v3.26.1
Callaway Energy Center (Insurance Disclosure) (Details)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
Jun. 30, 2026
USD ($)
yr
Nuclear Waste Matters [Line Items]    
Frequency of Decommissioning Cost Study   3 years
Number Of Years The Limit Of Liability And The Maximum Potential Annual Payments Are Adjusted   5 years
Number Of Weeks Of Coverage After The First Twelve Weeks Of An Outage | yr   1
Number Of Additional Weeks After Initial Indemnity Coverage For Power Outage | yr   1.365
Union Electric Company    
Nuclear Waste Matters [Line Items]    
Future Decommissioning Cost $ 0.0  
Public Liability And Nuclear Worker Liability - American Nuclear Insurers | Union Electric Company    
Nuclear Waste Matters [Line Items]    
Insurance Aggregate Maximum Coverage 500.0 $ 500.0
Insurance Maximum Coverage per Incident 0.0 0.0
Public Liability And Nuclear Worker Liability - Pool Participation | Union Electric Company    
Nuclear Waste Matters [Line Items]    
Insurance Aggregate Maximum Coverage 15,763.0 15,763.0
Insurance Maximum Coverage per Incident 166.0 166.0
Threshold Amount For Retrospective Insurance Assessment For Covered Loss Under Public Liability And Nuclear Worker Liability Insurance Policy   500.0
Maximum Annual Payment Per Incident At Licensed Commercial Nuclear Reactor   25.0
Public Liability | Union Electric Company    
Nuclear Waste Matters [Line Items]    
Insurance Aggregate Maximum Coverage 16,263.0 16,263.0
Insurance Maximum Coverage per Incident 166.0 166.0
Property Damage - Nuclear Electric Insurance Ltd | Union Electric Company    
Nuclear Waste Matters [Line Items]    
Insurance Aggregate Maximum Coverage 3,200.0 3,200.0
Insurance Maximum Coverage per Incident 23.0 23.0
Accidental Outage - Nuclear Electric Insurance Ltd | Union Electric Company    
Nuclear Waste Matters [Line Items]    
Insurance Aggregate Maximum Coverage 490.0 490.0
Insurance Maximum Coverage per Incident 9.0 9.0
Amount Of Weekly Indemnity Coverage Commencing Twelve Weeks After Power Outage   4.5
Amount Of Additional Weekly Indemnity Coverage Commencing After Initial Indemnity Coverage   3.6
Amount Of Weekly Indemnity Coverage Thereafter Not Exceeding Policy Limit   490.0
Sub-Limit Of Amount Of Weekly Indemnity Coverage Thereafter Not Exceeding Policy Limit For Non-Nuclear Events   291.0
Radiation Event | Union Electric Company    
Nuclear Waste Matters [Line Items]    
Insurance Aggregate Maximum Coverage 2,700.0 2,700.0
Aggregate Nuclear Power Industry Insurance Policy Limit For Losses From Terrorist Attacks Within Twelve Month Period   3,200.0
Non-Radiation Event    
Nuclear Waste Matters [Line Items]    
Insurance Aggregate Maximum Coverage 700.0 700.0
Non-Radiation Event | Union Electric Company    
Nuclear Waste Matters [Line Items]    
Aggregate Nuclear Power Industry Insurance Policy Limit For Losses From Terrorist Attacks Within Twelve Month Period   1,800.0
Property Damage European Mutual Association for Nuclear Insurance | Union Electric Company    
Nuclear Waste Matters [Line Items]    
Insurance Aggregate Maximum Coverage $ 490.0 $ 490.0