Callaway Energy Center (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Accidental Outage - Nuclear Electric Insurance Ltd
Nuclear Waste Matters [Line Items]
Amount of Weekly Indemnity Coverage Commencing Twelve Weeks After Power Outage	$ 4.5
Union Electric Company
Nuclear Waste Matters [Line Items]
Frequency of Decommissioning Cost Study	3 years
Union Electric Company | Minimum | Nuclear Decommissioning Trust Fund
Nuclear Waste Matters [Line Items]
Trust Fund Investments, Target Allocation Percentage	60.00%
Union Electric Company | Maximum | Nuclear Decommissioning Trust Fund
Nuclear Waste Matters [Line Items]
Trust Fund Investments, Target Allocation Percentage	70.00%
Union Electric Company | Nuclear Plant
Nuclear Waste Matters [Line Items]
Estimated Nuclear Generator Repairs	$ 60.0
Annual decommissioning costs included in costs of service	$ 7.0