Regulatory Matters Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Regulatory Assets And Liabilities [Line Items]
Securitized regulatory assets		$ 1,919	$ 2,373
Unrecognized equity return (1)	[1]	(329)	(393)
Unamortized loss on reacquired debt		84	93
Regulatory assets		1,793	2,211
Regulatory liabilities		530	542
Total regulatory assets and liabilities, net		1,263	1,669
Amount of allowed equity return on the true-up balance that was recognized in the period		64	49	$ 68
Pension and Other Postretirement Plans Costs [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Regulatory assets		34	50
Other Regulatory Assets (Liabilities) [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Regulatory assets	[2]	85	88
Removal Costs [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		345	350
Other Regulatory Assets (Liabilities) [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		$ 185	$ 192

[1] The unrecognized allowed equity return will be recognized as it is recovered in rates through 2024. During the years ended December 31, 2016, 2015 and 2014, Houston Electric recognized approximately $64 million, $49 million and $68 million, respectively, of the allowed equity return. The timing of Houston Electric’s recognition of the allowed equity return will vary each period based on amounts actually collected during the period. The actual amounts recovered for the allowed equity return are reviewed and adjusted at least annually by the PUCT to correct any over-collections or under-collections during the preceding 12 months and to provide for the full and timely recovery of the allowed equity return.

[2] Other regulatory assets that are not earning a return were not material as of December 31, 2016 and 2015.