Stock-Based Incentive Compensation Plans and Employee Benefit Plans Plan Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Savings Plan [Abstract]
Maximum percentage of eligible compensation employees may contribute to the savings plan (in hundredths)		50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		6.00%
Defined Contribution Plan, Cost		$ 43		$ 41		$ 38
Postemployment Benefits [Abstract]
Postemployment Benefits, Period Expense		3		6		5
Other Non-Qualified Plans [Abstract]
Benefit expense related to deferred compensation plans		3		$ 3		$ 3
Non-qualified Pension Plan [Member]
Total contributions to the plans during the period		9
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		$ 7
Pension Plan [Member]
Discount Rate		4.35%	[1]	3.65%	[1]	4.15%
Plan assets, fair value		$ 1,516		$ 1,801		$ 1,656
Defined Benefits Plan, Fair Value Of Plan Assets, Excluding Investments Measured at Net Asset Value		860		877
Obligation To Return Cash Received As Collateral From Securities Lending,		(77)		(76)
Defined Benefit Plan, Contribution by Employer, Qualified Plan		60
Total contributions to the plans during the period		69		$ 48
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		86
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2019		141
Pension benefit payments 2020		146
Pension benefit payments 2021		154
Pension benefit payments 2022		155
Pension benefit payments 2023		156
Pension benefit payments 2024 - 2028		$ 759
Other Non-Qualified Plans [Abstract]
Annualized individual discount rates based on time period, minimum		6 months
Annualized individual discount rates based on time period, maximum		99 years
Postretirement Benefits [Member]
Discount Rate	[2]	4.35%		3.60%
Plan assets, fair value		$ 114		$ 120		113
Total contributions to the plans during the period		14		16
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		17
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2019		16
Pension benefit payments 2020		19
Pension benefit payments 2021		20
Pension benefit payments 2022		21
Pension benefit payments 2023		22
Pension benefit payments 2024 - 2028		$ 116
Other Non-Qualified Plans [Abstract]
Annualized individual discount rates based on time period, minimum		6 months
Annualized individual discount rates based on time period, maximum		99 years
Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		$ 442		372
Obligation To Return Cash Received As Collateral From Securities Lending,		(77)		(76)
Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		418		505
Obligation To Return Cash Received As Collateral From Securities Lending,		0		0
Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Obligation To Return Cash Received As Collateral From Securities Lending,		0		0
U.S. Equity [Member] | Pension Plan [Member]
Plan assets, fair value		60		76
U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		60		76
U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Cash and Cash Equivalents [Member] | Pension Plan [Member]
Plan assets, fair value		19		18
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		19		18
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Common Collective Trust Funds [Member] | Pension Plan [Member]
Plan assets, fair value	[3],[4]	$ 656		$ 924
Common Collective Trust Funds [Member] | International Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		37.00%		34.00%
Common Collective Trust Funds [Member] | Fixed Income Funds [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		54.00%		55.00%
Common Collective Trust Funds [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		5.00%		6.00%
Common Collective Trust Funds [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		4.00%		5.00%
Investment grade or above [Member] | Pension Plan [Member]
Plan assets, fair value		$ 368		$ 432
Investment grade or above [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Investment grade or above [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		368		432
Investment grade or above [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Cash received as collateral from securities [Member] | Pension Plan [Member]
Plan assets, fair value		77		76
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		77		76
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
U.S. treasuries [Member] | Pension Plan [Member]
Plan assets, fair value		196		67
U.S. treasuries [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		196		67
U.S. treasuries [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
U.S. treasuries [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mortgage backed securities [Member] | Pension Plan [Member]
Plan assets, fair value		6		8
Mortgage backed securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mortgage backed securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		6		8
Mortgage backed securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Asset backed securities [Member] | Pension Plan [Member]
Plan assets, fair value		1		1
Asset backed securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Asset backed securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		1		1
Asset backed securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Municipal bonds [Member] | Pension Plan [Member]
Plan assets, fair value		27		47
Municipal bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Municipal bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		27		47
Municipal bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mutual funds [Member] | Pension Plan [Member]
Plan assets, fair value		167		211
Mutual funds [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 114		$ 120
Mutual funds [Member] | International Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		51.00%		57.00%
Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		7.00%		8.00%
Mutual funds [Member] | Fixed Income Funds [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		0.00%		0.00%
Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		74.00%		74.00%
Mutual funds [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		15.00%		13.00%
Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		19.00%		18.00%
Mutual funds [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		34.00%		30.00%
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		$ 167		$ 211
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		114		120
Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
International government bonds [Member] | Pension Plan [Member]
Plan assets, fair value		16		17
International government bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
International government bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		16		17
International government bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Benefit Obligation [Member]
Postemployment Benefits [Abstract]
Postemployment benefit obligations		11		20
Other Non-Qualified Plans [Abstract]
Other non-qualified plans benefit obligations deferred compensation		42		45
Benefit obligations related to split-dollar life insurance arrangements		$ 36		39
Minimum [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		12.00%
Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%
Minimum [Member] | International Developed Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		7.00%
Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		3.00%
Minimum [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		5.00%
Minimum [Member] | Fixed Income [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		55.00%
Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		69.00%
Minimum [Member] | Cash and Cash Equivalents [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%
Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%
Maximum [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		28.00%
Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		23.00%
Maximum [Member] | International Developed Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		17.00%
Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%
Maximum [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		11.00%
Maximum [Member] | Fixed Income [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		65.00%
Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		79.00%
Maximum [Member] | Cash and Cash Equivalents [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
Common Stock [Member] | CenterPoint Energy [Member]
Savings Plan [Abstract]
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage		25.00%
Number of Common stock held by the savings plan (in shares)		12,062,915
Percentage of investment in common stocks (in hundredths)		16.00%
Houston Electric [Member]
Savings Plan [Abstract]
Maximum percentage of eligible compensation employees may contribute to the savings plan (in hundredths)		50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		6.00%
Defined Contribution Plan, Cost		$ 17		17		15
Postemployment Benefits [Abstract]
Postemployment Benefits, Period Expense		4		1		3
Other Non-Qualified Plans [Abstract]
Benefit expense related to deferred compensation plans		1		$ 1		1
Houston Electric [Member] | Non-qualified Pension Plan [Member]
Total contributions to the plans during the period		0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		0
Houston Electric [Member] | Pension Plan [Member]
Defined Benefit Plan, Contribution by Employer, Qualified Plan		0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		$ 0
Houston Electric [Member] | Postretirement Benefits [Member]
Discount Rate	[2]	4.35%		3.60%
Plan assets, fair value		$ 89		$ 93		88
Total contributions to the plans during the period		9		10
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		10
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2019		9
Pension benefit payments 2020		10
Pension benefit payments 2021		11
Pension benefit payments 2022		11
Pension benefit payments 2023		12
Pension benefit payments 2024 - 2028		$ 61
Other Non-Qualified Plans [Abstract]
Annualized individual discount rates based on time period, minimum		6 months
Annualized individual discount rates based on time period, maximum		99 years
Houston Electric [Member] | Mutual funds [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 89		$ 93
Houston Electric [Member] | Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		7.00%		8.00%
Houston Electric [Member] | Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		74.00%		74.00%
Houston Electric [Member] | Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		19.00%		18.00%
Houston Electric [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 89		$ 93
Houston Electric [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
Houston Electric [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
Houston Electric [Member] | Benefit Obligation [Member]
Postemployment Benefits [Abstract]
Postemployment benefit obligations		3		3
Other Non-Qualified Plans [Abstract]
Other non-qualified plans benefit obligations deferred compensation		9		10
Benefit obligations related to split-dollar life insurance arrangements		$ 1		1
Houston Electric [Member] | Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%
Houston Electric [Member] | Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		3.00%
Houston Electric [Member] | Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		69.00%
Houston Electric [Member] | Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%
Houston Electric [Member] | Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		23.00%
Houston Electric [Member] | Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%
Houston Electric [Member] | Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		79.00%
Houston Electric [Member] | Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
Houston Electric [Member] | Common Stock [Member] | CenterPoint Energy [Member]
Savings Plan [Abstract]
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage		25.00%
Number of Common stock held by the savings plan (in shares)		12,062,915
Percentage of investment in common stocks (in hundredths)		16.00%
CERC Corp [Member]
Savings Plan [Abstract]
Maximum percentage of eligible compensation employees may contribute to the savings plan (in hundredths)		50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		6.00%
Defined Contribution Plan, Cost		$ 18		17		16
Postemployment Benefits [Abstract]
Postemployment Benefits, Period Expense		1		4		3
Other Non-Qualified Plans [Abstract]
Benefit expense related to deferred compensation plans		0		$ 0		0
CERC Corp [Member] | Non-qualified Pension Plan [Member]
Total contributions to the plans during the period		0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		0
CERC Corp [Member] | Pension Plan [Member]
Defined Benefit Plan, Contribution by Employer, Qualified Plan		0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		$ 0
CERC Corp [Member] | Postretirement Benefits [Member]
Discount Rate	[2]	4.35%		3.60%
Plan assets, fair value		$ 25		$ 26		$ 25
Total contributions to the plans during the period		4		5
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		4
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2019		5
Pension benefit payments 2020		6
Pension benefit payments 2021		6
Pension benefit payments 2022		7
Pension benefit payments 2023		7
Pension benefit payments 2024 - 2028		$ 37
Other Non-Qualified Plans [Abstract]
Annualized individual discount rates based on time period, minimum		6 months
Annualized individual discount rates based on time period, maximum		99 years
CERC Corp [Member] | Mutual funds [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 25		$ 26
CERC Corp [Member] | Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		6.00%		8.00%
CERC Corp [Member] | Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		73.00%		71.00%
CERC Corp [Member] | Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		21.00%		21.00%
CERC Corp [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 25		$ 26
CERC Corp [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
CERC Corp [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
CERC Corp [Member] | Benefit Obligation [Member]
Postemployment Benefits [Abstract]
Postemployment benefit obligations		7		14
Other Non-Qualified Plans [Abstract]
Other non-qualified plans benefit obligations deferred compensation		3		3
Benefit obligations related to split-dollar life insurance arrangements		$ 0		$ 0
CERC Corp [Member] | Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		15.00%
CERC Corp [Member] | Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
CERC Corp [Member] | Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		68.00%
CERC Corp [Member] | Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%
CERC Corp [Member] | Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		25.00%
CERC Corp [Member] | Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		12.00%
CERC Corp [Member] | Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		78.00%
CERC Corp [Member] | Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
CERC Corp [Member] | Common Stock [Member] | CenterPoint Energy [Member]
Savings Plan [Abstract]
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage		25.00%
Number of Common stock held by the savings plan (in shares)		12,062,915
Percentage of investment in common stocks (in hundredths)		16.00%

[1] The discount rate assumption was determined by matching the projected cash flows of CenterPoint Energy’s plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years.

[2] The discount rate assumption was determined by matching the projected cash flows of the plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years.

[3] Represents investments in common collective trust funds.

[4] The amounts invested in mutual funds and common collective trust funds were allocated as follows: As of December 31, 2018 2017 Mutual Funds Common Collective Trust Funds Mutual Funds Common Collective Trust FundsInternational equities51% 37% 57% 34%Emerging market equities34% 4% 30% 5%U.S. equities15% 5% 13% 6%Fixed income— 54% — 55%