Regulatory Accounting (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Securitized regulatory assets		$ 895		$ 895		$ 1,059
Unrecognized equity return (2)	[1]	(189)		(189)		(213)
Unamortized loss on reacquired debt (3)	[2]	65		65		68
Regulatory assets		2,228		2,228		1,967
Total regulatory assets		2,248		2,248		2,044
Regulatory liabilities		3,467		3,467		2,525
Total regulatory liabilities		3,522		3,522		2,563
Total regulatory assets and liabilities, net		(1,274)		(1,274)		(519)
Amount of allowed equity return on the true-up balance that was recognized in the period		13	$ 24	24	$ 45
Houston Electric [Member]
Securitized regulatory assets		895		895		1,059
Unrecognized equity return (2)	[1]	(189)		(189)		(213)
Unamortized loss on reacquired debt (3)	[2]	65		65		68
Regulatory assets		1,016		1,016		1,124
Total regulatory assets		1,016		1,016		1,124
Regulatory liabilities		1,286		1,286		1,298
Total regulatory liabilities		1,291		1,291		1,315
Total regulatory assets and liabilities, net		(275)		(275)		(191)
Amount of allowed equity return on the true-up balance that was recognized in the period		13	$ 24	24	$ 45
CERC Corp [Member]
Securitized regulatory assets		0		0		0
Unrecognized equity return (2)		0		0		0
Unamortized loss on reacquired debt (3)		0		0		0
Regulatory assets		187		187		181
Total regulatory assets		207		207		258
Regulatory liabilities		1,234		1,234		1,227
Total regulatory liabilities		1,277		1,277		1,248
Total regulatory assets and liabilities, net		(1,070)		(1,070)		(990)
Hurricane Harvey [Member]
Regulatory assets	[2]	68		68		68
Hurricane Harvey [Member] | Houston Electric [Member]
Regulatory assets	[2]	64		64		64
Hurricane Harvey [Member] | CERC Corp [Member]
Regulatory assets	[2]	4		4		4
Prepaid expenses and other current assets [Member]
Current regulatory assets (1)	[3]	20		20		77
Prepaid expenses and other current assets [Member] | Houston Electric [Member]
Current regulatory assets (1)	[3]	0		0		0
Prepaid expenses and other current assets [Member] | CERC Corp [Member]
Current regulatory assets (1)	[3]	20		20		77
Other current liabilities [Member]
Current regulatory liabilities (6)	[4]	55		55		38
Other current liabilities [Member] | Houston Electric [Member]
Current regulatory liabilities (6)	[4]	5		5		17
Other current liabilities [Member] | CERC Corp [Member]
Current regulatory liabilities (6)	[4]	43		43		21
Asset Retirement Obligation Costs [Member]
Regulatory assets	[2]	140		140		109
Asset Retirement Obligation Costs [Member] | Houston Electric [Member]
Regulatory assets	[2]	25		25		24
Asset Retirement Obligation Costs [Member] | CERC Corp [Member]
Regulatory assets	[2]	90		90		85
Pension and Other Postretirement Plans Costs [Member]
Regulatory assets	[2]	697		697		725
Pension and Other Postretirement Plans Costs [Member] | Houston Electric [Member]
Regulatory assets	[2]	34		34		33
Pension and Other Postretirement Plans Costs [Member] | CERC Corp [Member]
Regulatory assets	[2]	28		28		30
Amounts related to TCJA [Member]
Regulatory assets	[2],[5]	30		30		33
Amounts related to TCJA [Member] | Houston Electric [Member]
Regulatory assets	[2],[5]	23		23		23
Amounts related to TCJA [Member] | CERC Corp [Member]
Regulatory assets	[2],[5]	7		7		10
Other Regulatory Assets (Liabilities) [Member]
Regulatory assets		389		389		37
Other regulatory assets-not earning a return (5)	[6]	133		133		81
Other Regulatory Assets (Liabilities) [Member] | Houston Electric [Member]
Regulatory assets		25		25		11
Other regulatory assets-not earning a return (5)	[6]	74		74		55
Other Regulatory Assets (Liabilities) [Member] | CERC Corp [Member]
Regulatory assets		30		30		26
Other regulatory assets-not earning a return (5)	[6]	28		28		26
Amounts related to TCJA [Member]
Regulatory liabilities	[5]	1,616		1,616		1,323
Amounts related to TCJA [Member] | Houston Electric [Member]
Regulatory liabilities	[5]	834		834		847
Amounts related to TCJA [Member] | CERC Corp [Member]
Regulatory liabilities	[5]	453		453		476
Removal Costs [Member]
Regulatory liabilities		1,415		1,415		886
Removal Costs [Member] | Houston Electric [Member]
Regulatory liabilities		271		271		269
Removal Costs [Member] | CERC Corp [Member]
Regulatory liabilities		629		629		617
Other Regulatory Assets (Liabilities) [Member]
Regulatory liabilities		436		436		316
Other Regulatory Assets (Liabilities) [Member] | Houston Electric [Member]
Regulatory liabilities		181		181		182
Other Regulatory Assets (Liabilities) [Member] | CERC Corp [Member]
Regulatory liabilities		$ 152		$ 152		$ 134

[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.   Three Months Ended June 30,   Six Months Ended June 30,   2019   2018   2019   2018   CenterPoint Energy   Houston Electric   CenterPoint Energy   Houston Electric   CenterPoint Energy   Houston Electric   CenterPoint Energy   Houston Electric   (in millions) Allowed equity return recognized $ 13
  $ 13
  $ 24
  $ 24
  $ 24
  $ 24
  $ 45
  $ 45

[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 Condensed Consolidated Balance Sheets.

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

[5] The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities.

[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.