Rate And Regulatory Matters (Narrative-Missouri) (Details) $ in Millions	1 Months Ended			2 Months Ended	3 Months Ended				6 Months Ended
	Jul. 31, 2026 MWh	Jun. 30, 2026 MWh	May 31, 2026 MWh	Jun. 30, 2026 MWh	Sep. 30, 2025 MWh	Jun. 30, 2025 MWh	Sep. 30, 2024 MWh	Dec. 31, 2023 MWh	Jun. 30, 2026 USD ($) MWh	Jun. 30, 2025 USD ($)
Rate And Regulatory Matters [Line Items]
Capital expenditures \| $									$ 2,653	$ 2,130
Union Electric Company
Rate And Regulatory Matters [Line Items]
Capital expenditures \| $									1,771	$ 1,325
Union Electric Company \| Generation Facilities
Rate And Regulatory Matters [Line Items]
Capital expenditures \| $									3,600
Union Electric Company \| Split Rail Solar Project
Rate And Regulatory Matters [Line Items]
Capital expenditures \| $									600
Union Electric Company \| Self-build \| Solar generation facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts \| MWh					250			50
Union Electric Company \| Self-build \| Natural Gas Generation Facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts \| MWh						800	800
Union Electric Company \| Self-build \| Natural Gas Generation Facility \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Amount of Megawatts \| MWh	2,100
Union Electric Company \| Self-build \| Energy Storage Facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts \| MWh		200	250	95		400
Union Electric Company \| Build-transfer \| Solar generation facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts \| MWh		225	175					300
Union Electric Company \| Electric \| Pending Rate Case
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount \| $									$ 343
Public Utilities, Requested Return on Equity, Percentage									10.25%
Public Utilities, Requested Equity Capital Structure, Percentage									52.00%
Requested rate base \| $									$ 16,700
Amount of Megawatts \| MWh									400
Months to complete a rate proceeding									11 months