Property And Plant, Net (Schedule Of Property And Plant, Net) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) equipment	Dec. 31, 2021 USD ($)
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	$ 43,839	$ 41,602
Accumulated depreciation and amortization	14,465	14,214
Property and plant, before construction work in progress	29,374	27,388
Property, plant, and equipment, net	$ 31,262	29,261
Number of combustion turbine electric generation equipment with related financing obligations | equipment	2
Gross asset value, financing obligations	$ 125	243
Total accumulated depreciation, financing obligations	54	105
Coal Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	3,454	3,955
Plant To Be Abandoned, Net	582	604
Natural Gas and Oil Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	961	1,105
Nuclear Powered Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	5,725	5,615
Renewable Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	1,968	1,889
Electric distribution
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	15,344	14,303
Electric transmission
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	8,316	7,533
Natural gas
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	4,523	4,193
Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	3,548	3,009
Construction work in progress:	1,198	1,136
Nuclear fuel in process
Property, Plant and Equipment [Line Items]
Construction work in progress:	108	133
Oil Fired Electric Generation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	29	29
Union Electric Company
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	24,518	23,669
Accumulated depreciation and amortization	9,682	9,784
Property and plant, before construction work in progress	14,836	13,885
Property, plant, and equipment, net	16,124	15,296
Union Electric Company | Coal Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	3,454	3,955
Plant To Be Abandoned, Net	582	604
Union Electric Company | Natural Gas and Oil Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	961	1,105
Union Electric Company | Nuclear Powered Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	5,725	5,615
Union Electric Company | Renewable Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	1,957	1,889
Union Electric Company | Electric distribution
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	7,993	7,286
Union Electric Company | Electric transmission
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	1,884	1,628
Union Electric Company | Natural gas
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	640	607
Union Electric Company | Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	1,904	1,584
Construction work in progress:	598	674
Union Electric Company | Nuclear fuel in process
Property, Plant and Equipment [Line Items]
Construction work in progress:	108	133
Ameren Illinois Company
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	17,257	15,891
Accumulated depreciation and amortization	4,418	4,100
Property and plant, before construction work in progress	12,839	11,791
Property, plant, and equipment, net	13,353	12,223
Ameren Illinois Company | Coal Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Plant To Be Abandoned, Net	0	0
Ameren Illinois Company | Natural Gas and Oil Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Ameren Illinois Company | Nuclear Powered Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Ameren Illinois Company | Renewable Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	11	0
Ameren Illinois Company | Electric distribution
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	7,351	7,017
Ameren Illinois Company | Electric transmission
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	4,617	4,105
Ameren Illinois Company | Natural gas
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	3,883	3,586
Ameren Illinois Company | Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	1,395	1,183
Construction work in progress:	514	432
Ameren Illinois Company | Nuclear fuel in process
Property, Plant and Equipment [Line Items]
Construction work in progress:	0	0
Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	2,064	2,042
Accumulated depreciation and amortization	365	330
Property and plant, before construction work in progress	1,699	1,712
Property, plant, and equipment, net	1,785	1,742
Other | Coal Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Plant To Be Abandoned, Net	0	0
Other | Natural Gas and Oil Fired Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Nuclear Powered Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Renewable Electric Generation Equipment
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Electric distribution
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Electric transmission
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	1,815	1,800
Other | Natural gas
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	0	0
Other | Other
Property, Plant and Equipment [Line Items]
Property and plant, at original cost	249	242
Construction work in progress:	86	30
Other | Nuclear fuel in process
Property, Plant and Equipment [Line Items]
Construction work in progress:	$ 0	$ 0
Minimum | Electric distribution
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Minimum | Electric transmission
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	50 years
Minimum | Natural gas
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Minimum | Other
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Minimum | Electric generation
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Maximum | Electric distribution
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	80 years
Maximum | Electric transmission
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	75 years
Maximum | Natural gas
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	80 years
Maximum | Other
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	55 years
Maximum | Electric generation
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	72 years
Maximum | Union Electric Company | Electric generation
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	150 years