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Unconsolidated Affiliate (CenterPoint Energy and CERC) - Narrative (Details) - USD ($)
$ / shares in Units, $ in Millions
6 Months Ended
Jun. 30, 2021
Feb. 16, 2021
Schedule of Equity Method Investments [Line Items]    
Merger exchange ratio (share per common unit)   0.8595
Proceeds from merger - interest   $ 5
Aggregate liquidation preference   385
Percentage of sales that trigger right of first refusal 5.00%  
OGE    
Schedule of Equity Method Investments [Line Items]    
Payment upon termination of partnership   $ 30
Percentage of sales that trigger right of first refusal 5.00%  
Enable Midstream Partners    
Schedule of Equity Method Investments [Line Items]    
Share price (in dollars per share) $ 9.11  
Enable Midstream Partners    
Schedule of Equity Method Investments [Line Items]    
Ownership percentage of equity method investment 100.00%  
Enable Midstream Partners | CenterPoint Energy and OGE    
Schedule of Equity Method Investments [Line Items]    
Ownership percentage of equity method investment 79.20%  
Enable Midstream Partners | OGE    
Schedule of Equity Method Investments [Line Items]    
Ownership percentage of equity method investment 25.50%