Short-term Borrowings and Long-term Debt - Schedule of Utilization of Credit Facilities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
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	0	979
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	$ 0	$ 559
Weighted Average Interest Rate	0.00%	3.86%
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	$ 0	$ 420
Weighted Average Interest Rate	0.00%	3.78%