Consolidated Statement of Income (Loss) and Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating Revenues:
Total operating revenues	$ 1,760	$ 1,726	$ 3,822	$ 3,605
Operating Expenses:
Fuel	152	83	265	259
Purchased Power	328	318	823	495
Natural gas purchased for resale	42	80	250	373
Other operations and maintenance	450	491	898	952
Depreciation and amortization	335	316	655	615
Taxes other than income taxes	124	129	251	271
Total operating expenses	1,431	1,417	3,142	2,965
Operating Income	329	309	680	640
Other Income, Net	82	62	160	122
Interest Charges	134	126	261	230
Income Before Income Taxes	277	245	579	532
Income Taxes	38	36	75	70
Net Income	239	209	504	462
Less: Net Income Attributable to Noncontrolling Interests	2	2	3	3
Net Income Attributable to Ameren Common Shareholders	237	207	501	459
Pension and other postretirement benefit plan activity, net of income taxes (benefit)	(1)	0	(2)	1
Comprehensive Income	238	209	502	463
Less: Comprehensive Income Attributable to Noncontrolling Interests	2	2	3	3
Comprehensive Income Attributable to Ameren Common Shareholders	$ 236	$ 207	$ 499	$ 460
Earnings Per Share, Basic [Abstract]
Earnings per Common Share – Basic	$ 0.90	$ 0.80	$ 1.91	$ 1.78
Earnings Per Share, Diluted [Abstract]
Earnings per Common Share – Diluted	$ 0.90	$ 0.80	$ 1.90	$ 1.77
Weighted-average Common Shares Outstanding – Basic	262.6	258.2	262.4	258.0
Weighted-average Common Shares Outstanding – Diluted	263.2	259.4	263.2	259.2
Electric
Operating Revenues:
Total operating revenues	$ 1,585	$ 1,513	$ 3,175	$ 2,831
Natural gas
Operating Revenues:
Total operating revenues	175	213	647	774
Union Electric Company
Operating Revenues:
Total operating revenues	941	919	1,864	1,737
Operating Expenses:
Fuel	152	83	265	259
Purchased Power	137	161	345	211
Natural gas purchased for resale	9	12	56	58
Other operations and maintenance	237	260	476	492
Depreciation and amortization	186	178	362	342
Taxes other than income taxes	88	90	168	175
Total operating expenses	809	784	1,672	1,537
Operating Income	132	135	192	200
Other Income, Net	22	24	41	47
Interest Charges	52	60	103	99
Income Before Income Taxes	102	99	130	148
Income Taxes	(1)	(2)	(2)	(4)
Net Income	103	101	132	152
Preferred Stock Dividends	1	1	2	2
Net Income Attributable to Parent	102	100	130	150
Union Electric Company | Electric
Operating Revenues:
Total operating revenues	918	890	1,759	1,628
Union Electric Company | Natural gas
Operating Revenues:
Total operating revenues	23	29	105	109
Ameren Illinois Company
Operating Revenues:
Total operating revenues	779	769	1,880	1,793
Operating Expenses:
Purchased Power	192	158	479	289
Natural gas purchased for resale	33	68	194	315
Other operations and maintenance	201	225	403	448
Depreciation and amortization	138	128	271	252
Taxes other than income taxes	32	35	74	88
Total operating expenses	596	614	1,421	1,392
Operating Income	183	155	459	401
Other Income, Net	41	25	78	49
Interest Charges	50	41	97	83
Income Before Income Taxes	174	139	440	367
Income Taxes	44	35	112	94
Net Income	130	104	328	273
Preferred Stock Dividends	1	1	1	1
Net Income Attributable to Parent	129	103	327	272
Ameren Illinois Company | Electric
Operating Revenues:
Total operating revenues	627	585	1,337	1,128
Ameren Illinois Company | Natural gas
Operating Revenues:
Total operating revenues	$ 152	$ 184	$ 543	$ 665