Regulatory Accounting	9 Months Ended
Sep. 30, 2017
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Regulatory Accounting [Text Block]	Regulatory Accounting Equity Return. As of September 30, 2017, Houston Electric has not recognized an allowed equity return of $299 million because such return will be recognized as it is recovered in rates. During the three months ended September 30, 2017 and 2016, Houston Electric recognized approximately $13 million and $22 million, respectively, of the allowed equity return not previously recognized. During the nine months ended September 30, 2017 and 2016, Houston Electric recognized approximately $30 million and $52 million, respectively, of the allowed equity return not previously recognized. Hurricane Harvey. Houston Electric’s electric delivery system suffered damage as a result of Hurricane Harvey, a major storm classified as a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale, that first struck the Texas coast on Friday, August 25, 2017 and remained over the Houston area for the next several days. The unprecedented flooding from torrential amounts of rainfall accompanying the storm caused significant damage to or destruction of residences and businesses served by Houston Electric. Currently, Houston Electric estimates that total costs to restore the electric delivery facilities damaged as a result of Hurricane Harvey will range from $110 million to $120 million and estimates that the total restoration costs covered by insurance will be approximately $35 million. Houston Electric will defer the uninsured storm restoration costs as management believes it is probable that such costs will be recovered through traditional rate adjustment mechanisms for capital costs and through the next rate proceeding for operation and maintenance expenses. As of September 30, 2017, Houston Electric recorded an increase of $4 million in property, plant and equipment and $73 million in regulatory assets, net of $23 million in insurance receivables recorded, for restoration costs incurred. As a result, storm restoration costs should not materially affect Houston Electric’s reported net income for 2017.

Regulatory Accounting

Equity Return. As of September 30, 2017, Houston Electric has not recognized an allowed equity return of $299 million because such return will be recognized as it is recovered in rates. During the three months ended September 30, 2017 and 2016, Houston Electric recognized approximately $13 million and $22 million, respectively, of the allowed equity return not previously recognized. During the nine months ended September 30, 2017 and 2016, Houston Electric recognized approximately $30 million and $52 million, respectively, of the allowed equity return not previously recognized.

Hurricane Harvey. Houston Electric’s electric delivery system suffered damage as a result of Hurricane Harvey, a major storm classified as a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale, that first struck the Texas coast on Friday, August 25, 2017 and remained over the Houston area for the next several days. The unprecedented flooding from torrential amounts of rainfall accompanying the storm caused significant damage to or destruction of residences and businesses served by Houston Electric.

Currently, Houston Electric estimates that total costs to restore the electric delivery facilities damaged as a result of Hurricane Harvey will range from $110 million to $120 million and estimates that the total restoration costs covered by insurance will be approximately $35 million. Houston Electric will defer the uninsured storm restoration costs as management believes it is probable that such costs will be recovered through traditional rate adjustment mechanisms for capital costs and through the next rate proceeding for operation and maintenance expenses. As of September 30, 2017, Houston Electric recorded an increase of $4 million in property, plant and equipment and $73 million in regulatory assets, net of $23 million in insurance receivables recorded, for restoration costs incurred. As a result, storm restoration costs should not materially affect Houston Electric’s reported net income for 2017.