v3.25.3
Short-term Borrowings and Long-term Debt - Schedule of Revolving Credit Facilities (Details)
$ in Millions
 9 Months Ended
Sep. 30, 2025
USD ($)
Debt Instrument [Line Items]  
Size of Facility $ 4,000
SIGECO  
Debt Instrument [Line Items]  
Size of Facility 250
Houston Electric  
Debt Instrument [Line Items]  
Size of Facility 300
CERC  
Debt Instrument [Line Items]  
Size of Facility $ 1,050
Line of Credit | SIGECO  
Debt Instrument [Line Items]  
Basis spread on variable rate (as a percent) 1.125%
Ratio of indebtedness to net capital (as a percent) 0.650
Percentage on limitation of debt to total capitalization under covenant (as a percent) 44.90%
Line of Credit | Houston Electric  
Debt Instrument [Line Items]  
Basis spread on variable rate (as a percent) 1.25%
Ratio of indebtedness to net capital (as a percent) 0.675
Percentage on limitation of debt to total capitalization under covenant (as a percent) 55.10%
Line of Credit | CERC  
Debt Instrument [Line Items]  
Basis spread on variable rate (as a percent) 1.125%
Ratio of indebtedness to net capital (as a percent) 0.650
Percentage on limitation of debt to total capitalization under covenant (as a percent) 39.80%
Parent Company  
Debt Instrument [Line Items]  
Size of Facility $ 2,400
Parent Company | Line of Credit  
Debt Instrument [Line Items]  
Basis spread on variable rate (as a percent) 1.50%
Ratio of indebtedness to net capital (as a percent) 0.650
Percentage on limitation of debt to total capitalization under covenant (as a percent) 59.80%
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths) (as a percent) 70.00%
Restoration cost expected cost $ 100
Consecutive period for system restoration costs to exceed $100 million (in months) 12 months