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Document and Entity Information Document - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Jun. 30, 2015
Document 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-K/A
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Amendment Flag	true
Amendment Description	CenterPoint Energy Houston Electric, LLC. (CenterPoint Houston or the Company) hereby amends Items 8 and 9A of Part II and Item 15 of Part IV of its Annual Report on Form 10-K for the year ended December 31, 2015 filed on February 26, 2016 (Form 10-K), as amended by Amendment No. 1 thereto on Form 10-K/A filed on May 13, 2016 (Amendment No. 1), to reflect the restatement of the Company’s consolidated financial statements as discussed in Note 12. For purposes of this Form 10-K/A, and in accordance with Rule 12b-15 under the Securities Exchange Act of 1934, as amended, each item of the Form 10-K, as amended by Amendment No. 1, that was affected by the restatement has been amended to the extent affected and restated in its entirety. No attempt has been made in this Form 10-K/A to update other disclosures as presented in the Form 10-K, as amended by Amendment No. 1, except as required to reflect the effects of the restatement. Accordingly, this Form 10-K/A should be read in conjunction with the Company’s SEC filings made subsequent to the filing of the Form 10-K, including any amendments of those filings. In addition, this Form 10-K/A includes updated certifications from the Company’s CEO and CFO as Exhibits 31.1, 31.2, 32.1 and 32.2.
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

STATEMENTS OF CONSOLIDATED INCOME - USD ($) $ in Millions	12 Months Ended
STATEMENTS OF CONSOLIDATED INCOME - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues	$ 2,846	$ 2,846	$ 2,577
Expenses:
Operation and maintenance	1,311	1,258	1,053
Depreciation and amortization	705	768	685
Taxes other than income taxes	222	224	225
Total	2,238	2,250	1,963
Operating Income	608	596	614
Other Income (Expense):
Interest and other finance charges	(118)	(109)	(99)
Interest on transition and system restoration bonds	(105)	(118)	(133)
Other, net	21	14	33
Total	(202)	(213)	(199)
Income Before Income Taxes	406	383	415
Income tax expense	145	131	146
Net Income	$ 261	$ 252	$ 269

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents ($264 and $290 related to VIEs, respectively)	$ 264	$ 290
Accounts and notes receivable, net ($64 and $58 related to VIEs, respectively), less bad debt reserve of $1 and $3, respectively	234	237
Accounts and notes receivable—affiliated companies	16	119
Accrued unbilled revenues	96	96
Inventory	133	126
Taxes receivable	59	103
Other ($35 and $47 related to VIEs, respectively)	63	74
Total current assets	865	1,045
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, net	6,933	6,343
Other Assets:
Regulatory assets ($2,373 and $2,738 related to VIEs, respectively)	2,211	2,629
Other	37	34
Total other assets	2,248	2,663
Total Assets	10,046	10,051
Current Liabilities:
Current portion of VIE transition and system restoration bonds long-term debt	391	372
Accounts payable	153	148
Accounts and notes payable—affiliated companies	348	121
Taxes accrued	100	104
Interest accrued	70	75
Other	69	109
Total current liabilities	1,131	929
Other Liabilities:
Deferred income taxes, net	2,032	1,999
Benefit obligations	192	260
Regulatory liabilities	542	537
Other	59	54
Total other liabilities	2,825	2,850
Long-Term Debt:
VIE transition and system restoration bonds	2,283	2,674
Other long-term debt	2,206	2,006
Total long-term debt	4,489	4,680
Commitments and Contingencies (Note 10)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Member’s Equity	1,601	1,592
Total Liabilities and Member’s Equity	$ 10,046	$ 10,051

CONSOLIDATED BALANCE SHEETS (PARENTHETICAL) Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Cash and cash equivalents ($264 and $290 related to VIEs, respectively)	$ 264	$ 290
Allowance for Doubtful Accounts Receivable, Current	1	3
Accounts and notes receivable, net ($64 and $58 related to VIEs, respectively), less bad debt reserve of $1 and $3, respectively	234	237
Other ($35 and $47 related to VIEs, respectively)	63	74
Regulatory assets ($2,373 and $2,738 related to VIEs, respectively)	2,211	2,629
Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents ($264 and $290 related to VIEs, respectively)	264	290
Accounts and notes receivable, net ($64 and $58 related to VIEs, respectively), less bad debt reserve of $1 and $3, respectively	64	58
Other ($35 and $47 related to VIEs, respectively)	35	47
Regulatory assets ($2,373 and $2,738 related to VIEs, respectively)	$ 2,373	$ 2,738

STATEMENTS OF CONSOLIDATED CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows from Operating Activities:
Net income	$ 261	$ 252	$ 269
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	705	768	685
Amortization of deferred financing costs	15	16	16
Deferred income taxes	18	(24)	(75)
Changes in other assets and liabilities:
Accounts and notes receivable, net	3	15	(46)
Accounts receivable/payable–affiliated companies	(89)	37	(5)
Inventory	(7)	(21)	(11)
Accounts payable	0	(3)	48
Taxes receivable	44	(103)	7
Interest and taxes accrued	(9)	(40)	37
Net regulatory assets and liabilities	3	(28)	(6)
Other current assets	(1)	(2)	(2)
Other current liabilities	(40)	(19)	16
Other assets	(7)	11	(11)
Other liabilities	(1)	5	6
Other, net	0	(6)	0
Net cash provided by operating activities	895	858	928
Cash Flows from Investing Activities:
Capital expenditures	(929)	(804)	(753)
Decrease (increase) in notes receivable–affiliated companies	107	(107)	1,183
Decrease (increase) in restricted cash of transition and system restoration bond companies	12	(7)	17
Other, net	1	1	(2)
Net cash provided by (used in) investing activities	(809)	(917)	445
Cash Flows from Financing Activities:
Proceeds from long-term debt	0	600	0
Payments of long-term debt	(372)	(537)	(897)
Long-term revolving credit facility	200	0	0
Dividend to parent	(252)	0	(766)
Increase (decrease) in notes payable–affiliated companies	312	(3)	(148)
Cash paid for debt retirements	0	(1)	(2)
Debt issuance costs	0	(7)	0
Contribution from parent	0	90	0
Other, net	0	0	1
Net cash provided by (used in) financing activities	(112)	142	(1,812)
Net Increase (Decrease) in Cash and Cash Equivalents	(26)	83	(439)
Cash and Cash Equivalents at Beginning of the Year	290	207	646
Cash and Cash Equivalents at End of the Year	264	290	207
Cash Payments:
Interest, net of capitalized interest	213	215	238
Income taxes	81	296	147
Non-cash transactions:
Accounts payable related to capital expenditures	$ 69	$ 64	$ 50

STATEMENTS OF CONSOLIDATED MEMBER'S EQUITY - USD ($) $ in Millions	Total	Preference Stock [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]
Shares, Outstanding at Dec. 31, 2012				1,000
Shares, Outstanding at Dec. 31, 2013		0	0	1,000
Balance at Dec. 31, 2012				$ 0	$ 1,231	$ 515
Contribution from parent					0
Other					1
Net income	$ 269					269
Dividend to parent						(766)
Balance at Dec. 31, 2013	1,250	$ 0	$ 0	$ 0	1,232	18
Shares, Outstanding at Dec. 31, 2014		0	0	1,000
Contribution from parent					90
Other					0
Net income	252					252
Dividend to parent						0
Balance at Dec. 31, 2014	1,592	$ 0	$ 0	$ 0	1,322	270
Shares, Outstanding at Dec. 31, 2015		0	0	1,000
Contribution from parent					0
Other					0
Net income	261					261
Dividend to parent						(252)
Balance at Dec. 31, 2015	$ 1,601	$ 0	$ 0	$ 0	$ 1,322	$ 279

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

STATEMENTS OF CONSOLIDATED MEMBER'S EQUITY (PARENTHETICAL) (Parentheticals) - $ / shares	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	20,000,000	20,000,000	20,000,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01	$ 0.01
Common Stock, Shares Authorized	1,000,000,000	1,000,000,000	1,000,000,000

Background	12 Months Ended
Background	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Background CenterPoint Energy Houston Electric, LLC (CenterPoint Houston) engages in the electric transmission and distribution business in the Texas Gulf Coast area that includes the city of Houston. CenterPoint Houston is an indirect, wholly-owned subsidiary of CenterPoint Energy, Inc. (CenterPoint Energy), a public utility holding company. As of December 31, 2015, CenterPoint Houston had the following subsidiaries: CenterPoint Energy Transition Bond Company, LLC, CenterPoint Energy Transition Bond Company II, LLC, CenterPoint Energy Transition Bond Company III, LLC, CenterPoint Energy Restoration Bond Company, LLC and CenterPoint Energy Transition Bond Company IV, LLC (Bond Company IV) (collectively, the transition and system restoration bond companies). Each is a special purpose Delaware limited liability company formed solely for the purpose of purchasing and owning transition or system restoration property through the issuance of transition bonds or system restoration bonds and activities incidental thereto. Because CenterPoint Houston is an indirect, wholly-owned subsidiary of CenterPoint Energy, CenterPoint Houston’s determination of reportable business segments considers the strategic operating units under which CenterPoint Energy manages sales, allocates resources and assesses performance of various products and services to wholesale or retail customers in differing regulatory environments. The accounting policies of the business segments are the same as those described in the summary of significant accounting policies except that some executive benefit costs have not been allocated to CenterPoint Houston. CenterPoint Houston uses operating income as the measure of profit or loss for its business segments. CenterPoint Houston consists of a single reportable segment: Electric Transmission & Distribution.

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Summary of Significant Accounting Policies (a) Use of Estimates 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. (b) Principles of Consolidation The accounts of CenterPoint Houston and its wholly-owned subsidiaries are included in CenterPoint Houston’s consolidated financial statements. All intercompany transactions and balances are eliminated in consolidation. As of December 31, 2015, CenterPoint Houston had variable interest entities (VIEs) consisting of transition and system restoration 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 CenterPoint Houston have no recourse to any assets or revenues of the transition and system restoration 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 CenterPoint Houston. (c) Revenues CenterPoint Houston records revenue for electricity delivery under the accrual method and these revenues are recognized upon delivery to customers. Electricity deliveries not billed by month-end are accrued based on actual advanced metering system data, daily supply volumes and applicable rates. (d) Long-Lived Assets and Intangibles CenterPoint Houston records property, plant and equipment at historical cost. CenterPoint Houston expenses repair and maintenance costs as incurred. CenterPoint Houston periodically evaluates long-lived assets, including property, plant and equipment, and specifically identifiable intangibles, when events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. The determination of whether an impairment has occurred is based on an estimate of undiscounted cash flows attributable to the assets compared to the carrying value of the assets. (e) Regulatory Assets and Liabilities CenterPoint Houston applies the guidance for accounting for regulated operations. CenterPoint Houston’s rate-regulated subsidiaries may collect revenues subject to refund pending final determination in rate proceedings. In connection with such revenues, estimated rate refund liabilities are recorded which reflect management’s current judgment of the ultimate outcomes of the proceedings. CenterPoint Houston recognizes removal costs as a component of depreciation expense in accordance with regulatory treatment. As of December 31, 2015 and 2014, these removal costs of $350 million and $353 million, respectively, are classified as regulatory liabilities in CenterPoint Houston’s Consolidated Balance Sheets. In addition, a portion of the amount of removal costs that relate to asset retirement obligations has been reclassified from a regulatory liability to an asset retirement liability in accordance with accounting guidance for asset retirement obligations. (f) Depreciation and Amortization Expense Depreciation is computed using the straight-line method based on economic lives or a regulatory-mandated recovery period. Transition and system restoration property is being amortized over the expected life of the transition and system restoration bonds (12 to 14 years), based on estimated revenue from transition or system restoration charges, interest accruals and other expenses. Other amortization expense includes amortization of regulatory assets and other intangibles. (g) Allowance for Funds Used During Construction Allowance for funds used during construction (AFUDC) is capitalized as a component of projects under construction and is amortized over the assets’ estimated useful lives once the assets are placed in service. AFUDC represents the composite interest cost of borrowed funds and a reasonable return on the equity funds used for construction. Although AFUDC increases both utility plant and earnings, it is realized in cash when the assets are included in rates. During 2015, 2014 and 2013, CenterPoint Houston capitalized AFUDC interest of $8 million, $10 million and $10 million, respectively. During 2015, 2014 and 2013, CenterPoint Energy recorded AFUDC equity of $12 million, $14 million and $8 million, respectively, which is included in Other Income in its Statements of Consolidated Income. (h) Income Taxes CenterPoint Houston is included in the consolidated income tax returns of CenterPoint Energy. CenterPoint Houston calculates its income tax provision on a separate return basis under a tax sharing agreement with CenterPoint Energy. CenterPoint Houston uses the asset and liability method of accounting for deferred income taxes. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. A valuation allowance is established against deferred tax assets for which management believes realization is not considered to be more likely than not. CenterPoint Houston recognizes interest and penalties as a component of income tax expense. Current federal and certain state income taxes are payable to or receivable from CenterPoint Energy. (i) Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are recorded at the invoiced amount and do not bear interest. It is the policy of management to review the outstanding accounts receivable monthly, as well as the bad debt write-offs experienced in the past, and establish an allowance for doubtful accounts. Account balances are charged off against the allowance when management determines it is probable the receivable will not be recovered. The provision for doubtful accounts in CenterPoint Houston’s Statements of Consolidated Income for 2015, 2014 and 2013 was less than $1 million, $3 million and $2 million, respectively. (j) Inventory Inventory consists principally of materials and supplies and is valued at the lower of average cost or market. Materials and supplies are recorded to inventory when purchased and subsequently charged to expense or capitalized to plant when installed. (k) Statements of Consolidated Cash Flows For purposes of reporting cash flows, CenterPoint Houston considers cash equivalents to be short-term, highly-liquid investments with maturities of three months or less from the date of purchase. In connection with the issuance of transition bonds and system restoration bonds, CenterPoint Houston was required to establish restricted cash accounts to collateralize the bonds that were issued in these financing transactions. These restricted cash accounts are not available for withdrawal until the maturity of the bonds and are not included in cash and cash equivalents. These restricted cash accounts of $35 million and $47 million as of December 31, 2015 and 2014, respectively, are included in other current assets in CenterPoint Houston’s Consolidated Balance Sheets. For additional information regarding transition and system restoration bonds, see Note 8. Cash and cash equivalents included $264 million and $290 million as of December 31, 2015 and 2014, respectively, that was held by CenterPoint Houston’s transition and system restoration bond subsidiaries solely to support servicing the transition and system restoration bonds. (l) New Accounting Pronouncements In February 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis (ASU 2015-02). ASU 2015-02 changes the analysis that reporting organizations must perform to evaluate whether they should consolidate certain legal entities, such as limited partnerships. The changes include, among others, modification of the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities and elimination of the presumption that a general partner should consolidate a limited partnership. ASU 2015-02 does not amend the related party guidance for situations in which power is shared between two or more entities that hold interests in a VIE. ASU 2015-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015. CenterPoint Houston does not believe that ASU 2015-02 will have a material impact on its financial position, results of operations, cash flows and disclosures. In April 2015, the FASB issued Accounting Standards Update No. 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost (ASU 2015-03). ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by ASU 2015-03. CenterPoint Houston will adopt ASU 2015-03 retrospectively on January 1, 2016, which will result in a reduction of both other long-term assets and long-term debt on its Consolidated Balance Sheets. CenterPoint Houston had debt issuance costs of $22 million and $26 million included in other long-term assets on its Consolidated Balance Sheets as of December 31, 2015 and 2014, respectively. In April 2015, the FASB issued Accounting Standards Update No. 2015-05, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40) (ASU 2015-05). ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The guidance will not change a customer’s accounting for service contracts. ASU 2015-05 is effective for fiscal years, and interim periods within the fiscal years, beginning after December 15, 2015 and may be adopted either prospectively or retrospectively. CenterPoint Houston will adopt ASU 2015-05 prospectively on January 1, 2016. CenterPoint Houston does not believe that ASU 2015-05 will have a material impact on its financial position, results of operations, cash flows and disclosures. In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09), which supersedes most current revenue recognition guidance. ASU 2014-09 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. ASU 2014-09 was initially effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. Early adoption is not permitted, and entities have the option of using either a full retrospective or a modified retrospective adoption approach. In August 2015, the FASB issued Accounting Standard Update No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which delays the effective date of ASU 2014-09 by one year. CenterPoint Houston is currently evaluating the impact that ASU 2014-09 will have on its financial position, results of operations, cash flows and disclosures, and will adopt ASU 2014-09 on January 1, 2018 as permitted by the new guidance. In July 2015, the FASB issued Accounting Standards Update No. 2015-11, Inventory (Topic 330) Simplifying the Measurement of Inventory (ASU 2015-11). ASU 2015-11 changes the subsequent measurement guidance for inventory accounted for using methods other than the last in, first out (LIFO) and Retail Inventory methods. Companies will subsequently measure inventory at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. Subsequent measurement is unchanged for inventory measured using LIFO or the retail inventory method. ASU 2015-11 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016, with early adoption permitted. CenterPoint Houston does not believe that ASU 2015-11 will have a material impact on its financial position, results of operations, cash flows and disclosures. In November 2015, the FASB issued Accounting Standards Update No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes (ASU 2015-17). ASU 2015-17 requires deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. CenterPoint Houston adopted ASU 2015-17 retrospectively starting with fiscal year 2015. As such, certain prior period amounts have been reclassified to conform to the current presentation. In the Consolidated Balance Sheet as of December 31, 2014, CenterPoint Houston reclassified $2 million from current deferred tax assets to reduce deferred income taxes within non-current liabilities. See Note 9 for additional information. Management believes that other recently issued standards, which are not yet effective, will not have a material impact on CenterPoint Energy’s consolidated financial position, results of operations or cash flows upon adoption. (m) Other Current Liabilities Included in other current liabilities in the Consolidated Balance Sheets as of December 31, 2015 and 2014 was $12 million and $24 million, respectively, of customer deposits primarily held by the transition and system restoration bond companies. (n) Environmental Costs CenterPoint Houston expenses or capitalizes environmental expenditures, as appropriate, depending on their future economic benefit. CenterPoint Houston expenses amounts that relate to an existing condition caused by past operations that do not have future economic benefit. CenterPoint Houston records undiscounted liabilities related to these future costs when environmental assessments and/or remediation activities are probable and the costs can be reasonably estimated.

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

(a) Property, Plant and Equipment

Property, plant and equipment includes the following:



	Weighted Average Useful	December 31,
	Lives (Years)	2015		2014
		(in millions)
Transmission	41	$	2,196	$	2,057
Distribution	30	6,556		6,170
Other	16	1,390		1,166
Total		10,142		9,393
Accumulated depreciation		3,209		3,050
Property, plant and equipment, net		$	6,933	$	6,343

(b) Depreciation and Amortization

The following table presents depreciation and amortization expense for 2015, 2014 and 2013:



	Year Ended December 31,
	2015		2014		2013
	(in millions)
Depreciation expense	$	316	$	295	$	280
Amortization of securitized regulatory assets	365		441		383
Other amortization	24		32		22
Total depreciation and amortization	$	705	$	768	$	685

A reconciliation of the changes in the asset retirement obligation (ARO) liability is as follows:



	December 31,
	2015		2014
	(in millions)
Beginning balance	$	36	$	33
Accretion expense	1		1
Revisions in estimates of cash flows	—		2
Ending balance	$	37	$	36

CenterPoint Houston recorded AROs associated with the removal of asbestos and asbestos-containing material in its buildings, including substation building structures. CenterPoint Houston also recorded AROs relating to treated wood poles for electric distribution, distribution transformers containing PCB (also known as Polychlorinated Biphenyl), and underground fuel storage tanks. The estimates of future liabilities were developed using historical information, and where available, quoted prices from outside contractors.

The increase of $2 million in the ARO from the revision of estimate in 2014 is primarily attributable to an increase in the expected future cash flows for asbestos remediation. There were no material additions or settlements during the years ended December 31, 2015 and 2014.

Regulatory Matters

12 Months Ended

Dec. 31, 2015

Regulatory Assets and Liabilities, Other Disclosures [Abstract]

Regulatory Matters [Text Block]

Regulatory Matters

The following is a list of regulatory assets/liabilities reflected on CenterPoint Houston’s Consolidated Balance Sheets as of December 31, 2015 and 2014:



	December 31,
	2015			2014
	(in millions)
Securitized regulatory assets	$	2,373		$	2,738
Unrecognized equity return (1)	(393		)	(442		)
Unamortized loss on reacquired debt	93			104
Pension and postretirement-related regulatory asset	50			107
Other long-term regulatory assets (2)	88			122
Total regulatory assets	2,211			2,629

Estimated removal costs	350			353
Other long-term regulatory liabilities	192			184
Total regulatory liabilities	542			537

Total regulatory assets and liabilities, net	$	1,669		$	2,092

(1)

As of December 31, 2015, CenterPoint Houston has not recognized an allowed equity return of $393 million because such return will be recognized as it is recovered in rates through 2024. During the years ended December 31, 2015, 2014 and 2013, CenterPoint Houston recognized approximately $49 million, $68 million and $45 million, respectively, of the allowed equity return. The timing of CenterPoint Houston’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 Texas Utility Commission 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, 2015 and 2014.

Employee Benefit Plans

12 Months Ended

Dec. 31, 2015

Compensation and Retirement Disclosure [Abstract]

Pension and Other Postretirement Benefits Disclosure [Text Block]

Employee Benefit Plans

(a) Pension Plans

Substantially all of CenterPoint Houston’s employees participate in CenterPoint Energy’s non-contributory qualified defined benefit plan. Under the cash balance formula, participants accumulate a retirement benefit based upon 5% of eligible earnings and accrued interest.

CenterPoint Energy’s funding policy is to review amounts annually in accordance with applicable regulations in order to achieve adequate funding of projected benefit obligations. Pension expense is allocated to CenterPoint Houston based on covered employees. This calculation is intended to allocate pension costs in the same manner as a separate employer plan. Assets of the plan are not segregated or restricted by CenterPoint Energy’s participating subsidiaries. CenterPoint Houston recognized pension expense of $35 million, $26 million and $25 million for the years ended December 31, 2015, 2014 and 2013, respectively.

In addition to the pension plan, CenterPoint Houston participates in CenterPoint Energy’s non-qualified benefit restoration plans, which allow participants to receive the benefits to which they would have been entitled under the non-contributory pension plan except for federally mandated limits on qualified plan benefits or on the level of compensation on which qualified plan benefits may be calculated. The expense associated with the non-qualified pension plan was $1 million for each of the years ended December 31, 2015, 2014 and 2013.

(b) Savings Plan

CenterPoint Houston participates in CenterPoint Energy’s qualified savings plan, which includes a cash or deferred arrangement under Section 401(k) of the Internal Revenue Code of 1986, as amended (the Code), and an Employee Stock Ownership Plan (ESOP) under Section 4975(e)(7) of the Code. Under the plan, participating employees may contribute a portion of their compensation, on a pre-tax or after-tax basis, generally up to a maximum of 50% of eligible compensation. CenterPoint Houston matches 100% of the first 6% of each employee’s compensation contributed. The matching contributions are fully vested at all times.

Participating employees may elect to invest all (prior to January 1, 2016) or a portion of their contributions to the plan in CenterPoint Energy common stock, to have dividends reinvested in additional shares or to receive dividend payments in cash on any investment in CenterPoint Energy common stock, and to transfer all or part of their investment in CenterPoint Energy common stock to other investment options offered by the plan.

Effective January 1, 2016 the savings plan was amended to limit the percentage of future contributions that could be invested in CenterPoint Energy common stock to 25% and to prohibit transfers of account balances where the transfer would result in more than 25% of a participant’s total account balance invested in CenterPoint Energy common stock.

The savings plan has significant holdings of CenterPoint Energy common stock. As of December 31, 2015, 16,942,974 shares of CenterPoint Energy’s common stock were held by the savings plan, which represented approximately 17% of its investments. Given the concentration of the investments in CenterPoint Energy’s common stock, the savings plan and its participants have market risk related to this investment.

CenterPoint Energy allocates to CenterPoint Houston the savings plan benefit expense related to CenterPoint Houston’s employees. Savings plan benefit expense was $14 million, $13 million and $13 million for each of the years ended December 31, 2015, 2014 and 2013.

CenterPoint Houston’s employees participate in CenterPoint Energy’s benefit plans which provide certain healthcare and life insurance benefits for retired employees on both a contributory and non-contributory basis. Employees become eligible for these benefits if they have met certain age and service requirements at retirement, as defined in the plans. Under plan amendments effective in early 1999, healthcare benefits for future retirees were changed to limit employer contributions for medical coverage. Such benefit costs are accrued over the active service period of employees.

CenterPoint Houston is required to fund a portion of its obligations in accordance with rate orders. The net postretirement benefit cost includes the following components:



	Year Ended December 31,
	2015			2014			2013
	(in millions)
Service cost - benefits earned during the period	$	1		$	1		$	1
Interest cost on accumulated benefit obligation	13			14			13
Expected return on plan assets	(6		)	(6		)	(7		)
Amortization of transition obligation	—			4			6
Amortization of prior service credit	(2		)	(2		)	(1		)
Amortization of loss	3			1			4
Net postretirement benefit cost	$	9		$	12		$	16

CenterPoint Houston used the following assumptions to determine net postretirement benefit costs:



	Year Ended December 31,
	2015		2014		2013
Discount rate	3.90	%	4.75	%	3.90	%
Expected return on plan assets	5.45	%	6.00	%	6.00	%

In determining net periodic benefits cost, CenterPoint Houston uses fair value, as of the beginning of the year, as its basis for determining expected return on plan assets.

Following are reconciliations of CenterPoint Houston’s beginning and ending balances of its postretirement benefit plan’s benefit obligation, plan assets and funded status for 2015 and 2014. The measurement dates for plan assets and obligations were December 31, 2015 and 2014.



	December 31,
	2015			2014
	(in millions)
Change in Benefit Obligation
Accumulated benefit obligation, beginning of year	$	347		$	311
Service cost	1			1
Interest cost	13			14
Benefits paid	(17		)	(18		)
Participant contributions	3			3
Medicare drug reimbursement	1			1
Plan amendment	(4		)	—
Actuarial (gain) loss	(61		)	35
Accumulated benefit obligation, end of year	$	283		$	347
Change in Plan Assets
Plan assets, beginning of year	$	115		$	114
Benefits paid	(17		)	(18		)
Employer contributions	9			9
Participant contributions	3			3
Actual investment return	—			7
Plan assets, end of year	$	110		$	115
Amounts Recognized in Balance Sheets
Other liabilities-benefit obligations	$	(173	)	$	(232	)
Net liability, end of year	$	(173	)	$	(232	)
Actuarial Assumptions
Discount rate	4.35		%	3.90		%
Expected long-term return on assets	5.00		%	5.45		%
Healthcare cost trend rate assumed for the next year - Pre 65	6.00		%	7.25		%
Healthcare cost trend rate assumed for the next year - Post 65	5.50		%	8.50		%
Prescription drug cost trend rate assumed for the next year	11.00		%	6.50		%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate)	5.00		%	5.00		%
Year that the healthcare rate reaches the ultimate trend rate	2024			2024
Year that the prescription drug rate reaches the ultimate trend rate	2024			2024

The discount rate assumption was determined by matching the projected cash flows of CenterPoint Energy’s plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years.

The expected rate of return assumption was developed by a weighted-average return analysis of the targeted asset allocation of CenterPoint Energy’s plans and the expected real return for each asset class, based on the long-term capital market assumptions, adjusted for investment fees and diversification effects, in addition to expected inflation.

For measurement purposes, medical costs are assumed to increase 6.00% and 5.50% for the pre-65 and post-65 retirees during 2016, respectively, and the prescription cost is assumed to increase 11.00% during 2016, after which these rates decrease until reaching the ultimate trend rate of 5.00% in 2024.

CenterPoint Houston does not have amounts recognized in accumulated other comprehensive income related to its postretirement benefit plans as of December 31, 2015 and 2014. Unrecognized costs were recorded as a regulatory asset because CenterPoint Houston historically and currently recovers postretirement expenses in rates.

Assumed healthcare cost trend rates have a significant effect on the reported amounts for CenterPoint Houston’s postretirement benefit plans. A 1% change in the assumed healthcare cost trend rate would have the following effects:



	1% Increase		1% Decrease
	(in millions)
Effect on the postretirement benefit obligation	$	9	$	8
Effect on total of service and interest cost	—		—

In managing the investments associated with the postretirement benefit plans, CenterPoint Houston’s objective is to preserve and enhance the value of plan assets while maintaining an acceptable level of volatility. These objectives are expected to be achieved through an investment strategy that manages liquidity requirements while maintaining a long-term horizon in making investment decisions and efficient and effective management of plan assets.

As part of the investment strategy discussed above, CenterPoint Houston has adopted and maintained the following asset allocation ranges for its postretirement benefit plans:



U.S. equity	14–24%
International equity	3–13%
Fixed income	68–78%
Cash	0–2%

The following tables present by level, within the fair value hierarchy, CenterPoint Houston’s postretirement plan assets as of December 31, 2015 and 2014, by asset category as follows:



	Fair Value Measurements as of December 31, 2015
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in millions)
Mutual funds (1)	$	110	$	110	$	—	$	—
Total	$	110	$	110	$	—	$	—


(1)	73% of the amount invested in mutual funds was in fixed income securities; 19% was in U.S. equities and 8% was in international equities.



	Fair Value Measurements as of December 31, 2014
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in millions)
Mutual funds (1)	$	115	$	115	$	—	$	—
Total	$	115	$	115	$	—	$	—


(1)	73% of the amount invested in mutual funds was in fixed income securities; 19% was in U.S. equities and 8% was in international equities.

CenterPoint Houston expects to contribute $7 million to its postretirement benefits plan in 2016. The following benefit payments are expected to be paid by the postretirement benefit plan:



	Postretirement Benefit Plan
	Benefit Payments		Medicare Subsidy Receipts
	(in millions)
2016	$	20	$	(2	)
2017	21		(2		)
2018	22		(3		)
2019	23		(3		)
2020	24		(3		)
2021-2025	124		(19		)

(d) Postemployment Benefits

CenterPoint Houston participates in CenterPoint Energy’s plan which provides postemployment benefits for certain former or inactive employees, their beneficiaries and covered dependents, after employment but before retirement (primarily health care and life insurance benefits for participants in the long-term disability plan). CenterPoint Houston recorded a postemployment credit of $1 million, and expenses of $1 million and $4 million for the years ended December 31, 2015, 2014 and 2013, respectively. Amounts relating to postemployment obligations included in Benefit Obligations in the accompanying Consolidated Balance Sheets as of December 31, 2015 and 2014 were $6 million and $14 million, respectively.

(e) Other Non-Qualified Plans

CenterPoint Houston participates in CenterPoint Energy’s deferred compensation plans that provide benefits payable to directors, officers and certain key employees or their designated beneficiaries at specified future dates, upon termination, retirement or death. Benefit payments are made from the general assets of CenterPoint Houston. CenterPoint Houston recorded benefit expense relating to these plans of $1 million in each of the years ended December 31, 2015, 2014 and 2013. Amounts relating to deferred compensation plans included in Benefit Obligations in the accompanying Consolidated Balance Sheets as of December 31, 2015 and 2014 were $11 million and $12 million, respectively.

(f) Other Employee Matters

As of December 31, 2015, CenterPoint Houston had 2,665 full-time employees, of which approximately 51% were subject to a collective bargaining agreement. The collective bargaining agreement with the International Brotherhood of Electrical Workers Local 66 is scheduled to expire in May of 2016. CenterPoint Houston believes it has a good relationship with this bargaining unit and expects to negotiate a new agreement in 2016.

Fair Value Measurements

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Fair Value Disclosures [Text Block]

Fair Value Measurements

Assets and liabilities that are recorded at fair value in the 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. At December 31, 2015 and 2014, CenterPoint Houston held Level 1 investments of $32 million and $43 million, respectively, which were primarily investments in money market funds and are included in other current assets in the 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. CenterPoint Houston had no Level 2 assets or liabilities at either December 31, 2015 and 2014.

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 CenterPoint Houston’s judgments about the assumptions market participants would use in determining fair value. CenterPoint Houston had no Level 3 assets or liabilities at either December 31, 2015 and 2014.

CenterPoint Houston 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 years ended December 31, 2015 and 2014, 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 Consolidated Balance Sheets but for which the fair value is disclosed, would be classified as Level 1 in the fair value hierarchy.



	December 31, 2015				December 31, 2014
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(in millions)
Financial liabilities:
Long-term debt, including current portion	$	4,880	$	5,108	$	5,052	$	5,441

- 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

12 Months Ended

Dec. 31, 2015

Related Party Transactions and Major Customers

(a) Related Party Transactions

CenterPoint Houston 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. CenterPoint Houston had borrowings from the money pool of $312 million and investments in the money pool of $107 million as of December 31, 2015 and 2014, respectively, which are included in accounts and notes receivable-affiliated companies and accounts and notes payable-affiliated companies, respectively, in the Consolidated Balance Sheets. As of December 31, 2015, CenterPoint Houston’s money pool borrowings had a weighted-average interest rate of 0.80%.

For the years ended December 31, 2015, 2014 and 2013, CenterPoint Houston had affiliate related net interest income (expense) of $(1) million, less than $(1) million and $20 million, respectively.

CenterPoint Energy provides some corporate services to CenterPoint Houston. The costs of services have been charged directly to CenterPoint Houston 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. CenterPoint Energy Resources Corp. (CERC Corp., and together with its subsidiaries, CERC) provides certain services to CenterPoint Houston. These services are billed at actual cost, either directly or as an allocation and include line locating and other miscellaneous services. Additionally, CenterPoint Houston 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, radio communications, data circuit management and field operations. These charges are not necessarily indicative of what would have been incurred had CenterPoint Houston not been an affiliate. Amounts charged to CenterPoint Houston for these services were as follows and are included primarily in operation and maintenance expenses:



	Year Ended December 31,
	2015			2014			2013
	(in millions)
Corporate service charges	$	176		$	159		$	147

Charges from CERC for services provided	6			5			9

Billings to CERC for services provided	(18		)	(17		)	(21		)

CenterPoint Houston paid dividends of $252 million, $-0- and $766 million on its common shares to Utility Holding, LLC in 2015, 2014 and 2013, respectively. In 2014, CenterPoint Energy made an equity contribution of $90 million to CenterPoint Houston.

(b) Major Customers

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



	Year Ended December 31,
	2015		2014		2013
	(in millions)
Affiliates of NRG	$	741	$	735	$	658
Affiliates of Energy Future Holdings Corp.	$	220	$	189	$	167

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

Long-term Debt

12 Months Ended

Dec. 31, 2015

Debt Disclosure [Abstract]

Debt Disclosure [Text Block]

Long-term Debt



	December 31, 2015					December 31, 2014
	Long-Term			Current (1)		Long-Term			Current (1)
	(in millions)
Long-term debt:
Bank Loans	$	200		$	—	$	—		$	—
First mortgage bonds 9.15% due 2021	102			—		102			—
General mortgage bonds 2.25% to 6.95% due 2022 to 2044 (2)	1,912			—		1,912			—
System restoration bonds 3.46% to 4.243% due 2018 to 2022	365			50		415			48
Transition bonds 0.901% to 5.302% due 2017 to 2024	1,918			341		2,259			324
Other	(8		)	—		(8		)	—
Total long-term debt	$	4,489		$	391	$	4,680		$	372


(1)	Includes amounts due or scheduled to be paid within one year of the date noted.


(2)	Debt issued as collateral is excluded from the financial statements because of the contingent nature of the obligation.

Transition and System Restoration Bonds. As of December 31, 2015, CenterPoint Houston had special purpose subsidiaries consisting of transition and system restoration bond companies, which it consolidates. The consolidated special purpose subsidiaries are wholly-owned bankruptcy remote entities that were formed solely for the purpose of purchasing and owning transition or system restoration property through the issuance of transition bonds or system restoration bonds and activities incidental thereto. These transition bonds and system restoration bonds are payable only through the imposition and collection of “transition” or “system restoration” charges, as defined in the Texas Public Utility Regulatory Act, which are irrevocable, non-bypassable charges payable by most of CenterPoint Houston’s retail electric customers in order to provide recovery of authorized qualified costs. CenterPoint Houston has no payment obligations in respect of the transition and system restoration bonds other than to remit the applicable transition or system restoration charges it collects. Each special purpose entity is the sole owner of the right to impose, collect and receive the applicable transition or system restoration charges securing the bonds issued by that entity. Creditors of CenterPoint Energy or CenterPoint Houston have no recourse to any assets or revenues of the transition and system restoration bond companies (including the transition and system restoration charges), and the holders of transition bonds or system restoration bonds have no recourse to the assets or revenues of CenterPoint Energy or CenterPoint Houston.

Revolving Credit Facility. As of December 31, 2015 and 2014, CenterPoint Houston had the following revolving credit facility and utilization of such facility:



December 31, 2015							December 31, 2014
Size of Facility		Loans			Letters of Credit		Size of Facility		Loans		Letters of Credit
(in millions)
$	300	$	200	(1)	$	4	$	300	$	—	$	4


(1)	Weighted average interest rate was 1.637% as of December 31, 2015.

CenterPoint Houston’s $300 million revolving credit facility, which is scheduled to terminate on September 9, 2019, can be drawn at LIBOR plus 1.125% based on CenterPoint Houston’s current credit ratings. The revolving credit facility contains a financial covenant which limits CenterPoint Houston’s consolidated debt (excluding transition and system restoration bonds) to an amount not to exceed 65% of CenterPoint Houston’s consolidated capitalization. CenterPoint Houston was in compliance with all financial covenants as of December 31, 2015. As of December 31, 2015, CenterPoint Houston’s debt (excluding transition and system restoration bonds) to capital ratio, as defined in its credit facility agreement, was 51.7%.

Maturities. CenterPoint Houston has no maturities of long-term debt for 2016 through 2020 other than the maturity of $200 million of bank loans in 2019. CenterPoint Houston’s scheduled payments on transition and system restoration bonds are $391 million in 2016, $411 million in 2017, $434 million in 2018, $458 million in 2019 and $231 million in 2020.

Liens. As of December 31, 2015, CenterPoint Houston’s assets were subject to liens securing approximately $102 million of first mortgage bonds. Sinking or improvement fund and replacement fund requirements on the first mortgage bonds may be satisfied by certification of property additions. Sinking fund and replacement fund requirements for 2015, 2014 and 2013 have been satisfied by certification of property additions. The replacement fund requirement to be satisfied in 2016 is approximately $223 million, and the sinking fund requirement to be satisfied in 2016 is approximately $1.6 million. CenterPoint Houston expects to meet these 2016 obligations by certification of property additions. As of December 31, 2015, CenterPoint Houston’s assets were also subject to liens securing approximately $2.1 billion of general mortgage bonds which are junior to the liens of the first mortgage bonds.

Income Taxes

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Income Tax Disclosure [Text Block]

Income Taxes

The components of CenterPoint Houston’s income tax expense were as follows:



	Year Ended December 31,
	2015		2014			2013
	(in millions)
Current income tax expense:
Federal	$	106	$	136		$	201
State	21		19			20
Total current expense	127		155			221
Deferred income tax expense (benefit):
Federal	18		(24		)	(75		)
Total deferred expense (benefit)	18		(24		)	(75		)
Total income tax expense	$	145	$	131		$	146

A reconciliation of income tax expense using the federal statutory income tax rate to the actual income tax expense and resulting effective income tax rate is as follows:



	Year Ended December 31,
	2015			2014			2013
	(in millions)
Income before income taxes	$	406		$	383		$	415
Federal statutory income tax rate	35.0		%	35.0		%	35.0		%
Expected federal income tax expense	142			134			145
Increase (decrease) in tax expense resulting from:
State income tax expense, net of federal income tax	14			12			13
Decrease in settled and uncertain tax positions	—			—			(5		)
Other, net	(11		)	(15		)	(7		)
Total	3			(3		)	1
Total income tax expense	$	145		$	131		$	146
Effective tax rate	35.7		%	34.2		%	35.2		%

In 2014, CenterPoint Houston recognized a $6 million reversal of previously accrued taxes as a result of final positions taken in the 2013 income tax returns. CenterPoint Houston recognized a tax benefit of $5 million from favorable audit settlements for the year ended December 31, 2013.

The tax effects of temporary differences that give rise to significant portions of deferred tax assets and liabilities were as follows:



	December 31,
	2015		2014
	(in millions)
Deferred tax assets:
Benefits and compensation	$	69	$	92
Loss and credit carryforwards	6		—
Asset retirement obligations	13		12
Other	7		7
Total deferred tax assets	95		111

Deferred tax liabilities:
Property, plant, and equipment	1,447		1,284
Regulatory assets/liabilities, net	680		826
Total deferred tax liabilities	2,127		2,110
Net deferred tax liabilities	$	2,032	$	1,999

Effective December 31, 2015, all deferred taxes for 2014 and 2015 are classified as noncurrent. See Note 2.

CenterPoint Houston is included in the consolidated income tax returns of CenterPoint Energy. CenterPoint Houston calculates its income tax provision on a separate return basis under a tax sharing agreement with CenterPoint Energy.

Uncertain Income Tax Positions. CenterPoint Houston reported no uncertain tax liability as of December 31, 2015 and expects no significant change to the uncertain tax liability over the next twelve months ending December 31, 2016.

Tax Audits and Settlements. CenterPoint Energy’s tax years through 2013 have been audited and settled with the Internal Revenue Service (IRS). For 2014 and 2015, CenterPoint Energy is a participant in the IRS’s Compliance Assurance Process. CenterPoint Energy has considered the effects of these examinations in its accrual for settled issues and liability for uncertain income tax positions (if any) as of December 31, 2015.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	Commitments and Contingencies (a) Lease Commitments CenterPoint Houston currently has obligations under non-cancelable long-term operating leases of less than $1 million per year for the years 2016 to 2020. Total lease expense for all operating leases was less than $1 million in each of the years ended December 31, 2015, 2014 and 2013. (b) Legal and Environmental Matters Legal Matters Gas Market Manipulation Cases. CenterPoint Energy, CenterPoint Houston or their predecessor, Reliant Energy, Incorporated (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, Reliant Resources, Inc. (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 Energy, Inc. (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 CenterPoint Houston, 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 but one such case. CenterPoint Energy Services, Inc. (CES), a subsidiary of CERC Corp., is a defendant in a case now pending in federal court in Nevada alleging a conspiracy to inflate Wisconsin natural gas prices in 2000–2002. In July 2011, the court issued an order dismissing the plaintiffs’ claims against other defendants in the case, each of whom had demonstrated Federal Energy Regulatory Commission jurisdictional sales for resale during the relevant period, based on federal preemption, and stayed the remainder of the case pending outcome of the appeals. The plaintiffs appealed this ruling to the U.S. Court of Appeals for the Ninth Circuit, which reversed the trial court’s dismissal of the plaintiffs’ claims. On April 21, 2015, the U.S. Supreme Court affirmed the Ninth Circuit’s ruling and remanded the case to the district court for further proceedings, which are now underway. CenterPoint Energy and CES intend to continue vigorously defending against the plaintiffs’ claims. CenterPoint Energy 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. Environmental Matters Asbestos. Some facilities owned by CenterPoint Energy contain or have contained asbestos insulation and other asbestos-containing materials. CenterPoint Energy or its subsidiaries, including CenterPoint Houston, have been named, along with numerous others, as a defendant in lawsuits filed by a number of individuals who claim injury due to exposure to asbestos. Some of the claimants have worked at locations owned by CenterPoint Energy or CenterPoint Houston, but most existing claims relate to facilities previously owned by CenterPoint Energy’s other subsidiaries or CenterPoint Houston. In 2004 and early 2005, CenterPoint Energy sold its generating business, to which most of these claims relate, to a company which is now an affiliate of NRG. Under the terms of the arrangements regarding separation of the generating business from CenterPoint Energy and its sale of that business, ultimate financial responsibility for uninsured losses from claims relating to the generating business has been assumed by the NRG affiliate, but CenterPoint Energy has agreed to continue to defend such claims to the extent they are covered by insurance maintained by CenterPoint Energy, subject to reimbursement of the costs of such defense by the NRG affiliate. CenterPoint Energy anticipates that additional claims like those received may be asserted in the future. Although their ultimate outcome cannot be predicted at this time, CenterPoint Houston or CenterPoint Energy, as appropriate, intends to continue vigorously contesting claims that it does not consider to have merit and, based on its experience to date, CenterPoint Houston 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, CenterPoint Houston identifies the presence of environmental contaminants on property where it conducts or has conducted operations. Other such sites involving contaminants may be identified in the future. CenterPoint Houston has and expects to continue to remediate identified sites consistent with its legal obligations. From time to time, CenterPoint Houston 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, CenterPoint Houston 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, CenterPoint Houston does not expect, based on its experience to date, 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 CenterPoint Houston 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, CenterPoint Houston 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. CenterPoint Houston regularly analyzes current information and, as necessary, provides accruals for probable and reasonably estimable liabilities on the eventual disposition of these matters. CenterPoint Houston does not expect the disposition of these matters to have a material adverse effect on CenterPoint Houston’s financial condition, results of operations or cash flows.

Unaudited Quarterly Information

12 Months Ended

Dec. 31, 2015

Unaudited Quarterly Information [Abstract]

Quarterly Financial Information [Text Block]

Unaudited Quarterly Information

Summarized quarterly financial data is as follows:



	Year Ended December 31, 2015
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in millions)
Revenues	$	617	$	705	$	827	$	697
Operating income	101		158		244		105
Net income	31		69		124		37



	Year Ended December 31, 2014
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in millions)
Revenues	$	630	$	698	$	839	$	679
Operating income	106		145		232		113
Net income	35		57		119		41

Restatement (Notes)

12 Months Ended

Dec. 31, 2015

Restatement

Accounting Changes and Error Corrections [Text Block]

Restatement of Statement of Consolidated Cash Flows

As disclosed in Note 7, CenterPoint Houston participates in a centralized cash management arrangement or money pool with affiliates. Investments in the money pool are included in the consolidated balance sheets as accounts and notes receivable–affiliated companies, while borrowings are included in accounts and notes payable–affiliated companies. Under generally accepted accounting principles, receivables from an affiliate in a centralized cash management arrangement such as the money pool are considered loans, and corresponding changes should be classified in cash flows from investing activities in the statements of consolidated cash flows, while payables are considered borrowings and should be classified in cash flows from financing activities. Subsequent to the issuance of CenterPoint Houston’s consolidated financial statements for the year ended December 31, 2015, CenterPoint Houston determined that borrowings from the money pool were incorrectly classified in its statement of consolidated cash flows, resulting in an overstatement of accounts receivable/payable–affiliated companies and net cash provided by operating activities by approximately $312 million, an understatement of increase in notes payable–affiliated companies by approximately $312 million and an overstatement of net cash used in financing activities by approximately $312 million. As a result, the accompanying 2015 statement of consolidated cash flows has been restated from the amounts previously reported to reflect correct cash flow classification of borrowings from the money pool. There was no effect on CenterPoint Houston’s previously reported statements of consolidated income, consolidated balance sheets, and statements of consolidated member’s equity for 2015.

A summary of the significant effects of the restatement is as follows:



	Year Ended December 31, 2015
	As Restated			As Previously Reported
	(in millions)
Statements of Consolidated Cash Flows:
Cash Flows from Operating Activities:
Accounts receivable/payable–affiliated companies	$	(89	)	$	223
Net cash provided by operating activities	895			1,207
Cash Flows from Financing Activities:
Increase in notes payable–affiliated companies	312			—
Net cash used in financing activities	(112		)	(424		)

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2015
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates 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.
Principles of Consolidation	Principles of Consolidation The accounts of CenterPoint Houston and its wholly-owned subsidiaries are included in CenterPoint Houston’s consolidated financial statements. All intercompany transactions and balances are eliminated in consolidation. As of December 31, 2015, CenterPoint Houston had variable interest entities (VIEs) consisting of transition and system restoration 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 CenterPoint Houston have no recourse to any assets or revenues of the transition and system restoration 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 CenterPoint Houston.
Revenues	Revenues CenterPoint Houston records revenue for electricity delivery under the accrual method and these revenues are recognized upon delivery to customers. Electricity deliveries not billed by month-end are accrued based on actual advanced metering system data, daily supply volumes and applicable rates.
Long-Lived Assets and Intangibles	Long-Lived Assets and Intangibles CenterPoint Houston records property, plant and equipment at historical cost. CenterPoint Houston expenses repair and maintenance costs as incurred. CenterPoint Houston periodically evaluates long-lived assets, including property, plant and equipment, and specifically identifiable intangibles, when events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. The determination of whether an impairment has occurred is based on an estimate of undiscounted cash flows attributable to the assets compared to the carrying value of the assets.
Regulatory Assets and Liabilities	Regulatory Assets and Liabilities CenterPoint Houston applies the guidance for accounting for regulated operations. CenterPoint Houston’s rate-regulated subsidiaries may collect revenues subject to refund pending final determination in rate proceedings. In connection with such revenues, estimated rate refund liabilities are recorded which reflect management’s current judgment of the ultimate outcomes of the proceedings. CenterPoint Houston recognizes removal costs as a component of depreciation expense in accordance with regulatory treatment. As of December 31, 2015 and 2014, these removal costs of $350 million and $353 million, respectively, are classified as regulatory liabilities in CenterPoint Houston’s Consolidated Balance Sheets. In addition, a portion of the amount of removal costs that relate to asset retirement obligations has been reclassified from a regulatory liability to an asset retirement liability in accordance with accounting guidance for asset retirement obligations.
Depreciation and Amortization Expense	Depreciation and Amortization Expense Depreciation is computed using the straight-line method based on economic lives or a regulatory-mandated recovery period. Transition and system restoration property is being amortized over the expected life of the transition and system restoration bonds (12 to 14 years), based on estimated revenue from transition or system restoration charges, interest accruals and other expenses. Other amortization expense includes amortization of regulatory assets and other intangibles.
Allowance for Funds Used During Construction	Allowance for Funds Used During Construction Allowance for funds used during construction (AFUDC) is capitalized as a component of projects under construction and is amortized over the assets’ estimated useful lives once the assets are placed in service. AFUDC represents the composite interest cost of borrowed funds and a reasonable return on the equity funds used for construction. Although AFUDC increases both utility plant and earnings, it is realized in cash when the assets are included in rates. During 2015, 2014 and 2013, CenterPoint Houston capitalized AFUDC interest of $8 million, $10 million and $10 million, respectively. During 2015, 2014 and 2013, CenterPoint Energy recorded AFUDC equity of $12 million, $14 million and $8 million, respectively, which is included in Other Income in its Statements of Consolidated Income.
Income Taxes	Income Taxes CenterPoint Houston is included in the consolidated income tax returns of CenterPoint Energy. CenterPoint Houston calculates its income tax provision on a separate return basis under a tax sharing agreement with CenterPoint Energy. CenterPoint Houston uses the asset and liability method of accounting for deferred income taxes. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. A valuation allowance is established against deferred tax assets for which management believes realization is not considered to be more likely than not. CenterPoint Houston recognizes interest and penalties as a component of income tax expense. Current federal and certain state income taxes are payable to or receivable from CenterPoint Energy.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are recorded at the invoiced amount and do not bear interest. It is the policy of management to review the outstanding accounts receivable monthly, as well as the bad debt write-offs experienced in the past, and establish an allowance for doubtful accounts. Account balances are charged off against the allowance when management determines it is probable the receivable will not be recovered. The provision for doubtful accounts in CenterPoint Houston’s Statements of Consolidated Income for 2015, 2014 and 2013 was less than $1 million, $3 million and $2 million, respectively.
Inventory	Inventory Inventory consists principally of materials and supplies and is valued at the lower of average cost or market. Materials and supplies are recorded to inventory when purchased and subsequently charged to expense or capitalized to plant when installed.
Statements of Consolidated Cash Flows	Statements of Consolidated Cash Flows For purposes of reporting cash flows, CenterPoint Houston considers cash equivalents to be short-term, highly-liquid investments with maturities of three months or less from the date of purchase. In connection with the issuance of transition bonds and system restoration bonds, CenterPoint Houston was required to establish restricted cash accounts to collateralize the bonds that were issued in these financing transactions. These restricted cash accounts are not available for withdrawal until the maturity of the bonds and are not included in cash and cash equivalents. These restricted cash accounts of $35 million and $47 million as of December 31, 2015 and 2014, respectively, are included in other current assets in CenterPoint Houston’s Consolidated Balance Sheets. For additional information regarding transition and system restoration bonds, see Note 8. Cash and cash equivalents included $264 million and $290 million as of December 31, 2015 and 2014, respectively, that was held by CenterPoint Houston’s transition and system restoration bond subsidiaries solely to support servicing the transition and system restoration bonds.
New Accounting Pronouncements, Policy [Policy Text Block]	New Accounting Pronouncements In February 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis (ASU 2015-02). ASU 2015-02 changes the analysis that reporting organizations must perform to evaluate whether they should consolidate certain legal entities, such as limited partnerships. The changes include, among others, modification of the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities and elimination of the presumption that a general partner should consolidate a limited partnership. ASU 2015-02 does not amend the related party guidance for situations in which power is shared between two or more entities that hold interests in a VIE. ASU 2015-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015. CenterPoint Houston does not believe that ASU 2015-02 will have a material impact on its financial position, results of operations, cash flows and disclosures. In April 2015, the FASB issued Accounting Standards Update No. 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost (ASU 2015-03). ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by ASU 2015-03. CenterPoint Houston will adopt ASU 2015-03 retrospectively on January 1, 2016, which will result in a reduction of both other long-term assets and long-term debt on its Consolidated Balance Sheets. CenterPoint Houston had debt issuance costs of $22 million and $26 million included in other long-term assets on its Consolidated Balance Sheets as of December 31, 2015 and 2014, respectively. In April 2015, the FASB issued Accounting Standards Update No. 2015-05, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40) (ASU 2015-05). ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The guidance will not change a customer’s accounting for service contracts. ASU 2015-05 is effective for fiscal years, and interim periods within the fiscal years, beginning after December 15, 2015 and may be adopted either prospectively or retrospectively. CenterPoint Houston will adopt ASU 2015-05 prospectively on January 1, 2016. CenterPoint Houston does not believe that ASU 2015-05 will have a material impact on its financial position, results of operations, cash flows and disclosures. In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09), which supersedes most current revenue recognition guidance. ASU 2014-09 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. ASU 2014-09 was initially effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. Early adoption is not permitted, and entities have the option of using either a full retrospective or a modified retrospective adoption approach. In August 2015, the FASB issued Accounting Standard Update No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which delays the effective date of ASU 2014-09 by one year. CenterPoint Houston is currently evaluating the impact that ASU 2014-09 will have on its financial position, results of operations, cash flows and disclosures, and will adopt ASU 2014-09 on January 1, 2018 as permitted by the new guidance. In July 2015, the FASB issued Accounting Standards Update No. 2015-11, Inventory (Topic 330) Simplifying the Measurement of Inventory (ASU 2015-11). ASU 2015-11 changes the subsequent measurement guidance for inventory accounted for using methods other than the last in, first out (LIFO) and Retail Inventory methods. Companies will subsequently measure inventory at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. Subsequent measurement is unchanged for inventory measured using LIFO or the retail inventory method. ASU 2015-11 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016, with early adoption permitted. CenterPoint Houston does not believe that ASU 2015-11 will have a material impact on its financial position, results of operations, cash flows and disclosures. In November 2015, the FASB issued Accounting Standards Update No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes (ASU 2015-17). ASU 2015-17 requires deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. CenterPoint Houston adopted ASU 2015-17 retrospectively starting with fiscal year 2015. As such, certain prior period amounts have been reclassified to conform to the current presentation. In the Consolidated Balance Sheet as of December 31, 2014, CenterPoint Houston reclassified $2 million from current deferred tax assets to reduce deferred income taxes within non-current liabilities. See Note 9 for additional information. Management believes that other recently issued standards, which are not yet effective, will not have a material impact on CenterPoint Energy’s consolidated financial position, results of operations or cash flows upon adoption.
Other Current Liabilities [Policy Text Block]	Other Current Liabilities Included in other current liabilities in the Consolidated Balance Sheets as of December 31, 2015 and 2014 was $12 million and $24 million, respectively, of customer deposits primarily held by the transition and system restoration bond companies.
Environmental Costs, Policy [Policy Text Block]	Environmental Costs CenterPoint Houston expenses or capitalizes environmental expenditures, as appropriate, depending on their future economic benefit. CenterPoint Houston expenses amounts that relate to an existing condition caused by past operations that do not have future economic benefit. CenterPoint Houston records undiscounted liabilities related to these future costs when environmental assessments and/or remediation activities are probable and the costs can be reasonably estimated.

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Equipment

Property, plant and equipment includes the following:



	Weighted Average Useful	December 31,
	Lives (Years)	2015		2014
		(in millions)
Transmission	41	$	2,196	$	2,057
Distribution	30	6,556		6,170
Other	16	1,390		1,166
Total		10,142		9,393
Accumulated depreciation		3,209		3,050
Property, plant and equipment, net		$	6,933	$	6,343

Depreciation and Amortization

The following table presents depreciation and amortization expense for 2015, 2014 and 2013:



	Year Ended December 31,
	2015		2014		2013
	(in millions)
Depreciation expense	$	316	$	295	$	280
Amortization of securitized regulatory assets	365		441		383
Other amortization	24		32		22
Total depreciation and amortization	$	705	$	768	$	685

Asset Retirement Obligation

A reconciliation of the changes in the asset retirement obligation (ARO) liability is as follows:



	December 31,
	2015		2014
	(in millions)
Beginning balance	$	36	$	33
Accretion expense	1		1
Revisions in estimates of cash flows	—		2
Ending balance	$	37	$	36

Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2015

Regulatory Assets and Liabilities, Other Disclosures [Abstract]

Schedule of Regulatory Assets and Liabilities [Text Block]

The following is a list of regulatory assets/liabilities reflected on CenterPoint Houston’s Consolidated Balance Sheets as of December 31, 2015 and 2014:



	December 31,
	2015			2014
	(in millions)
Securitized regulatory assets	$	2,373		$	2,738
Unrecognized equity return (1)	(393		)	(442		)
Unamortized loss on reacquired debt	93			104
Pension and postretirement-related regulatory asset	50			107
Other long-term regulatory assets (2)	88			122
Total regulatory assets	2,211			2,629

Estimated removal costs	350			353
Other long-term regulatory liabilities	192			184
Total regulatory liabilities	542			537

Total regulatory assets and liabilities, net	$	1,669		$	2,092

(1)


(2)	Other regulatory assets that are not earning a return were not material as of December 31, 2015 and 2014.

Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2015

Compensation and Retirement Disclosure [Abstract]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

CenterPoint Houston is required to fund a portion of its obligations in accordance with rate orders. The net postretirement benefit cost includes the following components:



	Year Ended December 31,
	2015			2014			2013
	(in millions)
Service cost - benefits earned during the period	$	1		$	1		$	1
Interest cost on accumulated benefit obligation	13			14			13
Expected return on plan assets	(6		)	(6		)	(7		)
Amortization of transition obligation	—			4			6
Amortization of prior service credit	(2		)	(2		)	(1		)
Amortization of loss	3			1			4
Net postretirement benefit cost	$	9		$	12		$	16

CenterPoint Houston used the following assumptions to determine net postretirement benefit costs:



	Year Ended December 31,
	2015		2014		2013
Discount rate	3.90	%	4.75	%	3.90	%
Expected return on plan assets	5.45	%	6.00	%	6.00	%

CenterPoint Houston expects to contribute $7 million to its postretirement benefits plan in 2016. The following benefit payments are expected to be paid by the postretirement benefit plan:



	Postretirement Benefit Plan
	Benefit Payments		Medicare Subsidy Receipts
	(in millions)
2016	$	20	$	(2	)
2017	21		(2		)
2018	22		(3		)
2019	23		(3		)
2020	24		(3		)
2021-2025	124		(19		)



	December 31,
	2015			2014
	(in millions)
Change in Benefit Obligation
Accumulated benefit obligation, beginning of year	$	347		$	311
Service cost	1			1
Interest cost	13			14
Benefits paid	(17		)	(18		)
Participant contributions	3			3
Medicare drug reimbursement	1			1
Plan amendment	(4		)	—
Actuarial (gain) loss	(61		)	35
Accumulated benefit obligation, end of year	$	283		$	347
Change in Plan Assets
Plan assets, beginning of year	$	115		$	114
Benefits paid	(17		)	(18		)
Employer contributions	9			9
Participant contributions	3			3
Actual investment return	—			7
Plan assets, end of year	$	110		$	115
Amounts Recognized in Balance Sheets
Other liabilities-benefit obligations	$	(173	)	$	(232	)
Net liability, end of year	$	(173	)	$	(232	)
Actuarial Assumptions
Discount rate	4.35		%	3.90		%
Expected long-term return on assets	5.00		%	5.45		%
Healthcare cost trend rate assumed for the next year - Pre 65	6.00		%	7.25		%
Healthcare cost trend rate assumed for the next year - Post 65	5.50		%	8.50		%
Prescription drug cost trend rate assumed for the next year	11.00		%	6.50		%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate)	5.00		%	5.00		%
Year that the healthcare rate reaches the ultimate trend rate	2024			2024
Year that the prescription drug rate reaches the ultimate trend rate	2024			2024

As part of the investment strategy discussed above, CenterPoint Houston has adopted and maintained the following asset allocation ranges for its postretirement benefit plans:



U.S. equity	14–24%
International equity	3–13%
Fixed income	68–78%
Cash	0–2%

Schedule of a one-percent point change In Assumed Health Care Cost Trend Rates [Table Text Block]



	1% Increase		1% Decrease
	(in millions)
Effect on the postretirement benefit obligation	$	9	$	8
Effect on total of service and interest cost	—		—

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Text Block]

The following tables present by level, within the fair value hierarchy, CenterPoint Houston’s postretirement plan assets as of December 31, 2015 and 2014, by asset category as follows:



	Fair Value Measurements as of December 31, 2015
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in millions)
Mutual funds (1)	$	110	$	110	$	—	$	—
Total	$	110	$	110	$	—	$	—


(1)	73% of the amount invested in mutual funds was in fixed income securities; 19% was in U.S. equities and 8% was in international equities.



	Fair Value Measurements as of December 31, 2014
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in millions)
Mutual funds (1)	$	115	$	115	$	—	$	—
Total	$	115	$	115	$	—	$	—


(1)	73% of the amount invested in mutual funds was in fixed income securities; 19% was in U.S. equities and 8% was in international equities.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Estimated Fair Value of Financial Instruments, Debt Instruments [Table Text Block]



	December 31, 2015				December 31, 2014
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(in millions)
Financial liabilities:
Long-term debt, including current portion	$	4,880	$	5,108	$	5,052	$	5,441

Related Party Transactions and Major Customers Related Party Transactions and Major Customers (Tables)

12 Months Ended

Dec. 31, 2015

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

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



	Year Ended December 31,
	2015		2014		2013
	(in millions)
Affiliates of NRG	$	741	$	735	$	658
Affiliates of Energy Future Holdings Corp.	$	220	$	189	$	167



	Year Ended December 31,
	2015			2014			2013
	(in millions)
Corporate service charges	$	176		$	159		$	147

Charges from CERC for services provided	6			5			9

Billings to CERC for services provided	(18		)	(17		)	(21		)

Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2015

Debt Disclosure [Abstract]

Schedule of Debt [Table Text Block]



	December 31, 2015					December 31, 2014
	Long-Term			Current (1)		Long-Term			Current (1)
	(in millions)
Long-term debt:
Bank Loans	$	200		$	—	$	—		$	—
First mortgage bonds 9.15% due 2021	102			—		102			—
General mortgage bonds 2.25% to 6.95% due 2022 to 2044 (2)	1,912			—		1,912			—
System restoration bonds 3.46% to 4.243% due 2018 to 2022	365			50		415			48
Transition bonds 0.901% to 5.302% due 2017 to 2024	1,918			341		2,259			324
Other	(8		)	—		(8		)	—
Total long-term debt	$	4,489		$	391	$	4,680		$	372


(1)	Includes amounts due or scheduled to be paid within one year of the date noted.


(2)	Debt issued as collateral is excluded from the financial statements because of the contingent nature of the obligation.

Schedule of Line of Credit Facilities [Table Text Block]

Revolving Credit Facility. As of December 31, 2015 and 2014, CenterPoint Houston had the following revolving credit facility and utilization of such facility:



December 31, 2015							December 31, 2014
Size of Facility		Loans			Letters of Credit		Size of Facility		Loans		Letters of Credit
(in millions)
$	300	$	200	(1)	$	4	$	300	$	—	$	4

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Income Tax Expense

The components of CenterPoint Houston’s income tax expense were as follows:



	Year Ended December 31,
	2015		2014			2013
	(in millions)
Current income tax expense:
Federal	$	106	$	136		$	201
State	21		19			20
Total current expense	127		155			221
Deferred income tax expense (benefit):
Federal	18		(24		)	(75		)
Total deferred expense (benefit)	18		(24		)	(75		)
Total income tax expense	$	145	$	131		$	146

Reconciliation Of Expected Federal Income Tax Expense To Actual

A reconciliation of income tax expense using the federal statutory income tax rate to the actual income tax expense and resulting effective income tax rate is as follows:



	Year Ended December 31,
	2015			2014			2013
	(in millions)
Income before income taxes	$	406		$	383		$	415
Federal statutory income tax rate	35.0		%	35.0		%	35.0		%
Expected federal income tax expense	142			134			145
Increase (decrease) in tax expense resulting from:
State income tax expense, net of federal income tax	14			12			13
Decrease in settled and uncertain tax positions	—			—			(5		)
Other, net	(11		)	(15		)	(7		)
Total	3			(3		)	1
Total income tax expense	$	145		$	131		$	146
Effective tax rate	35.7		%	34.2		%	35.2		%

Income Tax Asset Liability Disclosure

The tax effects of temporary differences that give rise to significant portions of deferred tax assets and liabilities were as follows:



	December 31,
	2015		2014
	(in millions)
Deferred tax assets:
Benefits and compensation	$	69	$	92
Loss and credit carryforwards	6		—
Asset retirement obligations	13		12
Other	7		7
Total deferred tax assets	95		111

Deferred tax liabilities:
Property, plant, and equipment	1,447		1,284
Regulatory assets/liabilities, net	680		826
Total deferred tax liabilities	2,127		2,110
Net deferred tax liabilities	$	2,032	$	1,999

Unaudited Quarterly Information Unaudited Quarterly Information (Tables)

12 Months Ended

Dec. 31, 2015

Unaudited Quarterly Information [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]

Summarized quarterly financial data is as follows:



	Year Ended December 31, 2015
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in millions)
Revenues	$	617	$	705	$	827	$	697
Operating income	101		158		244		105
Net income	31		69		124		37



	Year Ended December 31, 2014
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in millions)
Revenues	$	630	$	698	$	839	$	679
Operating income	106		145		232		113
Net income	35		57		119		41

Schedule II - Valuation and Qualifying Accounts (Tables)

12 Months Ended

Dec. 31, 2015

Valuation and Qualifying Accounts Disclosure [Line Items]

Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]

CENTERPOINT ENERGY HOUSTON ELECTRIC, LLC AND SUBSIDIARIES

(An Indirect, Wholly-Owned Subsidiary of CenterPoint Energy, Inc.)

SCHEDULE II —VALUATION AND QUALIFYING ACCOUNTS

For the Three Years Ended December 31, 2015



Column A	Column B		Column C		Column D		Column E
Description	Balance At Beginning of Period		Additions Charged to Income		Deductions From Reserves (1)		Balance At End Of Period
	(in millions)
Year Ended December 31, 2015:
Accumulated provisions:
Uncollectible accounts receivable	$	3	$	—	$	2	$	1
Year Ended December 31, 2014:
Accumulated provisions:
Uncollectible accounts receivable	$	3	$	3	$	3	$	3
Year Ended December 31, 2013:
Accumulated provisions:
Uncollectible accounts receivable	$	2	$	2	$	1	$	3


(1)	Deductions from reserves represent losses or expenses for which the respective reserves were created. In the case of the uncollectible accounts reserve, such deductions are net of recoveries of amounts previously written off.

Restatement (Tables)

12 Months Ended

Dec. 31, 2015

Restatement

Schedule of Error Corrections and Prior Period Adjustments [Table Text Block]

A summary of the significant effects of the restatement is as follows:



	Year Ended December 31, 2015
	As Restated			As Previously Reported
	(in millions)
Statements of Consolidated Cash Flows:
Cash Flows from Operating Activities:
Accounts receivable/payable–affiliated companies	$	(89	)	$	223
Net cash provided by operating activities	895			1,207
Cash Flows from Financing Activities:
Increase in notes payable–affiliated companies	312			—
Net cash used in financing activities	(112		)	(424		)

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Significant Accounting Policies [Line Items]
Regulatory liabilities	$ 542	$ 537
Amortization Period, Transition Property (in years)	12 to 14 years
Capitalized Interest Costs, Including Allowance for Funds Used During Construction	$ 8	10	$ 10
Provision for doubtful accounts	1	3	2
Cash and cash equivalents ($264 and $290 related to VIEs, respectively)	264	290	207	$ 646
Customer deposits included in other current liabilities	12	24
Deferred Tax Asset, Reclassified To Deferred Tax Liability Noncurrent		2
Removal Costs [Member]
Significant Accounting Policies [Line Items]
Regulatory liabilities	350	353
Other Income [Member]
Significant Accounting Policies [Line Items]
AFUDC equity	12	14	$ 8
Prepaid Expenses and Other Current Assets [Member]
Significant Accounting Policies [Line Items]
Restricted cash accounts	35	47
Other Noncurrent Assets [Member]
Significant Accounting Policies [Line Items]
Unamortized Debt Issuance Expense	22	26
Variable Interest Entity, Primary Beneficiary [Member]
Significant Accounting Policies [Line Items]
Cash and cash equivalents ($264 and $290 related to VIEs, respectively)	$ 264	$ 290

Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment, Net, by Type [Abstract]
Total	$ 10,142	$ 9,393
Accumulated depreciation	3,209	3,050
Property, plant and equipment, net	6,933	6,343
Depreciation, Depletion and Amortization [Abstract]
Depreciation expense	316	295	$ 280
Amortization of securitized regulatory assets	365	441	383
Other amortization	24	32	22
Total depreciation and amortization	705	768	685
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	36	33
Accretion expense	1	1
Revisions in estimates of cash flows	0	2
Ending balance	37	36	$ 33
Transmission [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	2,196	2,057
Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	6,556	6,170
Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	$ 1,390	$ 1,166
Weighted Average [Member] \| Transmission [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	41 years
Weighted Average [Member] \| Distribution [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	30 years
Weighted Average [Member] \| Other [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	16 years

Regulatory Matters Regulatory Assets and Liabilities (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Schedule Of Regulatory Assets And Liabilities [Line Items]

Regulatory Assets, Noncurrent

$ 2,211

$ 2,629

Regulatory liabilities

542

537

Unrecognized Equity Return

^[1]

(393)

(442)

Total regulatory assets and liabilities, net

1,669

2,092

Amount of allowed equity return on the true-up balance that was recognized in the period

$ 45

Other Regulatory Assets (Liabilities) [Member]

Schedule Of Regulatory Assets And Liabilities [Line Items]

Regulatory Assets, Noncurrent

^[2]

122

Pension And Postretirement Related Regulatory Asset [Member]

Schedule Of Regulatory Assets And Liabilities [Line Items]

Regulatory Assets, Noncurrent

107

Loss on Reacquired Debt [Member]

Schedule Of Regulatory Assets And Liabilities [Line Items]

Regulatory Assets, Noncurrent

104

Securitized Regulatory Asset Member

Schedule Of Regulatory Assets And Liabilities [Line Items]

Regulatory Assets, Noncurrent

2,373

2,738

Removal Costs [Member]

Schedule Of Regulatory Assets And Liabilities [Line Items]

Regulatory liabilities

350

353

Other Regulatory Assets (Liabilities) [Member]

Schedule Of Regulatory Assets And Liabilities [Line Items]

Regulatory liabilities

$ 192

$ 184

[1]

[2]

Other regulatory assets that are not earning a return were not material as of December 31, 2015 and 2014.

Employee Benefit Plans Pension and Postretirement Benefits (Details) - USD ($) $ in Millions			12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
New percentage of eligible earnings used to determine retirement benefits	5.00%		5.00%
Recognized pension expense			$ 35	$ 26	$ 25
Non Qualified Pension Plan Expense			1	1	1
Deferred Compensation Arrangement with Individual, Compensation Expense			$ 1	1	1
Maximum Percentage Of Employee Compensation Eligible For Contribution To Savings Plan			50.00%
Description Of Company Match Under Savings Plan			100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			6.00%
Defined Contribution Plan, Cost Recognized			$ 14	13	13
Components of net periodic costs [Abstract]
Service cost			1	1	1
Interest cost			13	14	13
Expected return on plan assets			(6)	(6)	(7)
Amortization of transition obligation			0	4	6
Amortization of prior service credit			(2)	(2)	(1)
Amortization of loss			3	1	4
Net postretirement benefit cost			$ 9	$ 12	$ 16
Assumptions used to determine net periodic benefit (income) cost [Abstract]
Discount rate			3.90%	4.75%	3.90%
Expected long-term return on assets	5.00%	5.45%	5.45%	6.00%	6.00%
Change in Benefit Obligation
Accumulated benefit obligation, beginning of year			$ 347	$ 311
Service cost			1	1	$ 1
Interest cost			13	14	13
Benefits paid			(17)	(18)
Participant contributions			3	3
Medicare drug reimbursement			1	1
Plan amendment			(4)	0
Actuarial (gain) loss			(61)	35
Accumulated benefit obligation, end of year	$ 283	$ 347	283	347	311
Change in Plan Assets
Plan assets, beginning of year			115	114
Benefits paid			(17)	(18)
Employer contributions			9	9
Participant contributions			3	3
Actual investment return			0	7
Plan assets, end of year	110	115	110	115	$ 114
Amounts Recognized in Balance Sheets
Other liabilities-benefit obligations	(192)	(260)	(192)	(260)
Net liability, end of year	$ (173)	$ (232)	$ (173)	$ (232)
Actuarial Assumptions
Discount rate	4.35%	3.90%	4.35%	3.90%
Expected long-term return on assets	5.00%	5.45%	5.45%	6.00%	6.00%
Prescription drug cost trend rate assumed for the next year			11.00%	6.50%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate)			5.00%	5.00%
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect of One Percentage Point Increase on Postretirement Benefit Obligation			$ 9
Effect of One Percentage Point Decrease on Postretirement Benefit Obligation			8
Effect of One Percentage Point Increase on Total Service and Interest Cost			0
Effect of One Percentage Point Decrease on Total Service and Interest Cost			$ 0
Annualized individual discount rates based on time period, minimum			6 months
Annualized individual discount rates based on time period, maximum			99 years
Other Postretirement Benefit Plans, Defined Benefit [Member]
Amounts Recognized in Balance Sheets
Other liabilities-benefit obligations	$ (173)	$ (232)	$ (173)	$ (232)
Maximum [Member]
Actuarial Assumptions
Healthcare cost trend rate assumed for the next year			5.50%	8.50%
Minimum [Member]
Actuarial Assumptions
Healthcare cost trend rate assumed for the next year			6.00%	7.25%
Common Stock [Member] \| CenterPoint Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage			25.00%
Number Of Shares In Common Stock Held By Savings Plan	16,942,974		16,942,974
Percentage of investment in common stocks	17.00%		17.00%
Health Care [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Actuarial Assumptions
Year that the healthcare rate reaches the ultimate trend rate	2024	2024	2024	2024
Prescription Drug [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Actuarial Assumptions
Year that the healthcare rate reaches the ultimate trend rate	2024	2024	2024	2024

Employee Benefit Plans Plan Assets (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Pension plan assets, fair value

$ 110

$ 115

$ 114

Estimated future contribution to postretirement benefit plan in next fiscal year

Postemployment Benefits, Period Credit

(1)

Postemployment Benefits, Period Expense

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Benefit expense related to deferred compensation plans

$ 1

Equity Funds [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Pension plan assets, fair value

$ 110

^[1]

115

^[2]

U.S. Equity [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Defined Benefit Plan, Target Plan Asset Allocations Range Minimum

14.00%

Defined Benefit Plan, Target Plan Asset Allocations Range Maximum

24.00%

International Equity [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Defined Benefit Plan, Target Plan Asset Allocations Range Minimum

3.00%

Defined Benefit Plan, Target Plan Asset Allocations Range Maximum

13.00%

Fixed Income [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Defined Benefit Plan, Target Plan Asset Allocations Range Minimum

68.00%

Defined Benefit Plan, Target Plan Asset Allocations Range Maximum

78.00%

Cash and Cash Equivalents [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Defined Benefit Plan, Target Plan Asset Allocations Range Minimum

0.00%

Defined Benefit Plan, Target Plan Asset Allocations Range Maximum

2.00%

Fair Value, Inputs, Level 1 [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Pension plan assets, fair value

$ 110

115

Fair Value, Inputs, Level 1 [Member] | Equity Funds [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Pension plan assets, fair value

110

^[1]

115

^[2]

Fair Value, Inputs, Level 2 [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Pension plan assets, fair value

Fair Value, Inputs, Level 2 [Member] | Equity Funds [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Pension plan assets, fair value

^[1]

^[2]

Fair Value, Inputs, Level 3 [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Pension plan assets, fair value

Fair Value, Inputs, Level 3 [Member] | Equity Funds [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Pension plan assets, fair value

^[1]

$ 0

^[2]

Other Postretirement Benefit Plans, Defined Benefit [Member]

Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]

Postretirement benefit payments - 2016

Postretirement benefit payments - 2017

Postretirement benefit payments - 2018

Postretirement benefit payments - 2019

Postretirement benefit payments - 2020

Postretirement benefit payments - 2021-2025

124

Medicare Subsidy Receipts - 2016

(2)

Medicare Subsidy Receipts - 2017

(2)

Medicare Subsidy Receipts - 2018

(3)

Medicare Subsidy Receipts - 2019

(3)

Medicare Subsidy Receipts - 2020

(3)

Medicare Subsidy Receipts - 2021-2025

$ (19)

International Equity [Member] | Equity Funds [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Defined Benefit Plan, Actual Plan Asset Allocations

8.00%

Fixed Income Funds [Member] | Equity Funds [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Defined Benefit Plan, Actual Plan Asset Allocations

73.00%

U.S. Equity [Member] | Equity Funds [Member]

Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]

Defined Benefit Plan, Actual Plan Asset Allocations

19.00%

Benefit Obligation [Member]

Postemployment Benefits [Abstract]

Postemployment benefit obligations

$ 6

$ 14

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Other non-qualified plans benefit obligations deferred compensation

$ 11

$ 12

[1]	73% of the amount invested in mutual funds was in fixed income securities; 19% was in U.S. equities and 8% was in international equities.
[2]	73% of the amount invested in mutual funds was in fixed income securities; 19% was in U.S. equities and 8% was in international equities.

Employee Benefit Plans Other Employee Matters (Details)	12 Months Ended
Employee Benefit Plans Other Employee Matters (Details)	Dec. 31, 2015
Concentration Risk [Line Items]
Number of full-time employees	2,665
Employees Subject To Collective Bargaining Agreements [Member] \| Labor Force Concentration Risk [Member] \| Number of Employees [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	51.00%

Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Carrying Amount [Member]
Fair Value Assets and Liabilities Measured on Recurring Basis Disclosure Items [Line Items]
Long-term debt, including current portion	$ 4,880	$ 5,052
Fair Value [Member]
Fair Value Assets and Liabilities Measured on Recurring Basis Disclosure Items [Line Items]
Long-term debt, including current portion	5,108	5,441
Fair Value, Inputs, Level 1 [Member]
Fair Value Assets and Liabilities Measured on Recurring Basis Disclosure Items [Line Items]
Investments, including money market funds	32	43
Fair Value, Inputs, Level 2 [Member]
Fair Value Assets and Liabilities Measured on Recurring Basis Disclosure Items [Line Items]
Assets or liabilities	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets and Liabilities Measured on Recurring Basis Disclosure Items [Line Items]
Assets or liabilities	$ 0	$ 0

Related Party Transactions and Major Customers (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Money Pool Borrowings	$ (312)								$ (312)
Investments in Money Pool					$ 107					$ 107
Debt, Weighted Average Interest Rate	0.80%								0.80%
Interest Income (Expense) Net, Related Party									$ (1)	(1)	$ 20
Cash Dividends Paid to Parent Company									252	0	766
Proceeds from Contributions from Parent									0	90	0
Revenues	$ 697	$ 827	$ 705	$ 617	$ 679	$ 839	$ 698	$ 630	2,846	2,846	2,577
Affiliates of NRG Energy, Inc. [Member]
Related Party Transaction [Line Items]
Revenues									741	735	658
Affiliates of Energy Future Holdings Corp. [Member]
Related Party Transaction [Line Items]
Revenues									220	189	167
Operation And Maintenance Expense Member \| CenterPoint Energy [Member]
Related Party Transaction [Line Items]
Corporate service charges									176	159	147
Operation And Maintenance Expense Member \| CERC Corp [Member]
Related Party Transaction [Line Items]
Corporate service charges									6	5	9
Related Party Transaction, Other Revenues from Transactions with Related Party									$ (18)	$ (17)	$ (21)

Long-term Debt (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Debt Instrument [Line Items]

Debt, Weighted Average Interest Rate

0.80%

Other

$ (8.0)

Long-term Debt, Excluding Current Maturities

4,489.0

4,680.0

Long-term Debt, Current Maturities

^[1]

391.0

372.0

Line of Credit Facility [Abstract]

Size of Credit Facility

300.0

Annual maturities of long-term debt [Abstract]

0.0

0.0

0.0

200.0

0.0

Transition And System Restoration Bonds [Member]

Annual maturities of long-term debt [Abstract]

391.0

411.0

434.0

458.0

231.0

Debt Instrument [Line Items]

Long-term Debt, Gross, Noncurrent

200.0

0.0

Long-term Debt, Gross, Current

^[1]

0.0

First mortgage bonds 9.15% due 2021

Debt Instrument [Line Items]

Long-term Debt, Gross, Noncurrent

102.0

Long-term Debt, Gross, Current

^[1]

$ 0.0

0.0

Debt Instrument, Interest Rate, Stated Percentage

9.15%

Annual maturities of long-term debt [Abstract]

Secured Debt

$ 102.0

Replacement Fund Requirements

223.0

Sinking Fund Requirements

1.6

General mortgage bonds 2.25% to 6.95% due 2022 to 2044 (2)

Debt Instrument [Line Items]

Long-term Debt, Gross, Noncurrent

^[2]

1,912.0

Long-term Debt, Gross, Current

^[1],[2]

$ 0.0

0.0

Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum

2.25%

Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum

6.95%

Annual maturities of long-term debt [Abstract]

Secured Debt

$ 2,100.0

System restoration bonds 3.46% to 4.243% due 2018 to 2022

Debt Instrument [Line Items]

Long-term Debt, Gross, Noncurrent

365.0

415.0

Long-term Debt, Gross, Current

^[1]

$ 50.0

48.0

Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum

3.46%

Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum

4.243%

Transition bonds 0.901% to 5.302% due 2017 to 2024

Debt Instrument [Line Items]

Long-term Debt, Gross, Noncurrent

$ 1,918.0

2,259.0

Long-term Debt, Gross, Current

^[1]

$ 341.0

324.0

Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum

0.901%

Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum

5.302%

Revolving Credit Facility [Member]

Line of Credit Facility [Abstract]

Loans Outstanding

$ 200.0

^[3]

0.0

Revolving Credit Facility [Member]

Debt Instrument [Line Items]

Debt, Weighted Average Interest Rate

1.637%

Line of Credit [Member]

Line of Credit Facility [Abstract]

Percentage on limitation of debt to total capitalization under covenant (in hundredths)

65.00%

Line of Credit [Member] | CenterPoint Houston [Member]

Line of Credit Facility [Abstract]

Ratio of Indebtedness to Net Capital

0.517

Letter of Credit [Member]

Line of Credit Facility [Abstract]

Loans Outstanding

$ 4.0

London Interbank Offered Rate (LIBOR) [Member] | Line of Credit [Member]

Line of Credit Facility [Abstract]

Line of Credit Facility, Interest Rate Description

1.125%

[1]	Includes amounts due or scheduled to be paid within one year of the date noted.
[2]	Debt issued as collateral is excluded from the financial statements because of the contingent nature of the obligation.
[3]	Weighted average interest rate was 1.637% as of December 31, 2015.

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Income Tax Expense [Abstract]
Federal	$ 106	$ 136	$ 201
State	21	19	20
Total current expense	127	155	221
Deferred Income Tax Expense (Benefit) [Abstract]
Federal	18	(24)	(75)
Total deferred expense (benefit)	18	(24)	(75)
Total income tax expense	145	131	146
Income Tax Reconciliation [Abstract]
Income before income taxes	$ 406	$ 383	$ 415
Federal statutory income tax rate	35.00%	35.00%	35.00%
Expected federal income tax expense	$ 142	$ 134	$ 145
Increase (decrease) in tax expense resulting from:
State income tax expense, net of federal income tax	14	12	13
Decrease in settled and uncertain tax positions	0	0	(5)
Other, net	(11)	(15)	(7)
Total	3	(3)	1
Total income tax expense	$ 145	$ 131	$ 146
Effective tax rate	35.70%	34.20%	35.20%
Tax benefits recognized		$ (6)	$ (5)
Deferred tax assets:
Benefits and compensation	$ 69	92
Loss and credit carryforwards	6	0
Asset retirement obligations	13	12
Other	7	7
Total deferred tax assets	95	111
Deferred tax liabilities:
Deferred Tax Liabilities, Property, Plant and Equipment	1,447	1,284
Regulatory assets/liabilities, net	680	826
Total deferred tax liabilities	2,127	2,110
Net deferred tax liabilities	$ 2,032	$ 1,999

Commitments and Contingencies (Details) $ in Millions	12 Months Ended
Commitments and Contingencies (Details) $ in Millions	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2016	$ 1
2017	1
2018	1
2019	1
2020	1
Operating lease rent expense	$ 1	$ 1	$ 1
Gas Market Manipulation Cases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Loss Contingency, Pending Claims, Number	1

Unaudited Quarterly Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues	$ 697	$ 827	$ 705	$ 617	$ 679	$ 839	$ 698	$ 630	$ 2,846	$ 2,846	$ 2,577
Operating income	105	244	158	101	113	232	145	106	608	596	614
Net income	$ 37	$ 124	$ 69	$ 31	$ 41	$ 119	$ 57	$ 35	$ 261	$ 252	$ 269

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Trade Receivables [Member] - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Valuation and Qualifying Accounts Disclosure [Line Items]

Balance at Beginning of Period

$ 3

$ 2

Additions Charged to Income

Deductions From Reserves

^[1]

Balance at End of Period

$ 1

$ 3

[1]	Deductions from reserves represent losses or expenses for which the respective reserves were created. In the case of the uncollectible accounts reserve, such deductions are net of recoveries of amounts previously written off.

Restatement (Details) - USD ($) $ in Millions	12 Months Ended
Restatement (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restatement
Accounts Receivable Payable, Affiliated Companies, Overstated Amount	$ 312
Net Cash Provided by Operating Activities, Overstated Amount	312
Increase In Notes Payable, Affiliated Companies, Understated Amount	312
Net Cash Used in Financing Activites, Overstated Amount	312
Accounts receivable/payable–affiliated companies	(89)	$ 37	$ (5)
Net cash provided by operating activities	895	858	928
Increase in notes payable–affiliated companies	312	(3)	(148)
Net cash used in financing activities	(112)	$ 142	$ (1,812)
Scenario, Previously Reported [Member]
Restatement
Accounts receivable/payable–affiliated companies	223
Net cash provided by operating activities	1,207
Increase in notes payable–affiliated companies	0
Net cash used in financing activities	$ (424)