Rate And Regulatory Matters (Narrative-Missouri) (Details) $ in Millions	3 Months Ended					9 Months Ended
	Sep. 30, 2023 USD ($)	Jun. 30, 2023 MWh	Sep. 30, 2022 USD ($) MWh	Jun. 30, 2022 MWh	Mar. 31, 2022 MWh	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Rate And Regulatory Matters [Line Items]
Depreciation and amortization	$ 369		$ 350			$ 1,024	$ 965
Other Income, Net	101		58			261	180
Capital expenditures						2,571	2,437
Revenues	2,060		2,306			5,882	5,911
Union Electric Company
Rate And Regulatory Matters [Line Items]
Depreciation and amortization	217		208			579	550
Other Income, Net	$ 44		$ 25			85	72
Capital expenditures						1,255	$ 1,237
Union Electric Company | Solar generation facility
Rate And Regulatory Matters [Line Items]
Capital expenditures						650
Union Electric Company | Electric | Final Rate Order
Rate And Regulatory Matters [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount						140
Reduction to annualized base level of net energy costs						40
Depreciation and amortization						90
Other Income, Net						100
Union Electric Company | Electric | MEEIA 2019 [Domain]
Rate And Regulatory Matters [Line Items]
Revenues						12
Energy efficiency investments in MEEIA 2019 programs						$ 76
Union Electric Company | Build-transfer | Solar generation facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts | MWh		300		200	150
Union Electric Company | Development-transfer | Solar generation facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts | MWh		150
Union Electric Company | Self-build | Solar generation facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts | MWh		50	50
Union Electric Company | Maximum
Rate And Regulatory Matters [Line Items]
Percentage of energy sourced from renewable resources		100.00%