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Document And Entity Information - USD ($) $ in Millions	9 Months Ended
Document And Entity Information - USD ($) $ in Millions	Sep. 30, 2012	Oct. 16, 2012	Jun. 30, 2011
Document and Entity Information [Abstract]
Entity Registrant Name	CENTERPOINT ENERGY HOUSTON ELECTRIC LLC
Entity Central Index Key	0000048732
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0

CONDENSED STATEMENTS OF CONSOLIDATED INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues	$ 748	$ 707	$ 1,955	$ 1,802
Expenses:
Operation and maintenance	233	230	692	661
Depreciation and amortization	219	179	563	453
Taxes other than income taxes	54	54	160	158
Total	506	463	1,415	1,272
Operating Income	242	244	540	530
Other Income (Expense):
Interest and other finance charges	(36)	(38)	(110)	(113)
Interest on transition and system restoration bonds	(37)	(31)	(112)	(96)
Return on true-up balance	0	352	0	352
Other, net	15	15	32	30
Total	(58)	298	(190)	173
Income Before Income Taxes	184	542	350	703
Income tax expense	46	175	98	233
Income Before Extraordinary Item	138	367	252	470
Extraordinary Item, net of tax	0	598	0	598
Net Income	$ 138	$ 965	$ 252	$ 1,068

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Sep. 30, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents ($220 and $194 related to VIEs at December 31, 2011 and September 30, 2012, respectively)	$ 699	$ 220
Accounts and notes receivable, net ($52 and $104 related to VIEs at December 31, 2011 and September 30, 2012, respectively)	307	201
Accounts and notes receivable—affiliated companies	293	1,027
Accrued unbilled revenues	90	72
Inventory	91	80
Taxes receivable	0	2
Deferred tax asset	6	3
Other ($42 and $53 related to VIEs at December 31, 2011 and September 30, 2012, respectively)	67	65
Total current assets	1,553	1,670
Property, Plant and Equipment:
Property, plant and equipment	8,052	7,827
Less accumulated depreciation and amortization	2,800	2,784
Property, Plant and Equipment, net	5,252	5,043
Other Assets:
Regulatory assets ($2,289 and $3,635 related to VIEs at December 31, 2011 and September 30, 2012, respectively)	3,465	3,726
Notes receivable—affiliated companies	750	750
Other	36	35
Total other assets	4,251	4,511
Total Assets	11,056	11,224
Current Liabilities:
Current portion of VIE transition and system restoration bonds long-term debt	451	307
Current portion of other long-term debt	450	46
Accounts payable	78	113
Accounts and notes payable - affiliated companies	45	32
Taxes accrued	83	101
Interest accrued	51	96
Other	97	98
Total current liabilities	1,255	793
Other Liabilities:
Accumulated deferred income taxes, net	2,134	2,113
Benefit obligations	253	252
Regulatory liabilities	473	441
Notes payable—affiliated companies	151	151
Other	34	78
Total other liabilities	3,045	3,035
Long-Term Debt:
VIE transition and system restoration bonds	3,459	2,215
Other	1,595	2,047
Total long-term debt	5,054	4,262
Commitments And Contingencies (Note 8)
Member’s Equity:
Common stock	0	0
Paid-in capital	1,231	1,230
Retained earnings	471	1,904
Total member’s equity	1,702	3,134
Total Liabilities and Member’s Equity	$ 11,056	$ 11,224

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 699	$ 220
Accounts and notes receivable, net	307	201
Other	67	65
Other Assets:
Regulatory assets	3,465	3,726
Variable Interest Entity [Member]
Current Assets:
Cash and cash equivalents	194	220
Accounts and notes receivable, net	104	52
Other	53	42
Other Assets:
Regulatory assets	$ 3,635	$ 2,289

- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 1
-Article 5

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-Name Statement of Financial Accounting Standard (FAS)
-Number 95
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+ Details

CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash Flows from Operating Activities:
Net Income	$ 252	$ 1,068
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	563	453
Amortization of deferred financing costs	10	9
Deferred income taxes	(36)	188
Extraordinary Item, net of tax	0	(598)
Return on true-up balance	0	(352)
Changes in other assets and liabilities:
Accounts and notes receivable, net	(119)	(107)
Accounts receivable/payable, affiliates	1	4
Inventory	(11)	(4)
Accounts payable	(23)	2
Taxes receivable	2	63
Interest and taxes accrued	(63)	(73)
Net regulatory assets and liabilities	25	(25)
Other current assets	10	(1)
Other current liabilities	(1)	16
Other assets	3	(3)
Other liabilities	(1)	2
Other, net	(2)	0
Net cash provided by operating activities	610	642
Cash Flows from Investing Activities:
Capital expenditures	(429)	(449)
Decrease (increase) in notes receivable from affiliates, net	746	(117)
Increase in restricted cash of transition and system restoration bond companies	(12)	(2)
Cash received from U.S. Department of Energy grant	0	110
Other, net	(9)	5
Net cash provided by (used in) investing activities	296	(453)
Cash Flows from Financing Activities:
Proceeds from long-term debt	2,495	0
Payments of long-term debt	(1,153)	(283)
Dividend to parent	(1,685)	0
Cash paid for debt retirement	(69)	0
Debt issuance costs	(16)	(2)
Other, net	1	1
Net cash used in financing activities	(427)	(284)
Net Increase (Decrease) in Cash and Cash Equivalents	479	(95)
Cash and Cash Equivalents at Beginning of Period	220	198
Cash and Cash Equivalents at End of Period	699	103
Cash Payments:
Interest, net of capitalized interest	265	279
Income taxes (refunds), net	126	(29)
Non-cash transactions:
Accounts payable related to capital expenditures	$ 42	$ 38

Background and Basis of Presentation	9 Months Ended
Background and Basis of Presentation	Sep. 30, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Background and Basis of Presentation General. Included in this Quarterly Report on Form 10-Q (Form 10-Q) of CenterPoint Energy Houston Electric, LLC are the condensed consolidated interim financial statements and notes (Interim Condensed Financial Statements) of CenterPoint Energy Houston Electric, LLC and its subsidiaries (collectively, CenterPoint Houston). The Interim Condensed Financial Statements are unaudited, omit certain financial statement disclosures and should be read with the Annual Report on Form 10-K of CenterPoint Houston for the year ended December 31, 2011. Background. 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. At September 30, 2012, CenterPoint Houston had five 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). The transition and system restoration bond companies, which are classified as variable interest entities, 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 companies 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. Basis of Presentation. The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America 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. CenterPoint Houston’s Interim Condensed Financial Statements reflect all normal recurring adjustments that are, in the opinion of management, necessary to present fairly the financial position, results of operations and cash flows for the respective periods. Amounts reported in CenterPoint Houston’s Condensed Statements of Consolidated Income are not necessarily indicative of amounts expected for a full-year period due to the effects of, among other things, (a) seasonal fluctuations in demand for energy, (b) timing of maintenance and other expenditures and (c) acquisitions and dispositions of businesses, assets and other interests.

- Definition

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

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-Publisher AICPA
-Name Statement of Position (SOP)
-Number 94-6
-Paragraph 10
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-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
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+ Details

New Accounting Pronouncements	9 Months Ended
New Accounting Pronouncements	Sep. 30, 2012
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Description of New Accounting Pronouncements Not yet Adopted [Text Block]	New Accounting Pronouncements Management believes the impact of recently issued standards, which are not yet effective, will not have a material impact on CenterPoint Houston’s consolidated financial position, results of operations or cash flows upon adoption.

Employee Benefit Plans

9 Months Ended

Sep. 30, 2012

Compensation and Retirement Disclosure [Abstract]

Pension and Other Postretirement Benefits Disclosure [Text Block]

Employee Benefit Plans

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



	Three Months Ended September 30,						Nine Months Ended September 30,
	2011			2012			2011			2012
	(in millions)
Interest cost	$	4		$	4		$	12		$	12
Expected return on plan assets	(2		)	(2		)	(6		)	(5		)
Amortization of loss	1			1			1			2
Amortization of transition obligation	1			2			4			5
Net periodic cost	$	4		$	5		$	11		$	14

CenterPoint Houston expects to contribute approximately $7 million to its postretirement benefit plan in 2012, of which $6 million has been contributed as of September 30, 2012.

- Definition

The entire disclosure for pension and other postretirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/topic&trid=2235017

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-Name Emerging Issues Task Force (EITF)
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+ Details

Regulatory Accounting	9 Months Ended
Regulatory Accounting	Sep. 30, 2012
Regulatory Matters [Abstract]
Regulatory Matters [Text Block]	Regulatory Accounting As of September 30, 2012, CenterPoint Houston has not recognized an allowed equity return of $563 million because such return will be recognized as it is recovered in rates. During the three months ended September 30, 2011 and 2012, CenterPoint Houston recognized approximately $7 million and $16 million, respectively, of the allowed equity return not previously recognized. During the nine months ended September 30, 2011 and 2012, CenterPoint Houston recognized approximately $15 million and $37 million, respectively, of the allowed equity return not previously recognized.

Fair Value Measurements

9 Months Ended

Sep. 30, 2012

Fair Value Disclosures [Abstract]

Fair Value Disclosures [Text Block]

Fair Value Measurements

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

Level 1: Inputs are unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date. The types of assets carried at Level 1 fair value are investments listed in active markets. At December 31, 2011 and September 30, 2012, CenterPoint Houston held Level 1 investments of $38 million and $50 million, respectively, which were primarily money market funds.

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, 2011 or September 30, 2012.

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. These inputs reflect management’s best estimate of the assumptions market participants would use in determining fair value. CenterPoint Houston had no Level 3 assets or liabilities at either December 31, 2011 or September 30, 2012.

CenterPoint Houston determines the appropriate level for each financial asset and liability on a quarterly basis and recognizes any transfers at the end of the reporting period. For the quarter ended September 30, 2012, there were no transfers between levels.

Estimated Fair Value of Financial Instruments

The fair values of cash and cash equivalents, short-term borrowings and the $750 million note receivable from CenterPoint Houston’s parent are estimated to be equivalent to carrying amounts and have been excluded from the table below. The fair value of each debt instrument is determined by multiplying the principal amount of each debt instrument by the market price. These assets and liabilities, which are not measured at fair value in the Condensed Consolidated Balance Sheets but for which the fair value is disclosed, would be classified as Level 1 in the fair value hierarchy.



	December 31, 2011				September 30, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(in millions)
Financial liabilities:
Long-term debt (including $151 million of long-term notes payable to parent)	$	4,765	$	5,345	$	6,106	$	6,758

- 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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Section 50
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Related Party Transactions and Major Customers	9 Months Ended
Related Party Transactions and Major Customers	Sep. 30, 2012
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	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 investments in the money pool of $1.0 billion and $264 million at December 31, 2011 and September 30, 2012, respectively, which are included in accounts and notes receivable-affiliated companies in the Condensed Consolidated Balance Sheets. At December 31, 2011 and September 30, 2012, CenterPoint Houston had a $750 million note receivable from its parent. CenterPoint Houston had net interest income related to affiliate borrowings of $5 million for both the three months ended September 30, 2011 and 2012, and $15 million and $14 million, respectively, for the nine months ended September 30, 2011 and 2012, included in Other Income. 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. 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 $32 million and $33 million for the three months ended September 30, 2011 and 2012, respectively, and $103 million and $105 million for the nine months ended September 30, 2011 and 2012, respectively, and are included primarily in operation and maintenance expenses. (b) Major Customers Sales to affiliates of NRG Energy, Inc. (NRG) in the three months ended September 30, 2011 and 2012 represented approximately$188 million and $196 million, respectively, of CenterPoint Houston’s transmission and distribution revenues. Sales to affiliates of Energy Future Holdings Corp. in the three months ended September 30, 2011 and 2012 represented approximately $58 million and $49 million, respectively, of CenterPoint Houston’s transmission and distribution revenues. Sales to affiliates of NRG in the nine months ended September 30, 2011 and 2012 represented approximately $448 million and $488 million, respectively, of CenterPoint Houston’s transmission and distribution revenues. Sales to affiliates of Energy Future Holdings Corp. in the nine months ended September 30, 2011 and 2012 represented approximately $139 million and $123 million, respectively, of CenterPoint Houston's transmission and distribution revenues.

- 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.

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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
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-Article 3A

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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Long-term Debt

9 Months Ended

Sep. 30, 2012

Debt Disclosure [Abstract]

Debt Disclosure [Text Block]

Long-term Debt

Transition Bonds. In January 2012, Bond Company IV issued $1.695 billion of transition bonds in three tranches with interest rates ranging from 0.9012% to 3.0282% and final maturity dates ranging from April 15, 2018 to October 15, 2025. The transition bonds will be repaid over time through a charge imposed on customers in CenterPoint Houston’s service territory.

General Mortgage Bonds. In August 2012, CenterPoint Houston issued $300 million of 2.25% general mortgage bonds due 2022 and $500 million of 3.55% general mortgage bonds due 2042. The net proceeds from the sale of the bonds were used to fund a portion of the redemption of the general mortgage bonds discussed below.

In August 2012, CenterPoint Houston redeemed $300 million principal amount of its 5.75% general mortgage bonds due 2014 at a price of 107.332% of their principal amount and $500 million principal amount of its 7.00% general mortgage bonds due 2014 at a price of 109.397% of their principal amount. Redemption premiums for the two series aggregated approximately $69 million and were deferred as regulatory assets.

Revolving Credit Facility. As of December 31, 2011 and September 30, 2012, CenterPoint Houston had the following revolving credit facility and utilization of such facility (in millions):



		December 31, 2011				September 30, 2012
Size of Facility		Loans		Letters of Credit		Loans		Letters of Credit
$	300	$	—	$	4	$	—	$	4

CenterPoint Houston’s $300 million credit facility, which is scheduled to terminate September 9, 2016, can be drawn at the London Interbank Offered Rate plus 125 basis points based on CenterPoint Houston’s current credit ratings. The facility contains a debt (excluding transition and system restoration bonds) to total capitalization covenant, limiting debt to 65% of its capitalization.

Other. At both December 31, 2011 and September 30, 2012, CenterPoint Houston had issued $151 million of first mortgage bonds as collateral for long-term debt of CenterPoint Energy. As of December 31, 2011 and September 30, 2012, CenterPoint Houston had issued $508 million and $408 million of general mortgage bonds as collateral for long-term debt of CenterPoint Energy, respectively. These bonds are not reflected in the consolidated financial statements because of the contingent nature of the obligations.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References + Details

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2012
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	Commitments and Contingencies 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, including CenterPoint Houston, are entitled to be indemnified by RRI and its successors for any losses, including 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 July 2012, GenOn and NRG entered into a definitive merger agreement providing for NRG's acquisition of GenOn, subject to certain conditions. None of the sale of the retail business, the merger with Mirant Corporation or the pending 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’s former affiliate, RRI, was a participant in gas trading in the California and Western markets. These lawsuits, many of which were filed as class actions, allege violations of state and federal antitrust laws. Plaintiffs in these lawsuits are seeking a variety of forms of relief, including, among others, recovery of compensatory damages (in some cases in excess of $1 billion), a trebling of compensatory damages, full consideration damages and attorneys’ fees. CenterPoint Energy and/or Reliant Energy were named in approximately 30 of these lawsuits, which were instituted between 2003 and 2009. CenterPoint Energy and its affiliates have been released or dismissed from all but two of such cases. CenterPoint Energy Services, Inc. (CES), a subsidiary of CenterPoint Energy Resources 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 the 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. The plaintiffs have appealed this ruling to the United States Court of Appeals for the Ninth Circuit. Additionally, CenterPoint Energy was a defendant in a lawsuit filed in state court in Nevada that was dismissed in 2007, but in March 2010 the plaintiffs appealed the dismissal to the Nevada Supreme Court. In September 2012, the Nevada Supreme Court affirmed the dismissal. In October 2012, the Nevada Supreme Court granted the plaintiffs’ motion to stay the dismissal of this case pending the filing and final disposition of their petition for a writ of certiorari to the Supreme Court of the United States. CenterPoint Energy believes that neither it nor CES is a proper defendant in these remaining cases and will continue to pursue dismissal from those cases. CenterPoint Houston does not expect the ultimate outcome of these remaining matters to have a material impact 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, but currently owned by NRG Texas LP. CenterPoint Energy anticipates that additional claims like those received may be asserted in the future. 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. Although their ultimate outcome cannot be predicted at this time, CenterPoint Houston or CenterPoint Energy, as appropriate, intends to continue vigorously contesting claims that are not considered to have merit and 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 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. Some of these proceedings involve substantial amounts. CenterPoint Houston regularly analyzes current information and, as necessary, provides accruals for probable 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 its financial condition, results of operations or cash flows.

- Definition

The entire disclosure for commitments and contingencies.

+ References

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-Number 5
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+ Details

Income Taxes

9 Months Ended

Sep. 30, 2012

Income Tax Disclosure [Abstract]

Income Tax Disclosure [Text Block]

Income Taxes

The effective tax rate for the three and nine months ended September 30, 2012 was 25% and 28%, respectively, compared to 32% and 33% for the same periods in 2011. The decrease in the effective tax rate for the three and nine months ended September 30, 2012 was primarily due to favorable tax adjustments, including the re-measurement of certain unrecognized tax benefits, of $17 million and $25 million for the three and nine months ended September 30, 2012, respectively, related to CenterPoint Energy's Internal Revenue Service (IRS) settlement of tax years 2006 through 2009.

The following table summarizes CenterPoint Houston’s unrecognized tax benefits at December 31, 2011 and September 30, 2012:



	December 31, 2011		September 30, 2012
	(in millions)
Unrecognized tax benefits	$	44	$	—
Portion of unrecognized tax benefits that, if recognized, would reduce the effective income tax rate	18		—
Interest accrued on unrecognized tax benefits	5		—

CenterPoint Energy has a tentative settlement with the IRS for tax years 2008 and 2009 that is under review by the Joint Committee on Taxation. In September 2012, the IRS commenced its examination of CenterPoint Energy’s 2011 consolidated federal income tax return in conjunction with its review of CenterPoint Energy's 2010 consolidated federal income tax return.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

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+ Details

Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2012

Defined Benefit Plan Disclosure [Line Items]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]



	Three Months Ended September 30,						Nine Months Ended September 30,
	2011			2012			2011			2012
	(in millions)
Interest cost	$	4		$	4		$	12		$	12
Expected return on plan assets	(2		)	(2		)	(6		)	(5		)
Amortization of loss	1			1			1			2
Amortization of transition obligation	1			2			4			5
Net periodic cost	$	4		$	5		$	11		$	14

- Definition

Tabular disclosure of one or more of the entity's defined benefit pension plans or one or more other defined benefit postretirement plans, separately for pension plans and other postretirement benefit plans including the entity's schedule of fair value of plan assets for defined benefit or other postretirement plans.

+ References

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-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 4, 7, 16, 20, 21
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5, 6, 7
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2012

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

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



	December 31, 2011				September 30, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(in millions)
Financial liabilities:
Long-term debt (including $151 million of long-term notes payable to parent)	$	4,765	$	5,345	$	6,106	$	6,758

- Definition

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13476-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6447952&loc=d3e13220-108610

Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 19
-Subparagraph a, b, c(1), d(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 14
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15
-Subparagraph b-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
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-Subparagraph c(2), d, e, f
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-Subparagraph a, c(1), c(2), c(3), d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Long-term Debt (Tables)

9 Months Ended

Sep. 30, 2012

Line of Credit Facility [Line Items]

Schedule of Line of Credit Facilities [Table Text Block]

Revolving Credit Facility. As of December 31, 2011 and September 30, 2012, CenterPoint Houston had the following revolving credit facility and utilization of such facility (in millions):



		December 31, 2011				September 30, 2012
Size of Facility		Loans		Letters of Credit		Loans		Letters of Credit
$	300	$	—	$	4	$	—	$	4

Income Taxes (Tables)

9 Months Ended

Sep. 30, 2012

Income Tax Disclosure [Abstract]

Summary of Unrecognized Tax Benefits [Table Text Block]

The following table summarizes CenterPoint Houston’s unrecognized tax benefits at December 31, 2011 and September 30, 2012:



	December 31, 2011		September 30, 2012
	(in millions)
Unrecognized tax benefits	$	44	$	—
Portion of unrecognized tax benefits that, if recognized, would reduce the effective income tax rate	18		—
Interest accrued on unrecognized tax benefits	5		—

- Definition

Tabular disclosure of tax positions taken in the tax returns filed or to be filed for which it is more likely than not that the tax position will not be sustained upon examination by taxing authorities (i.e., uncertain tax positions) and other types of income tax contingencies, including: (1) the policy on classification of interest and penalties; (2) a tabular reconciliation of the total amounts of unrecognized tax benefits at the beginning and end of the period; the total amount(s) of: (3) unrecognized tax benefits that, if recognized, would affect the effective tax rate, and (4) interest and penalties recognized in each of the income statement and balance sheet; (5) for positions for which it is reasonably possible that the total amounts unrecognized will significantly change within 12 months of the reporting date the: (i) nature of the uncertainty, (ii) nature of the event that could occur that would cause the change, and (iii) an estimate of the range of the reasonably possible change or a statement that an estimate of the range cannot be made; and (6) a description of tax years that remain subject to examination by major tax jurisdictions.

+ References + Details

Background and Basis of Presentation (Details)	Sep. 30, 2012
Number Of Vies Consolidated In Financial Statements	5

Employee Benefit Plans (Details) - Other Postretirement Benefit Plans, Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 4	$ 4	$ 12	$ 12
Expected contribution to postretirement benefit plan in current year	7		7
Total contribution to the plan during the period			6
Expected return on plan assets	(2)	(2)	(5)	(6)
Amortization of loss	1	1	2	1
Amortization of transition obligation	2	1	5	4
Net periodic cost	$ 5	$ 4	$ 14	$ 11

- Definition

An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Glossary Expected Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512136

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Glossary Expected Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512171

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(3)
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph h
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References + Details

Regulatory Accounting (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Regulatory Accounting (Details) - USD ($) $ in Millions	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Unrecognized Amount Of Allowed Equity Return	$ 563		$ 563
Amount Of Allowed Equity Return Recognized In Period	$ 16	$ 7	$ 37	$ 15

Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Notes payable—affiliated companies	$ 151	$ 151
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, including money market funds	50	38
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, including money market funds	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, including money market funds	0	0
Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term debt (including $151 million of long-term notes payable to parent)	6,106	4,765
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term debt (including $151 million of long-term notes payable to parent)	$ 6,758	$ 5,345

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References + Details

Related Party Transactions and Major Customers (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Related Party Transaction [Line Items]
Money Pool Borrowings	$ 264		$ 264		$ 1,000
Notes Receivable from Parent	750		750		$ 750
Interest Income (Expense) Net, Related Party	5	$ 5	14	$ 15
Corporate service charges	33	32	105	103
Affiliates of NRG Energy, Inc. [Member]
Related Party Transaction [Line Items]
Sales to major customers	196	188	488	448
Affiliates of Energy Future Holdings Corp. [Member]
Related Party Transaction [Line Items]
Sales to major customers	$ 49	$ 58	$ 123	$ 139

- Definition

For an unclassified balance sheet, amounts due from parties associated with the reporting entity as evidenced by a written promise to pay.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.3)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Related Parties
-URI http://asc.fasb.org/extlink&oid=16382449

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 46R
-Paragraph 16, 17
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 3
-Article 7

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph k
-Subparagraph 1
-Article 4

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 57
-Paragraph 2
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Long-term Debt (Details) $ in Millions	1 Months Ended		9 Months Ended
Long-term Debt (Details) $ in Millions	Aug. 31, 2012 USD ($)	Jan. 31, 2012 USD ($) tranches	Sep. 30, 2012 USD ($)	Dec. 31, 2011 USD ($)
Debt Instrument [Line Items]
Amount Of Transition Bonds Issued To Recover Additional True Up Costs		$ 1,695
Number of tranches of transition bonds \| tranches		3
Minimum Interest Rate On Transition Bonds		0.9012%
Maximum Interest Rate On Transition Bonds		3.0282%
First Mortgage Bonds Used as Collateral			$ 151	$ 151
General mortgage bonds used as collateral			408	508
Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			300	300
Loans Outstanding			0	0
Letters Of Credit Outstanding			$ 4	$ 4
Revolving credit facility borrowing rate			London Interbank Offered Rate plus 125
Percentage on limitation of debt to total capitalization under covenant (in hundredths)			65.00%
CenterPoint Houston [Member] \| Bonds General Mortgage Due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 300
Debt Instrument, Interest Rate, Stated Percentage	2.25%
CenterPoint Houston [Member] \| Bonds General Mortgage Due 2042 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Interest Rate, Stated Percentage	3.55%
CenterPoint Houston [Member] \| Bonds General Mortgage Due January 2014 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.75%
Extinguishment Of Debt Purchase Price Percentage Of Principal	107.332%
Extinguishment of Debt, principal amount	$ 300
CenterPoint Houston [Member] \| Bonds General Mortgage Due March 2014 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.00%
Extinguishment Of Debt Purchase Price Percentage Of Principal	109.397%
Extinguishment of Debt, principal amount	$ 500
CenterPoint Houston [Member] \| Bonds General Mortgage Due 2014 [Member]
Debt Instrument [Line Items]
Number of general mortgage bond series called for redemption	2
Redemption Premium	$ 69

Commitments and Contingencies (Details)	9 Months Ended
Commitments and Contingencies (Details)	Sep. 30, 2012
Loss Contingencies [Line Items]
Recovery of compensatory damages sought by plaintiffs	in excess of $1 billion
Approximate number of gas market manipulation lawsuits naming CenterPoint Energy and/or Reliant Energy (in number of lawsuits)	30
Number of gas market manipulation lawsuits pending for CenterPoint and its affiliates (in number of lawsuits)	2

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Effective tax rate (in hundredths)	25.00%	32.00%	28.00%	33.00%
Reduction In Liability For Uncertain Tax Positions	$ 17		$ 25
Unrecognized tax benefits	0		0		$ 44
Portion of unrecognized tax benefits that, if recognized, would reduce the effective tax rate	0		0		18
Interest accrued on unrecognized tax benefits	$ 0		$ 0		$ 5