v3.25.3
Short-term Borrowings and Long-term Debt - Schedule of Utilization of Credit Facilities (Details) - USD ($)
$ in Millions
9 Months Ended
Sep. 30, 2025
Dec. 31, 2024
Debt Instrument [Line Items]    
Number of days until commercial paper maturity (in days) 60 days  
CERC    
Debt Instrument [Line Items]    
Number of days until commercial paper maturity (in days) 30 days  
Loans    
Debt Instrument [Line Items]    
Long-term line of credit $ 0 $ 0
Loans | SIGECO    
Debt Instrument [Line Items]    
Long-term line of credit 0 0
Loans | Houston Electric    
Debt Instrument [Line Items]    
Long-term line of credit 0 0
Loans | CERC    
Debt Instrument [Line Items]    
Long-term line of credit 0 0
Letters of Credit    
Debt Instrument [Line Items]    
Long-term line of credit 0 0
Letters of Credit | SIGECO    
Debt Instrument [Line Items]    
Long-term line of credit 0 0
Letters of Credit | Houston Electric    
Debt Instrument [Line Items]    
Long-term line of credit 0 0
Letters of Credit | CERC    
Debt Instrument [Line Items]    
Long-term line of credit 0 0
Commercial Paper    
Debt Instrument [Line Items]    
Long-term line of credit 575 981
Long-term debt, current maturities 280  
Commercial Paper | SIGECO    
Debt Instrument [Line Items]    
Long-term line of credit $ 0 $ 0
Weighted Average Interest Rate 0.00% 0.00%
Commercial Paper | Houston Electric    
Debt Instrument [Line Items]    
Long-term line of credit $ 0 $ 0
Weighted Average Interest Rate 0.00% 0.00%
Commercial Paper | CERC    
Debt Instrument [Line Items]    
Long-term line of credit $ 550 $ 599
Weighted Average Interest Rate 4.19% 4.62%
Parent Company | Loans    
Debt Instrument [Line Items]    
Long-term line of credit $ 0 $ 0
Parent Company | Letters of Credit    
Debt Instrument [Line Items]    
Long-term line of credit 0 0
Parent Company | Commercial Paper    
Debt Instrument [Line Items]    
Long-term line of credit $ 25 $ 382
Weighted Average Interest Rate 4.19% 4.59%