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Short-term Borrowings and Long-term Debt - Narrative (Details) - USD ($)
$ in Millions
1 Months Ended 12 Months Ended
Apr. 30, 2023
Dec. 31, 2023
Mar. 31, 2023
Dec. 31, 2022
Letters of Credit        
Debt Instrument [Line Items]        
Long-term line of credit     $ 12.0 $ 11.0
CERC        
Debt Instrument [Line Items]        
Aggregate Principal Amount     1,700.0  
CERC | Letters of Credit        
Debt Instrument [Line Items]        
Long-term line of credit     1.0 0.0
Houston Electric | Letters of Credit        
Debt Instrument [Line Items]        
Long-term line of credit     0.0 0.0
Houston Electric | General Mortgage Bonds        
Debt Instrument [Line Items]        
Aggregate Principal Amount     900.0  
Secured debt     7,100.0  
General mortgage bonds used as collateral     $ 68.0  
Percentage of property additions (as a percent)     70.00%  
Additional first mortgage bonds and general mortgage bonds that could be issued     $ 4,400.0  
SIGECO | Letters of Credit        
Debt Instrument [Line Items]        
Long-term line of credit     0.0 0.0
SIGECO | First Mortgage Bonds        
Debt Instrument [Line Items]        
Secured debt     $ 457.0  
Percentage of property additions (as a percent)     70.00%  
Additional first mortgage bonds and general mortgage bonds that could be issued     $ 1,200.0  
SIGECO | Forecast        
Debt Instrument [Line Items]        
Additional proceeds ​from Issuance​ of ​secured​ tax​ exempt ​debt   $ 38.0    
SIGECO | Subsequent Event        
Debt Instrument [Line Items]        
Proceeds from issuance of secured tax exempt debt $ 148.0      
Vectren | Letters of Credit        
Debt Instrument [Line Items]        
Long-term line of credit     0.2  
Vectren | Maximum | Letters of Credit        
Debt Instrument [Line Items]        
Long-term line of credit     5.0  
Third Party AMAs        
Debt Instrument [Line Items]        
Inventory financings     0.0 11.0
Third Party AMAs | CERC        
Debt Instrument [Line Items]        
Inventory financings     $ 0.0 $ 11.0
Environmental Improvement Revenue Bonds, Series 2013 | SIGECO | Subsequent Event        
Debt Instrument [Line Items]        
Aggregate Principal Amount 107.0      
Environmental Improvement Revenue Bonds, Series 2014 | SIGECO | Subsequent Event        
Debt Instrument [Line Items]        
Aggregate Principal Amount $ 41.0