Consolidated Statement of Income (Loss) and Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Operating Revenues:
Total operating revenues	$ 1,693	$ 1,760	$ 3,509	$ 3,822
Operating Expenses:
Fuel and purchased power	327	480	655	1,088
Natural gas purchased for resale	33	42	184	250
Other operations and maintenance	465	450	935	898
Depreciation and amortization	376	335	737	655
Taxes other than income taxes	131	124	266	251
Total operating expenses	1,332	1,431	2,777	3,142
Operating Income	361	329	732	680
Other Income, Net	103	82	192	160
Interest Charges	165	134	319	261
Income Before Income Taxes	299	277	605	579
Income Taxes	39	38	83	75
Net Income	260	239	522	504
Less: Net Income Attributable to Noncontrolling Interests	2	2	3	3
Net Income Attributable to Ameren Common Shareholders	258	237	519	501
Pension and other postretirement benefit plan activity, net of income taxes (benefit)	(2)	(1)	(3)	(2)
Comprehensive Income	258	238	519	502
Less: Comprehensive Income Attributable to Noncontrolling Interests	2	2	3	3
Comprehensive Income Attributable to Ameren Common Shareholders	$ 256	$ 236	$ 516	$ 499
Earnings Per Share, Basic [Abstract]
Earnings per Common Share – Basic	$ 0.97	$ 0.90	$ 1.95	$ 1.91
Earnings Per Share, Diluted [Abstract]
Earnings per Common Share – Diluted	$ 0.97	$ 0.90	$ 1.95	$ 1.90
Weighted-average Common Shares Outstanding – Basic	266.7	262.6	266.5	262.4
Weighted-average Common Shares Outstanding – Diluted	266.8	263.2	266.8	263.2
Electric
Operating Revenues:
Total operating revenues	$ 1,521	$ 1,585	$ 2,885	$ 3,175
Natural gas
Operating Revenues:
Total operating revenues	172	175	624	647
Union Electric Company
Operating Revenues:
Total operating revenues	888	941	1,663	1,864
Operating Expenses:
Fuel and purchased power	189	289	355	610
Natural gas purchased for resale	9	9	37	56
Other operations and maintenance	247	237	501	476
Depreciation and amortization	208	186	403	362
Taxes other than income taxes	91	88	178	168
Total operating expenses	744	809	1,474	1,672
Operating Income	144	132	189	192
Other Income, Net	49	22	93	41
Interest Charges	63	52	125	103
Income Before Income Taxes	130	102	157	130
Income Taxes	1	(1)	2	(2)
Net Income	129	103	155	132
Preferred Stock Dividends	1	1	2	2
Net Income Attributable to Parent	128	102	153	130
Union Electric Company | Electric
Operating Revenues:
Total operating revenues	864	918	1,578	1,759
Union Electric Company | Natural gas
Operating Revenues:
Total operating revenues	24	23	85	105
Ameren Illinois Company
Operating Revenues:
Total operating revenues	766	779	1,766	1,880
Operating Expenses:
Purchased Power	141	192	305	479
Natural gas purchased for resale	24	33	147	194
Other operations and maintenance	224	201	434	403
Depreciation and amortization	154	138	307	271
Taxes other than income taxes	35	32	79	74
Total operating expenses	578	596	1,272	1,421
Operating Income	188	183	494	459
Other Income, Net	37	41	68	78
Interest Charges	60	50	115	97
Income Before Income Taxes	165	174	447	440
Income Taxes	40	44	107	112
Net Income	125	130	340	328
Preferred Stock Dividends	1	1	1	1
Net Income Attributable to Parent	124	129	339	327
Ameren Illinois Company | Electric
Operating Revenues:
Total operating revenues	618	627	1,227	1,337
Ameren Illinois Company | Natural gas
Operating Revenues:
Total operating revenues	$ 148	$ 152	$ 539	$ 543