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Document and Entity Information Document - USD ($)	3 Months Ended
Document and Entity Information Document - USD ($)	Mar. 31, 2017	Apr. 21, 2017	Jun. 30, 2016
Entity Information [Line Items]
Entity Registrant Name	CENTERPOINT ENERGY HOUSTON ELECTRIC LLC
Entity Central Index Key	0000048732
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0

CONDENSED STATEMENTS OF CONSOLIDATED INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues	$ 638	$ 656
Expenses:
Operation and maintenance	349	331
Depreciation and amortization	152	189
Taxes other than income taxes	60	57
Total	561	577
Operating Income	77	79
Other Income (Expense):
Interest and other finance charges	(33)	(31)
Interest on securitization bonds	(20)	(24)
Other, net	4	3
Total	(49)	(52)
Income Before Income Taxes	28	27
Income tax expense	10	10
Net Income	$ 18	$ 17

CONDENSED STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 18	$ 17
Other comprehensive income:
Net deferred loss from cash flow hedges (net of tax of $-0- and $-0-)	(1)	0
Total	(1)	0
Comprehensive income	$ 17	$ 17

Comprehensive Income Parenthetical - USD ($) $ in Millions	3 Months Ended
Comprehensive Income Parenthetical - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016
Tax expense on net deferred gain from cash flow hedges	$ 0	$ 0

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents ($240 and $340 related to VIEs, respectively)	$ 240	$ 341
Accounts and notes receivable ($44 and $52 related to VIEs, respectively), less bad debt reserve of $1 and $1	218	225
Accounts and notes receivable–affiliated companies	209	101
Accrued unbilled revenues	90	106
Inventory	130	134
Taxes receivable	9	6
Other ($35 and $40 related to VIEs, respectively)	59	66
Total current assets	955	979
Property, Plant and Equipment:
Property, plant and equipment	11,011	10,840
Less: accumulated depreciation and amortization	3,508	3,443
Property, plant and equipment, net	7,503	7,397
Other Assets:
Regulatory assets ($1,863 and $1,919 related to VIEs, respectively)	1,743	1,793
Other	44	42
Total other assets	1,787	1,835
Total Assets	10,245	10,211
Current Liabilities:
Current portion of VIE securitization bonds long-term debt	421	411
Accounts payable	185	145
Accounts and notes payable–affiliated companies	33	88
Taxes accrued	50	106
Interest accrued	56	68
Other	87	90
Total current liabilities	832	908
Other Liabilities:
Deferred income taxes, net	2,013	2,003
Benefit obligations	147	148
Regulatory liabilities	511	530
Other	53	51
Total other liabilities	2,724	2,732
Long-term Debt:
VIE securitization bonds, net	1,702	1,867
Other, net	2,884	2,587
Total long-term debt, net	4,586	4,454
Commitments and Contingencies (Note 8)
Member’s Equity:
Common stock	0	0
Paid-in capital	1,697	1,696
Retained earnings	406	420
Accumulated other comprehensive income	0	1
Total member’s equity	2,103	2,117
Total Liabilities and Member’s Equity	$ 10,245	$ 10,211

Balance Sheet Parenthetical - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents	$ 240	$ 341
Bad debt reserve	1	1
Accounts and notes receivable, net	218	225
Other	59	66
Regulatory assets	1,743	1,793
Variable Interest Entity, Primary Beneficiary [Member]
Cash and Cash Equivalents	240	340
Accounts and notes receivable, net	44	52
Other	35	40
Regulatory assets	$ 1,863	$ 1,919

CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOWS (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash Flows from Operating Activities:
Net income	$ 18	$ 17
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	152	189
Amortization of deferred financing costs	3	3
Deferred income taxes	8	(3)
Changes in other assets and liabilities:
Accounts and notes receivable, net	23	26
Accounts receivable/payable–affiliated companies	(56)	(60)
Inventory	4	4
Accounts payable	48	(14)
Taxes receivable	(3)	59
Interest and taxes accrued	(68)	(52)
Net regulatory assets and liabilities	(28)	(31)
Other current assets	2	15
Other current liabilities	(3)	10
Other assets	3	6
Other liabilities	4	0
Other, net	(1)	0
Net cash provided by operating activities	106	169
Cash Flows from Investing Activities:
Capital expenditures	(210)	(227)
Increase in notes receivable–affiliated companies	(107)	0
Decrease (increase) in restricted cash of Bond Companies	4	(4)
Other, net	(4)	(4)
Net cash used in investing activities	(317)	(235)
Cash Flows from Financing Activities:
Proceeds from long-term debt, net	298	0
Payments of long-term debt	(155)	(145)
Increase in short-term notes payable–affiliated companies	0	153
Dividend to parent	(32)	0
Debt issuance costs	(2)	(1)
Other, net	1	0
Net cash provided by financing activities	110	7
Net Decrease in Cash and Cash Equivalents	(101)	(59)
Cash and Cash Equivalents at Beginning of Period	341	264
Cash and Cash Equivalents at End of Period	240	205
Cash Payments/Receipts:
Interest, net of capitalized interest	64	67
Income tax refunds, net	0	(65)
Non-cash transactions:
Accounts payable related to capital expenditures	$ 57	$ 54

Background and Basis of Presentation	3 Months Ended
Background and Basis of Presentation	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation [Text Block]	Background and Basis of Presentation General. Included in this Form 10-Q are the Interim Condensed Financial Statements of Houston Electric. The Interim Condensed Financial Statements are unaudited, omit certain financial statement disclosures and should be read with the 2016 Form 10-K. Background. Houston Electric is an indirect, wholly-owned subsidiary of CenterPoint Energy, Inc., a public utility holding company. Houston Electric provides electric transmission and distribution services to REPs serving over 2.4 million metered customers in the Texas Gulf Coast area that includes the city of Houston. As of March 31, 2017, Houston Electric had the following subsidiaries: Bond Company II, Bond Company III, Restoration Bond Company and Bond Company IV. As of March 31, 2017, Houston Electric had VIEs consisting of the Bond Companies, which it consolidates. The consolidated VIEs are wholly-owned, bankruptcy-remote, special purpose entities that were formed specifically for the purpose of securitizing transition and system restoration-related property. Creditors of Houston Electric have no recourse to any assets or revenues of the Bond Companies. The bonds issued by these VIEs are payable only from and secured by transition and system restoration property, and the bondholders have no recourse to the general credit of Houston Electric. Basis of Presentation. The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Houston Electric’s Interim Condensed Financial Statements reflect all normal recurring adjustments that are, in the opinion of management, necessary to present fairly the financial position, results of operations and cash flows for the respective periods. Amounts reported in Houston Electric’s Condensed Statements of Consolidated Income are not necessarily indicative of amounts expected for a full-year period due to the effects of, among other things, (a) seasonal fluctuations in demand for energy, (b) timing of maintenance and other expenditures and (c) acquisitions and dispositions of businesses, assets and other interests. Houston Electric consists of a single reportable business segment: Electric Transmission & Distribution.

New Accounting Pronouncements	3 Months Ended
New Accounting Pronouncements	Mar. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements [Text Block]	New Accounting Pronouncements In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01). ASU 2016-01 requires equity investments that do not result in consolidation and are not accounted for under the equity method to be measured at fair value and to recognize any changes in fair value in net income unless the investments qualify for the new practicability exception. It does not change the guidance for classifying and measuring investments in debt securities and loans. ASU 2016-01 also changes certain disclosure requirements and other aspects related to recognition and measurement of financial assets and financial liabilities. ASU 2016-01 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. As of the first reporting period in which the guidance is adopted, a cumulative-effect adjustment to beginning retained earnings will be made, with two features that will be adopted prospectively. Houston Electric does not believe this standard will have a material impact on its financial position, results of operations, cash flows and disclosures. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 provides a comprehensive new lease model that requires lessees to recognize assets and liabilities for most leases and would change certain aspects of lessor accounting. ASU 2016-02 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. A modified retrospective adoption approach is required. Houston Electric is currently assessing the impact that this standard will have on its financial position, results of operations, cash flows and disclosures. In 2016, the FASB issued ASUs which amended ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09, as amended, provides a comprehensive new revenue recognition model that requires revenue to be recognized in a manner that depicts the transfer of goods or services to a customer at an amount that reflects the consideration expected to be received in exchange for those goods or services. Early adoption is permitted, and entities have the option of using either a full retrospective or a modified retrospective adoption approach. Houston Electric is currently evaluating its revenue streams under these ASUs and has not yet identified any significant changes as the result of these new standards. A substantial amount of Houston Electric’s revenues are tariff based, which we do not anticipate will be significantly impacted by these ASUs. Houston Electric expects to adopt these ASUs on January 1, 2018 and is evaluating the method of adoption. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (ASU 2016-15). ASU 2016-15 provides clarifying guidance on the classification of certain cash receipts and payments in the statement of cash flows and eliminates the variation in practice related to such classifications. ASU 2016-15 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. A retrospective adoption approach is required. Houston Electric is currently assessing the impact that this standard will have on its statement of cash flows. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (ASU 2016-18). ASU 2016-18 requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. ASU 2016-18 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. A retrospective adoption approach is required. Houston Electric is currently assessing the impact that this standard will have on its statement of cash flows and disclosures. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business (ASU 2017-01). ASU 2017-01 revises the definition of a business. If substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, then under ASU 2017-01, the asset or group of assets is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs to be more closely aligned with how outputs are described in ASC 606. ASU 2017-01 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted in certain circumstances. A prospective adoption approach is required. ASU 2017-01 could have a potential impact on Houston Electric’s accounting for future acquisitions. In February 2017, the FASB issued ASU No. 2017-05, Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets (ASU 2017-05). ASU 2017-05 clarifies when and how to apply ASC 610-20 Gains and Losses from the Derecognition of Nonfinancial Assets, which was issued as part of ASU 2014-09 Revenue from Contracts with Customers (Topic 606). ASU 2017-05 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. Companies can elect a retrospective or modified retrospective approach to adoption. Houston Electric is currently assessing the impact that this standard will have on its financial position, results of operations, cash flows and disclosures. In March 2017, the FASB issued ASU No. 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost (ASU 2017-07). ASU 2017-07 requires an employer to report the service cost component of the net periodic pension cost and postretirement benefit cost in the same line item(s) as other employee compensation costs arising from services rendered during the period; all other components will be presented separately from the line item(s) that includes the service cost and outside of any subtotal of operating income. In addition, only the service cost component will be eligible for capitalization in assets. ASU 2017-07 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. ASU 2017-07 should be applied retrospectively for the presentation of the service cost component and the other components and prospectively for the capitalization of the service cost component. Houston Electric is currently assessing the impact that this standard will have on its financial position, results of operations, cash flows and disclosures. Management believes that other recently issued standards, which are not yet effective, will not have a material impact on Houston Electric’s consolidated financial position, results of operations or cash flows upon adoption.

Employee Benefit Plans

3 Months Ended

Mar. 31, 2017

Compensation and Retirement Disclosure [Abstract]

Employee Benefit Plans [Text Block]

Employee Benefit Plans

Houston Electric’s employees participate in CenterPoint Energy’s postretirement benefit plan. Houston Electric’s net periodic cost includes the following components relating to postretirement benefits:



	Three Months Ended March 31,
	2017			2016
	(in millions)
Interest cost	$	2		$	3
Expected return on plan assets	(1		)	(1		)
Amortization of prior service credit	(1		)	(1		)
Net periodic cost	$	—		$	1

Houston Electric expects to contribute approximately $9 million to its postretirement benefit plan in 2017, of which approximately $2 million was contributed during the three months ended March 31, 2017.

Regulatory Accounting	3 Months Ended
Regulatory Accounting	Mar. 31, 2017
regulatory accounting [Abstract]
Regulatory Accounting [Text Block]	Regulatory Accounting As of March 31, 2017, Houston Electric has not recognized an allowed equity return of $322 million because such return will be recognized as it is recovered in rates. During the three months ended March 31, 2017 and 2016, Houston Electric recognized approximately $7 million and $13 million, respectively, of the allowed equity return not previously recognized.

Fair Value Measurements

3 Months Ended

Mar. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements [Text Block]

Fair Value Measurements

Assets and liabilities that are recorded at fair value in the Condensed Consolidated Balance Sheets are categorized based upon the level of judgment associated with the inputs used to measure their value. Hierarchical levels, as defined below and directly related to the amount of subjectivity associated with the inputs to fair valuations of these assets and liabilities, are as follows:

Level 1: Inputs are unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date. The types of assets carried at Level 1 fair value are investments listed in active markets. As of March 31, 2017 and December 31, 2016, Houston Electric held Level 1 investments of $53 million and $59 million, respectively, which were primarily investments in money market funds and are included in other current assets and other assets in the Condensed Consolidated Balance Sheets.

Level 2: Inputs, other than quoted prices included in Level 1, are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar instruments in active markets, and inputs other than quoted prices that are observable for the asset or liability. Houston Electric had no Level 2 assets or liabilities as of either March 31, 2017 or December 31, 2016.

Level 3: Inputs are unobservable for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. Unobservable inputs reflect Houston Electric’s judgments about the assumptions market participants would use in determining fair value. Houston Electric had no Level 3 assets or liabilities as of either March 31, 2017 or December 31, 2016.

Houston Electric determines the appropriate level for each financial asset and liability on a quarterly basis and recognizes transfers between levels at the end of the reporting period. For the three months ended March 31, 2017, there were no transfers between levels.

Estimated Fair Value of Financial Instruments

The fair values of cash and cash equivalents and short-term borrowings are estimated to be approximately equivalent to carrying amounts and have been excluded from the table below. The fair value of each debt instrument is determined by multiplying the principal amount of each debt instrument by the market price. These assets and liabilities, which are not measured at fair value in the Condensed Consolidated Balance Sheets but for which the fair value is disclosed, would be classified as Level 1 in the fair value hierarchy.



	March 31, 2017				December 31, 2016
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Financial liabilities:	(in millions)
Long-term debt	$	5,007	$	5,228	$	4,865	$	5,079

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Related Party Transactions and Major Customers

3 Months Ended

Mar. 31, 2017

Related Party Transactions and Major Customers

(a) Related Party Transactions

Houston Electric participates in a money pool through which it can borrow or invest on a short-term basis. Funding needs are aggregated and external borrowing or investing is based on the net cash position. The net funding requirements of the money pool are expected to be met with borrowings under CenterPoint Energy’s revolving credit facility or the sale of CenterPoint Energy’s commercial paper. Houston Electric had investments in the money pool of $203 million and $96 million as of March 31, 2017 and December 31, 2016, respectively, which are included in accounts and notes receivable-affiliated companies, in the Condensed Consolidated Balance Sheets. As of March 31, 2017, Houston Electric’s money pool investments had a weighted-average interest rate of 1.25%.

Houston Electric had affiliate related net interest income of $1 million and net interest expense of $1 million for the three months ended March 31, 2017 and 2016, respectively.

CenterPoint Energy provides some corporate services to Houston Electric. The costs of services have been charged directly to Houston Electric using methods that management believes are reasonable. These methods include negotiated usage rates, dedicated asset assignment and proportionate corporate formulas based on operating expenses, assets, gross margin, employees and a composite of assets, gross margin and employees. CERC provides certain services to Houston Electric. These services are billed at actual cost, either directly or as an allocation and include line locating and other miscellaneous services. Additionally, Houston Electric provides a number of services to CERC. These services are billed at actual cost, either directly or as an allocation and include fleet services, shop services, geographic services, surveying and right-of-way services, radio communications, data circuit management and field operations. These charges are not necessarily indicative of what would have been incurred had Houston Electric not been an affiliate. Amounts charged to and by Houston Electric for these services were as follows and are included primarily in operation and maintenance expenses:



	Three Months Ended March 31,
	2017			2016
	(in millions)
Corporate service charges	$	42		$	45
Charges from CERC for services provided	2			1
Billings to CERC for services provided	(3		)	(4		)

(b) Major Customers

Houston Electric’s transmission and distribution revenues from major customers are as follows:



	Three Months Ended March 31,
	2017		2016
	(in millions)
Affiliates of NRG	$	152	$	145
Affiliates of Energy Future Holdings Corp.	47		45

Long-term Debt

3 Months Ended

Mar. 31, 2017

Long-term Debt, Unclassified [Abstract]

Long-term Debt [Text Block]

Long-term Debt

Debt Issuances. During the three months ended March 31, 2017, Houston Electric issued the following general mortgage bonds:



Issuance Date	Aggregate Principal Amount		Interest Rate	Maturity Date
	(in millions)
January 2017	$	300	3.00%	2027

The proceeds from the issuance of these bonds were used to repay short-term debt and for general limited liability company purposes.

Revolving Credit Facility. As of March 31, 2017 and December 31, 2016, Houston Electric had the following revolving credit facility and utilization of such facility:



		March 31, 2017				December 31, 2016
Size of Facility		Loans		Letters of Credit		Loans		Letters of Credit
(in millions)
$	300	$	—	$	4	$	—	$	4

Execution Date

Size of

Facility

Draw Rate of LIBOR plus (1)

Financial Covenant Limit on Debt to Capital Ratio (2)

Debt to Capital

Ratio as of

March 31, 2017 (3)

Termination Date

(in millions)

March 3, 2016

300

1.125%

65%

50.2%

March 3, 2021


(1)	Based on current credit ratings.

(2)

The financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and Houston Electric certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive twelve-month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date Houston Electric delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of Houston Electric’s certification or (iii) the revocation of such certification.


(3)	As defined in the revolving credit facility agreement, excluding Securitization Bonds.

Houston Electric was in compliance with all financial debt covenants as of March 31, 2017.

Hedging of Interest Expense for Future Debt Issuances. In January 2017, Houston Electric entered into forward interest rate agreements with several counterparties, having an aggregate notional amount of $150 million. These agreements were executed to hedge, in part, volatility in the 10-year U.S. treasury rate by reducing Houston Electric’s exposure to variability in cash flows related to interest payments of Houston Electric’s $300 million issuance of fixed rate debt in January 2017. These forward interest rate agreements were designated as cash flow hedges. Accordingly, the effective portion of realized losses associated with the agreements, which totaled approximately $0.5 million, is a component of accumulated other comprehensive income in 2017 and will be amortized over the life of the bonds.

Other. As of both March 31, 2017 and December 31, 2016, Houston Electric had issued $118 million of general mortgage bonds as collateral for long-term debt of CenterPoint Energy. These bonds are not reflected in the consolidated financial statements because of the contingent nature of the obligations.

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies [Text Block]	Commitments and Contingencies Legal Matters Gas Market Manipulation Cases. CenterPoint Energy, Houston Electric or their predecessor, Reliant Energy, and certain of their former subsidiaries have been named as defendants in certain lawsuits described below. Under a master separation agreement between CenterPoint Energy and a former subsidiary, RRI, CenterPoint Energy and its subsidiaries are entitled to be indemnified by RRI and its successors for any losses, including certain attorneys’ fees and other costs, arising out of these lawsuits. In May 2009, RRI sold its Texas retail business to a subsidiary of NRG and RRI changed its name to RRI Energy, Inc. In December 2010, Mirant Corporation merged with and became a wholly-owned subsidiary of RRI, and RRI changed its name to GenOn. In December 2012, NRG acquired GenOn through a merger in which GenOn became a wholly-owned subsidiary of NRG. None of the sale of the retail business, the merger with Mirant Corporation, or the acquisition of GenOn by NRG alters RRI’s (now GenOn’s) contractual obligations to indemnify CenterPoint Energy and its subsidiaries, including Houston Electric, for certain liabilities, including their indemnification obligations regarding the gas market manipulation litigation. A large number of lawsuits were filed against numerous gas market participants in a number of federal and western state courts in connection with the operation of the natural gas markets in 2000–2002. CenterPoint Energy and its affiliates have since been released or dismissed from all such cases. CES, a subsidiary of CERC Corp., was a defendant in a case now pending in federal court in Nevada alleging a conspiracy to inflate Wisconsin natural gas prices in 2000–2002. On May 24, 2016, the district court granted CES’s motion for summary judgment, dismissing CES from the case. The plaintiffs have appealed that ruling. CenterPoint Energy and CES intend to continue vigorously defending against the plaintiffs’ claims. Houston Electric does not expect the ultimate outcome of this matter to have a material adverse effect on its financial condition, results of operations or cash flows. GenOn has publicly disclosed that it may be unable to continue as a going concern and is exploring various options, including negotiations with creditors and lessors, refinancing, potential sale of assets, as well as the possibility of filing for protection under Chapter 11 of the U.S. Bankruptcy Code. If GenOn were unable to meet its indemnity obligations or satisfy a liability that has been assumed in the gas market manipulation litigation, then Houston Electric, CenterPoint Energy or CERC could incur liability and be responsible for satisfying the liability. Environmental Matters Asbestos. Some facilities owned by Houston Electric contain or have contained asbestos insulation and other asbestos-containing materials. CenterPoint Energy and its subsidiaries, including Houston Electric, are from time to time named, along with numerous others, as defendants in lawsuits filed by a number of individuals who claim injury due to exposure to asbestos, and CenterPoint Energy anticipates that additional claims may be asserted in the future. Although their ultimate outcome cannot be predicted at this time, Houston Electric does not expect these matters, either individually or in the aggregate, to have a material adverse effect on its financial condition, results of operations or cash flows. Other Environmental. From time to time, Houston Electric identifies the presence of environmental contaminants during its operations or on property where its predecessor companies have conducted operations. Other such sites involving contaminants may be identified in the future. Houston Electric has and expects to continue to remediate identified sites consistent with its legal obligations. From time to time, Houston Electric has received notices from regulatory authorities or others regarding its status as a potentially responsible party in connection with sites found to require remediation due to the presence of environmental contaminants. In addition, Houston Electric has been named from time to time as a defendant in litigation related to such sites. Although the ultimate outcome of such matters cannot be predicted at this time, Houston Electric does not expect these matters, either individually or in the aggregate, to have a material adverse effect on its financial condition, results of operations or cash flows. Other Proceedings Houston Electric is involved in other legal, environmental, tax and regulatory proceedings before various courts, regulatory commissions and governmental agencies regarding matters arising in the ordinary course of business. From time to time, Houston Electric is also a defendant in legal proceedings with respect to claims brought by various plaintiffs against broad groups of participants in the energy industry. Some of these proceedings involve substantial amounts. Houston Electric regularly analyzes current information and, as necessary, provides accruals for probable and reasonably estimable liabilities on the eventual disposition of these matters. Houston Electric does not expect the disposition of these matters to have a material adverse effect on Houston Electric’s financial condition, results of operations or cash flows.

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes [Text Block]	Income Taxes The effective tax rate reported for the three months ended March 31, 2017 was 36% compared to 37% for the same period in 2016. Houston Electric reported no uncertain tax liability as of March 31, 2017 and expects no significant change to the uncertain tax liability over the next twelve months. Tax years through 2014 have been audited and settled with the IRS. For the 2015-2017 tax years, CenterPoint Energy is a participant in the IRS’s Compliance Assurance Process.

Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2017

Defined Benefit Plan Disclosure [Line Items]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]



	Three Months Ended March 31,
	2017			2016
	(in millions)
Interest cost	$	2		$	3
Expected return on plan assets	(1		)	(1		)
Amortization of prior service credit	(1		)	(1		)
Net periodic cost	$	—		$	1

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2017

Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]

Fair Value, by Balance Sheet Grouping [Table Text Block]

Estimated Fair Value of Financial Instruments



	March 31, 2017				December 31, 2016
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Financial liabilities:	(in millions)
Long-term debt	$	5,007	$	5,228	$	4,865	$	5,079

Related Party Transactions and Major Customers (Tables)

3 Months Ended

Mar. 31, 2017



	Three Months Ended March 31,
	2017			2016
	(in millions)
Corporate service charges	$	42		$	45
Charges from CERC for services provided	2			1
Billings to CERC for services provided	(3		)	(4		)

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

Houston Electric’s transmission and distribution revenues from major customers are as follows:



	Three Months Ended March 31,
	2017		2016
	(in millions)
Affiliates of NRG	$	152	$	145
Affiliates of Energy Future Holdings Corp.	47		45

Long-term Debt (Tables)

3 Months Ended

Mar. 31, 2017

Line of Credit Facility [Line Items]

Schedule of Debt [Table Text Block]

Debt Issuances. During the three months ended March 31, 2017, Houston Electric issued the following general mortgage bonds:



Issuance Date	Aggregate Principal Amount		Interest Rate	Maturity Date
	(in millions)
January 2017	$	300	3.00%	2027

Schedule of Line of Credit Facilities [Table Text Block]

Revolving Credit Facility. As of March 31, 2017 and December 31, 2016, Houston Electric had the following revolving credit facility and utilization of such facility:



		March 31, 2017				December 31, 2016
Size of Facility		Loans		Letters of Credit		Loans		Letters of Credit
(in millions)
$	300	$	—	$	4	$	—	$	4

Execution Date

Size of

Facility

Draw Rate of LIBOR plus (1)

Financial Covenant Limit on Debt to Capital Ratio (2)

Debt to Capital

Ratio as of

March 31, 2017 (3)

Termination Date

(in millions)

March 3, 2016

300

1.125%

65%

50.2%

March 3, 2021


(1)	Based on current credit ratings.

(2)


(3)	As defined in the revolving credit facility agreement, excluding Securitization Bonds.

Background and Basis of Presentation (Details) number in Millions	Mar. 31, 2017
Number of Metered Customers	2.4

Employee Benefit Plans (Details) - Other Postretirement Benefit Plans, Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 2	$ 3
Expected return on plan assets	(1)	(1)
Amortization of prior service credit	(1)	(1)
Net periodic cost	0	$ 1
Expected contribution to postretirement benefit plan in current year	9
Total contribution to the plan during the period	$ 2

Regulatory Accounting (Details) - USD ($) $ in Millions	3 Months Ended
Regulatory Accounting (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016
Unrecognized Equity Return	$ 322
Amount Of Allowed Equity Return Recognized In Period	$ 7	$ 13

Fair Value Measurements (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Level 1 to Level 2 Transfers, Assets	$ 0
Level 2 to Level 1 Transfers, Assets	0
Level 1 to Level 2 Transfers, Liabilities	0
Level 2 to Level 1 Transfers, Liabilities	0
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	53	$ 59
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets or liabilities	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets or liabilities	0	0
Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term debt	5,007	4,865
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term debt	$ 5,228	$ 5,079

Related Party Transactions and Major Customers (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Related Party Transaction [Line Items]
Investments in Money Pool	$ 203		$ 96
Interest Income (Expense) Net, Related Party	1	$ (1)
Sales to major customers	638	656
Affiliates of NRG Energy, Inc. [Member]
Related Party Transaction [Line Items]
Sales to major customers	152	145
Affiliates of Energy Future Holdings Corp. [Member]
Related Party Transaction [Line Items]
Sales to major customers	47	45
Operation And Maintenance Expense [Member] \| CenterPoint Energy [Member]
Related Party Transaction [Line Items]
Corporate service charges	42	45
Operation And Maintenance Expense [Member] \| CERC Corp [Member]
Related Party Transaction [Line Items]
Corporate service charges	2	1
Related Party Transaction, Other Revenues from Transactions with Related Party	$ (3)	$ (4)
Investments [Member]
Related Party Transaction [Line Items]
Money Pool Investments, Weighted Average Interest Rate	1.25%

Long-term Debt (Details) $ in Millions		3 Months Ended
Long-term Debt (Details) $ in Millions	Jan. 12, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 300.0	$ 300.0
General mortgage bonds used as collateral		118.0	118.0
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Loans Outstanding		0.0	0.0
Letter of Credit [Member]
Debt Instrument [Line Items]
Loans Outstanding		$ 4.0	$ 4.0
Line of Credit [Member]
Debt Instrument [Line Items]
Percentage on limitation of debt to total capitalization under covenant		65.00%
Ratio of Indebtedness to Net Capital		0.502
Percentage on limitation of debt to total capitalization under covenant amended		70.00%
Restoration Cost Expected Cost		$ 100.0
Consecutive Period for System Restoration Costs to Exceed $100 million (in months)		12
Line of Credit [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Interest Rate Description		1.125%
Treasury Lock [Member] \| January [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 300.0
Aggregate Notional Amount		150.0
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		$ (0.5)
Bonds General Mortgage Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 300.0
Debt Instrument, Interest Rate, Stated Percentage	3.00%
Debt Instrument, Maturity Date	Feb. 01, 2027

Income Taxes (Details)	3 Months Ended
Income Taxes (Details)	Mar. 31, 2017	Mar. 31, 2016
Effective tax rate	36.00%	37.00%