Rate And Regulatory Matters (Narrative-Missouri) (Details) $ in Millions	3 Months Ended					9 Months Ended		12 Months Ended
	Jun. 30, 2024 MWh	Sep. 30, 2023 MWh	Dec. 31, 2022 MWh	Sep. 30, 2022 MWh	Jun. 30, 2022 MWh	Sep. 30, 2024 USD ($) MWh	Sep. 30, 2023 USD ($)	Dec. 31, 2027 USD ($)	Dec. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)	Nov. 30, 2023
Rate And Regulatory Matters [Line Items]
Capital expenditures						$ 3,029	$ 2,571
Union Electric Company
Rate And Regulatory Matters [Line Items]
Cass County, Boomtown, and Huck Finn Solar Project Purchase Price						900
Capital expenditures						1,839	$ 1,255
Union Electric Company | Rush Island Energy Center
Rate And Regulatory Matters [Line Items]
MoPSC Approved Costs to be Securitized						$ 470
Regulatory Asset, Amortization Period											15 years
Union Electric Company | Solar generation facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts | MWh						500
Union Electric Company | Generation Facilities
Rate And Regulatory Matters [Line Items]
Capital expenditures						$ 1,700
Union Electric Company | Electric | Pending Rate Case
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount						$ 446
Public Utilities, Requested Return on Equity, Percentage						10.25%
Public Utilities, Requested Equity Capital Structure, Percentage						52.00%
Rate Base						$ 14,000
Months to complete a rate proceeding						11 months
Union Electric Company | Electric | MEEIA 2024 | Forecast
Rate And Regulatory Matters [Line Items]
Energy efficiency investments in MEEIA 2019 programs								$ 22	$ 51	$ 51
Percentage of MEEIA Energy Efficiency Goals Achieved										100.00%
Incentive award if energy efficiency goals are exceeded								$ 2	$ 5	$ 5
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 | Self-build | Natural Gas Generation Facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts | MWh	800
Union Electric Company | Natural gas | Pending Rate Case
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount						$ 40
Public Utilities, Requested Return on Equity, Percentage						10.25%
Public Utilities, Requested Equity Capital Structure, Percentage						52.00%
Rate Base						$ 531
Months to complete a rate proceeding						11 months