v3.25.3
Fair Value Measurements - Schedule of Estimated Fair Value of Financial Instruments (Details) - USD ($)
$ in Millions
Sep. 30, 2025
Dec. 31, 2024
Carrying amount    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt, fair value $ 22,303 $ 20,961
Carrying amount | Houston Electric    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt, fair value 10,311 8,822
Carrying amount | CERC    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt, fair value 4,707 5,184
Fair value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt, fair value 21,667 19,597
Fair value | Houston Electric    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt, fair value 9,516 7,746
Fair value | CERC    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt, fair value $ 4,704 $ 5,032