Regulatory Accounting (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Securitized regulatory assets		$ 1,455		$ 1,590
Unrecognized equity return (1)	[1]	(266)		(287)
Unamortized loss on reacquired debt		74		75
Regulatory assets		1,457		1,570
Total regulatory assets		1,457		1,570
Regulatory liabilities		1,265		1,263
Total regulatory liabilities		1,279		1,285
Total regulatory assets and liabilities, net		178		285
Amount of allowed equity return on the true-up balance that was recognized in the period		21	$ 7
Hurricane Harvey [Member]
Regulatory assets	[2]	57		58
Amounts related to TCJA [Member]
Regulatory liabilities	[3]	874		862
Removal Costs [Member]
Regulatory liabilities		282		285
Other Regulatory Assets (Liabilities) [Member]
Regulatory liabilities		109		116
Pension and Other Postretirement Plans Costs [Member]
Regulatory assets		32		31
Other Regulatory Assets (Liabilities) [Member]
Regulatory assets	[4]	72		70
Amounts related to TCJA [Member]
Regulatory assets	[3]	33		33
Other current liabilities [Member]
Current regulatory liabilities (5)	[5]	$ 14		$ 22

[1] The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended March 31, 2018 and 2017, Houston Electric recognized approximately $21 million and $7 million, respectively, of the allowed equity return. The timing of 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.

[2] Houston Electric is not earning a return on its Hurricane Harvey restoration costs.

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

[4] Other long-term regulatory assets that are not earning a return were not material as of March 31, 2018 and December 31, 2017.

[5] Current regulatory liabilities are included in Other current liabilities in Houston Electric’s Condensed Consolidated Balance Sheets.