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Employee Benefit Plans (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Pension plans    
Defined Benefit Plan Disclosure [Line Items]    
Service cost $ 6 $ 6
Interest cost 20 19
Expected return on plan assets (20) (19)
Amortization of net loss 7 7
Net periodic cost (benefit) 13 13
Total contributions expected in current year 112  
Total contributions to the plans during the period 63  
Pension plans | Houston Electric    
Defined Benefit Plan Disclosure [Line Items]    
Total contributions expected in current year 0  
Total contributions to the plans during the period 0  
Pension plans | CERC    
Defined Benefit Plan Disclosure [Line Items]    
Total contributions expected in current year 0  
Total contributions to the plans during the period 0  
Postretirement benefit plans    
Defined Benefit Plan Disclosure [Line Items]    
Interest cost 3 3
Expected return on plan assets (1) (1)
Amortization of prior service cost (credit) (1) (1)
Amortization of net loss (2) (2)
Net periodic cost (benefit) (1) (1)
Total contributions expected in current year 9  
Total contributions to the plans during the period 3  
Postretirement benefit plans | Houston Electric    
Defined Benefit Plan Disclosure [Line Items]    
Interest cost 1 1
Expected return on plan assets (1) (1)
Amortization of prior service cost (credit) (1) (1)
Amortization of net loss (1) (1)
Net periodic cost (benefit) (2) (2)
Total contributions expected in current year 1  
Total contributions to the plans during the period 0  
Postretirement benefit plans | CERC    
Defined Benefit Plan Disclosure [Line Items]    
Interest cost 1 1
Expected return on plan assets 0 0
Amortization of prior service cost (credit) 1 1
Amortization of net loss (1) (1)
Net periodic cost (benefit) 1 $ 1
Total contributions expected in current year 5  
Total contributions to the plans during the period $ 2