Regulatory Matters Regulatory Assets and Regulatory Liabilities (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Schedule of Regulatory Assets and Liabilities [Line Items]
Securitized regulatory assets		$ 788		$ 1,059
Unrecognized equity return (2)	[1]	(168)		(213)
Unamortized loss on reacquired debt (3)	[2]	62		68
Non-current regulatory assets		2,117		1,967
Total regulatory assets		2,129		2,044
Non-current regulatory liabilities		3,474		2,525
Total regulatory liabilities		3,521		2,563
Total regulatory assets and liabilities, net		(1,392)		(519)
Amount of allowed equity return on the true-up balance that was recognized in the period		45		74		$ 42
Prepaid Expenses and Other Current Assets [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory assets (1)	[3]	12		77
Other Current Liabilities [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory liabilities (6)	[4]	47		38
Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities	[5]	1,582		1,323
Removal Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		1,429		886
Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		463		316
Pension and Other Postretirement Plans Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2]	637		725
Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2],[5]	30		33
Asset Retirement Obligation Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2]	131		109
Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets		422		37
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		147	[6]	81	[2]
Hurricane Harvey [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2]	68		68
Houston Electric [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Securitized regulatory assets		788		1,059
Unrecognized equity return (2)	[1]	(168)		(213)
Unamortized loss on reacquired debt (3)	[2]	62		68
Non-current regulatory assets		915		1,124
Total regulatory assets		915		1,124
Non-current regulatory liabilities		1,288		1,298
Total regulatory liabilities		1,288		1,315
Total regulatory assets and liabilities, net		(373)		(191)
Amount of allowed equity return on the true-up balance that was recognized in the period		45		74		$ 42
Houston Electric [Member] | Prepaid Expenses and Other Current Assets [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory assets (1)	[3]	0		0
Houston Electric [Member] | Other Current Liabilities [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory liabilities (6)	[4]	0		17
Houston Electric [Member] | Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities	[5]	821		847
Houston Electric [Member] | Removal Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		244		269
Houston Electric [Member] | Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		223		182
Houston Electric [Member] | Pension and Other Postretirement Plans Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2]	34		33
Houston Electric [Member] | Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2],[5]	23		23
Houston Electric [Member] | Asset Retirement Obligation Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2]	26		24
Houston Electric [Member] | Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets		29		11
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		57	[6]	55	[2]
Houston Electric [Member] | Hurricane Harvey [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2]	64		64
CERC Corp [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Securitized regulatory assets		0		0
Unrecognized equity return (2)	[1]	0		0
Unamortized loss on reacquired debt (3)	[2]	0		0
Non-current regulatory assets		191		181
Total regulatory assets		203		258
Non-current regulatory liabilities		1,219		1,227
Total regulatory liabilities		1,266		1,248
Total regulatory assets and liabilities, net		(1,063)		(990)
CERC Corp [Member] | Prepaid Expenses and Other Current Assets [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory assets (1)	[3]	12		77
CERC Corp [Member] | Other Current Liabilities [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory liabilities (6)	[4]	47		21
CERC Corp [Member] | Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities	[5]	442		476
CERC Corp [Member] | Removal Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		637		617
CERC Corp [Member] | Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		140		134
CERC Corp [Member] | Pension and Other Postretirement Plans Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2]	22		30
CERC Corp [Member] | Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2],[5]	7		10
CERC Corp [Member] | Asset Retirement Obligation Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2]	94		85
CERC Corp [Member] | Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets		16		26
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		48	[6]	26	[2]
CERC Corp [Member] | Hurricane Harvey [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[2]	$ 4		$ 4

[1] The unrecognized equity return will be recognized as it is recovered in rates through 2024. The timing of CenterPoint Energy’s and Houston Electric’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months.   Year Ended December 31,   2019   2018   2017   CenterPoint Energy   Houston Electric   CenterPoint Energy   Houston Electric   CenterPoint Energy   Houston Electric     Allowed equity return recognized $ 45
  $ 45
  $ 74
  $ 74
  $ 42
  $ 42

[2] Substantially all of these regulatory assets are not earning a return.

[3] Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ respective Consolidated Balance Sheets.

[4] Current regulatory liabilities are included in Other current liabilities in each of the Registrants’ respective Consolidated Balance Sheets.

[5] The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities. See Note 15 for additional information.

[6] Regulatory assets acquired in the Merger and not earning a return were recorded at fair value as of the Merger Date. Such fair value adjustments are recognized over time until the regulatory asset is recovered.