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Stock-Based Incentive Compensation Plans and Employee Benefit Plans - Plan Assets (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Savings Plan [Abstract]      
Number of Common stock held by the savings plan (in shares) 7,335,725    
Percentage of investment in common stocks (in hundredths) 9.00%    
Defined contribution plan cost $ 72 $ 58 $ 58
Postemployment Benefits [Abstract]      
Postemployment Benefits, Period Expense 4 3 1
Benefit expense related to deferred compensation plans 1 3 4
Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 1,212 2,072 2,135
Obligation to return cash received as collateral from securities lending (47) (80)  
Defined benefits plan, fair value of plan assets, excluding investments measured at net asset value $ 708 $ 1,303  
Discount rate (as a percent) 5.15% 2.80%  
Contributions in 2022 $ 35 $ 61  
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]      
2023 134    
2024 138    
2025 137    
2026 134    
2027 134    
2028-2032 608    
Pension Plan | Qualified Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Contributions in 2022 27    
Expected Minimum Contributions in 2023 0    
Pension Plan | Nonqualified Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Contributions in 2022 8    
Expected Minimum Contributions in 2023 7    
Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 109 $ 132 134
Discount rate (as a percent) 5.15% 2.85%  
Contributions in 2022 $ 8 $ 7  
Expected Minimum Contributions in 2023 8    
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]      
2023 15    
2024 17    
2025 18    
2026 19    
2027 20    
2028-2032 106    
Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 199 400  
Obligation to return cash received as collateral from securities lending (47) (80)  
Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 509 903  
Obligation to return cash received as collateral from securities lending 0 0  
Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Obligation to return cash received as collateral from securities lending 0 0  
U.S. equity | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 29 89  
U.S. equity | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 29 89  
U.S. equity | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
U.S. equity | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Cash | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 7 26  
Cash | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 7 26  
Cash | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Cash | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Investment grade or above | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 467 833  
Investment grade or above | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Investment grade or above | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 467 833  
Investment grade or above | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Cash received as collateral from securities lending | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 47 80  
Cash received as collateral from securities lending | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 47 80  
Cash received as collateral from securities lending | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Cash received as collateral from securities lending | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
U.S. treasuries and government agencies | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 163 285  
U.S. treasuries and government agencies | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 163 285  
U.S. treasuries and government agencies | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
U.S. treasuries and government agencies | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Mortgage backed securities | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 6 7  
Mortgage backed securities | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Mortgage backed securities | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 6 7  
Mortgage backed securities | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Asset backed securities | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 2 3  
Asset backed securities | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Asset backed securities | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 2 3  
Asset backed securities | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Municipal bonds | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 24 40  
Municipal bonds | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Municipal bonds | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 24 40  
Municipal bonds | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Mutual funds | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Mutual funds | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 109 $ 133  
Mutual funds | International equities | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 8.00% 8.00%  
Mutual funds | U.S. equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 18.00% 20.00%  
Mutual funds | Fixed income | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 74.00% 72.00%  
Mutual funds | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 0 $ 0  
Mutual funds | Level 1 | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 109 133  
Mutual funds | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Mutual funds | Level 2 | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Mutual funds | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Mutual funds | Level 3 | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
International government bonds | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 10 20  
International government bonds | Level 1 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
International government bonds | Level 2 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 10 20  
International government bonds | Level 3 | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Common Collective Trust Funds | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 504 $ 769  
Common Collective Trust Funds | International equities | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 40.00% 41.00%  
Common Collective Trust Funds | U.S. equity | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 56.00% 58.00%  
Common Collective Trust Funds | Fixed income | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 4.00% 1.00%  
Benefit Obligation      
Postemployment Benefits [Abstract]      
Postemployment benefit obligations $ 9 $ 8  
Other non-qualified plans benefit obligations deferred compensation 28 40  
Benefit obligations related to split-dollar life insurance arrangements $ 22 29  
Minimum | U.S. equity | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 17.00%    
Minimum | U.S. equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 13.00%    
Minimum | International equity | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 9.00%    
Minimum | International equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 3.00%    
Minimum | Real estate | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 2.00%    
Minimum | Fixed income | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 54.00%    
Minimum | Fixed income | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 69.00%    
Minimum | Cash | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 0.00%    
Minimum | Cash | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 0.00%    
Maximum | U.S. equity | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 27.00%    
Maximum | U.S. equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 23.00%    
Maximum | International equity | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 19.00%    
Maximum | International equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 13.00%    
Maximum | Real estate | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 11.00%    
Maximum | Fixed income | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 64.00%    
Maximum | Fixed income | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 79.00%    
Maximum | Cash | Pension Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 2.00%    
Maximum | Cash | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 2.00%    
Common Stock | CenterPoint Energy      
Savings Plan [Abstract]      
Maximum limit of account balance in company stock (as a percent) 25.00%    
Houston Electric      
Savings Plan [Abstract]      
Defined contribution plan cost $ 23 20 18
Postemployment Benefits [Abstract]      
Postemployment Benefits, Period Expense 1 1 1
Benefit expense related to deferred compensation plans 0 0 1
Houston Electric | Pension Plan | Qualified Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Contributions in 2022 0    
Expected Minimum Contributions in 2023 0    
Houston Electric | Pension Plan | Nonqualified Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Contributions in 2022 0    
Expected Minimum Contributions in 2023 0    
Houston Electric | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 84 $ 104 106
Discount rate (as a percent) 5.15% 2.85%  
Contributions in 2022 $ 1 $ 1  
Expected Minimum Contributions in 2023 1    
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]      
2023 6    
2024 7    
2025 8    
2026 9    
2027 9    
2028-2032 49    
Houston Electric | Mutual funds | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 84 $ 105  
Houston Electric | Mutual funds | International equities | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 8.00% 8.00%  
Houston Electric | Mutual funds | U.S. equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 17.00% 19.00%  
Houston Electric | Mutual funds | Fixed income | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 74.00% 73.00%  
Houston Electric | Mutual funds | Level 1 | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 84 $ 105  
Houston Electric | Mutual funds | Level 2 | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Houston Electric | Mutual funds | Level 3 | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
Houston Electric | Benefit Obligation      
Postemployment Benefits [Abstract]      
Postemployment benefit obligations 3 3  
Other non-qualified plans benefit obligations deferred compensation 4 6  
Benefit obligations related to split-dollar life insurance arrangements $ 1 1  
Houston Electric | Minimum | U.S. equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 13.00%    
Houston Electric | Minimum | International equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 3.00%    
Houston Electric | Minimum | Fixed income | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 69.00%    
Houston Electric | Minimum | Cash | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 0.00%    
Houston Electric | Maximum | U.S. equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 23.00%    
Houston Electric | Maximum | International equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 13.00%    
Houston Electric | Maximum | Fixed income | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 79.00%    
Houston Electric | Maximum | Cash | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 2.00%    
CERC Corp      
Savings Plan [Abstract]      
Defined contribution plan cost $ 22 23 25
Postemployment Benefits [Abstract]      
Postemployment Benefits, Period Expense 1 2 0
Benefit expense related to deferred compensation plans 0 0 0
CERC Corp | Pension Plan | Qualified Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Contributions in 2022 0    
Expected Minimum Contributions in 2023 0    
CERC Corp | Pension Plan | Nonqualified Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Contributions in 2022 0    
Expected Minimum Contributions in 2023 0    
CERC Corp | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 25 $ 29 $ 28
Discount rate (as a percent) 5.15% 2.85%  
Contributions in 2022 $ 4 $ 4  
Expected Minimum Contributions in 2023 4    
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]      
2023 6    
2024 6    
2025 6    
2026 7    
2027 7    
2028-2032 35    
CERC Corp | Mutual funds | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 25 $ 28  
CERC Corp | Mutual funds | International equities | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 6.00% 7.00%  
CERC Corp | Mutual funds | U.S. equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 20.00% 22.00%  
CERC Corp | Mutual funds | Fixed income | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, actual allocation (as a percent) 74.00% 71.00%  
CERC Corp | Mutual funds | Level 1 | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value $ 25 $ 28  
CERC Corp | Mutual funds | Level 2 | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
CERC Corp | Mutual funds | Level 3 | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Plan assets, fair value 0 0  
CERC Corp | Benefit Obligation      
Postemployment Benefits [Abstract]      
Postemployment benefit obligations 4 5  
Other non-qualified plans benefit obligations deferred compensation 1 4  
Benefit obligations related to split-dollar life insurance arrangements $ 0 $ 0  
CERC Corp | Minimum | U.S. equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 15.00%    
CERC Corp | Minimum | International equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 2.00%    
CERC Corp | Minimum | Fixed income | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 68.00%    
CERC Corp | Minimum | Cash | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 0.00%    
CERC Corp | Maximum | U.S. equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 25.00%    
CERC Corp | Maximum | International equity | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 12.00%    
CERC Corp | Maximum | Fixed income | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 78.00%    
CERC Corp | Maximum | Cash | Other Postretirement Benefits Plan      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Target allocation (as a percent) 2.00%