States Supreme Court have granted applications to stay the EPA’s imposition of the federal implementation plan until resolution of appellate court challenges. A decision on the Good Neighbor Rule by the United States Court of Appeals for the Eighth Circuit is expected in 2025. 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 NOx air pollution control equipment. Reducing the amount of state budget NOx allowances for compliance with NOx emission limits could result in additional controls being required on Ameren Missouri’s generating units and/or the reduction of operations. Any additional costs for compliance are expected to be recovered from customers, subject to MoPSC prudence review, through the FAC or higher base rates. CO2 Emissions Standards In June 2022, the United States Supreme Court issued its decision in West Virginia v. EPA, clarifying that there are limits on how the EPA may regulate greenhouse gases absent further direction from the United States Congress. The court concluded that the EPA’s proposed rules were designed to shift generation from fossil-fuel-fired power plants to renewable energy facilities, which was improper absent specific congressional authorization. In response to that ruling, in April 2024, the EPA issued a final rule that sets CO2 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 natural gas-fired power plants. In July 2024, the United States Court of Appeals for the District of Columbia Circuit denied a request for stay by various stakeholders including state attorney generals and industry groups but indicated it would establish an expedited schedule to determine the legal merits of the final rule. In October 2024, the United States Supreme Court denied motions for stay of the final rule. Ameren and Ameren Missouri are monitoring the legal challenges and assessing the impacts of the final rule and, at this time, cannot predict the 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 are monitoring the legal challenges and assessing the impacts of the revised rule and, at this time, cannot predict the impacts on their results of operations, financial position, and liquidity. 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 granted Ameren Missouri’s request to modify 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. The United States Department of Justice is seeking an order from the district court providing for additional mitigation relief related to prior emissions. In November 2024, Ameren Missouri and the United States Department of Justice reached an agreement in principle, which, if approved by the district court, would resolve all outstanding claims in this case and would require 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 September 30, 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 $15 million and $44 million in “Other operations and maintenance” on their consolidated statements of income in the first and third quarters of 2024, respectively, 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 would exclude any additional mitigation relief ordered in the NSR and Clean Air Act litigation discussed above. 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 2015, the EPA issued a rule to revise the effluent limitation guidelines applicable to steam electric generating units. These guidelines established national standards for water discharges, prohibit effluent discharges of certain waste streams, and impose more stringent limitations on certain water discharges from power plants by 2025. To comply with these guidelines, Ameren Missouri installed dry ash handling systems and wastewater treatment facilities at its coal-fired energy centers. 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. Ameren and Ameren Missouri have AROs of $47 million associated with CCR storage facilities recorded on their respective balance sheets as of September 30, 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 September 30, 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 $45 million to $93 million. Ameren and Ameren Illinois recorded a liability of $45 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.

Callaway Energy Center

9 Months Ended

Sep. 30, 2024

Nuclear Waste Matters [Abstract]

CALLAWAY ENERGY CENTER

See Note 9 – Callaway Energy Center under Part II, Item 8, of the Form 10-K for information regarding spent nuclear fuel recovery, recovery of decommissioning costs, and the nuclear decommissioning trust fund. 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 related regulatory liability. Ameren and Ameren Missouri have recorded an ARO for the Callaway Energy Center decommissioning costs at fair value, which represents the present value of estimated future cash outflows. 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 is 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. See Note 13 – Supplemental Information for more information on Ameren Missouri’s AROs.

Insurance

The following table presents insurance coverage at Ameren Missouri’s Callaway Energy Center at April 1, 2024:


Type and Source of Coverage	Most Recent Renewal Date	Maximum Coverages			Maximum Assessments for Single Incidents
Public liability and nuclear worker liability:
American Nuclear Insurers	January 1, 2024	$	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 $24.7 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 insurance limits, 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

9 Months Ended

Sep. 30, 2024

Retirement Benefits [Abstract]

RETIREMENT BENEFITS

The following table presents the components of the net periodic benefit cost (income) incurred for Ameren’s pension and postretirement benefit plans for the three and nine months ended September 30, 2024 and 2023:


	Pension Benefits								Postretirement Benefits
	Three Months				Nine Months				Three Months				Nine Months
	2024		2023		2024		2023		2024		2023		2024		2023
Service cost(a)	$	22	$	10	$	66	$	56	$	3	$	3	$	9	$	9
Non-service cost components:
Interest cost	56		55		167		166		11		11		33		34
Expected return on plan assets(b)	(82)		(84)		(246)		(251)		(23)		(22)		(69)		(68)
Amortization of(b):

Prior service benefit	—		—		—		—		(1)		(1)		(3)		(3)
Actuarial (gain)	(17)		(29)		(50)		(86)		(9)		(12)		(29)		(35)
Total non-service cost components(c)	$	(43)	$	(58)	$	(129)	$	(171)	$	(22)	$	(24)	$	(68)	$	(72)

Net periodic benefit income(d)	$	(21)	$	(48)	$	(63)	$	(115)	$	(19)	$	(21)	$	(59)	$	(63)

(a)Service cost, net of capitalization, is reflected in “Operating Expenses – Other operations and maintenance” on Ameren’s statement of income.

(b)Prior service benefit is amortized on a straight-line basis over the average future service of active participants benefiting under a 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 5 – 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.

Ameren Missouri and Ameren Illinois are responsible for their respective share of Ameren’s pension and other postretirement costs. The following table presents the respective share of net periodic pension and other postretirement benefit costs (income) incurred for the three and nine months ended September 30, 2024 and 2023:


	Pension Benefits								Postretirement Benefits
	Three Months				Nine Months				Three Months				Nine Months
	2024		2023		2024		2023		2024		2023		2024		2023
Ameren Missouri(a)	$	(11)	$	(24)	$	(33)	$	(59)	$	(6)	$	(8)	$	(20)	$	(23)
Ameren Illinois	(8)		(21)		(25)		(48)		(13)		(13)		(39)		(40)
Other	(2)		(3)		(5)		(8)		—		—		—		—
Ameren(a)	$	(21)	$	(48)	$	(63)	$	(115)	$	(19)	$	(21)	$	(59)	$	(63)

(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 rates.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Income Taxes

9 Months Ended

Sep. 30, 2024

Income Tax Disclosure [Abstract]

Income Taxes

INCOME TAXES

The following table presents a reconciliation of the federal statutory corporate income tax rate to the effective income tax rate for the three and nine months ended September 30, 2024 and 2023:


	Ameren				Ameren Missouri				Ameren Illinois
	2024		2023		2024		2023		2024		2023
Three Months
Federal statutory corporate income tax rate	21	%	21	%	21	%	21	%	21	%	21	%
Increases (decreases) from:
Amortization of excess deferred taxes(a)	(9)		(7)		(15)		(15)		(4)		(2)
Amortization of deferred investment tax credit	—		—		—		(1)		—		—
Renewable and other tax credits(b)	(4)		(5)		(10)		(11)		—		(1)
State tax	4		4		3		3		7		7
Depreciation differences	—		(1)		(1)		—		—		—


Other permanent items	(1)		—		—		—		—		—
Effective income tax rate	11	%	12	%	(2)	%	(3)	%	24	%	25	%
Nine Months
Federal statutory corporate income tax rate	21	%	21	%	21	%	21	%	21	%	21	%
Increases (decreases) from:
Amortization of excess deferred taxes(a)	(8)		(8)		(14)		(15)		(4)		(2)
Amortization of deferred investment tax credit	—		—		—		(1)		—		—

Renewable and other tax credits(b)	(5)		(5)		(10)		(11)		—		—
State tax	5		5		3		3		7		7

Depreciation differences	—		—		(1)		—		—		(1)

Effective income tax rate	13	%	13	%	(1)	%	(3)	%	24	%	25	%

(a)Reflects the amortization of amounts resulting from the revaluation of deferred income taxes subject to regulatory ratemaking, which are being refunded to customers. Deferred income taxes are revalued when federal or state income tax rates change, and the offset to the revaluation of deferred income taxes subject to regulatory ratemaking is recorded to a regulatory asset or liability.

(b)The benefit of the credits associated with Missouri renewable energy standard compliance is refunded to customers through the RESRAM.

- Definition

The entire disclosure for income tax.

+ References

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-Topic 740
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+ Details

Supplemental Information

9 Months Ended

Sep. 30, 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 at September 30, 2024, and December 31, 2023:


	September 30, 2024						December 31, 2023
	Ameren		Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri		Ameren Illinois
“Cash and cash equivalents”	$	17	$	—	$	—	$	25	$	—	$	—

Restricted cash included in “Other current assets”	15		5		6		13		5		5
Restricted cash included in “Other assets”	287		—		287		229		—		229
Restricted cash included in “Nuclear decommissioning trust fund”	5		5		—		5		5		—
Total cash, cash equivalents, and restricted cash	$	324	$	10	$	293	$	272	$	10	$	234

Restricted cash included in “Other current assets” primarily represents funds held by an irrevocable Voluntary Employee Beneficiary Association (VEBA) trust, which provides health care benefits for active employees. 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 September 30, 2024, and December 31, 2023, “Other current liabilities” on Ameren’s and Ameren Illinois’ balance sheets included payables for purchased receivables of $53 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 three and nine months ended September 30, 2024 and 2023:


	Three Months				Nine Months
	2024		2023		2024		2023
Ameren:
Beginning of period	$	37	$	39	$	30	$	31
Bad debt expense	12		18		28		41
Charged to other accounts(a)	2		2		6		3
Net write-offs	(20)		(26)		(33)		(42)
End of period	$	31	$	33	$	31	$	33
Ameren Missouri:
Beginning of period	$	12	$	12	$	12	$	13
Bad debt expense	3		5		8		9
Net write-offs	(3)		(5)		(8)		(10)
End of period	$	12	$	12	$	12	$	12
Ameren Illinois:(b)
Beginning of period	$	25	$	27	$	18	$	18
Bad debt expense	9		13		20		32
Charged to other accounts(a)	2		2		6		3
Net write-offs	(17)		(21)		(25)		(32)
End of period	$	19	$	21	$	19	$	21

(a)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.

(b)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. The table above does not include the impact related to the riders.

Leases

Ameren and Ameren Missouri primarily lease rail cars and land related to solar generation facilities under operating lease arrangements. The land leases are related to the acquisitions of the Cass County Solar Project and Boomtown Solar Project. 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 Solar Project and Boomtown Solar Project have options to extend or terminate those leases. 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. No termination options have been 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 September 30, 2024:


	Ameren			Ameren Missouri
Other assets	$	38		$	35
Other current liabilities	6			5
Other deferred credits and liabilities	32			30
Weighted average remaining operating lease term	23 years			24 years
Weighted average discount rate(a)	5.4		%	5.4		%

(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 September 30, 2024:


	Ameren		Ameren Missouri
2024	$	2	$	2
2025	6		5
2026	3		2
2027	2		2
2028	2		2
Thereafter	55		53
Total lease payments	$	70	$	66
Less imputed interest	32		31
Total	$	38	$	35

Supplemental Cash Flow Information

The following table provides noncash financing and investing activity excluded from the statements of cash flows for the nine months ended September 30, 2024 and 2023:


	September 30, 2024						September 30, 2023
	Ameren		Ameren Missouri				Ameren Illinois	Ameren		Ameren Missouri		Ameren Illinois
Investing:
Accrued capital expenditures, including nuclear fuel expenditures	$	404	$	257	$	127		$	518	$	246	$	237

Net realized and unrealized gain – nuclear decommissioning trust fund	163		163		—			66		66		—
Return of investment in industrial development revenue bonds(a)	—		—		—			240		240		—
Financing:
Issuance of common stock for stock-based compensation	$	16	$	—	$	—		$	37	$	—	$	—
Issuance of common stock under the DRPlus	7		—		—			7		—		—
Termination of a financing obligation(a)	—		—		—			240		240		—

(a)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.

Asset Retirement Obligations

The following table provides a reconciliation of the beginning and ending carrying amount of AROs for the nine months ended September 30, 2024:


	Ameren Missouri			Ameren Illinois			Ameren
Balance at December 31, 2023	$	787	(a)	$	4	(b)	$	791	(a)
Liabilities incurred	17		(c)	—			17		(c)
Liabilities settled	(9)			(1)			(10)
Accretion	26		(d)	—			26		(d)
Change in estimates	(7)			—			(7)
Balance at September 30, 2024	$	814	(a)	$	3	(b)	$	817	(a)

(a)Balance included $19 million in “Other current liabilities” on the balance sheet as of both September 30, 2024, and December 31, 2023.

(b)Included in “Other deferred credits and liabilities” on the balance sheet.

(c)In June and September 2024, Ameren and Ameren Missouri recorded an ARO related to the decommissioning for the Cass County Solar Project and the Boomtown Solar Project, respectively. 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 9 – Commitments and Contingencies for additional information.

(d)Accretion expense attributable to Ameren Missouri was recorded as a decrease to regulatory liabilities.

Stock-based Compensation

In the first quarter of 2024, Ameren granted 359,133 performance share units with a grant date fair value of $21 million and 153,887 restricted share units with a grant date fair value of $11 million. Awards vest approximately 3 years after the grant date based on continued employment or on a pro-rata basis upon death or eligible retirement. The performance share units vest based on the achievement of certain specified market performance measures (307,816 performance share units) or clean energy transition targets (51,317 performance share units). The exact number of shares issued pursuant to a performance share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the performance goals.

For the nine months ended September 30, 2024 and 2023, excess tax benefits (deficiencies) associated with the settlement of stock-based compensation awards increased income tax expense by $1 million and reduced income tax expense by $6 million, respectively.

Deferred Compensation

At September 30, 2024, and December 31, 2023, the present value of benefits to be paid for deferred compensation obligations was $81 million and $85 million, respectively, which was primarily reflected in “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet.

Operating Revenues

As of September 30, 2024 and 2023, our remaining performance obligations for contracts with a term greater than one year 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.

See Note 14 – Segment Information for disaggregated revenue information.

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 three and nine months ended September 30, 2024 and 2023:


	Three Months				Nine Months
	2024		2023		2024		2023
Ameren Missouri	$	60	$	60	$	136	$	133
Ameren Illinois	29		27		94		90
Ameren	$	89	$	87	$	230	$	223

Earnings per Share

The following table reconciles the basic weighted-average number of common shares outstanding to the diluted weighted-average number of common shares outstanding for the three and nine months ended September 30, 2024 and 2023:


	Three Months		Nine Months
	2024	2023	2024	2023


Weighted-average Common Shares Outstanding – Basic	266.8	262.8	266.6	262.5
Assumed settlement of performance share units and restricted stock units	0.4	0.6	0.3	0.7
Dilutive effect of forward sale agreements	0.1	—	—	—
Weighted-average Common Shares Outstanding – Diluted(a)	267.3	263.4	266.9	263.2

(a)There was an immaterial number of anti-dilutive performance share units excluded from the earnings per diluted share calculations for the three and nine months ended September 30, 2024 and 2023. Outstanding forward sale agreements as of September 30, 2024 that were anti-dilutive for the three and nine months ended September 30, 2024 were excluded from the earnings per diluted share calculation as calculated using the treasury stock method. The outstanding forward sale agreements as of September 30, 2023 were anti-dilutive for the three and nine months ended September 30, 2023, and were 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 4 – Long-term Debt and Equity Financings.

Segment Information

9 Months Ended

Sep. 30, 2024

Segment Reporting [Abstract]

SEGMENT INFORMATION

The following tables present revenues, net income attributable to common shareholders, and capital expenditures by segment at Ameren and Ameren Illinois for the three and nine months ended September 30, 2024 and 2023. Ameren, Ameren Missouri, and Ameren Illinois management review segment capital expenditure information rather than any individual or total asset amount. For additional information about our segments, see Note 16 – Segment Information under Part II, Item 8, of the Form 10-K.

Ameren


	Ameren Missouri		Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Transmission			Other		Intersegment Eliminations		Ameren
Three Months 2024:
External revenues	$	1,333	$	551	$	121	$	168		$	—	$	—	$	2,173
Intersegment revenues	9		1		—		42			—		(52)		—
Net income (loss) attributable to Ameren common shareholders	381		56		(10)		90		(a)	(61)		—		456
Capital expenditures	735		152		83		174			2		(9)		1,137
Three Months 2023:
External revenues	$	1,228	$	557	$	121	$	154		$	—	$	—	$	2,060
Intersegment revenues	9		1		1		34			—		(45)		—
Net income (loss) attributable to Ameren common shareholders	411		66		(5)		86		(a)	(65)		—		493
Capital expenditures	341		177		80		160			2		(11)		749
Nine Months 2024:
External revenues	$	2,980	$	1,566	$	660	$	476		$	—	$	—	$	5,682
Intersegment revenues	25		1		—		110			—		(136)		—
Net income (loss) attributable to Ameren common shareholders	534		173		102		241		(a)	(75)		—		975
Capital expenditures	1,839		468		202		515			6		(1)		3,029
Nine Months 2023:
External revenues	$	3,074	$	1,721	$	664	$	423		$	—	$	—	$	5,882
Intersegment revenues	27		1		1		89			—		(118)		—
Net income (loss) attributable to Ameren common shareholders	541		193		93		229		(a)	(62)		—		994
Capital expenditures	1,255		527		221		570			7		(9)		2,571

(a)Ameren Transmission earnings reflect an allocation of financing costs from Ameren (parent).

Ameren Illinois


	Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Illinois Transmission		Intersegment Eliminations		Ameren Illinois
Three Months 2024:
External revenues	$	552	$	121	$	120	$	—	$	793
Intersegment revenues	—		—		35		(35)		—
Net income (loss) available to common shareholder	56		(10)		68		—		114
Capital expenditures	152		83		139		—		374
Three Months 2023:
External revenues	$	558	$	122	$	103	$	—	$	783
Intersegment revenues	—		—		33		(33)		—
Net income (loss) available to common shareholder	66		(5)		64		—		125
Capital expenditures	177		80		125		—		382
Nine Months 2024:
External revenues	$	1,567	$	660	$	332	$	—	$	2,559
Intersegment revenues	—		—		90		(90)		—
Net income available to common shareholder	173		102		178		—		453
Capital expenditures	468		202		421		—		1,091
Nine Months 2023:
External revenues	$	1,722	$	665	$	276	$	—	$	2,663
Intersegment revenues	—		—		87		(87)		—
Net income available to common shareholder	193		93		166		—		452
Capital expenditures	527		221		478		—		1,226

The following tables present disaggregated revenues by segment at Ameren and Ameren Illinois for the three and nine months ended September 30, 2024 and 2023. 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, off-system sales, and capacity revenues.

Ameren


	Ameren Missouri		Ameren Illinois Electric Distribution			Ameren Illinois Natural Gas		Ameren Transmission		Intersegment Eliminations		Ameren
Three Months 2024:
Residential	$	590	$	339		$	—	$	—	$	—	$	929
Commercial	465		184			—		—		—		649
Industrial	108		38			—		—		—		146
Other	161		(9)		(a)	—		210		(51)		311
Total electric revenues	$	1,324	$	552		$	—	$	210	$	(51)	$	2,035
Residential	$	9	$	—		$	77	$	—	$	—	$	86
Commercial	5		—			19		—		—		24
Industrial	—		—			2		—		—		2
Other	4		—			23		—		(1)		26
Total natural gas revenues	$	18	$	—		$	121	$	—	$	(1)	$	138
Total revenues(b)	$	1,342	$	552		$	121	$	210	$	(52)	$	2,173


	Ameren Missouri		Ameren Illinois Electric Distribution			Ameren Illinois Natural Gas		Ameren Transmission		Intersegment Eliminations		Ameren
Three Months 2023:
Residential	$	590	$	330		$	—	$	—	$	—	$	920
Commercial	468		189			—		—		—		657
Industrial	107		40			—		—		—		147
Other	54		(1)		(a)	—		188		(44)		197
Total electric revenues	$	1,219	$	558		$	—	$	188	$	(44)	$	1,921
Residential	$	9	$	—		$	75	$	—	$	—	$	84
Commercial	5		—			19		—		—		24
Industrial	1		—			1		—		—		2
Other	3		—			27		—		(1)		29
Total natural gas revenues	$	18	$	—		$	122	$	—	$	(1)	$	139
Total revenues(b)	$	1,237	$	558		$	122	$	188	$	(45)	$	2,060
Nine Months 2024:
Residential	$	1,326	$	947		$	—	$	—	$	—	$	2,273
Commercial	1,048		512			—		—		—		1,560
Industrial	246		130			—		—		—		376
Other	282		(22)		(a)	—		586		(135)		711
Total electric revenues	$	2,902	$	1,567		$	—	$	586	$	(135)	$	4,920
Residential	$	62	$	—		$	466	$	—	$	—	$	528
Commercial	26		—			111		—		—		137
Industrial	3		—			7		—		—		10
Other	12		—			76		—		(1)		87
Total natural gas revenues	$	103	$	—		$	660	$	—	$	(1)	$	762
Total revenues(b)	$	3,005	$	1,567		$	660	$	586	$	(136)	$	5,682
Nine Months 2023:
Residential	$	1,274	$	1,049		$	—	$	—	$	—	$	2,323
Commercial	1,026		582			—		—		—		1,608
Industrial	243		136			—		—		—		379
Other	435		(45)		(a)	—		512		(116)		786
Total electric revenues	$	2,978	$	1,722		$	—	$	512	$	(116)	$	5,096
Residential	$	74	$	—		$	469	$	—	$	—	$	543
Commercial	34		—			121		—		—		155
Industrial	4		—			10		—		—		14
Other	11		—			65		—		(2)		74
Total natural gas revenues	$	123	$	—		$	665	$	—	$	(2)	$	786
Total revenues(b)	$	3,101	$	1,722		$	665	$	512	$	(118)	$	5,882

(a)Includes over-recoveries of various riders.

(b)The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the three and nine months ended September 30, 2024 and 2023:


	Ameren Missouri			Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Transmission		Ameren
Three Months 2024:
Revenues from alternative revenue programs	$	—		$	(144)	$	(9)	$	(2)	$	(155)
Other revenues not from contracts with customers	2			2		—		—		4
Three Months 2023:
Revenues from alternative revenue programs	$	(9)		$	(94)	$	(1)	$	(5)	$	(109)
Other revenues not from contracts with customers	(1)		(a)	2		—		—		1		(a)
Nine Months 2024:
Revenues from alternative revenue programs	$	(7)		$	(83)	$	10	$	11	$	(69)
Other revenues not from contracts with customers	4			5		2		—		11
Nine Months 2023:
Revenues from alternative revenue programs	$	(11)		$	30	$	36	$	8	$	63
Other revenues not from contracts with customers	(9)		(a)	6		2		—		(1)		(a)

(a)Includes net realized losses on derivative power contracts.

Ameren Illinois


	Ameren Illinois Electric Distribution			Ameren Illinois Natural Gas		Ameren Illinois Transmission		Intersegment Eliminations		Ameren Illinois
Three Months 2024:
Residential	$	339		$	77	$	—	$	—	$	416
Commercial	184			19		—		—		203
Industrial	38			2		—		—		40
Other	(9)		(a)	23		155		(35)		134
Total revenues(b)	$	552		$	121	$	155	$	(35)	$	793
Three Months 2023:
Residential	$	330		$	75	$	—	$	—	$	405
Commercial	189			19		—		—		208
Industrial	40			1		—		—		41
Other	(1)		(a)	27		136		(33)		129
Total revenues(b)	$	558		$	122	$	136	$	(33)	$	783
Nine Months 2024:
Residential	$	947		$	466	$	—	$	—	$	1,413
Commercial	512			111		—		—		623
Industrial	130			7		—		—		137
Other	(22)		(a)	76		422		(90)		386
Total revenues(b)	$	1,567		$	660	$	422	$	(90)	$	2,559
Nine Months 2023:
Residential	$	1,049		$	469	$	—	$	—	$	1,518
Commercial	582			121		—		—		703
Industrial	136			10		—		—		146
Other	(45)		(a)	65		363		(87)		296
Total revenues(b)	$	1,722		$	665	$	363	$	(87)	$	2,663

(a)Includes over-recoveries of various riders.

(b)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 three and nine months ended September 30, 2024 and 2023:


	Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Illinois Transmission		Ameren Illinois
Three Months 2024:
Revenues from alternative revenue programs	$	(144)	$	(9)	$	(1)	$	(154)
Other revenues not from contracts with customers	2		—		—		2
Three Months 2023:
Revenues from alternative revenue programs	$	(94)	$	(1)	$	(6)	$	(101)
Other revenues not from contracts with customers	2		—		—		2
Nine Months 2024:
Revenues from alternative revenue programs	$	(83)	$	10	$	9	$	(64)
Other revenues not from contracts with customers	5		2		—		7
Nine Months 2023:
Revenues from alternative revenue programs	$	30	$	36	$	4	$	70
Other revenues not from contracts with customers	6		2		—		8

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 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

Summary Of Significant Accounting Policies (Policies)	9 Months Ended
Summary Of Significant Accounting Policies (Policies)	Sep. 30, 2024
Accounting Policies [Abstract]
Nature of Operations	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 Illinois Company, doing business as Ameren Illinois, operates rate-regulated electric transmission, electric distribution, and natural gas distribution businesses in Illinois. •ATXI operates a FERC rate-regulated electric transmission business within the MISO.
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 Missouri’s subsidiaries were created for the ownership of renewable generation projects. 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 statement 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 reporting periods. Actual results could differ from those estimates. The results of operations for an interim period may not give a true indication of results that may be expected for a full year. These financial statements should be read in conjunction with the financial statements and accompanying notes included in the Form 10-K.
Consolidation, Variable Interest Entity, Policy	Variable Interest Entities As of September 30, 2024, and December 31, 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 September 30, 2024, Ameren’s maximum exposure to loss related to these variable interests is limited to its investment of $74 million plus associated outstanding funding commitments of $12 million.
Life Insurance, Corporate Or Bank Owned	COLI Ameren 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.
Derivatives, Policy	We use derivatives to manage the risk of changes in market prices for natural gas, power, and uranium, 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 the purchase of these 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. 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. We believe that entering into master netting arrangements or similar agreements mitigates the level of financial loss that could result from default by allowing net settlement of derivative assets and liabilities. These master netting arrangements allow the counterparties to net settle sale and purchase transactions. Further, collateral requirements are calculated at the master netting arrangement or similar agreement level by counterparty.
Lessee, Leases	Leases Ameren and Ameren Missouri primarily lease rail cars and land related to solar generation facilities under operating lease arrangements. The land leases are related to the acquisitions of the Cass County Solar Project and Boomtown Solar Project. 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 Solar Project and Boomtown Solar Project have options to extend or terminate those leases. 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. No termination options have been included in any of the lease measurements used to record the leased assets and liabilities in the tables below.
Deferred Compensation	Deferred Compensation At September 30, 2024, and December 31, 2023, the present value of benefits to be paid for deferred compensation obligations was $81 million and $85 million, respectively, which was primarily reflected in “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet.
Revenue from Contract with Customer	Operating Revenues As of September 30, 2024 and 2023, our remaining performance obligations for contracts with a term greater than one year 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. See Note 14 – Segment Information for disaggregated revenue information.
Excise Taxes	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.

Rate and Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2024

Regulated Operations [Abstract]

Schedule of Generation Facilities

The following table provides information with respect to each agreement: