CenterPoint Energy (CNP) 10-K 26 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 17, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	CENTERPOINT ENERGY INC
Entity Central Index Key	1130310
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		429,802,703
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$10,907,234,073

STATEMENTS_OF_CONSOLIDATED_INC

STATEMENTS OF CONSOLIDATED INCOME (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statements of Consolidated Income
Revenues	$9,226	$8,106	$7,452
Expenses:
Natural gas	4,921	3,908	2,873
Operation and maintenance	1,969	1,847	1,874
Depreciation and amortization	1,013	954	1,050
Taxes other than income taxes	388	387	365
Goodwill impairment	0	0	252
Total	8,291	7,096	6,414
Operating Income	935	1,010	1,038
Other Income (Expense):
Gain on marketable securities	163	236	154
Loss on indexed debt securities	-86	-193	-71
Interest and other finance charges	-353	-351	-422
Interest on transition and system restoration bonds	-118	-133	-147
Equity in earnings of unconsolidated affiliates	308	188	31
Step acquisition gain	0	0	136
Other, net	36	24	38
Total	-50	-229	-281
Income Before Income Taxes	885	781	757
Income tax expense	274	470	340
Net Income	$611	$311	$417
Basic Earnings Per Share:
Basic Earnings Per Share	$1.42	$0.73	$0.98
Diluted Earnings Per Share:
Diluted Earnings Per Share	$1.42	$0.72	$0.97
Weighted Average Shares Outstanding, Basic	429,634,000	428,466,000	427,189,000
Weighted Average Shares Outstanding, Diluted	431,668,000	430,930,000	429,794,000

STATEMENTS_OF_CONSOLIDATED_COM

STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (USD $)	3 Months Ended										12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statements of Consolidated Comprehensive Income
Net income	$176	[1]	$143	$107	$185	$113	$151	($100)	[2]	$147	$611	$311	$417
Other comprehensive income (loss):
Adjustment to pension and other postretirement plans (net of tax of $5, $25 and $2, respectively)											3	44	-2
Reclassification of deferred loss from cash flow hedges realized in net income (net of tax)											1	1	0
Other comprehensive income (loss)											4	45	-2
Comprehensive income											$615	$356	$415
[1]	CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.
[2]	Effective May 1, 2013, CenterPoint Energy contributed CenterPoint Midstream to Enable. See Note 2(b) and Note 9 for further discussion on the formation of Enable and CenterPoint Energy’s investment in Enable, respectively.

STATEMENTS_OF_CONSOLIDATED_COM1

STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Parenthetical) STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Parentheticals) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Adjustment to pension and other postretirement plans (net of tax of $5, $25 and $2, respectively	$5	$25	$2

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Current Assets:
Cash and cash equivalents ($290 and $207 related to VIEs, respectively)	$298		$208
Investment in marketable securities	930		767
Accounts receivable ($58 and $60 related to VIEs, respectively), less bad debt reserve of $26 and $28, respectively	837		851
Accrued unbilled revenues	357		398
Inventory	379		285
Non-trading derivative assets	99		24
Taxes receivable	190		0
Prepaid expense and other current assets ($47 and $41 related to VIEs, respectively)	178		125
Total current assets	3,268		2,658
Property, Plant and Equipment, net	10,502		9,593
Other Assets:
Goodwill	840		840
Regulatory assets ($2,738 and $3,179 related to VIEs, respectively)	3,527		3,726
Notes receivable - affiliated companies	363		363
Non-trading derivative assets	32		10
Investment in unconsolidated affiliates	4,521		4,518
Other	147		162
Total other assets	9,430		9,619
Total Assets	23,200		21,870
Current Liabilities:
Short-term borrowings	53	[1]	43	[1]
Current portion of VIE transition and system restoration bonds long-term debt	372		354
Indexed debt	152		143
Current portion of other long-term debt	271		0
Indexed debt securities derivative	541		455
Accounts payable	716		689
Taxes accrued	161		184
Interest accrued	124		124
Non-trading derivative liabilities	19		17
Accumulated deferred income taxes, net	683		608
Other	383		402
Total current liabilities	3,475		3,019
Other Liabilities:
Accumulated deferred income taxes, net	4,757		4,542
Non-trading derivative liabilities	1		4
Benefit obligations	953		802
Regulatory liabilities	1,206		1,152
Other	251		205
Total other liabilities	7,168		6,705
Long-term Debt:
VIE transition and system restoration bonds	2,674		3,046
Other long-term debt	5,335		4,771
Total long-term debt	8,009		7,817
Commitments and Contingencies (Note 14)
Shareholders’ Equity	4,548		4,329
Total Liabilities and Shareholders’ Equity	$23,200		$21,870
[1]	Includes amounts due or exchangeable within one year of the date noted.

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current Assets:
Cash and cash equivalents ($290 and $207 related to VIEs, respectively)	$298	$208
Allowance for Doubtful Accounts Receivable, Current	26	28
Accounts receivable ($58 and $60 related to VIEs, respectively), less bad debt reserve of $26 and $28, respectively	837	851
Prepaid expense and other current assets ($47 and $41 related to VIEs, respectively)	178	125
Other Assets:
Regulatory assets ($2,738 and $3,179 related to VIEs, respectively)	3,527	3,726
Variable Interest Entity, Primary Beneficiary [Member]
Current Assets:
Cash and cash equivalents ($290 and $207 related to VIEs, respectively)	290	207
Accounts receivable ($58 and $60 related to VIEs, respectively), less bad debt reserve of $26 and $28, respectively	58	60
Prepaid expense and other current assets ($47 and $41 related to VIEs, respectively)	47	41
Other Assets:
Regulatory assets ($2,738 and $3,179 related to VIEs, respectively)	$2,738	$3,179

STATEMENTS_OF_CONSOLIDATED_CAS

STATEMENTS OF CONSOLIDATED CASH FLOWS (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Cash Flows [Abstract]
Net income	$611	$311	$417
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,013	954	1,050
Amortization of deferred financing costs	28	30	32
Deferred income taxes	280	356	328
Goodwill impairment	0	0	252
Step acquisition gain	0	0	-136
Unrealized gain on marketable securities	-163	-236	-154
Unrealized loss on indexed debt securities	86	193	71
Write-down of natural gas inventory	8	4	4
Equity in earnings of unconsolidated affiliates, net of distributions	-2	-58	8
Pension contributions	-97	-91	-82
Changes in other assets and liabilities:
Accounts receivable and unbilled revenues, net	39	-256	10
Inventory	-102	-22	27
Taxes receivable	-190	7	-7
Accounts payable	-3	152	-6
Fuel cost recovery	-41	108	-52
Non-trading derivatives, net	-34	4	20
Margin deposits, net	-79	16	53
Interest and taxes accrued	-23	41	-62
Net regulatory assets and liabilities	22	61	66
Other current assets	1	-2	-12
Other current liabilities	-20	21	18
Other assets	9	-24	-18
Other liabilities	41	20	16
Other, net	13	24	17
Net cash provided by operating activities	1,397	1,613	1,860
Capital expenditures, net of acquisitions	-1,372	-1,286	-1,212
Acquisitions, net of cash acquired	0	0	-360
Decrease (increase) in restricted cash of transition and system restoration bond companies	-7	17	-13
Investment in unconsolidated affiliates	-1	0	-5
Cash contribution to Enable	0	-38	0
Proceeds from sale of marketable securities	0	9	0
Other, net	-4	-2	-13
Net cash used in investing activities	-1,384	-1,300	-1,603
Increase (decrease) in short-term borrowings, net	10	5	-24
Proceeds from (payments of) commercial paper, net	414	118	-285
Proceeds from long-term debt	600	1,050	2,495
Payments of long-term debt	-537	-1,573	-1,590
Cash paid for debt exchange and debt retirement	-1	-7	-69
Debt issuance costs	-8	-3	-16
Redemption of indexed debt securities	0	-8	0
Payment of common stock dividends	-408	-355	-346
Proceeds from issuance of common stock, net	1	4	4
Other, net	6	18	0
Net cash provided by (used in) financing activities	77	-751	169
Net Increase (Decrease) in Cash and Cash Equivalents	90	-438	426
Cash and Cash Equivalents at Beginning of Year	208	646	220
Cash and Cash Equivalents at End of Year	298	208	646
Cash Payments:
Interest, net of capitalized interest	434	475	556
Income taxes, net	192	35	46
Non-cash transactions:
Accounts payable related to capital expenditures	104	74	110
Formation of Enable	0		0
Exercise of SESH put to Enable		0	0
Exercise of SESH put to Enable [Member]
Non-cash transactions:
Exercise of SESH put to Enable	196
Formation of Enable [Member]
Non-cash transactions:
Formation of Enable		$4,252

STATEMENTS_OF_CONSOLIDATED_SHA

STATEMENTS OF CONSOLIDATED SHAREHOLDERS' EQUITY (USD $)	Total	Preference Stock [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Adjustment to pension and postretirement plans [Member]	Net deferred loss from cash flow hedges [Member]	Total accumulated other comprehensive loss, end of year [Member]
In Millions, unless otherwise specified
Balance at Dec. 31, 2011				$4	$4,120	$231
Shares, Outstanding at Dec. 31, 2011				426
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance related to benefit and investment plans				0	10
Issuance related to benefit and investment plans (in shares)				2
Net income	417					417
Common stock dividends						-346
Balance at Dec. 31, 2012	4,301	0	0	4	4,130	302	-132	-3	-135
Shares, Outstanding at Dec. 31, 2012		0	0	428
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance related to benefit and investment plans				0	27
Issuance related to benefit and investment plans (in shares)				1
Net income	311					311
Common stock dividends						-355
Balance at Dec. 31, 2013	4,329	0	0	4	4,157	258	-88	-2	-90
Shares, Outstanding at Dec. 31, 2013		0	0	429
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance related to benefit and investment plans				0	12
Issuance related to benefit and investment plans (in shares)				1
Net income	611					611
Common stock dividends						-408
Balance at Dec. 31, 2014	$4,548	$0	$0	$4	$4,169	$461	($85)	($1)	($86)
Shares, Outstanding at Dec. 31, 2014		0	0	430

STATEMENTS_OF_CONSOLIDATED_SHA1

STATEMENTS OF CONSOLIDATED SHAREHOLDERS' EQUITY (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Stockholders' Equity [Abstract]
Preferred Stock, Shares Outstanding	0	0	0
Cumulative preferred stock par value (in dollars per share)	$0.01	$0.01	$0.01
Cumulative preferred stock shares authorized (in shares)	20,000,000	20,000,000	20,000,000
Common stock shares par value (in dollars per share)	$0.01	$0.01	$0.01
Common stock shares authorized (in shares)	1,000,000,000	1,000,000,000	1,000,000,000

Background

Background	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background	Background
	CenterPoint Energy, Inc. is a public utility holding company. CenterPoint Energy’s operating subsidiaries own and operate electric transmission and distribution facilities and natural gas distribution facilities and own interests in Enable Midstream Partners, LP (Enable) as described below. As of December 31, 2014, CenterPoint Energy’s indirect wholly owned subsidiaries included:
	•	CenterPoint Energy Houston Electric, LLC (CenterPoint Houston), which engages in the electric transmission and distribution business in the Texas Gulf Coast area that includes the city of Houston; and
	•	CenterPoint Energy Resources Corp. (CERC Corp. and, together with its subsidiaries, CERC), which owns and operates natural gas distribution systems (NGD). A wholly owned subsidiary of CERC Corp. offers variable and fixed-price physical natural gas supplies primarily to commercial and industrial customers and electric and gas utilities. As of December 31, 2014, CERC Corp. also owned approximately 55.4% of the limited partner interests in Enable, which owns, operates and develops natural gas and crude oil infrastructure assets.
	For a description of CenterPoint Energy’s reportable business segments, see Note 17.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	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 Energy and its wholly owned and majority owned subsidiaries are included in the consolidated financial statements. All intercompany transactions and balances are eliminated in consolidation. CenterPoint Energy generally uses the equity method of accounting for investments in entities in which CenterPoint Energy has an ownership interest between 20% and 50% and exercises significant influence. CenterPoint Energy also uses the equity method for investments in which it has ownership percentages greater than 50%, when it exercises significant influence, does not have control and is not considered the primary beneficiary, if applicable.
	On March 14, 2013, CenterPoint Energy entered into a Master Formation Agreement (MFA) with OGE Energy Corp. (OGE) and affiliates of ArcLight Capital Partners, LLC (ArcLight), pursuant to which CenterPoint Energy, OGE and ArcLight agreed to form Enable as a private limited partnership. On May 1, 2013, the parties closed on the formation of Enable. In connection with the closing (i) CERC Corp. converted its direct wholly owned subsidiary, CenterPoint Energy Field Services, LLC, a Delaware limited liability company (CEFS), into a Delaware limited partnership that became Enable, (ii) CERC Corp. contributed to Enable its equity interests in each of CenterPoint Energy Gas Transmission Company, LLC, which has been subsequently renamed Enable Gas Transmission, LLC (EGT), CenterPoint Energy - Mississippi River Transmission, LLC, which has been subsequently renamed Enable Mississippi River Transmission, LLC (MRT), certain of its other midstream subsidiaries (Other CNP Midstream Subsidiaries), and a 24.95% interest in Southeast Supply Header, LLC (SESH and, collectively with CEFS, EGT, MRT and Other CNP Midstream Subsidiaries, CenterPoint Midstream), and (iii) OGE and ArcLight indirectly contributed 100% of the equity interests in Enogex LLC, which has been subsequently renamed Enable Oklahoma Intrastate Transmission, LLC (Enogex), to Enable.
	The formation of Enable by CenterPoint Energy was considered a contribution of in-substance real estate to a limited partnership as the businesses are composed of, and reliant upon, substantial real estate assets and integral equipment. Real estate assets and integral equipment primarily include gas transmission pipelines, compressor station equipment, rights of way, storage and processing assets and long-term customer contracts. Accordingly, CenterPoint Energy did not recognize a gain or loss upon contribution and recorded its investment in Enable using the equity method of accounting based on the historical cost of the contributed assets and liabilities as of May 1, 2013 (Closing Date). Approximately $5.8 billion of assets (which includes $4.7 billion in property, plant and equipment, net, $629 million in goodwill and $197 million for the 24.95% investment in SESH) and $1.5 billion of liabilities (which includes a term loan and the indebtedness owed to CERC of $1.05 billion and $363 million, respectively) were contributed by CERC Corp. CenterPoint Energy has the ability to significantly influence the operating and financial policies of, but not solely control, Enable and, accordingly, recorded an equity method investment, at the historical costs of net assets contributed, of $4.3 billion in Enable on the Closing Date. Pursuant to the MFA, CenterPoint Energy retained certain assets and liabilities historically held by CenterPoint Midstream such as balances relating to federal income taxes and benefit plan obligations.
	Under the equity method, CenterPoint Energy adjusts its investment in Enable each period for contributions made, distributions received, CenterPoint Energy’s share of Enable’s comprehensive income and accretion of basis differences, as appropriate. CenterPoint Energy evaluates its equity method investments for impairment when events or changes in circumstances indicate there is a loss in value of the investment that is other than a temporary decline.
	CenterPoint Energy’s investment in Enable is considered to be a variable interest entity (VIE) because the power to direct the activities that most significantly impact Enable’s economic performance does not reside with the holders of equity investment at risk. However, CenterPoint Energy is not considered the primary beneficiary of Enable since it does not have the power to direct the activities of Enable that are considered most significant to the economic performance of Enable.
	As of December 31, 2014, CERC Corp. and OGE held approximately 55.4% and 26.3%, respectively, of the limited partner interests in Enable. Enable is controlled jointly by CERC Corp. and OGE, and each own 50% of the management rights in the general partner of Enable.
	As of December 31, 2014, CERC Corp. and OGE also own a 40% and 60% interest, respectively, in the incentive distribution rights held by the general partner of Enable. Enable is expected to pay a minimum quarterly distribution of $0.2875 per unit on its outstanding units to the extent it has sufficient cash from operations after establishment of cash reserves and payment of fees and expenses, including payments to its general partner and its affiliates, within 45 days after the end of each quarter. If cash distributions to Enable’s unitholders exceed $0.330625 per unit in any quarter, the general partner will receive increasing percentages or incentive distributions rights, up to 50%, of the cash Enable distributes in excess of that amount. In certain circumstances the general partner of Enable will have the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election.
	Prior to July 2012, CenterPoint Energy owned a 50% interest in Waskom Gas Processing Company (Waskom), a Texas general partnership, which owns and operates a natural gas processing plant and natural gas gathering assets. On July 31, 2012, CenterPoint Energy purchased the 50% interest that it did not already own in Waskom, as well as other gathering and related assets from a third-party for approximately $273 million. The purchase of the 50% interest in Waskom was determined to be a business combination achieved in stages, and as such CenterPoint Energy recorded a pre-tax gain of approximately $136 million on July 31, 2012, which is the result of remeasuring its original 50% interest in Waskom to fair value.
	Other investments, excluding marketable securities, are carried at cost.
	As of December 31, 2014, CenterPoint Energy had 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 Energy 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 Energy.
	(c)	Revenues
	CenterPoint Energy records revenue for electricity delivery and natural gas sales and services 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. Natural gas sales not billed by month-end are accrued based upon estimated purchased gas volumes, estimated lost and unaccounted for gas and currently effective tariff rates.
	(d) Long-lived Assets and Intangibles
	CenterPoint Energy records property, plant and equipment at historical cost. CenterPoint Energy expenses repair and maintenance costs as incurred.
	CenterPoint Energy 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 Energy applies the guidance for accounting for regulated operations to the Electric Transmission & Distribution business segment and the Natural Gas Distribution business segment. CenterPoint Energy’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 Energy’s rate-regulated businesses recognize removal costs as a component of depreciation expense in accordance with regulatory treatment. As of December 31, 2014 and 2013, these removal costs of $958 million and $941 million, respectively, are classified as regulatory liabilities in CenterPoint Energy’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 and amortization is computed using the straight-line method based on economic lives or regulatory-mandated recovery periods. Amortization expense includes amortization of regulatory assets and other intangibles.
	(g) Capitalization of Interest and Allowance for Funds Used During Construction
	Interest and allowance for funds used during construction (AFUDC) are capitalized as a component of projects under construction and are 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 for subsidiaries that apply the guidance for accounting for regulated operations. During 2014, 2013 and 2012, CenterPoint Energy capitalized interest and AFUDC of $11 million, $11 million and $9 million, respectively. During 2014, 2013 and 2012, CenterPoint Energy recorded AFUDC equity of $14 million, $8 million and $6 million, respectively, which is included in Other Income in its Statements of Consolidated Income.
	(h) Income Taxes
	CenterPoint Energy 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 Energy recognizes interest and penalties as a component of income tax expense.
	(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 Energy’s Statements of Consolidated Income for 2014, 2013 and 2012 was $22 million, $21 million and $16 million, respectively.
	(j) Inventory
	Inventory consists principally of materials and supplies and natural gas. Materials and supplies are 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. Natural gas inventories of CenterPoint Energy’s Energy Services business segment are valued at the lower of average cost or market. Natural gas inventories of CenterPoint Energy’s Natural Gas Distribution business segment are primarily valued at weighted average cost. During 2014, 2013 and 2012, CenterPoint Energy recorded $8 million, $4 million and $4 million, respectively, in write-downs of natural gas inventory to the lower of average cost or market.
		December 31,
		2014		2013
	Materials and supplies	$	168	$	140
	Natural gas	211		145
	Total inventory	$	379	$	285
	(k) Derivative Instruments
	CenterPoint Energy is exposed to various market risks. These risks arise from transactions entered into in the normal course of business.  CenterPoint Energy utilizes derivative instruments such as physical forward contracts, swaps and options to mitigate the impact of changes in commodity prices and weather on its operating results and cash flows. Such derivatives are recognized in CenterPoint Energy’s Consolidated Balance Sheets at their fair value unless CenterPoint Energy elects the normal purchase and sales exemption for qualified physical transactions. A derivative may be designated as a normal purchase or normal sale if the intent is to physically receive or deliver the product for use or sale in the normal course of business.
	CenterPoint Energy has a Risk Oversight Committee composed of corporate and business segment officers that oversees all commodity price, weather and credit risk activities, including CenterPoint Energy’s marketing, risk management services and hedging activities. The committee’s duties are to establish CenterPoint Energy’s commodity risk policies, allocate board-approved commercial risk limits, approve the use of new products and commodities, monitor positions and ensure compliance with CenterPoint Energy’s risk management policies and procedures and limits established by CenterPoint Energy’s board of directors.
	CenterPoint Energy’s policies prohibit the use of leveraged financial instruments. A leveraged financial instrument, for this purpose, is a transaction involving a derivative whose financial impact will be based on an amount other than the notional amount or volume of the instrument.
	(l) Investments in Other Debt and Equity Securities
	CenterPoint Energy reports securities classified as trading at estimated fair value in its Consolidated Balance Sheets, and any unrealized holding gains and losses are recorded as other income (expense) in its Statements of Consolidated Income.
	(m) Environmental Costs
	CenterPoint Energy expenses or capitalizes environmental expenditures, as appropriate, depending on their future economic benefit. CenterPoint Energy expenses amounts that relate to an existing condition caused by past operations that do not have future economic benefit. CenterPoint Energy records undiscounted liabilities related to these future costs when environmental assessments and/or remediation activities are probable and the costs can be reasonably estimated.
	(n) Statements of Consolidated Cash Flows
	For purposes of reporting cash flows, CenterPoint Energy 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 Energy 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 $47 million and $41 million at December 31, 2014 and 2013, respectively, are included in other current assets in CenterPoint Energy’s Consolidated Balance Sheets. Cash and cash equivalents included $290 million and $207 million at December 31, 2014 and 2013, respectively, that was held by CenterPoint Energy’s transition and system restoration bond subsidiaries solely to support servicing the transition and system restoration bonds.
	CenterPoint Energy considers distributions received from equity method investments which do not exceed cumulative equity in earnings subsequent to the date of investment to be a return on investment and classifies these distributions as operating activities in the Statements of Consolidated Cash Flows. CenterPoint Energy considers distributions received from equity method investments in excess of cumulative equity in earnings subsequent to the date of investment to be a return of investment and classifies these distributions as investing activities in the Statements of Consolidated Cash Flows.
	(o) New Accounting Pronouncements
	In April 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (ASU 2014-08), which significantly changes the existing accounting guidance on discontinued operations. Under ASU 2014-08, only those disposals of components of an entity that represent a strategic shift that has (or will have) a major effect on an entity’s operations and financial results should be reported as a discontinued operation.  ASU 2014-08 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2014.  ASU 2014-08 should be applied to components classified as held for sale after its effective date. Early adoption is permitted, but only for disposals (or classifications as held for sale) that have not been reported in financial statements previously issued or available for issuance. The adoption is expected to reduce the number of disposals that meet the definition of a discontinued operation.
	In May 2014, the FASB issued ASU 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 is 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. Accordingly, CenterPoint Energy will adopt ASU 2014-09 on January 1, 2017, and is currently evaluating the impact that this standard will have on its financial position, results of operations, cash flows and disclosures.
	In November 2014, the FASB issued ASU No. 2014-16, Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity (ASU 2014-16).  ASU 2014-16 clarifies how current guidance should be interpreted in evaluating the economic characteristics and risks of a host contract in a hybrid financial instrument that is issued in the form of a share. Specifically, the amendments clarify that an entity should consider all relevant terms and features, including the embedded derivative feature being evaluated for bifurcation, in evaluating the nature of a host contract. ASU 2014-16 is effective for fiscal years and interim periods beginning after December 15, 2015. CenterPoint Energy is currently assessing the impact, if any, that this standard will have on its financial position, results of operations, cash flows and disclosures.
	In January 2015, the FASB issued ASU No. 2015-01, Income Statement-Extraordinary and Unusual Items (Subtopic 225-20)-Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items (ASU 2015-01), which eliminates the concept of extraordinary items. ASU 2015-01 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015, and may be applied either prospectively or retrospectively. CenterPoint Energy will adopt ASU 2015-01 on January 1, 2016 and does not anticipate the adoption to have a material impact on its consolidated financial statements.
	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.

Property_Plant_and_Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment
	(a) Property, Plant and Equipment
	Property, plant and equipment includes the following:
		Weighted Average		December 31,
		Useful Lives
		(Years)		2014				2013
				(in millions)
	Electric Transmission & Distribution	31		$	9,393			$	8,741
	Natural Gas Distribution	33		5,235				4,694
	Energy Services	27		84				82
	Other property	22		646				621
	Total			15,358				14,138
	Accumulated depreciation and amortization:
	Electric Transmission & Distribution			3,050				2,907
	Natural Gas Distribution			1,493				1,324
	Energy Services			31				28
	Other property			282				286
	Total accumulated depreciation and amortization			4,856				4,545
	Property, plant and equipment, net			$	10,502			$	9,593
	(b) Depreciation and Amortization
	The following table presents depreciation and amortization expense for 2014, 2013 and 2012 (in millions).
		2014				2013				2012
	Depreciation expense	$	521			$	531			$	562
	Amortization expense	492				423				488
	Total depreciation and amortization expense	$	1,013			$	954			$	1,050
	(c) Asset Retirement Obligations
	A reconciliation of the changes in the asset retirement obligation (ARO) liability is as follows (in millions):
		December 31,
		2014				2013
	Beginning balance	$	134			$	164
	Accretion expense	5				5
	Revisions in estimates of cash flows	37				(35		)
	Ending balance	$	176			$	134
	CenterPoint Energy recorded asset retirement obligations associated with the removal of asbestos and asbestos-containing material in its buildings, including substation building structures. CenterPoint Energy also recorded asset retirement obligations relating to gas pipelines abandoned in place, 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 $37 million in the ARO from the revision of estimate in 2014 is primarily attributable to a reduction of the estimated service lives of steel and plastic pipe. The decrease of $35 million in the ARO from the revision of estimate in 2013 is primarily attributable to a decrease in the future expected cash flows associated with the retirement of steel pipe.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill
	Goodwill by reportable business segment as of both December 31, 2014 and 2013 are as follows (in millions):
	Natural Gas Distribution		$	746
	Energy Services (1)		83
	Other		11
	Total		$	840
	-1	Amounts presented are net of accumulated goodwill impairment charge of $252 million.
	CenterPoint Energy performs its goodwill impairment tests at least annually and evaluates goodwill when events or changes in circumstances indicate that its carrying value may not be recoverable. The impairment evaluation for goodwill is performed by using a two-step process. In the first step, the fair value of each reporting unit, which approximate the reportable business segments, is compared with the carrying amount of the reporting unit, including goodwill. The estimated fair value of the reporting unit is generally determined on the basis of discounted cash flows. If the estimated fair value of the reporting unit is less than the carrying amount of the reporting unit, then a second step must be completed in order to determine the amount of the goodwill impairment that should be recorded. In the second step, the implied fair value of the reporting unit’s goodwill is determined by allocating the reporting unit’s fair value to all of its assets and liabilities other than goodwill (including any unrecognized intangible assets) in a manner similar to a purchase price allocation. The resulting implied fair value of the goodwill that results from the application of this second step is then compared to the carrying amount of the goodwill and an impairment charge is recorded for the difference.
	CenterPoint Energy performed its annual impairment test in the third quarter of each of 2014 and 2013 and determined, based on the results of the first step, that no impairment charge was required for any reportable segment. Other intangibles were not material as of December 31, 2014 and 2013.
	CenterPoint Energy’s annual impairment test in the third quarter of 2012 resulted in a non-cash goodwill impairment charge in the amount of $252 million for the Energy Services reportable segment. The Energy Services reporting unit fair value analysis resulted in an implied fair value of goodwill of $83 million for this reporting unit, and as a result, the non-cash impairment charge was recorded in the third quarter of 2012. The adverse wholesale market conditions facing CenterPoint Energy’s Energy Services business, specifically the prospects for continued low geographic and seasonal price differentials for natural gas, led to a reduction in the estimate of the fair value of goodwill associated with this reporting unit.
	CenterPoint Energy estimated the value of the Energy Services reporting unit using an income approach. Under this approach, the fair value of the reporting unit is determined by using the present value of future expected cash flows, which are based on management projections of revenue growth, gross margin, and overall market conditions. These estimated future cash flows are then discounted using a rate that approximates the weighted average cost of capital of a market participant.

Regulatory_Accounting

Regulatory Accounting	12 Months Ended
	Dec. 31, 2014
Regulated Operations [Abstract]
Regulatory Matters	Regulatory Accounting
	The following is a list of regulatory assets/liabilities reflected on CenterPoint Energy’s Consolidated Balance Sheets as of December 31, 2014 and 2013:
		December 31,
		2014			2013
		(in millions)
	Securitized regulatory assets	$	2,738		$	3,179
	Unrecognized equity return (1)	(442		)	(508		)
	Unamortized loss on reacquired debt	104			111
	Pension and postretirement-related regulatory asset (2)	922			732
	Other long-term regulatory assets (3)	205			212
	Total regulatory assets	3,527			3,726
	Estimated removal costs	958			941
	Other long-term regulatory liabilities	248			211
	Total regulatory liabilities	1,206			1,152
	Total regulatory assets and liabilities, net	$	2,321		$	2,574
	-1	As of December 31, 2014, CenterPoint Energy has not recognized an allowed equity return of $442 million because such return will be recognized as it is recovered in rates through 2024. During the years ended December 31, 2014, 2013 and 2012, CenterPoint Houston recognized approximately $68 million, $45 million and $47 million, respectively, of the allowed equity return. The timing of CenterPoint Energy’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	CenterPoint Houston’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates is being deferred for rate making purposes. Deferred pension and other postemployment expenses of $-0- and $5 million as of December 31, 2014 and 2013, respectively, were not earning a return.
	-3	Other regulatory assets that are not earning a return were not material as of December 31, 2014 and 2013.

StockBased_Incentive_Compensat

Stock-Based Incentive Compensation Plans and Employee Benefit Plans	12 Months Ended
	Dec. 31, 2014
Disclosure of Stock-Based Incentive Compensation Plans and Employee Benefit Plans [Abstract]
Stock-Based Incentive Compensation Plans and Employee Benefit Plans	Stock-Based Incentive Compensation Plans and Employee Benefit Plans
	(a) Stock-Based Incentive Compensation Plans
	CenterPoint Energy has long-term incentive plans (LTIPs) that provide for the issuance of stock-based incentives, including stock options, performance awards, restricted stock unit awards and restricted and unrestricted stock awards to officers, employees and non-employee directors.  Approximately 14 million shares of CenterPoint Energy common stock are authorized under these plans for awards.
	Equity awards are granted to employees without cost to the participants. The performance awards granted in 2014, 2013 and 2012 are distributed based upon the achievement of certain objectives over a three-year performance cycle. The stock awards granted in 2014 are service based. The stock awards granted in 2013 and 2012 are subject to the performance condition that total common dividends declared during the three-year vesting period must be at least $2.49 and $2.43 per share, respectively. The stock awards generally vest at the end of a three-year period. Upon vesting, both the performance and stock awards are issued to the participants along with the value of dividend equivalents earned over the performance cycle or vesting period. CenterPoint Energy issues new shares in order to satisfy stock-based payments related to LTIPs.
	CenterPoint Energy recorded LTIP compensation expense of $18 million, $19 million and $18 million for the years ended December 31, 2014, 2013 and 2012, respectively.  This expense is included in Operation and Maintenance Expense in the Statements of Consolidated Income.
	The total income tax benefit recognized related to LTIPs was $7 million for each of the years ended December 31, 2014, 2013 and 2012. No compensation cost related to LTIPs was capitalized as a part of inventory or fixed assets in 2014, 2013 or 2012. The actual tax benefit realized for tax deductions related to LTIPs totaled $13 million, $13 million and $14 million for 2014, 2013 and 2012, respectively.
	Compensation costs for the performance and stock awards granted under LTIPs are measured using fair value and expected achievement levels on the grant date.  For performance awards with operational goals, the achievement levels are revised as goals are evaluated. The fair value of awards granted to employees is based on the closing stock price of CenterPoint Energy’s common stock on the grant date.  The compensation expense is recorded on a straight-line basis over the vesting period.  Forfeitures are estimated on the date of grant based on historical averages, and estimates are updated periodically throughout the vesting period.
	The following tables summarize CenterPoint Energy’s LTIP activity for 2014:
	Stock Options
		Outstanding Options
		Year Ended December 31, 2014
		Shares			Weighted-Average				Remaining Average			Aggregate
		(Thousands)			Exercise Price				Contractual			Intrinsic
									Life (Years)			Value (Millions)
	Outstanding at December 31, 2013	120			$	10.93
	Exercised	(120	)		10.93
	Outstanding at December 31, 2014	—			—				—			$	—
	Exercisable at December 31, 2014	—			—				—			—
	Cash received from stock options exercised was $1 million, $3 million and $3 million for 2014, 2013 and 2012, respectively.
	CenterPoint Energy has not issued stock options since 2004.
	Performance Awards
		Outstanding and Non-Vested Shares
		Year Ended December 31, 2014
		Shares			Weighted-Average				Remaining Average		Aggregate
		(Thousands)			Grant Date				Contractual		Intrinsic
					Fair Value				Life (Years)		Value (Millions)
	Outstanding at December 31, 2013	2,703			$	18.17
	Granted	1,198			23.7
	Forfeited or cancelled	(515	)		21.09
	Vested and released to participants	(926	)		15.5
	Outstanding at December 31, 2014	2,460			21.26				1.1		$	40
	The outstanding and non-vested shares displayed in the table above assumes that shares are issued at the maximum performance level. The aggregate intrinsic value reflects the impact of current expectations of achievement and stock price.
	Stock Awards
		Outstanding and Non-Vested Shares
		Year Ended December 31, 2014
		Shares			Weighted-Average				Remaining Average		Aggregate
		(Thousands)			Grant Date				Contractual		Intrinsic
					Fair Value				Life (Years)		Value (Millions)
	Outstanding at December 31, 2013	898			$	18.72
	Granted	322			23.89
	Forfeited or cancelled	(122	)		21.6
	Vested and released to participants	(375	)		17.03
	Outstanding at December 31, 2014	723			21.41				1		$	17
	The weighted-average grant-date fair values per unit of awards granted were as follows for 2014, 2013 and 2012:
		Year Ended December 31,
		2014				2013				2012
	Performance awards	$	23.7			$	20.67			$	18.79
	Stock awards	23.89				21.53				18.96
	Valuation Data
	The total intrinsic value of awards received by participants was as follows for 2014, 2013 and 2012:
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Stock options exercised	$	2			$	4			$	6
	Performance awards	24				20				24
	Stock awards	10				10				9
	The total grant date fair value of performance and stock awards which vested during the years ended December 31, 2014, 2013 and 2012 was $21 million, $19 million and $19 million, respectively.  As of December 31, 2014, there was $17 million of total unrecognized compensation cost related to non-vested performance and stock awards which is expected to be recognized over a weighted-average period of 1.6 years.
	(b) Pension and Postretirement Benefits
	CenterPoint Energy maintains a non-contributory qualified defined benefit pension plan covering substantially all employees, with benefits determined using a cash balance formula. Under the cash balance formula, participants accumulate a retirement benefit based upon 5% of eligible earnings and accrued interest. Participants are 100% vested in their benefit after completing three years of service. In addition to the non-contributory qualified defined benefit pension plan, CenterPoint Energy maintains unfunded non-qualified benefit restoration plans which allow participants to receive the benefits to which they would have been entitled under CenterPoint Energy’s 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.
	CenterPoint Energy provides 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. The net unrecognized transition obligation is being amortized over approximately 20 years.
	CenterPoint Energy’s net periodic cost includes the following components relating to pension, including the benefit restoration plan, and postretirement benefits:
		Year Ended December 31,
		2014								2013								2012
	Pension				Post-retirement				Pension				Post-retirement				Pension			Post-retirement
	Benefits				Benefits				Benefits				Benefits				Benefits			Benefits
	(in millions)
Service cost	$	42			$	2			$	44			$	2			$	35		$	1
Interest cost	100				22				90				20				100			23
Expected return on plan assets	(125		)		(7		)		(135		)		(7		)		(121		)	(7		)
Amortization of prior service cost (credit)	10				(1		)		10				1				8			3
Amortization of net loss	44				1				63				6				60			4
Amortization of transition obligation	—				5				—				7				—			7
Benefit enhancement	—				—				—				—				—			1
Curtailment (1)	6				—				—				—				—			—
Net periodic cost	$	77			$	22			$	72			$	29			$	82		$	32
-1	During the fourth quarter of 2014, CenterPoint Energy recognized a curtailment pension loss of $6 million related to employees seconded to Enable. Substantially all of the seconded employees became employees of Enable effective January 1, 2015.
CenterPoint Energy used the following assumptions to determine net periodic cost relating to pension and postretirement benefits:
	Year Ended December 31,
	2014						2013						2012
	Pension			Post-retirement			Pension			Post-retirement			Pension			Post-retirement
	Benefits			Benefits			Benefits			Benefits			Benefits			Benefits
Discount rate	4.8	%		4.75	%		4	%		3.9	%		4.9	%		4.8	%
Expected return on plan assets	7			5.5			8			5.5			8			5.5
Rate of increase in compensation levels	3.9			—			4			—			4.2			—
In determining net periodic benefits cost, CenterPoint Energy uses fair value, as of the beginning of the year, as its basis for determining expected return on plan assets.
The following table summarizes changes in the benefit obligation, plan assets, the amounts recognized in consolidated balance sheets and the key assumptions of CenterPoint Energy’s pension, including benefit restoration, and postretirement plans. The measurement dates for plan assets and obligations were December 31, 2014 and 2013.
	December 31,
	2014								2013
	Pension				Post-retirement				Pension				Post-retirement
	Benefits				Benefits				Benefits				Benefits
	(in millions, except for actuarial assumptions)
Change in Benefit Obligation
Benefit obligation, beginning of year	$	2,153			$	476			$	2,316			$	538
Service cost	42				2				44				2
Interest cost	100				22				90				20
Participant contributions	—				7				—				7
Benefits paid	(156		)		(32		)		(142		)		(34		)
Actuarial (gain) loss	264				52				(155		)		(60		)
Medicare reimbursement	—				3				—				3
Plan amendment	—				1				—				—
Curtailment	—				(2		)		—				—
Benefit obligation, end of year	2,403				529				2,153				476
Change in Plan Assets
Fair value of plan assets, beginning of year	1,803				140				1,698				139
Employer contributions	97				18				91				19
Participant contributions	—				7				—				7
Benefits paid	(156		)		(32		)		(142		)		(34		)
Actual investment return	181				8				156				9
Fair value of plan assets, end of year	1,925				141				1,803				140
Funded status, end of year	$	(478	)		$	(388	)		$	(350	)		$	(336	)
Amounts Recognized in Balance Sheets
Current liabilities-other	$	(31	)		$	(9	)		$	(9	)		$	(9	)
Other liabilities-benefit obligations	(447		)		(379		)		(341		)		(327		)
Net liability, end of year	$	(478	)		$	(388	)		$	(350	)		$	(336	)
Actuarial Assumptions
Discount rate	4.05		%		3.9		%		4.8		%		4.75		%
Expected return on plan assets	6.5				5.2				7				5.5
Rate of increase in compensation levels	4				—				3.9				—
Healthcare cost trend rate assumed for the next year - Pre-65	—				7.25				—				7
Healthcare cost trend rate assumed for the next year - Post-65	—				8.5				—				7.5
Prescription drug cost trend rate assumed for the next year	—				6.5				—				7
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	—				5				—				5.5
Year that the healthcare rate reaches the ultimate trend rate	—				2024				—				2018
Year that the prescription drug rate reaches the ultimate trend rate	—				2024				—				2018
The accumulated benefit obligation for all defined benefit pension plans was $2,371 million and $2,123 million as of December 31, 2014 and 2013, respectively.
The expected rate of return assumption was developed using the targeted asset allocation of CenterPoint Energy’s plans and the expected return for each asset class.
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.
For measurement purposes, medical costs are assumed to increase 7.25% and 8.50% for the pre-65 and post-65 retirees during 2015, respectively, and the prescription cost is assumed to increase 6.50% during 2015, after which these rates decrease until reaching the ultimate trend rate of 5.00% in 2024.
CenterPoint Energy’s changes in accumulated comprehensive loss related to defined benefit, postretirement and other postemployment plans are as follows (in millions):
		Year Ended December 31,
		2014				2013
Beginning Balance		$	(88	)		$	(132	)
Other comprehensive income (loss) before reclassifications (1)		(3		)		52
Amounts reclassified from accumulated other comprehensive income:
Prior service cost (2)		2				3
Actuarial losses (2)		9				14
Total reclassifications from accumulated other comprehensive income		11				17
Tax expense		(5		)		(25		)
Net current period other comprehensive income		3				44
Ending Balance		$	(85	)		$	(88	)
________________
-1	Total other comprehensive income (loss) related to the re-measurement of pension, postretirement and other postemployment plans.
-2	These accumulated other comprehensive components are included in the computation of net periodic cost.
Amounts recognized in accumulated other comprehensive loss consist of the following:
	December 31,
	2014								2013
	Pension				Postretirement				Pension				Postretirement
	Benefits				Benefits				Benefits				Benefits
	(in millions)
Unrecognized actuarial loss	$	113			$	14			$	126			$	7
Unrecognized prior service cost	4				2				12				1
Net amount recognized in accumulated other comprehensive loss	$	117			$	16			$	138			$	8
The changes in plan assets and benefit obligations recognized in other comprehensive income during 2014 are as follows (in millions):
	Pension				Postretirement
	Benefits				Benefits
Net gain (loss)	$	10			$	(6	)
Amortization of net loss (gain)	9				(1		)
Amortization of prior service credit (cost)	2				(1		)
Total recognized in comprehensive income	$	21			$	(8	)
The total expense recognized in net periodic costs and other comprehensive income was $56 million and $30 million for pension and postretirement benefits, respectively, for the year ended December 31, 2014.
The amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2015 are as follows (in millions):
	Pension				Postretirement
	Benefits				Benefits
Unrecognized actuarial loss	$	12			$	1
Unrecognized prior service cost	1				—
Amounts in accumulated comprehensive loss to be recognized in net periodic cost in 2015	$	13			$	1
The following table displays pension benefits related to CenterPoint Energy’s pension plans that have accumulated benefit obligations in excess of plan assets:
	December 31,
	2014								2013
	Pension				Pension				Pension				Pension
	Qualified				Non-qualified				Qualified				Non-qualified
	(in millions)
Accumulated benefit obligation	$	2,273			$	98			$	2,031			$	92
Projected benefit obligation	2,304				98				2,061				92
Fair value of plan assets	1,925				—				1,803				—
Assumed healthcare cost trend rates have a significant effect on the reported amounts for CenterPoint Energy’s postretirement benefit plans. A 1% change in the assumed healthcare cost trend rate would have the following effects:
	1%				1%
	Increase				Decrease
	(in millions)
Effect on the postretirement benefit obligation	$	19			$	16
Effect on total of service and interest cost	1				1
In managing the investments associated with the benefit plans, CenterPoint Energy’s objective is to achieve and maintain a fully funded plan.  This objective is  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 Energy maintained the following weighted average allocation targets for its benefit plans as of December 31, 2014:
	Pension		Postretirement
	Benefits		Benefits
U.S. equity	12 – 28%		14 – 24%
International developed market equity	7 – 17%		3 – 13%
Emerging market equity	3 – 13%		—
Fixed income	54 – 66%		68 – 78%
Cash	0 – 2%		0 – 2%
The following tables set forth by level, within the fair value hierarchy (see Note 8), CenterPoint Energy’s pension plan assets at fair value as of December 31, 2014 and 2013:
	Fair Value Measurements at December 31, 2014
	(in millions)
	Total				Quoted Prices in				Significant				Significant
					Active Markets for				Observable Inputs				Unobservable
					Identical Assets				(Level 2)				Inputs
					(Level 1)								(Level 3)
Cash	$	6			$	6			$	—			$	—
Common collective trust funds (1)	1,108				—				1,108				—
Corporate bonds:
Investment grade or above	368				—				368				—
Equity securities:
International companies	49				49				—				—
U.S. companies	83				83				—				—
Cash received as collateral from securities lending	86				86				—				—
U.S. treasuries	47				47				—				—
Mortgage backed securities	4				—				4				—
Asset backed securities	4				—				4				—
Municipal bonds	79				—				79				—
Mutual funds (2)	161				161				—				—
International government bonds	15				—				15				—
Real estate	1				—				—				1
Obligation to return cash received as collateral from securities lending	(86		)		(86		)		—				—
Total	$	1,925			$	346			$	1,578			$	1
-1	61% of the amount invested in common collective trust funds is in fixed income securities, 14% is in U.S. equities, 22% is in international equities and 3% is in emerging market equities.
-2	57% of the amount invested in mutual funds is in international equities, 30% is in emerging market equities and 13% is in U.S. equities.
	Fair Value Measurements at December 31, 2013
	(in millions)
	Total				Quoted Prices in				Significant				Significant
					Active Markets for				Observable Inputs				Unobservable
					Identical Assets				(Level 2)				Inputs
					(Level 1)								(Level 3)
Cash	$	11			$	11			$	—			$	—
Common collective trust funds (1)	1,107				—				1,107				—
Corporate bonds:
Investment grade or above	256				—				256				—
Equity securities:
International companies	75				75				—				—
U.S. companies	77				77				—				—
Cash received as collateral from securities lending	71				71				—				—
U.S. government backed agencies bonds	1				1				—				—
U.S. treasuries	18				18				—				—
Mortgage backed securities	7				—				7				—
Asset backed securities	6				—				6				—
Municipal bonds	61				—				61				—
Mutual funds (2)	172				172				—				—
International government bonds	11				—				11				—
Real estate	1				—				—				1
Obligation to return cash received as collateral from securities lending	(71		)		(71		)		—				—
Total	$	1,803			$	354			$	1,448			$	1
-1	50% of the amount invested in common collective trust funds is in fixed income securities, 20% is in U.S. equities, 25% is in international equities and 5% is in emerging market equities.
-2	58% of the amount invested in mutual funds is in international equities, 30% is in emerging market equities and 12% is in U.S. equities.
The pension plan utilized both exchange traded and over-the-counter financial instruments such as futures, interest rate options and swaps that were marked to market daily with the gains/losses settled in the cash accounts. The pension plan did not include any holdings of CenterPoint Energy common stock as of December 31, 2014 or 2013.
The changes in the fair value of the pension plan’s level 3 investments for the years ended December 31, 2014 and 2013 were not material.
The following tables present by level, within the fair value hierarchy, CenterPoint Energy’s postretirement plan assets at fair value as of December 31, 2014 and 2013, by asset category:
	Fair Value Measurements at December 31, 2014
	(in millions)
	Total				Quoted Prices				Significant				Significant
					in Active				Observable				Unobservable
					Markets for				Inputs				Inputs
					Identical Assets				(Level 2)				(Level 3)
					(Level 1)
Mutual funds (1)	$	141			$	141			$	—			$	—
Total	$	141			$	141			$	—			$	—
-1	73% of the amount invested in mutual funds is in fixed income securities, 19% is in U.S. equities and 8% is in international equities.
	Fair Value Measurements at December 31, 2013
	(in millions)
	Total				Quoted Prices				Significant				Significant
					in Active				Observable				Unobservable
					Markets for				Inputs				Inputs
					Identical Assets				(Level 2)				(Level 3)
					(Level 1)
Mutual funds (1)	$	140			$	140			$	—			$	—
Total	$	140			$	140			$	—			$	—
-1	72% of the amount invested in mutual funds is in fixed income securities, 20% is in U.S. equities and 8% is in international equities.
CenterPoint Energy contributed $87 million, $10 million and $18 million to its qualified pension, non-qualified pension and postretirement benefits plans, respectively, in 2014. CenterPoint Energy expects to contribute approximately $35 million, $31 million and $17 million to its qualified pension, non-qualified pension and postretirement benefits plans, respectively, in 2015.
The following benefit payments are expected to be paid by the pension and postretirement benefit plans (in millions):
					Postretirement Benefit Plan
	Pension				Benefit				Medicare
	Benefits				Payments				Subsidy
									Receipts
2015	$	223			$	35			$	(4	)
2016	143				36				(4		)
2017	147				38				(5		)
2018	154				40				(5		)
2019	152				42				(6		)
2020-2024	785				228				(39		)
(c) Savings Plan
CenterPoint Energy has a tax-qualified employee savings plan that 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. The Company 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 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.
The savings plan has significant holdings of CenterPoint Energy common stock. As of December 31, 2014, 17,497,676 shares of CenterPoint Energy’s common stock were held by the savings plan, which represented approximately 20% 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’s savings plan benefit expenses were $39 million, $38 million and $36 million in 2014, 2013 and 2012, respectively.
(d) Postemployment Benefits
CenterPoint Energy provides postemployment benefits for former or inactive employees, their beneficiaries and covered dependents, after employment but before retirement (primarily healthcare and life insurance benefits for participants in the long-term disability plan). The Company recorded postemployment expenses of $3 million, $4 million and $8 million in 2014, 2013 and 2012, respectively.
Included in “Benefit Obligations” in the accompanying Consolidated Balance Sheets at December 31, 2014 and 2013 was $28 million and $30 million, respectively, relating to postemployment obligations.
(e) Other Non-Qualified Plans
CenterPoint Energy has non-qualified 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 Energy. CenterPoint Energy recorded benefit expense relating to these plans of $5 million for each of the years in 2014, 2013 and 2012. Included in “Benefit Obligations” in the accompanying Consolidated Balance Sheets at December 31, 2014 and 2013 was $60 million and $64 million, respectively, relating to deferred compensation plans.
Included in Benefit Obligations in CenterPoint Energy’s Consolidated Balance Sheets at December 31, 2014 and 2013 was $33 million and $28 million, respectively, relating to split-dollar life insurance arrangements.
(f) Change in Control Agreements and Other Employee Matters
CenterPoint Energy had change in control agreements with certain of its officers, which expired December 31, 2014.  In lieu of these agreements, our Board of Directors approved a new change in control plan, which was effective January 1, 2015.  The plan, like the expired agreements, generally provides, to the extent applicable, in the case of a change in control of CenterPoint Energy and termination of employment, for severance benefits of up to three times annual base salary plus bonus, and other benefits.  Our officers, including our Executive Chairman, are participants under the plan.
As of December 31, 2014, approximately 31% of CenterPoint Energy’s employees were subject to collective bargaining agreements. The collective bargaining agreements with the Gas Workers Local Union 340 and International Brotherhood of Electrical Workers Local 949 in Minnesota, which collectively cover approximately 8% of CenterPoint Energy’s employees, are scheduled to expire in April and December 2015, respectively. CenterPoint Energy believes it has good relationships with these bargaining units and expects to negotiate new agreements in 2015.

Derivative_Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments
	CenterPoint Energy is exposed to various market risks. These risks arise from transactions entered into in the normal course of business.  CenterPoint Energy utilizes derivative instruments such as physical forward contracts, swaps and options to mitigate the impact of changes in commodity prices and weather on its operating results and cash flows.
	(a) Non-Trading Activities
	Derivative Instruments. CenterPoint Energy enters into certain derivative instruments to manage physical commodity price risk and does not engage in proprietary or speculative commodity trading.  These financial instruments do not qualify or are not designated as cash flow or fair value hedges.
	Weather Hedges. CenterPoint Energy has weather normalization or other rate mechanisms that mitigate the impact of weather on NGD in Arkansas, Louisiana, Mississippi and Oklahoma. NGD in Texas and Minnesota and electric operations in Texas do not have such mechanisms. As a result, fluctuations from normal weather may have a significant positive or negative effect on NGD’s results in Texas and Minnesota and on CenterPoint Houston’s results in its service territory.
	CenterPoint Energy entered into heating-degree day swaps for certain NGD jurisdictions to mitigate the effect of fluctuations from normal weather on its results of operations and cash flows for the winter heating season, which contained a bilateral dollar cap of $15 million in 2012 - 2013, $16 million in 2013 - 2014 and $16 million in 2014 - 2015. In both 2013 and 2014, CenterPoint Energy also entered into a similar winter weather hedge for the CenterPoint Houston service territory, which each contained a bilateral dollar cap of $8 million. The swaps are based on ten-year normal weather. During the years ended December 31, 2014, 2013 and 2012, CenterPoint Energy recognized losses of $11 million, losses of $22 million and gains of $8 million, respectively, related to these swaps.  Weather hedge gains and losses are included in revenues in the Statements of Consolidated Income.
	(b) Derivative Fair Values and Income Statement Impacts
	The following tables present information about CenterPoint Energy’s derivative instruments and hedging activities. The first two tables provide a balance sheet overview of CenterPoint Energy’s Derivative Assets and Liabilities as of December 31, 2014 and 2013, while the last table provides a breakdown of the related income statement impacts for the years ending December 31, 2014 and 2013.
	Fair Value of Derivative Instruments
			December 31, 2014
	Total derivatives not designated		Balance Sheet		Derivative				Derivative
	as hedging instruments		Location		Assets				Liabilities
					Fair Value				Fair Value
					(in millions)
	Natural gas derivatives (1) (2) (3)		Current Assets: Non-trading derivative assets		$	101			$	1
	Natural gas derivatives (1) (2) (3)		Other Assets: Non-trading derivative assets		32				—
	Natural gas derivatives (1) (2) (3)		Current Liabilities: Non-trading derivative liabilities		14				83
	Natural gas derivatives (1) (2) (3)		Other Liabilities: Non-trading derivative liabilities		2				18
	Indexed debt securities derivative		Current Liabilities		—				541
	Total				$	149			$	643
	-1	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 804 billion cubic feet (Bcf) or a net 60 Bcf long position.  Of the net long position, basis swaps constitute 127 Bcf.
	-2	Natural gas contracts are presented on a net basis in the Consolidated Balance Sheets. Natural gas contracts are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $111 million asset as shown on CenterPoint Energy’s Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above offset by collateral netting of $64 million.
	-3	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
	Offsetting of Natural Gas Derivative Assets and Liabilities
			December 31, 2014
			Gross Amounts Recognized (1)				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amount Presented in the Consolidated Balance Sheets (2)
			(in millions)
	Current Assets: Non-trading derivative assets		$	115			$	(16	)		$	99
	Other Assets: Non-trading derivative assets		34				(2		)		32
	Current Liabilities: Non-trading derivative liabilities		(84		)		65				(19		)
	Other Liabilities: Non-trading derivative liabilities		(18		)		17				(1		)
	Total		$	47			$	64			$	111
	________________
	-1	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.
	-2	The derivative assets and liabilities on the Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
	Fair Value of Derivative Instruments
			December 31, 2013
	Total derivatives not designated		Balance Sheet		Derivative				Derivative
	as hedging instruments		Location		Assets				Liabilities
					Fair Value				Fair Value
					(in millions)
	Natural gas derivatives (1) (2) (3)		Current Assets: Non-trading derivative assets		$	28			$	4
	Natural gas derivatives (1) (2)		Other Assets: Non-trading derivative assets		10				—
	Natural gas derivatives (1) (2)		Current Liabilities: Non-trading derivative liabilities		4				21
	Natural gas derivatives (1) (2)		Other Liabilities: Non-trading derivative liabilities		1				5
	Indexed debt securities derivative		Current Liabilities		—				455
	Total				$	43			$	485
	-1	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 607 Bcf or a net 46 Bcf long position.  Of the net long position, basis swaps constitute 99 Bcf.
	-2	Natural gas contracts are presented on a net basis in the Consolidated Balance Sheets. Natural gas contracts are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $13 million asset as shown on CenterPoint Energy’s Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, offset by collateral netting of less than $1 million.
	-3	The $28 million Derivative Current Asset includes $1 million related to physical forwards purchased from Enable.
	Offsetting of Natural Gas Derivative Assets and Liabilities
			December 31, 2013
			Gross Amounts Recognized (1)				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amount Presented in the Consolidated Balance Sheets (2)
			(in millions)
	Current Assets: Non-trading derivative assets		$	32			$	(8	)		$	24
	Other Assets: Non-trading derivative assets		11				(1		)		10
	Current Liabilities: Non-trading derivative liabilities		(25		)		8				(17		)
	Other Liabilities: Non-trading derivative liabilities		(5		)		1				(4		)
	Total		$	13			$	—			$	13
	________________
	-1	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.
	-2	The derivative assets and liabilities on the Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
	For CenterPoint Energy’s price stabilization activities of the Natural Gas Distribution business segment, the settled costs of derivatives are ultimately recovered through purchased gas adjustments. Accordingly, the net unrealized gains and losses associated with these contracts are recorded as net regulatory assets. Realized and unrealized gains and losses on other derivatives are recognized in the Statements of Consolidated Income as revenue for retail sales derivative contracts and as natural gas expense for financial natural gas derivatives and non-retail related physical natural gas derivatives. Unrealized gains and losses on indexed debt securities are recorded as Other Income (Expense) in the Statements of Consolidated Income.
	Income Statement Impact of Derivative Activity
				Year Ended December 31,
Total derivatives not designated		Income Statement Location		2014				2013				2011
as hedging instruments
				(in millions)
Natural gas derivatives		Gains (Losses) in Revenue		$	35			$	11			$	43
Natural gas derivatives (1) (2)		Gains (Losses) in Expense: Natural Gas		11				10				(63		)
Indexed debt securities derivative		Gains (Losses) in Other Income (Expense)		(86		)		(193		)		(71		)
Total				$	(40	)		$	(172	)		$	(91	)
-1	The Gains (Losses) in Expense: Natural Gas includes $2 million and $(2) million during the years ended December 31, 2014 and 2013, respectively, related to physical forwards purchased from Enable.
-2	The Gains (Losses) in Expense: Natural Gas includes $-0-, $-0- and $(38) million of costs in 2014, 2013 and 2012, respectively, associated with price stabilization activities of the Natural Gas Distribution business segment that will be ultimately recovered through purchased gas adjustments.
(c) Credit Risk Contingent Features
CenterPoint Energy enters into financial derivative contracts containing material adverse change provisions.  These provisions could require CenterPoint Energy to post additional collateral if the Standard & Poor’s Ratings Services or Moody’s Investors Service, Inc. credit ratings of CenterPoint Energy, Inc. or its subsidiaries are downgraded.  The total fair value of the derivative instruments that contain credit risk contingent features that are in a net liability position at December 31, 2014 and 2013 was $2 million and $1 million, respectively.  The aggregate fair value of assets that are already posted as collateral was less than $1 million at both December 31, 2014 and 2013.  If all derivative contracts (in a net liability position) containing credit risk contingent features were triggered at December 31, 2014 and 2013, $2 million and $1 million, respectively, of additional assets would be required to be posted as collateral.
(d) Credit Quality of Counterparties
In addition to the risk associated with price movements, credit risk is also inherent in CenterPoint Energy’s non-trading derivative activities. Credit risk relates to the risk of loss resulting from non-performance of contractual obligations by a counterparty. The following table shows the composition of counterparties to the non-trading derivative assets of CenterPoint Energy as of December 31, 2014 and 2013 (in millions):
	December 31, 2014								December 31, 2013
	Investment				Total				Investment				Total
	Grade(1)								Grade(1)
Energy marketers	$	2			$	4			$	1			$	4
Financial institutions	—				—				1				9
End users (2)	2				127				1				21
Total	$	4			$	131			$	3			$	34
-1	“Investment grade” is primarily determined using publicly available credit ratings and considers credit support (including parent company guarantees) and collateral (including cash and standby letters of credit). For unrated counterparties, CenterPoint Energy determines a synthetic credit rating by performing financial statement analysis and considers contractual rights and restrictions and collateral.
-2	End users are comprised primarily of customers who have contracted to fix the price of a portion of their physical gas requirements for future periods.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements	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 generally are exchange-traded derivatives and equity securities.
	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. Fair value assets and liabilities that are generally included in this category are derivatives with fair values based on inputs from actively quoted markets.  A market approach is utilized to value CenterPoint Energy’s Level 2 assets or liabilities.
	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 Energy’s judgments about the assumptions market participants would use in pricing the asset or liability since limited market data exists. CenterPoint Energy develops these inputs based on the best information available, including CenterPoint Energy’s own data. A market approach is utilized to value CenterPoint Energy’s Level 3 assets or liabilities. At December 31, 2014, CenterPoint Energy’s Level 3 assets and liabilities are comprised of physical forward contracts and options. Level 3 physical forward contracts are valued using a discounted cash flow model which includes illiquid forward price curve locations (ranging from $1.60 to $4.23 per one million British thermal units (Btu)) as an unobservable input. Level 3 options are valued through Black-Scholes (including forward start) option models which include option volatilities (ranging from 0 to 88%) as an unobservable input.  CenterPoint Energy’s Level 3 derivative assets and liabilities consist of both long and short positions (forwards and options) and their fair value is sensitive to forward prices and volatilities.  If forward prices decrease, CenterPoint Energy’s long forwards lose value whereas its short forwards gain in value.  If volatility decreases, CenterPoint Energy’s long options lose value whereas its short options gain in value.
	CenterPoint Energy 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 year ended December 31, 2014, there were no transfers between Level 1 and 2. CenterPoint Energy also recognizes purchases of Level 3 financial assets and liabilities at their fair market value at the end of the reporting period.
	The following tables present information about CenterPoint Energy’s assets and liabilities (including derivatives that are presented net) measured at fair value on a recurring basis as of December 31, 2014 and 2013, and indicate the fair value hierarchy of the valuation techniques utilized by CenterPoint Energy to determine such fair value.
		Quoted Prices in			Significant Other			Significant			Netting			Balance at December 31, 2014
		Active Markets			Observable			Unobservable			Adjustments (1)
		for Identical Assets			Inputs			Inputs
		(Level 1)			(Level 2)			(Level 3)
		(in millions)
	Assets
	Corporate equities	$	932		$	—		$	—		$	—		$	932
	Investments, including money market funds	54			—			—			—			54
	Natural gas derivatives (2)	7			122			20			(18		)	131
	Total assets	$	993		$	122		$	20		$	(18	)	$	1,117
	Liabilities
	Indexed debt securities derivative	$	—		$	541		$	—		$	—		$	541
	Natural gas derivatives (2)	22			77			3			(82		)	20
	Total liabilities	$	22		$	618		$	3		$	(82	)	$	561
	-1	Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy to settle positive and negative positions and also include cash collateral of $64 million posted with the same counterparties.
	-2	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.
		Quoted Prices in			Significant Other			Significant			Netting			Balance at December 31, 2013
		Active Markets			Observable			Unobservable			Adjustments (1)
		for Identical Assets			Inputs			Inputs
		(Level 1)			(Level 2)			(Level 3)
		(in millions)
	Assets
	Corporate equities	$	770		$	—		$	—		$	—		$	770
	Investments, including money market funds	61			—			—			—			61
	Natural gas derivatives (2)	5			33			5			(9		)	34
	Total assets	$	836		$	33		$	5		$	(9	)	$	865
	Liabilities
	Indexed debt securities derivative	$	—		$	455		$	—		$	—		$	455
	Natural gas derivatives	1			27			2			(9		)	21
	Total liabilities	$	1		$	482		$	2		$	(9	)	$	476
	-1	Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy to settle positive and negative positions and also include cash collateral of less than $1 million posted with the same counterparties.
	-2	The (Level 2) Natural gas derivative assets of $33 million include $1 million related to physical forwards purchased from Enable.
	The following tables present additional information about assets or liabilities, including derivatives that are measured at fair value on a recurring basis for which CenterPoint Energy has utilized Level 3 inputs to determine fair value:
		Fair Value Measurements Using Significant
		Unobservable Inputs (Level 3)
		Derivative assets and liabilities, net
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Beginning balance	$	3		$	2		$	6
	Total gains	14			3			3
	Total settlements	1			(3		)	(6		)
	Transfers out of Level 3	—			—			(1		)
	Transfers into Level 3	(1		)	1			—
	Ending balance (1)	$	17		$	3		$	2
	The amount of total gains for the period included in earnings	$	16		$	2		$	1
	attributable to the change in unrealized gains or losses relating
	to assets still held at the reporting date
	-1	During 2014, 2013 and 2012, CenterPoint Energy did not have significant Level 3 purchases or sales.
	Estimated Fair Value of Financial Instruments
	The fair values of cash and cash equivalents, investments in debt and equity securities classified as “trading” and short-term borrowings are estimated to be approximately equivalent to carrying amounts and have been excluded from the table below. The carrying amounts of non-trading derivative assets and liabilities and CenterPoint Energy’s 2.0% Zero-Premium Exchangeable Subordinated Notes due 2029 (ZENS) indexed debt securities derivative are stated at fair value and are 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 or Level 2 in the fair value hierarchy.
		December 31, 2014						December 31, 2013
		Carrying			Fair			Carrying			Fair
		Amount			Value			Amount			Value
		(in millions)
	Financial assets:
	Notes receivable - affiliated companies	$	363		$	362		$	363		$	363
Financial liabilities:
Long-term debt	$	8,652		$	9,427		$	8,171		$	8,670

Unconsolidated_Affiliates_Note

Unconsolidated Affiliates (Notes)	12 Months Ended
	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments and Joint Ventures Disclosure [Text Block]	Unconsolidated Affiliates
	On May 1, 2013 (the Closing Date) CERC Corp., OGE Energy Corp. (OGE) and ArcLight Capital Partners, LLC (ArcLight) closed on the formation of Enable, and CenterPoint Energy recorded an equity method investment in Enable at the historical cost of the contributed net assets. See Note 2 for further information on the formation of Enable.
	CenterPoint Energy’s maximum exposure to loss related to Enable, a VIE in which CenterPoint Energy is not the primary beneficiary, is limited to its equity investment as presented in the Consolidated Balance Sheet at December 31, 2014, CERC Corp.’s guarantee of collection of Enable’s $1.1 billion senior notes due 2019 and 2024 (Guaranteed Senior Notes) and other guarantees discussed in Note 14, CERC Corp.’s $363 million notes receivable from Enable and outstanding current accounts receivable from Enable. The $363 million of notes receivable from Enable bears interest at an annual rate of 2.10% to 2.45% and matures in 2017. CenterPoint Energy recorded interest income of $8 million and $5 million during the year ended December 31, 2014 and 2013, respectively, for interest earned on or after the Closing Date and had interest receivable from Enable of $4 million as of both December 31, 2014 and 2013 on its notes receivable from Enable.
	Effective on the Closing Date, CenterPoint Energy and Enable entered into a Services Agreement, Employee Transition Agreement, Transitional Services Agreement and other agreements (collectively, Transition Agreements) whereby CenterPoint Energy agreed to provide certain support services to Enable such as accounting, legal, risk management and treasury functions for an initial term ending on April 30, 2016. Effective April 1, 2014, Enable’s general partner, CenterPoint Energy and OGE agreed to reduce certain governance related costs billed to Enable for transition services.  Effective December 31, 2014, Enable’s general partner, CenterPoint Energy and OGE agreed to terminate certain support services provided by CenterPoint Energy to Enable. CenterPoint Energy expects to terminate all remaining support services by April 2016.
	CenterPoint Energy billed Enable for reimbursement of transitional services, including the costs of seconded employees, $163 million and $119 million during the years ended December 31, 2014 and 2013, respectively, under the Transition Agreements for transition services incurred on or after the Closing Date. Actual transitional services costs are recorded net of reimbursements received from Enable. CenterPoint Energy had accounts receivable from Enable of $28 million and $21 million as of December 31, 2014 and 2013, respectively, for amounts billed for transitional services, including the cost of seconded employees.
	CenterPoint Energy provided seconded employees to Enable to support its operations for a term ending on December 31, 2014. Enable, at its discretion, had the right to select and offer employment to seconded employees from CenterPoint Energy. During the fourth quarter of 2014, Enable notified CenterPoint Energy that it selected seconded employees and provided employment offers to substantially all of the seconded employees from CenterPoint Energy. Substantially all of the seconded employees became employees of Enable effective January 1, 2015. See Note 6 for additional information.
	On April 16, 2014, Enable completed its initial public offering (IPO) of 28,750,000 common units, at a price of $20.00 per unit, which included 3,750,000 common units sold by ArcLight pursuant to an over-allotment option that was fully exercised by the underwriters. Enable received $464 million in net proceeds from the sale of the units, after deducting underwriting fees, structuring fees and other offering costs. In connection with Enable’s IPO, a portion of CenterPoint Energy’s common units were converted into subordinated units, as discussed further below. Subsequent to the IPO, Enable continues to be controlled jointly by CenterPoint Energy and OGE.
	As a result of Enable’s IPO, CenterPoint Energy’s limited partner interest in Enable was reduced from approximately 58.3% to approximately 54.7%. CenterPoint Energy accounted for the dilution of its investment in Enable as a result of Enable’s IPO as a failed partial sale of in-substance real estate. CenterPoint Energy did not receive any cash from Enable’s IPO and, as such, CenterPoint Energy did not recognize a gain or loss. CenterPoint Energy’s basis difference in Enable was reduced for the impact of the Enable IPO.
	In accordance with the Enable formation agreements, CenterPoint Energy had certain put rights, and Enable had certain call rights, exercisable with respect to the 25.05% interest in Southeast Supply Header, LLC (SESH) retained by CenterPoint Energy on the Closing Date, under which CenterPoint Energy would contribute its retained interest in SESH, in exchange for a specified number of limited partner common units in Enable and a cash payment, payable either from CenterPoint Energy to Enable or from Enable to CenterPoint Energy, to the extent of changes in the value of SESH subject to certain restrictions. Specifically, the rights were and are exercisable with respect to (1) a 24.95% interest in SESH (24.95% Put), which closed on May 30, 2014 as discussed below and (2) a 0.1% interest in SESH, which may be exercised no earlier than June 2015 for 25,341 common units in Enable.
	On May 30, 2014, CenterPoint Energy closed its 24.95% Put and contributed to Enable its 24.95% interest in SESH in exchange for 6,322,457 common units of Enable, which increased CenterPoint Energy’s limited partner interest in Enable from approximately 54.7% to approximately 55.4%. No cash payment was required to be made pursuant to the Enable formation agreements in connection with CenterPoint Energy’s exercise of the 24.95% Put. CenterPoint Energy accounted for the contribution of its 24.95% interest in SESH to Enable in exchange for common units of Enable as a non-monetary transaction of in-substance real estate equity method investments. As such, CenterPoint Energy recorded the 6,322,457 common units at the historical cost of the contributed 24.95% interest in SESH of $196 million and recorded no gain or loss in connection with its exercise of the 24.95% Put. As a result, CenterPoint Energy’s basis difference in Enable was reduced for the impact of its exercise of the 24.95% Put.
	CenterPoint Energy incurred natural gas expenses, including transportation and storage costs, of $130 million and $123 million during the year ended December 31, 2014 and 2013, respectively, for transactions with Enable occurring on or after the Closing Date. CenterPoint Energy had accounts payable to Enable of $23 million and $22 million at December 31, 2014 and 2013, respectively, from such transactions.
	As of December 31, 2014, CenterPoint Energy held an approximate 55.4% limited partner interest in Enable consisting of 94,126,366 common units and 139,704,916 subordinated units and a 0.1% interest in SESH. The principal difference between Enable common units and subordinated units is that in any quarter during the subordination period, holders of the subordinated units are not entitled to receive any distribution of available cash until the common units have received the minimum quarterly distribution plus any arrearages in the payment of the minimum quarterly distribution from prior quarters. If Enable does not pay distributions on its subordinated units, the subordinated units will not accrue arrearages for those unpaid distributions. At the end of the subordination period, CenterPoint Energy’s subordinated units in Enable will be converted to common units in Enable on a one-for-one basis.
	CenterPoint Energy evaluates its equity method investments for impairment when factors indicate that a decrease in value of its investment has occurred and the carrying amount of its investment may not be recoverable.  An impairment loss is recognized in earnings when an impairment is deemed to be other than temporary.  The carrying value of CenterPoint Energy’s investment in Enable is $19.33 per unit. As of December 31, 2014, Enable’s common unit price closed at $19.39 (approximately $14 million above carrying value). The lowest close price for Enable’s common units in January 2015 was $17.34 (approximately $465 million below carrying value). CenterPoint Energy performed an analysis of its investment in Enable as of December 31, 2014.  Based on that analysis, CenterPoint Energy believes that the decline in the value of its investment is temporary, and that CenterPoint Energy will recover the value of its investment of $4.5 billion.
	Investment in Unconsolidated Affiliates:
			Year Ended December 31,
			2014			2013
			(in millions)
	Enable		$	4,520		$	4,319
	SESH (1)		1			199
	Total		$	4,521		$	4,518
	-1	On May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
	Equity in Earnings of Unconsolidated Affiliates, net:
			Year Ended December 31,
			2014			2013			2012
			(in millions)
	Enable (1)		$	303		$	173		$	—
	SESH (2)		5			15			26
	Waskom (3)		—			—			5
	Total		$	308		$	188		$	31
	-1	On May 1, 2013, CenterPoint Energy formed Enable with OGE and ArcLight.
	-2	On each of May 1, 2013 and May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
	-3	On July 31, 2012, Waskom became a wholly owned subsidiary of CenterPoint Energy. Beginning on August 1, 2012, Waskom’s operating results are consolidated on the Statements of Consolidated Income. On May 1, 2013, CenterPoint Energy contributed Waskom to Enable.
	Summarized consolidated income information for Enable is as follows:
			Year Ended December 31,
			2014			2013 (1)
			(in millions)
	Operating revenues		$	3,367		$	2,123
	Cost of sales, excluding depreciation and amortization		1,914			1,241
	Operating income		586			322
	Net income attributable to Enable		530			289
	CenterPoint Energy’s approximate interest		$	298		$	168
	Basis difference accretion		5			5
	CenterPoint Energy’s equity in earnings, net		$	303		$	173
	-1	The amounts included in this column represent the eight month period from formation of Enable on May 1, 2013 through December 31, 2013.
	Summarized consolidated balance sheet information for Enable is as follows:
			December 31,
			2014			2013
			(in millions)
	Current assets		$	438		$	549
	Non-current assets		11,399			10,683
	Current liabilities		671			720
	Non-current liabilities		2,343			2,331
	Non-controlling interest		31			33
	Enable partners’ capital		8,792			8,148
	CenterPoint Energy’s ownership interest in Enable’s partner capital		$	4,869		$	4,753
	CenterPoint Energy’s basis difference attributable to goodwill (1)		(217		)	(229		)
	CenterPoint Energy’s accretable basis difference (2)		(132		)	(205		)
	CenterPoint Energy’s total basis difference		(349		)	(434		)
	CenterPoint Energy’s investment in Enable		$	4,520		$	4,319
	-1	The difference relates to CenterPoint Energy’s proportionate share of Enable’s goodwill arising from its acquisition of Enogex, and therefore will be recognized by CenterPoint Energy upon dilution or disposition of its interest in Enable.
	-2	The difference will be recognized by CenterPoint Energy over 30 years beginning May 1, 2013. CenterPoint Energy will also adjust the accretable basis difference for dilution or disposition of its interest in Enable.
	Enable concluded that the formation of Enable is considered a business combination, and CenterPoint Midstream is the acquirer for accounting purposes.  Under this method, the fair value of the consideration paid by CenterPoint Midstream for Enogex was allocated to the assets acquired and liabilities assumed on the Closing Date based on their fair value.  Enogex’s assets, liabilities and equity were accordingly adjusted to estimated fair value as of May 1, 2013.  Determining the fair value of assets and liabilities is judgmental in nature and involves the use of significant estimates and assumptions.  Enable used appraisers to assist in the determination of the estimated fair value of certain assets and liabilities contributed by Enogex.
	Distributions Received from Unconsolidated Affiliates:
			Year Ended December 31,
		2014			2013			2012
		(in millions)
Enable (1)		$	298		$	106		$	—
SESH (2)		7			23			32
Waskom (3)		—			—			7
Total		$	305		$	129		$	39
-1	On May 1, 2013, CenterPoint Energy formed Enable with OGE and ArcLight.
-2	On each of May 1, 2013 and May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
-3	On July 31, 2012, Waskom became a wholly owned subsidiary of CenterPoint Energy. Beginning on August 1, 2012, Waskom’s operating results are consolidated on the Statements of Consolidated Income. On May 1, 2013, CenterPoint Energy contributed Waskom to Enable.

Indexed_Debt_Securities_ZENS_a

Indexed Debt Securities (ZENS) and Securities Related to ZENS Indexed Debt Securities (ZENS) and Securities Related to ZENS (Notes)	12 Months Ended
	Dec. 31, 2014
Indexed Debt Securities [Abstract]
Indexed Debt Securities Text Block	Indexed Debt Securities (ZENS) and Securities Related to ZENS
	(a) Investment in Securities Related to ZENS
	In 1995, CenterPoint Energy sold a cable television subsidiary to Time Warner, Inc. (TW) and received TW securities as partial consideration. A subsidiary of CenterPoint Energy now holds 7.1 million shares of TW common stock (TW Common), 1.8 million shares of Time Warner Cable Inc. (TWC) common stock (TWC Common), 0.6 million shares of AOL, Inc. (AOL) common stock (AOL Common) and 0.9 million shares of Time Inc. common stock (Time Common) (together with the TW Common, TWC Common and AOL Common, the TW Securities) which are classified as trading securities and are expected to be held to facilitate CenterPoint Energy’s ability to meet its obligation under the ZENS. Unrealized gains and losses resulting from changes in the market value of the TW Securities are recorded in CenterPoint Energy’s Statements of Consolidated Income.
	(b) ZENS
	In September 1999, CenterPoint Energy issued ZENS having an original principal amount of $1 billion of which $828 million remain outstanding at December 31, 2014. Each ZENS note was originally exchangeable at the holder’s option at any time for an amount of cash equal to 95% of the market value of the reference shares of TW Common attributable to such note. The number and identity of the reference shares attributable to each ZENS note are adjusted for certain corporate events. As of December 31, 2014, the reference shares for each ZENS note consisted of 0.5 share of TW Common, 0.125505 share of TWC Common and 0.045455 share of AOL Common and 0.0625 share of Time Common. On February 13, 2014, TWC announced that it had agreed to merge with Comcast Corporation (Comcast). In the merger, each share of TWC Common would be exchanged for 2.875 shares of Comcast common stock (Comcast Common). Upon the closing of the merger (assuming no change in the merger consideration), the reference shares for each ZENS note would include 0.360827 share of Comcast Common in place of the current 0.125505 share of TWC Common. CenterPoint Energy pays interest on the ZENS at an annual rate of 2% plus the amount of any quarterly cash dividends paid in respect of the reference shares attributable to the ZENS. The principal amount of ZENS is subject to being increased or decreased to the extent that the annual yield from interest and cash dividends on the reference shares is less than or more than 2.309%. The adjusted principal amount is defined in the ZENS instrument as “contingent principal.” At December 31, 2014, ZENS having an original principal amount of $828 million and a contingent principal amount of $751 million were outstanding and were exchangeable, at the option of the holders, for cash equal to 95% of the market value of reference shares deemed to be attributable to the ZENS. At December 31, 2014, the market value of such shares was approximately $930 million, which would provide an exchange amount of $1,067 for each $1,000 original principal amount of ZENS. At maturity of the ZENS in 2029, CenterPoint Energy will be obligated to pay in cash the higher of the contingent principal amount of the ZENS or an amount based on the then-current market value of the reference shares, which will include any additional publicly-traded securities distributed with respect to the current reference shares prior to maturity.
	The ZENS obligation is bifurcated into a debt component and a derivative component (the holder’s option to receive the appreciated value of the reference shares at maturity). The bifurcated debt component accretes through interest charges at 17.3% annually up to the contingent principal amount of the ZENS in 2029. Such accretion will be reduced by annual cash interest payments, as described above. The derivative component is recorded at fair value and changes in the fair value of the derivative component are recorded in CenterPoint Energy’s Statements of Consolidated Income. Changes in the fair value of the TW Securities held by CenterPoint Energy are expected to substantially offset changes in the fair value of the derivative component of the ZENS.
	The following table sets forth summarized financial information regarding CenterPoint Energy’s investment in TW Securities and each component of CenterPoint Energy’s ZENS obligation (in millions).
		TW			Debt			Derivative
		Securities			Component			Component
					of ZENS			of ZENS
	Balance at December 31, 2011	$	386		$	131		$	197
	Accretion of debt component of ZENS	—			24			—
	2% interest paid	—			(17		)	—
	Loss on indexed debt securities	—			—			71
	Gain on TW Securities	154			—			—
	Balance at December 31, 2012	540			138			268
	Accretion of debt component of ZENS	—			24			—
	2% interest paid	—			(17		)	—
	Sale of TW Securities	(9		)	—			—
	Redemption of indexed debt securities	—			(2		)	(6		)
	Loss on indexed debt securities	—			—			193
	Gain on TW Securities	236			—			—
	Balance at December 31, 2013	767			143			455
	Accretion of debt component of ZENS	—			26			—
	2% interest paid	—			(17		)	—
	Loss on indexed debt securities	—			—			86
	Gain on TW Securities	163			—			—
	Balance at December 31, 2014	$	930		$	152		$	541

Equity

Equity	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Equity	Equity
	Capital Stock
	CenterPoint Energy has 1,020,000,000 authorized shares of capital stock, comprised of 1,000,000,000 shares of $0.01 par value common stock and 20,000,000 shares of $0.01 par value cumulative preferred stock.
	Dividends Declared
	CenterPoint Energy declared dividends per share of $0.95, $0.83 and $0.81, respectively, during the years ended December 31, 2014, 2013 and 2012.
	Undistributed Retained Earnings
	As of December 31, 2014 and 2013, CenterPoint Energy’s consolidated retained earnings balance includes undistributed earnings from Enable of $71 million and $67 million, respectively.

Short_Term_Borrowings_and_Long

Short Term Borrowings and Long Term Debt	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Short-term Borrowings and Long-term Debt	Short-term Borrowings and Long-term Debt
		December 31,					December 31,
		2014					2013
		Long-Term			Current(1)		Long-Term			Current(1)
		(in millions)
	Short-term borrowings:
	Inventory financing	$	—		$	53	$	—		$	43
	Total short-term borrowings	—			53		—			43
	Long-term debt:
	CenterPoint Energy:
	ZENS (2)	—			152		—			143
	Senior notes 5.95% to 6.85% due 2015 to 2018	550			200		750			—
	Pollution control bonds 4.90% to 5.125% due 2015 to 2028 (3)	118			69		187			—
	Commercial paper (4)	191			—		—			—
	Other	2			2		—			—
	CenterPoint Houston:
	First mortgage bonds 9.15% due 2021	102			—		102			—
	General mortgage bonds 2.25% to 6.95% due 2022 to 2044	1,912			—		1,312			—
	Pollution control bonds 4.25% to 5.60% due 2017 to 2027	—			—		183			—
	System restoration bonds 1.833% to 4.243% due 2015 to 2022	415			48		463			47
	Transition bonds 0.90% to 5.302% due 2015 to 2024	2,259			324		2,583			307
	Other	1			—		—			—
	CERC Corp.:
	Senior notes 4.50% to 6.625% due 2016 to 2041	2,168			—		2,168			—
	Commercial paper (4)	341			—		118			—
	Other	—			—		1			—
	Unamortized discount and premium, net	(50		)	—		(50		)	—
	Total long-term debt	8,009			795		7,817			497
	Total debt	$	8,009		$	848	$	7,817		$	540
	-1	Includes amounts due or exchangeable within one year of the date noted.
	-2	CenterPoint Energy’s ZENS obligation is bifurcated into a debt component and an embedded derivative component. For additional information regarding ZENS, see Note 10(b). As ZENS are exchangeable for cash at any time at the option of the holders, these notes are classified as a current portion of long-term debt.
	-3	$118 million of these series of debt were secured by general mortgage bonds of CenterPoint Houston at both December 31, 2014 and 2013.
	-4	Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted.
	(a) Short-term Borrowings
	Inventory Financing. NGD has asset management agreements associated with its utility distribution service in Arkansas, north Louisiana and Oklahoma that extend through 2018. Pursuant to the provisions of the agreements, NGD sells natural gas and agrees to repurchase an equivalent amount of natural gas during the winter heating seasons at the same cost, plus a financing charge. These transactions are accounted for as a financing and they had an associated principal obligation of $53 million and $43 million as of December 31, 2014 and 2013, respectively.
	(b) Long-term Debt
	On March 17, 2014, CenterPoint Energy Houston Electric, LLC issued $600 million principal amount of 4.50% General Mortgage Bonds due 2044.
	Debt Repayments. Approximately $44 million aggregate principal amount of pollution control bonds issued on behalf of CenterPoint Houston were redeemed on March 3, 2014 at 101% of their principal amount plus accrued interest. The bonds had an interest rate of 4.25%, were scheduled to mature in 2017 and were collateralized by general mortgage bonds of CenterPoint Houston.
	Approximately $56 million aggregate principal amount of pollution control bonds issued on behalf of CenterPoint Houston were purchased by CenterPoint Houston on March 3, 2014 at 101% of their principal amount plus accrued interest pursuant to the mandatory tender provisions of the bonds. The bonds had an interest rate of 5.60% prior to CenterPoint Houston’s purchase and have a variable rate thereafter. The bonds mature in 2027 and are collateralized by general mortgage bonds of CenterPoint Houston. The purchased pollution control bonds may be remarketed.
	Approximately $84 million aggregate principal amount of pollution control bonds issued on behalf of CenterPoint Houston were redeemed on June 2, 2014 at 100% of their principal amount plus accrued interest. The bonds had an interest rate of 4.25%, were scheduled to mature in 2017 and were collateralized by general mortgage bonds of CenterPoint Houston.
	Transition and System Restoration Bonds. As of December 31, 2014, 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.
	Credit Facilities. As of December 31, 2014 and 2013, CenterPoint Energy, CenterPoint Houston and CERC Corp. had the following revolving credit facilities and utilization of such facilities (in millions):
					December 31, 2014							December 31, 2013
		Size of			Loans		Letters			Commercial		Loans		Letters		Commercial
		Facility					of Credit			Paper				of Credit		Paper
	CenterPoint Energy	$	1,200		$	—	$	6		$	191	$	—	$	6	$	—
	CenterPoint Houston	300			—		4			—		—		4		—
	CERC Corp.	600			—		—			341		—		—		118
	Total	$	2,100		$	—	$	10		$	532	$	—	$	10	$	118
	CenterPoint Energy’s $1.2 billion revolving credit facility, which is scheduled to terminate on September 9, 2019, can be drawn at the London Interbank Offered Rate (LIBOR) plus 1.25% based on CenterPoint Energy’s current credit ratings. The revolving credit facility contains a financial covenant which limits CenterPoint Energy’s consolidated debt (excluding transition and system restoration bonds) to an amount not to exceed 65% of CenterPoint Energy’s consolidated capitalization. The financial covenant limit will temporarily increase from 65% to 70% if CenterPoint Houston experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that CenterPoint Houston has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive twelve-month period, all or part of which CenterPoint Houston intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date CenterPoint Energy delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of CenterPoint Energy’s certification or (iii) the revocation of such certification.
	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.
	CERC Corp.’s $600 million revolving credit facility, which is scheduled to terminate on September 9, 2019, can be drawn at LIBOR plus 1.50% based on CERC Corp.’s current credit ratings. The revolving credit facility contains a financial covenant which limits CERC’s consolidated debt to an amount not to exceed 65% of CERC’s consolidated capitalization.
	CenterPoint Energy, CenterPoint Houston and CERC Corp. were in compliance with all financial debt covenants as of December 31, 2014.
	Maturities.  CenterPoint Energy’s maturities of long-term debt, capital leases and sinking fund requirements, excluding the ZENS obligation, are $641 million in 2015, $716 million in 2016, $911 million in 2017, $1.1 billion in 2018 and $1.0 billion in 2019.  These maturities include transition and system restoration bond principal repayments on scheduled payment dates aggregating $372 million in 2015, $391 million in 2016, $411 million in 2017, $434 million in 2018 and $458 million in 2019.
	Liens.  As of December 31, 2014, 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 2014, 2013 and 2012 have been satisfied by certification of property additions. The replacement fund requirement to be satisfied in 2015 is approximately $209 million, and the sinking fund requirement to be satisfied in 2015 is approximately $1.6 million. CenterPoint Energy expects CenterPoint Houston to meet these 2015 obligations by certification of property additions. As of December 31, 2014, CenterPoint Houston’s assets were also subject to liens securing approximately $2.4 billion of general mortgage bonds which are junior to the liens of the first mortgage bonds.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	The components of CenterPoint Energy’s income tax expense were as follows:
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Current income tax expense (benefit):
	Federal	$	(20	)	$	91		$	—
	State	14			23			12
	Total current expense (benefit)	(6		)	114			12
	Deferred income tax expense (benefit):
	Federal	273			370			280
	State	7			(14		)	48
	Total deferred expense	280			356			328
	Total income tax expense	$	274		$	470		$	340
	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,
		2014			2013			2012
		(in millions)
	Income before income taxes	$	885		$	781		$	757
	Federal statutory income tax rate	35		%	35		%	35		%
	Expected federal income tax expense	310			273			265
	Increase (decrease) in tax expense resulting from:
	State income tax expense, net of federal income tax	16			21			39
	Amortization of investment tax credit	—			—			(2		)
	Tax effect related to the formation of Enable	—			196			—
	Decrease in settled and uncertain income tax positions	—			(9		)	(33		)
	Goodwill impairment	—			—			88
	Tax basis balance sheet adjustments	(29		)	—			—
	Other, net	(23		)	(11		)	(17		)
	Total	(36		)	197			75
	Total income tax expense	$	274		$	470		$	340
	Effective tax rate	31		%	60.2		%	44.9		%
	In 2014, CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.  The adjustment resulted in a decrease to deferred tax liabilities of $32 million, a decrease to income taxes payable of $5 million and a decrease to income tax regulatory assets of $8 million.  CenterPoint Energy determined the impact of the $29 million adjustment was not material to any prior period or the year ended December 31, 2014.
	In 2013, CenterPoint Energy recorded a deferred tax expense of $225 million at the formation of Enable related to the book-to-tax basis difference for contributed non-tax deductible goodwill and recognized a tax benefit of $29 million associated with the remeasurement of state deferred taxes at formation. In addition, CenterPoint Energy recognized a tax benefit of $8 million based on the settlement with the Internal Revenue Service (IRS) of outstanding tax claims for the 2002 and 2003 tax years.
	In 2012, CenterPoint Energy recorded a non-tax deductible impairment of goodwill of $252 million ($88 million tax effect) and a net decrease in income tax expense of $33 million related to favorable audit settlements.
	The tax effects of temporary differences that give rise to significant portions of deferred tax assets and liabilities were as follows:
		December 31,
		2014			2013
		(in millions)
	Deferred tax assets:
	Current:
	Allowance for doubtful accounts	$	10		$	11
	Deferred gas costs	—			7
	Other	13			12
	Total current deferred tax assets	23			30
	Non-current:
	Loss and credit carryforwards	69			51
	Employee benefits	327			258
	Other	89			76
	Total non-current deferred tax assets before valuation allowance	485			385
	Valuation allowance	(2		)	(2		)
	Total non-current deferred tax assets, net of valuation allowance	483			383
	Total deferred tax assets, net of valuation allowance	506			413
	Deferred tax liabilities:
	Current:
	Unrealized gain on indexed debt securities	636			541
	Unrealized gain on TW securities	65			97
	Deferred gas costs	6			—
	Total current deferred tax liabilities	707			638
	Non-current:
	Depreciation	2,201			1,908
	Regulatory assets, net	1,228			1,308
	Investment in unconsolidated affiliates	1,789			1,590
	Other	21			119
Total non-current deferred tax liabilities	5,239			4,925
Total deferred tax liabilities	5,946			5,563
Accumulated deferred income taxes, net	$	5,440		$	5,150
Tax Attribute Carryforwards and Valuation Allowance.  CenterPoint Energy has $9 million of federal capital loss carryforwards which expire in 2018, $725 million of state net operating loss carryforwards which expire between 2015 and 2034, $4 million of state tax credits which do not expire, and $244 million of state capital loss carryforwards which expire in 2017 for which management established a full valuation allowance of $2 million net of federal tax. The valuation allowance was established based upon management’s evaluation that loss carryforwards may not be fully realized.
Uncertain Income Tax Positions. The following table reconciles the beginning and ending balance of CenterPoint Energy’s unrecognized tax benefits (expenses):
	December 31,
	2014			2013			2012
	(in millions)
Balance, beginning of year	$	—		$	(23	)	$	51
Tax Positions related to prior years:
Reductions	—			(1		)	(75		)
Tax Positions related to current year:
Settlements	—			24			1
Balance, end of year	$	—		$	—		$	(23	)
CenterPoint Energy reported no uncertain tax liability as of December 31, 2014 and expects no significant change to the uncertain tax liability over the next twelve months ending December 31, 2015 to have a material impact on financial position, results of operations and cash flows.
CenterPoint Energy recognizes interest and penalties as a component of income tax expense.  CenterPoint Energy recognized $3 million of income tax expense, $3 million of income tax benefit and $7 million of income tax benefit related to interest on income tax positions during 2014, 2013 and 2012, respectively.  CenterPoint Energy had $5 million of interest receivable on income tax positions accrued at December 31, 2013.
Tax Audits and Settlements.   Tax years through 2011 have been audited and settled with the IRS. The consolidated federal income tax returns for the years 2012 and 2013 are currently under audit by the IRS. For 2014, 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 as of December 31, 2014.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	(a) Natural Gas Supply Commitments
	Natural gas supply commitments include natural gas contracts related to CenterPoint Energy’s Natural Gas Distribution and Energy Services business segments, which have various quantity requirements and durations, that are not classified as non-trading derivative assets and liabilities in CenterPoint Energy’s Consolidated Balance Sheets as of December 31, 2014 and 2013 as these contracts meet an exception as “normal purchases contracts” or do not meet the definition of a derivative. Natural gas supply commitments also include natural gas transportation contracts that do not meet the definition of a derivative. As of December 31, 2014, minimum payment obligations for natural gas supply commitments are approximately $696 million in 2015, $605 million in 2016, $551 million in 2017, $507 million in 2018, $255 million in 2019 and $114 million after 2019.
	(b) Asset Management Agreements
	NGD has asset management agreements (AMAs) associated with its utility distribution service in Arkansas, Louisiana, Mississippi, Oklahoma and Texas. Generally, these AMAs are contracts between NGD and an asset manager that are intended to transfer the working capital obligation and maximize the utilization of the assets.  In these AMAs, NGD agreed to release transportation and storage capacity to other parties to manage gas storage, supply and delivery arrangements for NGD and to use the released capacity for other purposes when it is not needed for NGD. NGD is compensated by the asset manager through payments made over the life of the AMAs based in part on the results of the asset optimization. NGD has an obligation to purchase its winter storage requirements that have been released to the asset manager under these AMAs. The AMAs have varying terms, the longest of which expires in 2018.
	(c) Lease Commitments
	The following table sets forth information concerning CenterPoint Energy’s obligations under non-cancelable long-term operating leases at December 31, 2014, which primarily consist of rental agreements for building space, data processing equipment, compression equipment and rights of way (in millions):
	2015	$	5
	2016	4
	2017	3
	2018	2
	2019	2
	2020 and beyond	7
	Total	$	23
	Total lease expense for all operating leases was $11 million, $21 million and $27 million during 2014, 2013 and 2012, respectively.
	(d) Legal, Environmental and Other Regulatory 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, nor does it affect the terms of existing guarantee arrangements for certain GenOn gas transportation contracts discussed below.
	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 United States Court of Appeals for the Ninth Circuit, which reversed the trial court’s dismissal of the plaintiffs’ claims. In August 2013, the other defendants filed a petition for review with the U.S. Supreme Court, which the court granted on July 1, 2014. Four amicus briefs favorable to our co-defendants were filed by the United States, Interstate Natural Gas Association of America, et. al., Washington Legal Foundation and Noble America Corporation, et. al. The Supreme Court heard arguments on January 12, 2015, and a ruling is expected by summer 2015. CenterPoint Energy believes that CES is not a proper defendant in this case and will continue to pursue a dismissal.  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
	Manufactured Gas Plant Sites. CERC and its predecessors operated manufactured gas plants (MGPs) in the past.  There are seven MGP sites in CERC’s Minnesota service territory.  CERC believes it never owned or operated, and therefore has no liability with respect to, two of these sites.  With respect to two other sites, CERC has completed state ordered remediation, other than ongoing monitoring and water treatment.
	At December 31, 2014, CERC had recorded a liability of $7 million for remediation of these Minnesota sites. The estimated range of possible remediation costs for the sites for which CERC believes it may have responsibility was $5 million to $29 million based on remediation continuing for 30 to 50 years. The cost estimates are based on studies of a site or industry average costs for remediation of sites of similar size. The actual remediation costs will be dependent upon the number of sites to be remediated, the participation of other potentially responsible parties (PRPs), if any, and the remediation methods used. As of December 31, 2014, CERC had collected $4 million from insurance companies to be used for future environmental remediation.
	In addition to the Minnesota sites, the United States Environmental Protection Agency and other regulators have investigated MGP sites that were owned or operated by CERC or may have been owned by one of its former affiliates. CERC and CenterPoint Energy do not expect the ultimate outcome of these investigations to have a material adverse effect on the financial condition, results of operations or cash flows of either CenterPoint Energy or CERC.
	Asbestos. Some facilities owned by CenterPoint Energy contain or have contained asbestos insulation and other asbestos-containing materials. CenterPoint Energy or its subsidiaries 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 subsidiaries of CenterPoint Energy, but most existing claims relate to facilities previously owned by CenterPoint Energy’s subsidiaries, some of which are currently owned by an affiliate of NRG. 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 Energy intends to continue vigorously contesting claims that it does not consider to have merit and, based on its experience to date, does not expect these matters, either individually or in the aggregate, to have a material adverse effect on CenterPoint Energy’s financial condition, results of operations or cash flows.
	Other Environmental. From time to time CenterPoint Energy identifies the presence of environmental contaminants on property where its subsidiaries conduct or have conducted operations.  Other such sites involving contaminants may be identified in the future.  CenterPoint Energy has and expects to continue to remediate identified sites consistent with its legal obligations. From time to time CenterPoint Energy has received notices from regulatory authorities or others regarding its status as a PRP in connection with sites found to require remediation due to the presence of environmental contaminants. In addition, CenterPoint Energy 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 Energy does not expect, based on its experience to date, these matters, either individually or in the aggregate, to have a material adverse effect on CenterPoint Energy’s financial condition, results of operations or cash flows.
	Other Proceedings
	CenterPoint Energy 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 Energy 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 Energy regularly analyzes current information and, as necessary, provides accruals for probable liabilities on the eventual disposition of these matters. CenterPoint Energy does not expect the disposition of these matters to have a material adverse effect on CenterPoint Energy’s financial condition, results of operations or cash flows.
	(e) Guarantees
	Prior to the distribution of CenterPoint Energy’s ownership in RRI to its shareholders, CERC had guaranteed certain contractual obligations of what became RRI’s trading subsidiary.  When the companies separated, RRI agreed to secure CERC against obligations under the guarantees RRI had been unable to extinguish by the time of separation.  Pursuant to such agreement, as amended in December 2007, RRI (now GenOn) agreed to provide to CERC cash or letters of credit as security against CERC’s obligations under its remaining guarantees for demand charges under certain gas transportation agreements if and to the extent changes in market conditions expose CERC to a risk of loss on those guarantees based on an annual calculation, with any required collateral to be posted each December.  The undiscounted maximum potential payout of the demand charges under these transportation contracts, which will be in effect until 2018, was approximately $42 million as of December 31, 2014.  Based on market conditions in the fourth quarter of 2014 at the time the most recent annual calculation was made under the agreement, GenOn was not obligated to post any security. If GenOn should fail to perform the contractual obligations, CERC could have to honor its guarantee and, in such event, any collateral then provided as security may be insufficient to satisfy CERC’s obligations.
	CenterPoint Energy has provided guarantees (CenterPoint Midstream Guarantees) with respect to the performance of certain obligations of Enable under long-term gas gathering and treating agreements with an indirect wholly owned subsidiary of Encana Corporation and an indirect wholly owned subsidiary of Royal Dutch Shell plc. As of December 31, 2014, CenterPoint Energy had guaranteed Enable’s obligations up to an aggregate amount of $100 million under these agreements. Under the terms of the omnibus agreement entered into in connection with the closing of the formation of Enable, Enable and CenterPoint Energy have agreed to use commercially reasonable efforts and cooperate with each other to terminate the CenterPoint Midstream Guarantees and to release CenterPoint Energy from such guarantees by causing Enable or one of its subsidiaries to enter into substitute guarantees or to assume the CenterPoint Midstream Guarantees as applicable.
	CERC Corp. has also provided a guarantee of collection of $1.1 billion of Enable’s Guaranteed Senior Notes. This guarantee is subordinated to all senior debt of CERC Corp. and is subject to automatic release on May 1, 2016.
	The fair value of these guarantees is not material.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share
	The following table reconciles numerators and denominators of CenterPoint Energy’s basic and diluted earnings per share calculations:
		For the Year Ended December 31,
		2014		2013		2012
		(in millions, except per share and share amounts)
	Net income	$	611	$	311	$	417
	Basic weighted average shares outstanding	429,634,000		428,466,000		427,189,000
	Plus: Incremental shares from assumed conversions:
	Stock options	—		41,000		152,000
	Restricted stock	2,034,000		2,423,000		2,453,000
	Diluted weighted average shares	431,668,000		430,930,000		429,794,000
	Basic earnings per share	$	1.42	$	0.73	$	0.98
	Diluted earnings per share	$	1.42	$	0.72	$	0.97

Unaudited_Quarterly_Informatio

Unaudited Quarterly Information	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	Unaudited Quarterly Information
	Summarized quarterly financial data is as follows:
		Year Ended December 31, 2014
		First		Second			Third		Fourth
		Quarter		Quarter			Quarter		Quarter (3)
		(in millions, except per share amounts)
	Revenues	$	3,163	$	1,884		$	1,807	$	2,372
	Operating income	295		186			233		221
	Net income	185		107			143		176
	Basic earnings per share(1)	$	0.43	$	0.25		$	0.33	$	0.41
	Diluted earnings per share(1)	$	0.43	$	0.25		$	0.33	$	0.41
		Year Ended December 31, 2013
		First		Second			Third		Fourth
		Quarter		Quarter (2)			Quarter		Quarter
		(in millions, except per share amounts)
	Revenues	$	2,388	$	1,894		$	1,640	$	2,184
	Operating income	332		223			244		211
	Net income (loss)	$	147	$	(100	)	$	151	$	113
	Basic earnings (loss) per share(1)	$	0.34	$	(0.23	)	$	0.35	$	0.26
	Diluted earnings (loss) per share(1)	$	0.34	$	(0.23	)	$	0.35	$	0.26
	-1	Quarterly earnings per common share are based on the weighted average number of shares outstanding during the quarter, and the sum of the quarters may not equal annual earnings per common share.
	-2	Effective May 1, 2013, CenterPoint Energy contributed CenterPoint Midstream to Enable.  See Note 2(b) and Note 9 for further discussion on the formation of Enable and CenterPoint Energy’s investment in Enable, respectively.
	-3	CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.

Reportable_Business_Segments

Reportable Business Segments	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Reportable Business Segments	Reportable Business Segments
	CenterPoint Energy’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. CenterPoint Energy uses operating income as the measure of profit or loss for its business segments.
	CenterPoint Energy’s reportable business segments include the following: Electric Transmission & Distribution, Natural Gas Distribution, Energy Services, Midstream Investments and Other Operations. The electric transmission and distribution function (CenterPoint Houston) is reported in the Electric Transmission & Distribution business segment. Natural Gas Distribution consists of intrastate natural gas sales to, and natural gas transportation and distribution for, residential, commercial, industrial and institutional customers. Energy Services represents CenterPoint Energy’s non-rate regulated gas sales and services operations. Midstream Investments consists primarily of CenterPoint Energy’s investment in Enable and its retained interest in SESH. Other Operations consists primarily of other corporate operations which support all of CenterPoint Energy’s business operations.
	Prior to May 1, 2013, CenterPoint Energy also reported an Interstate Pipelines business segment, which included CenterPoint Energy’s interstate natural gas pipeline operations, and a Field Services business segment, which included CenterPoint Energy’s non-rate regulated natural gas gathering, processing and treating operations. The formation of Enable closed on May 1, 2013. Enable now owns substantially all of CenterPoint Energy’s former Interstate Pipelines and Field Services business segments, except for a 0.1% interest in SESH. As a result, effective May 1, 2013, CenterPoint Energy reports equity earnings associated with its interest in Enable and equity earnings associated with its interest in SESH under its Midstream Investments segment, and no longer has Interstate Pipelines and Field Services reporting segments prospectively.
	Long-lived assets include net property, plant and equipment, goodwill and other intangibles and equity investments in unconsolidated subsidiaries. Intersegment sales are eliminated in consolidation.
	Financial data for business segments and products and services are as follows (in millions):
		Revenues				Intersegment			Depreciation			Operating			Total				Expenditures
		from				Revenues			and			Income (Loss)			Assets				for Long-Lived
		External							Amortization										Assets
		Customers
	As of and for the year ended December 31, 2014:
	Electric Transmission & Distribution	$	2,845		-1	$	—		$	768		$	595		$	10,066			$	818
	Natural Gas Distribution	3,271				30			201			287			5,464				525
	Energy Services	3,095				84			5			52			978				3
	Midstream Investments (2)	—				—			—			—			4,521				—
	Other	15				—			39			1			3,368			-3	56
	Reconciling Eliminations	—				(114		)	—			—			(1,197		)		—
	Consolidated	$	9,226			$	—		$	1,013		$	935		$	23,200			$	1,402
	As of and for the year ended December 31, 2013:
	Electric Transmission & Distribution	$	2,570		-1	$	—		$	685		$	607		$	9,605			$	759
	Natural Gas Distribution	2,837				26			185			263			4,976				430
	Energy Services	2,374				27			5			13			895				3
	Interstate Pipelines (4) (6)	133				53			20			72			—				29
	Field Services (5) (6)	178				18			20			73			—				16
	Midstream Investments (2)	—				—			—			—			4,518				—
	Other	14				—			39			(18		)	3,026			-3	35
	Reconciling Eliminations	—				(124		)	—			—			(1,150		)		—
	Consolidated	$	8,106			$	—		$	954		$	1,010		$	21,870			$	1,272
	As of and for the year ended December 31, 2012:
	Electric Transmission & Distribution	$	2,540		-1	$	—		$	729		$	639		$	11,174			$	599
	Natural Gas Distribution	2,320				22			173			226			4,775				359
	Energy Services	1,758				26			6			(250		)	839				6
	Interstate Pipelines (4)	356				146			56			207			4,004				132
	Field Services (5)	467				39			50			214			2,453				52
	Other	11				—			36			2			2,600			-3	40
	Reconciling Eliminations	—				(233		)	—			—			(2,974		)		—
	Consolidated	$	7,452			$	—		$	1,050		$	1,038		$	22,871			$	1,188
	-1	Sales to affiliates of NRG in 2014, 2013 and 2012 represented approximately $735 million, $658 million and $648 million, respectively, of CenterPoint Houston’s transmission and distribution revenues. Sales to affiliates of Energy Future Holdings Corp. in 2014, 2013 and 2012 represented approximately $189 million, $167 million and $162 million, respectively, of CenterPoint Houston’s transmission and distribution revenues.
	-2	Midstream Investments reported equity earnings of $303 million from Enable and $5 million of equity earnings from CenterPoint Energy’s interest in SESH for the year ended December 31, 2014. Midstream Investments reported equity earnings of $173 million from Enable and $8 million of equity earnings from CenterPoint Energy’s interest in SESH for the eight months ended December 31, 2013. Included in total assets of Midstream Investments as of December 31, 2014 and 2013 is $4,520 million and $4,319 million, respectively, related to CenterPoint Energy’s investment in Enable and $1 million and $199 million related to CenterPoint Energy’s retained interest in SESH, respectively.
	-3	Included in total assets of Other Operations as of December 31, 2014, 2013 and 2012, are pension and other postemployment related regulatory assets of $795 million, $627 million and $832 million, respectively.
	-4	Interstate Pipelines recorded equity income of $7 million and $26 million in the years ended December 31, 2013 and 2012, respectively, from its interest in SESH, a jointly-owned pipeline. These amounts are included in Equity in earnings of unconsolidated affiliates under the Other Income (Expense) caption.  Interstate Pipelines’ investment in SESH was $404 million as of December 31, 2012, and is included in Investment in unconsolidated affiliates. As discussed above, effective May 1, 2013, CenterPoint Energy reports equity earnings associated with its interest in Enable and equity earnings associated with its interest in SESH under its Midstream Investments segment, and no longer has an Interstate Pipelines reporting segment prospectively.
	-5	Field Services recorded equity income of $5 million for the year ended December 31, 2012 from its interest in Waskom. This amount is included in Equity in earnings of unconsolidated affiliates under the Other Income (Expense) caption. Beginning on August 1, 2012, financial results for Waskom are included in operating income due to the July 31, 2012 purchase of the 50% interest in Waskom that CenterPoint Energy did not already own. CenterPoint Energy contributed 100% interest in Waskom to Enable on May 1, 2013. Effective May 1, 2013, CenterPoint Energy reports equity earnings associated with its interest in Enable under its Midstream Investments segment, and no longer has a Field Services reporting segment prospectively.
	-6	Results reflected in the year ended December 31, 2013 represent only January 2013 through April 2013.
			Year Ended December 31,
	Revenues by Products and Services:		2014				2013			2012
	Electric delivery		$	2,845			$	2,570		$	2,540
	Retail gas sales		5,049				4,150			3,328
	Wholesale gas sales		1,159				913			613
	Gas transportation and processing		38				345			847
	Energy products and services		135				128			124
	Total		$	9,226			$	8,106		$	7,452

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events
	On January 22, 2015, CenterPoint Energy’s board of directors declared a regular quarterly cash dividend of $0.2475 per share of common stock payable on March 10, 2015, to shareholders of record as of the close of business on February 13, 2015.
	On January 23, 2015, Enable declared a quarterly cash distribution of $0.30875 per unit on all of its outstanding common and subordinated units for the quarter ended December 31, 2014. Accordingly, CERC Corp. expects to receive a cash distribution of approximately $72 million from Enable in the first quarter of 2015 to be made with respect to CERC Corp.’s limited partner interest in Enable for the fourth quarter of 2014.

Schedule_I_Financial_Informati

Schedule I: Financial Information of Centerpoint Energy, Inc. (Parent Company)	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule I - Condensed Financial Information of Centerpoint Energy, Inc. (Parent Company)	CENTERPOINT ENERGY, INC.
	SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF
	CENTERPOINT ENERGY, INC. (PARENT COMPANY)
	STATEMENTS OF INCOME
		For the Year Ended December 31,
		2014			2013			2012
		(in millions)
	Expenses:
	Operation and Maintenance Expenses	$	(22	)	$	(13	)	$	(20	)
	Total	(22		)	(13		)	(20		)
	Other Income (Expense):
	Interest Income from Subsidiaries	—			8			10
	Other Income (Expense)	(1		)	(5		)	6
	Loss on Indexed Debt Securities	(86		)	(193		)	(71		)
	Interest Expense to Subsidiaries	—			(24		)	(25		)
	Interest Expense	(103		)	(104		)	(112		)
	Total	(190		)	(318		)	(192		)
	Loss Before Income Taxes, Equity in Subsidiaries	(212		)	(331		)	(212		)
	Income Tax Benefit	115			137			87
	Loss Before Equity in Subsidiaries	(97		)	(194		)	(125		)
	Equity Income of Subsidiaries	708			505			542
	Net Income	$	611		$	311		$	417
	See Notes to Condensed Financial Information (Parent Company) and
	CenterPoint Energy, Inc. and Subsidiaries Notes to Consolidated Financial Statements in Part II, Item 8
	CENTERPOINT ENERGY, INC.
	SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF
	CENTERPOINT ENERGY, INC. (PARENT COMPANY)
	STATEMENTS OF COMPREHENSIVE INCOME
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Net income	$	611		$	311		$	417
	Other comprehensive income (loss):
	Adjustment to pension and other postretirement plans (net of tax of $5,$25 and $2)	3			44			(2		)
	Reclassification of deferred loss from cash flow hedges realized in net income (net of tax)	1			1			—
	Other comprehensive income (loss)	4			45			(2		)
	Comprehensive income	$	615		$	356		$	415
	See Notes to Condensed Financial Information (Parent Company) and
	CenterPoint Energy, Inc. and Subsidiaries Notes to Consolidated Financial Statements in Part II, Item 8
	CENTERPOINT ENERGY, INC.
	SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF
	CENTERPOINT ENERGY, INC. (PARENT COMPANY)
	BALANCE SHEETS
		December 31,
		2014			2013
		(in millions)
	ASSETS
	Current Assets:
	Cash and cash equivalents	$	—		$	—
	Notes receivable — subsidiaries	227			88
	Accounts receivable — subsidiaries	230			116
	Other assets	87			21
	Total current assets	544			225
	Other Assets:
	Investment in subsidiaries	6,529			6,142
	Other assets	811			649
	Total other assets	7,340			6,791
	Total Assets	$	7,884		$	7,016
	LIABILITIES AND SHAREHOLDERS’ EQUITY
	Current Liabilities:
	Notes payable — subsidiaries	$	142		$	11
	Indexed debt	152			143
	Current portion of other long-term debt	269			—
	Indexed debt securities derivative	541			455
Accounts payable:
Subsidiaries	80			35
Other	2			5
Taxes accrued	575			517
Interest accrued	13			13
Other	22			—
Total current liabilities	1,796			1,179
Other Liabilities:
Accumulated deferred tax liabilities	240			232
Benefit obligations	441			340
Other	1			—
Total non-current liabilities	682			572
Long-Term Debt	858			936
Shareholders’ Equity:
Common stock	4			4
Additional paid-in capital	4,169			4,157
Retained earnings	461			258
Accumulated other comprehensive loss	(86		)	(90		)
Total shareholders’ equity	4,548			4,329
Total Liabilities and Shareholders’ Equity	$	7,884		$	7,016
See Notes to Condensed Financial Information (Parent Company) and
CenterPoint Energy, Inc. and Subsidiaries Notes to Consolidated Financial Statements in Part II, Item 8
CENTERPOINT ENERGY, INC.
SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF
CENTERPOINT ENERGY, INC. (PARENT COMPANY)
STATEMENTS OF CASH FLOWS
	For the Year Ended December 31,
	2014			2013			2012
	(in millions)
Operating Activities:
Net income	$	611		$	311		$	417
Non-cash items included in net income:
Equity income of subsidiaries	(708		)	(505		)	(542		)
Deferred income tax expense	86			6			113
Amortization of debt issuance costs	4			4			4
Loss on indexed debt securities	86			193			71
Changes in working capital:
Accounts receivable/(payable) from subsidiaries, net	(7		)	47			39
Accounts payable	(3		)	5			—
Other current assets	—			—			26
Other current liabilities	(83		)	42			(63		)
Common stock dividends received from subsidiaries	315			766			1,700
Other	(76		)	(70		)	(72		)
Net cash provided by operating activities	225			799			1,693
Investing Activities:
Decrease (increase) in notes receivable from subsidiaries	(139		)	868			(398		)
Net cash provided by (used in) investing activities	(139		)	868			(398		)
Financing Activities:
Proceeds from commercial paper, net	191			—			—
Payments on long-term debt	—			(151		)	(375		)
Debt issuance costs	(1		)	(2		)	—
Common stock dividends paid	(408		)	(355		)	(346		)
Proceeds from issuance of common stock, net	1			4			4
Increase (decrease) in notes payable to subsidiaries	131			(1,173		)	(578		)
Redemption of indexed debt securities	—			(8		)	—
Other	—			18			—
Net cash used in financing activities	(86		)	(1,667		)	(1,295		)
Net Decrease in Cash and Cash Equivalents	—			—			—
Cash and Cash Equivalents at Beginning of Year	—			—			—
Cash and Cash Equivalents at End of Year	$	—		$	—		$	—
See Notes to Condensed Financial Information (Parent Company) and
CenterPoint Energy, Inc. and Subsidiaries Notes to Consolidated Financial Statements in Part II, Item 8
CENTERPOINT ENERGY, INC.
SCHEDULE I — NOTES TO CONDENSED FINANCIAL INFORMATION (PARENT COMPANY)
(1) Background. The condensed parent company financial statements and notes of CenterPoint Energy, Inc. (CenterPoint Energy) should be read in conjunction with the consolidated financial statements and notes of CenterPoint Energy, Inc. and subsidiaries appearing in the Annual Report on Form 10-K. Credit facilities at CenterPoint Energy Houston Electric, LLC (CenterPoint Houston) and CenterPoint Energy Resources Corp., indirect wholly owned subsidiaries of CenterPoint Energy, limit debt, excluding transition and system restoration bonds, as a percentage of their consolidated capitalization to 65%. These covenants could restrict the ability of these subsidiaries to distribute dividends to CenterPoint Energy.
(2) New Accounting Pronouncements. In April 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (ASU 2014-08), which significantly changes the existing accounting guidance on discontinued operations. Under ASU 2014-08, only those disposals of components of an entity that represent a strategic shift that has (or will have) a major effect on an entity’s operations and financial results should be reported as a discontinued operation.  ASU 2014-08 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2014.  ASU 2014-08 should be applied to components classified as held for sale after its effective date. Early adoption is permitted, but only for disposals (or classifications as held for sale) that have not been reported in financial statements previously issued or available for issuance. The adoption is expected to reduce the number of disposals that meet the definition of a discontinued operation.
In May 2014, the FASB issued ASU 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 is 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. Accordingly, CenterPoint Energy will adopt ASU 2014-09 on January 1, 2017, and is currently evaluating the impact that this standard will have on its financial position, results of operations, cash flows and disclosures.
In November 2014, the FASB issued ASU No. 2014-16, Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity (ASU 2014-16).  ASU 2014-16 clarifies how current guidance should be interpreted in evaluating the economic characteristics and risks of a host contract in a hybrid financial instrument that is issued in the form of a share. Specifically, the amendments clarify that an entity should consider all relevant terms and features, including the embedded derivative feature being evaluated for bifurcation, in evaluating the nature of a host contract. ASU 2014-16 is effective for fiscal years and interim periods beginning after December 15, 2015. CenterPoint Energy is currently assessing the impact, if any, that this standard will have on its financial position, results of operations, cash flows and disclosures.
In January 2015, the FASB issued ASU No. 2015-01, Income Statement-Extraordinary and Unusual Items (Subtopic 225-20)-Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items (ASU 2015-01), which eliminates the concept of extraordinary items. ASU 2015-01 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015, and may be applied either prospectively or retrospectively. CenterPoint Energy will adopt ASU 2015-01 on January 1, 2016 and does not anticipate the adoption to have a material impact on its consolidated financial statements.
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.
(3) Long-term Debt. As of December 31, 2014 and 2013, CenterPoint Energy had no borrowings and approximately $6 million and $6 million, respectively, of outstanding letters of credit under its $1.2 billion credit facility. There was $191 million of commercial paper outstanding that was backstopped by CenterPoint Energy’s $1.2 billion credit facility as of December 31, 2014. CenterPoint Energy was in compliance with all financial debt covenants as of December 31, 2014.
CenterPoint Energy’s $1.2 billion revolving credit facility, which is scheduled to terminate on September 9, 2019, can be drawn at the London Interbank Offered Rate (LIBOR) plus 1.25% based on CenterPoint Energy’s current credit ratings. The revolving credit facility contains a financial covenant which limits CenterPoint Energy’s consolidated debt (excluding transition and system restoration bonds) to an amount not to exceed 65% of CenterPoint Energy’s consolidated capitalization. The financial covenant limit will temporarily increase from 65% to 70% if CenterPoint Houston experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that CenterPoint Houston has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive twelve-month period, all or part of which CenterPoint Houston intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date CenterPoint Energy delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of CenterPoint Energy’s certification or (iii) the revocation of such certification.
CenterPoint Energy’s maturities of long-term debt, excluding the indexed debt securities obligation, are $269 million in 2015, $250 million in 2017, $350 million in 2018 and $191 million in 2019.  There are no maturities of long-term debt in 2016.
(4) Guarantees. CenterPoint Energy has provided guarantees (CenterPoint Midstream Guarantees) with respect to the performance of certain obligations of Enable under long-term gas gathering and treating agreements with an indirect wholly owned subsidiary of Encana Corporation and an indirect wholly owned subsidiary of Royal Dutch Shell plc. As of December 31, 2014, CenterPoint Energy had guaranteed Enable’s obligations up to an aggregate amount of $100 million under these agreements. Under the terms of the omnibus agreement entered into in connection with the closing of the formation of Enable, Enable and CenterPoint Energy have agreed to use commercially reasonable efforts and cooperate with each other to terminate the CenterPoint Midstream Guarantees and to release CenterPoint Energy from such guarantees by causing Enable or one of its subsidiaries to enter into substitute guarantees or to assume the CenterPoint Midstream Guarantees as applicable.

Schedule_II_Valuation_and_Qual

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts Disclosure	CENTERPOINT ENERGY, INC.
	SCHEDULE II —VALUATION AND QUALIFYING ACCOUNTS
	For the Three Years Ended December 31, 2014
	Column A		Column B		Column C						Column D		Column E
					Additions
			Balance at		Charged			Charged to			Deductions		Balance at
			Beginning		to Income			Other			From		End of
			of Period					Accounts			Reserves (1)		Period
	Description		(in millions)
	Year Ended December 31, 2014
	Accumulated provisions:
	Uncollectible accounts receivable		$	28	$	22		$	2		$	26	$	26
	Deferred tax asset valuation allowance		2		—			—			—		2
	Year Ended December 31, 2013
	Accumulated provisions:
	Uncollectible accounts receivable		$	25	$	21		$	1		$	19	$	28
	Deferred tax asset valuation allowance		2		—			—			—		2
	Year Ended December 31, 2012
	Accumulated provisions:
	Uncollectible accounts receivable		$	25	$	16		$	1		$	17	$	25
	Deferred tax asset valuation allowance		4		(1		)	(1		)	—		2
	-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.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
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 Energy and its wholly owned and majority owned subsidiaries are included in the consolidated financial statements. All intercompany transactions and balances are eliminated in consolidation. CenterPoint Energy generally uses the equity method of accounting for investments in entities in which CenterPoint Energy has an ownership interest between 20% and 50% and exercises significant influence. CenterPoint Energy also uses the equity method for investments in which it has ownership percentages greater than 50%, when it exercises significant influence, does not have control and is not considered the primary beneficiary, if applicable.
	On March 14, 2013, CenterPoint Energy entered into a Master Formation Agreement (MFA) with OGE Energy Corp. (OGE) and affiliates of ArcLight Capital Partners, LLC (ArcLight), pursuant to which CenterPoint Energy, OGE and ArcLight agreed to form Enable as a private limited partnership. On May 1, 2013, the parties closed on the formation of Enable. In connection with the closing (i) CERC Corp. converted its direct wholly owned subsidiary, CenterPoint Energy Field Services, LLC, a Delaware limited liability company (CEFS), into a Delaware limited partnership that became Enable, (ii) CERC Corp. contributed to Enable its equity interests in each of CenterPoint Energy Gas Transmission Company, LLC, which has been subsequently renamed Enable Gas Transmission, LLC (EGT), CenterPoint Energy - Mississippi River Transmission, LLC, which has been subsequently renamed Enable Mississippi River Transmission, LLC (MRT), certain of its other midstream subsidiaries (Other CNP Midstream Subsidiaries), and a 24.95% interest in Southeast Supply Header, LLC (SESH and, collectively with CEFS, EGT, MRT and Other CNP Midstream Subsidiaries, CenterPoint Midstream), and (iii) OGE and ArcLight indirectly contributed 100% of the equity interests in Enogex LLC, which has been subsequently renamed Enable Oklahoma Intrastate Transmission, LLC (Enogex), to Enable.
	The formation of Enable by CenterPoint Energy was considered a contribution of in-substance real estate to a limited partnership as the businesses are composed of, and reliant upon, substantial real estate assets and integral equipment. Real estate assets and integral equipment primarily include gas transmission pipelines, compressor station equipment, rights of way, storage and processing assets and long-term customer contracts. Accordingly, CenterPoint Energy did not recognize a gain or loss upon contribution and recorded its investment in Enable using the equity method of accounting based on the historical cost of the contributed assets and liabilities as of May 1, 2013 (Closing Date). Approximately $5.8 billion of assets (which includes $4.7 billion in property, plant and equipment, net, $629 million in goodwill and $197 million for the 24.95% investment in SESH) and $1.5 billion of liabilities (which includes a term loan and the indebtedness owed to CERC of $1.05 billion and $363 million, respectively) were contributed by CERC Corp. CenterPoint Energy has the ability to significantly influence the operating and financial policies of, but not solely control, Enable and, accordingly, recorded an equity method investment, at the historical costs of net assets contributed, of $4.3 billion in Enable on the Closing Date. Pursuant to the MFA, CenterPoint Energy retained certain assets and liabilities historically held by CenterPoint Midstream such as balances relating to federal income taxes and benefit plan obligations.
	Under the equity method, CenterPoint Energy adjusts its investment in Enable each period for contributions made, distributions received, CenterPoint Energy’s share of Enable’s comprehensive income and accretion of basis differences, as appropriate. CenterPoint Energy evaluates its equity method investments for impairment when events or changes in circumstances indicate there is a loss in value of the investment that is other than a temporary decline.
	CenterPoint Energy’s investment in Enable is considered to be a variable interest entity (VIE) because the power to direct the activities that most significantly impact Enable’s economic performance does not reside with the holders of equity investment at risk. However, CenterPoint Energy is not considered the primary beneficiary of Enable since it does not have the power to direct the activities of Enable that are considered most significant to the economic performance of Enable.
	As of December 31, 2014, CERC Corp. and OGE held approximately 55.4% and 26.3%, respectively, of the limited partner interests in Enable. Enable is controlled jointly by CERC Corp. and OGE, and each own 50% of the management rights in the general partner of Enable.
	As of December 31, 2014, CERC Corp. and OGE also own a 40% and 60% interest, respectively, in the incentive distribution rights held by the general partner of Enable. Enable is expected to pay a minimum quarterly distribution of $0.2875 per unit on its outstanding units to the extent it has sufficient cash from operations after establishment of cash reserves and payment of fees and expenses, including payments to its general partner and its affiliates, within 45 days after the end of each quarter. If cash distributions to Enable’s unitholders exceed $0.330625 per unit in any quarter, the general partner will receive increasing percentages or incentive distributions rights, up to 50%, of the cash Enable distributes in excess of that amount. In certain circumstances the general partner of Enable will have the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election.
	Prior to July 2012, CenterPoint Energy owned a 50% interest in Waskom Gas Processing Company (Waskom), a Texas general partnership, which owns and operates a natural gas processing plant and natural gas gathering assets. On July 31, 2012, CenterPoint Energy purchased the 50% interest that it did not already own in Waskom, as well as other gathering and related assets from a third-party for approximately $273 million. The purchase of the 50% interest in Waskom was determined to be a business combination achieved in stages, and as such CenterPoint Energy recorded a pre-tax gain of approximately $136 million on July 31, 2012, which is the result of remeasuring its original 50% interest in Waskom to fair value.
	Other investments, excluding marketable securities, are carried at cost.
	As of December 31, 2014, CenterPoint Energy had 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 Energy 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 Energy.
Revenues	Revenues
	CenterPoint Energy records revenue for electricity delivery and natural gas sales and services 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. Natural gas sales not billed by month-end are accrued based upon estimated purchased gas volumes, estimated lost and unaccounted for gas and currently effective tariff rates.
Long-lived Assets	Long-lived Assets and Intangibles
	CenterPoint Energy records property, plant and equipment at historical cost. CenterPoint Energy expenses repair and maintenance costs as incurred.
	CenterPoint Energy 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 Energy applies the guidance for accounting for regulated operations to the Electric Transmission & Distribution business segment and the Natural Gas Distribution business segment. CenterPoint Energy’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 Energy’s rate-regulated businesses recognize removal costs as a component of depreciation expense in accordance with regulatory treatment. As of December 31, 2014 and 2013, these removal costs of $958 million and $941 million, respectively, are classified as regulatory liabilities in CenterPoint Energy’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 and amortization is computed using the straight-line method based on economic lives or regulatory-mandated recovery periods. Amortization expense includes amortization of regulatory assets and other intangibles.
Capitalization of Interest and Allowance for Funds Used During Construction	Capitalization of Interest and Allowance for Funds Used During Construction
	Interest and allowance for funds used during construction (AFUDC) are capitalized as a component of projects under construction and are 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 for subsidiaries that apply the guidance for accounting for regulated operations. During 2014, 2013 and 2012, CenterPoint Energy capitalized interest and AFUDC of $11 million, $11 million and $9 million, respectively. During 2014, 2013 and 2012, CenterPoint Energy recorded AFUDC equity of $14 million, $8 million and $6 million, respectively, which is included in Other Income in its Statements of Consolidated Income.
Income Tax	Income Taxes
	CenterPoint Energy 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 Energy recognizes interest and penalties as a component of income tax expense.
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 Energy’s Statements of Consolidated Income for 2014, 2013 and 2012 was $22 million, $21 million and $16 million, respectively.
Inventory	Inventory
	Inventory consists principally of materials and supplies and natural gas. Materials and supplies are 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. Natural gas inventories of CenterPoint Energy’s Energy Services business segment are valued at the lower of average cost or market. Natural gas inventories of CenterPoint Energy’s Natural Gas Distribution business segment are primarily valued at weighted average cost. During 2014, 2013 and 2012, CenterPoint Energy recorded $8 million, $4 million and $4 million, respectively, in write-downs of natural gas inventory to the lower of average cost or market.
Derivative Instruments	Derivative Instruments
	CenterPoint Energy is exposed to various market risks. These risks arise from transactions entered into in the normal course of business.  CenterPoint Energy utilizes derivative instruments such as physical forward contracts, swaps and options to mitigate the impact of changes in commodity prices and weather on its operating results and cash flows. Such derivatives are recognized in CenterPoint Energy’s Consolidated Balance Sheets at their fair value unless CenterPoint Energy elects the normal purchase and sales exemption for qualified physical transactions. A derivative may be designated as a normal purchase or normal sale if the intent is to physically receive or deliver the product for use or sale in the normal course of business.
	CenterPoint Energy has a Risk Oversight Committee composed of corporate and business segment officers that oversees all commodity price, weather and credit risk activities, including CenterPoint Energy’s marketing, risk management services and hedging activities. The committee’s duties are to establish CenterPoint Energy’s commodity risk policies, allocate board-approved commercial risk limits, approve the use of new products and commodities, monitor positions and ensure compliance with CenterPoint Energy’s risk management policies and procedures and limits established by CenterPoint Energy’s board of directors.
	CenterPoint Energy’s policies prohibit the use of leveraged financial instruments. A leveraged financial instrument, for this purpose, is a transaction involving a derivative whose financial impact will be based on an amount other than the notional amount or volume of the instrument.
Investments in Other Debt and Equity Securities	Investments in Other Debt and Equity Securities
	CenterPoint Energy reports securities classified as trading at estimated fair value in its Consolidated Balance Sheets, and any unrealized holding gains and losses are recorded as other income (expense) in its Statements of Consolidated Income.
Environmental Costs	Environmental Costs
	CenterPoint Energy expenses or capitalizes environmental expenditures, as appropriate, depending on their future economic benefit. CenterPoint Energy expenses amounts that relate to an existing condition caused by past operations that do not have future economic benefit. CenterPoint Energy records undiscounted liabilities related to these future costs when environmental assessments and/or remediation activities are probable and the costs can be reasonably estimated.
Statement of Consolidated Cash Flows	Statements of Consolidated Cash Flows
	For purposes of reporting cash flows, CenterPoint Energy 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 Energy 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 $47 million and $41 million at December 31, 2014 and 2013, respectively, are included in other current assets in CenterPoint Energy’s Consolidated Balance Sheets. Cash and cash equivalents included $290 million and $207 million at December 31, 2014 and 2013, respectively, that was held by CenterPoint Energy’s transition and system restoration bond subsidiaries solely to support servicing the transition and system restoration bonds.
	CenterPoint Energy considers distributions received from equity method investments which do not exceed cumulative equity in earnings subsequent to the date of investment to be a return on investment and classifies these distributions as operating activities in the Statements of Consolidated Cash Flows. CenterPoint Energy considers distributions received from equity method investments in excess of cumulative equity in earnings subsequent to the date of investment to be a return of investment and classifies these distributions as investing activities in the Statements of Consolidated Cash Flows.
New Accounting Pronouncements, Policy [Policy Text Block]	New Accounting Pronouncements
	In April 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (ASU 2014-08), which significantly changes the existing accounting guidance on discontinued operations. Under ASU 2014-08, only those disposals of components of an entity that represent a strategic shift that has (or will have) a major effect on an entity’s operations and financial results should be reported as a discontinued operation.  ASU 2014-08 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2014.  ASU 2014-08 should be applied to components classified as held for sale after its effective date. Early adoption is permitted, but only for disposals (or classifications as held for sale) that have not been reported in financial statements previously issued or available for issuance. The adoption is expected to reduce the number of disposals that meet the definition of a discontinued operation.
	In May 2014, the FASB issued ASU 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 is 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. Accordingly, CenterPoint Energy will adopt ASU 2014-09 on January 1, 2017, and is currently evaluating the impact that this standard will have on its financial position, results of operations, cash flows and disclosures.
	In November 2014, the FASB issued ASU No. 2014-16, Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity (ASU 2014-16).  ASU 2014-16 clarifies how current guidance should be interpreted in evaluating the economic characteristics and risks of a host contract in a hybrid financial instrument that is issued in the form of a share. Specifically, the amendments clarify that an entity should consider all relevant terms and features, including the embedded derivative feature being evaluated for bifurcation, in evaluating the nature of a host contract. ASU 2014-16 is effective for fiscal years and interim periods beginning after December 15, 2015. CenterPoint Energy is currently assessing the impact, if any, that this standard will have on its financial position, results of operations, cash flows and disclosures.
	In January 2015, the FASB issued ASU No. 2015-01, Income Statement-Extraordinary and Unusual Items (Subtopic 225-20)-Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items (ASU 2015-01), which eliminates the concept of extraordinary items. ASU 2015-01 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015, and may be applied either prospectively or retrospectively. CenterPoint Energy will adopt ASU 2015-01 on January 1, 2016 and does not anticipate the adoption to have a material impact on its consolidated financial statements.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Schedule of Inventory
		December 31,
		2014		2013
	Materials and supplies	$	168	$	140
	Natural gas	211		145
	Total inventory	$	379	$	285

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	Property, plant and equipment includes the following:
		Weighted Average		December 31,
		Useful Lives
		(Years)		2014				2013
				(in millions)
	Electric Transmission & Distribution	31		$	9,393			$	8,741
	Natural Gas Distribution	33		5,235				4,694
	Energy Services	27		84				82
	Other property	22		646				621
	Total			15,358				14,138
	Accumulated depreciation and amortization:
	Electric Transmission & Distribution			3,050				2,907
	Natural Gas Distribution			1,493				1,324
	Energy Services			31				28
	Other property			282				286
	Total accumulated depreciation and amortization			4,856				4,545
	Property, plant and equipment, net			$	10,502			$	9,593
Depreciation and Amortization	The following table presents depreciation and amortization expense for 2014, 2013 and 2012 (in millions).
		2014				2013				2012
	Depreciation expense	$	521			$	531			$	562
	Amortization expense	492				423				488
	Total depreciation and amortization expense	$	1,013			$	954			$	1,050
Asset Retirement Obligation	A reconciliation of the changes in the asset retirement obligation (ARO) liability is as follows (in millions):
		December 31,
		2014				2013
	Beginning balance	$	134			$	164
	Accretion expense	5				5
	Revisions in estimates of cash flows	37				(35		)
	Ending balance	$	176			$	134

Goodwill_Tables

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill by Reportable Segments	Goodwill by reportable business segment as of both December 31, 2014 and 2013 are as follows (in millions):
	Natural Gas Distribution	$	746
	Energy Services (1)	83
	Other	11
	Total	$	840

Regulatory_Accounting_Tables

Regulatory Accounting (Tables)	12 Months Ended
	Dec. 31, 2014
Regulated Operations [Abstract]
Schedule of Regulatory Assets and Liabilities	The following is a list of regulatory assets/liabilities reflected on CenterPoint Energy’s Consolidated Balance Sheets as of December 31, 2014 and 2013:
		December 31,
		2014			2013
		(in millions)
	Securitized regulatory assets	$	2,738		$	3,179
	Unrecognized equity return (1)	(442		)	(508		)
	Unamortized loss on reacquired debt	104			111
	Pension and postretirement-related regulatory asset (2)	922			732
	Other long-term regulatory assets (3)	205			212
	Total regulatory assets	3,527			3,726
	Estimated removal costs	958			941
	Other long-term regulatory liabilities	248			211
	Total regulatory liabilities	1,206			1,152
	Total regulatory assets and liabilities, net	$	2,321		$	2,574
	-1	As of December 31, 2014, CenterPoint Energy has not recognized an allowed equity return of $442 million because such return will be recognized as it is recovered in rates through 2024. During the years ended December 31, 2014, 2013 and 2012, CenterPoint Houston recognized approximately $68 million, $45 million and $47 million, respectively, of the allowed equity return. The timing of CenterPoint Energy’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	CenterPoint Houston’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates is being deferred for rate making purposes. Deferred pension and other postemployment expenses of $-0- and $5 million as of December 31, 2014 and 2013, respectively, were not earning a return.
	-3	Other regulatory assets that are not earning a return were not material as of December 31, 2014 and 2013.

StockBased_Incentive_Compensat1

Stock-Based Incentive Compensation Plans and Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	The following tables summarize CenterPoint Energy’s LTIP activity for 2014:
	Stock Options
		Outstanding Options
		Year Ended December 31, 2014
		Shares			Weighted-Average				Remaining Average			Aggregate
		(Thousands)			Exercise Price				Contractual			Intrinsic
									Life (Years)			Value (Millions)
	Outstanding at December 31, 2013	120			$	10.93
	Exercised	(120	)		10.93
	Outstanding at December 31, 2014	—			—				—			$	—
	Exercisable at December 31, 2014	—			—				—			—
Schedule of Nonvested Performance-based Units Activity [Table Text Block]	Performance Awards
		Outstanding and Non-Vested Shares
		Year Ended December 31, 2014
		Shares			Weighted-Average				Remaining Average		Aggregate
		(Thousands)			Grant Date				Contractual		Intrinsic
					Fair Value				Life (Years)		Value (Millions)
	Outstanding at December 31, 2013	2,703			$	18.17
	Granted	1,198			23.7
	Forfeited or cancelled	(515	)		21.09
	Vested and released to participants	(926	)		15.5
	Outstanding at December 31, 2014	2,460			21.26				1.1		$	40
Schedule of Nonvested Share Activity [Table Text Block]	Stock Awards
		Outstanding and Non-Vested Shares
		Year Ended December 31, 2014
		Shares			Weighted-Average				Remaining Average		Aggregate
		(Thousands)			Grant Date				Contractual		Intrinsic
					Fair Value				Life (Years)		Value (Millions)
	Outstanding at December 31, 2013	898			$	18.72
	Granted	322			23.89
	Forfeited or cancelled	(122	)		21.6
	Vested and released to participants	(375	)		17.03
	Outstanding at December 31, 2014	723			21.41				1		$	17
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value [Table Text Block]	The weighted-average grant-date fair values per unit of awards granted were as follows for 2014, 2013 and 2012:
		Year Ended December 31,
		2014				2013				2012
	Performance awards	$	23.7			$	20.67			$	18.79
	Stock awards	23.89				21.53				18.96
Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value [Table Text Block]	Valuation Data
	The total intrinsic value of awards received by participants was as follows for 2014, 2013 and 2012:
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Stock options exercised	$	2			$	4			$	6
	Performance awards	24				20				24
	Stock awards	10				10				9
Schedule of Net Benefit Costs [Table Text Block]	CenterPoint Energy’s net periodic cost includes the following components relating to pension, including the benefit restoration plan, and postretirement benefits:
		Year Ended December 31,
		2014								2013								2012
		Pension				Post-retirement				Pension				Post-retirement				Pension			Post-retirement
		Benefits				Benefits				Benefits				Benefits				Benefits			Benefits
		(in millions)
	Service cost	$	42			$	2			$	44			$	2			$	35		$	1
	Interest cost	100				22				90				20				100			23
	Expected return on plan assets	(125		)		(7		)		(135		)		(7		)		(121		)	(7		)
	Amortization of prior service cost (credit)	10				(1		)		10				1				8			3
	Amortization of net loss	44				1				63				6				60			4
	Amortization of transition obligation	—				5				—				7				—			7
	Benefit enhancement	—				—				—				—				—			1
	Curtailment (1)	6				—				—				—				—			—
	Net periodic cost	$	77			$	22			$	72			$	29			$	82		$	32
	-1	During the fourth quarter of 2014, CenterPoint Energy recognized a curtailment pension loss of $6 million related to employees seconded to Enable. Substantially all of the seconded employees became employees of Enable effective January 1, 2015.
Schedule of Assumptions Used [Table Text Block]	CenterPoint Energy used the following assumptions to determine net periodic cost relating to pension and postretirement benefits:
		Year Ended December 31,
		2014						2013						2012
		Pension			Post-retirement			Pension			Post-retirement			Pension			Post-retirement
		Benefits			Benefits			Benefits			Benefits			Benefits			Benefits
	Discount rate	4.8	%		4.75	%		4	%		3.9	%		4.9	%		4.8	%
	Expected return on plan assets	7			5.5			8			5.5			8			5.5
	Rate of increase in compensation levels	3.9			—			4			—			4.2			—
Schedule of Net Pension and Post-retirement Benefit Costs	The following table summarizes changes in the benefit obligation, plan assets, the amounts recognized in consolidated balance sheets and the key assumptions of CenterPoint Energy’s pension, including benefit restoration, and postretirement plans. The measurement dates for plan assets and obligations were December 31, 2014 and 2013.
		December 31,
		2014								2013
		Pension				Post-retirement				Pension				Post-retirement
		Benefits				Benefits				Benefits				Benefits
		(in millions, except for actuarial assumptions)
	Change in Benefit Obligation
	Benefit obligation, beginning of year	$	2,153			$	476			$	2,316			$	538
	Service cost	42				2				44				2
	Interest cost	100				22				90				20
	Participant contributions	—				7				—				7
	Benefits paid	(156		)		(32		)		(142		)		(34		)
	Actuarial (gain) loss	264				52				(155		)		(60		)
	Medicare reimbursement	—				3				—				3
	Plan amendment	—				1				—				—
	Curtailment	—				(2		)		—				—
	Benefit obligation, end of year	2,403				529				2,153				476
	Change in Plan Assets
	Fair value of plan assets, beginning of year	1,803				140				1,698				139
	Employer contributions	97				18				91				19
	Participant contributions	—				7				—				7
	Benefits paid	(156		)		(32		)		(142		)		(34		)
	Actual investment return	181				8				156				9
	Fair value of plan assets, end of year	1,925				141				1,803				140
	Funded status, end of year	$	(478	)		$	(388	)		$	(350	)		$	(336	)
	Amounts Recognized in Balance Sheets
	Current liabilities-other	$	(31	)		$	(9	)		$	(9	)		$	(9	)
	Other liabilities-benefit obligations	(447		)		(379		)		(341		)		(327		)
	Net liability, end of year	$	(478	)		$	(388	)		$	(350	)		$	(336	)
	Actuarial Assumptions
	Discount rate	4.05		%		3.9		%		4.8		%		4.75		%
	Expected return on plan assets	6.5				5.2				7				5.5
	Rate of increase in compensation levels	4				—				3.9				—
	Healthcare cost trend rate assumed for the next year - Pre-65	—				7.25				—				7
	Healthcare cost trend rate assumed for the next year - Post-65	—				8.5				—				7.5
	Prescription drug cost trend rate assumed for the next year	—				6.5				—				7
	Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	—				5				—				5.5
	Year that the healthcare rate reaches the ultimate trend rate	—				2024				—				2018
	Year that the prescription drug rate reaches the ultimate trend rate	—				2024				—				2018
Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	The changes in plan assets and benefit obligations recognized in other comprehensive income during 2014 are as follows (in millions):
		Pension				Postretirement
		Benefits				Benefits
	Net gain (loss)	$	10			$	(6	)
	Amortization of net loss (gain)	9				(1		)
	Amortization of prior service credit (cost)	2				(1		)
	Total recognized in comprehensive income	$	21			$	(8	)
Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year [Table Text Block]	The amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2015 are as follows (in millions):
		Pension				Postretirement
		Benefits				Benefits
	Unrecognized actuarial loss	$	12			$	1
	Unrecognized prior service cost	1				—
	Amounts in accumulated comprehensive loss to be recognized in net periodic cost in 2015	$	13			$	1
Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]	The following table displays pension benefits related to CenterPoint Energy’s pension plans that have accumulated benefit obligations in excess of plan assets:
		December 31,
		2014								2013
		Pension				Pension				Pension				Pension
		Qualified				Non-qualified				Qualified				Non-qualified
		(in millions)
	Accumulated benefit obligation	$	2,273			$	98			$	2,031			$	92
	Projected benefit obligation	2,304				98				2,061				92
	Fair value of plan assets	1,925				—				1,803				—
Schedule of a One-percent Point Change in the Assumed Health Care Cost Trend Rates	Assumed healthcare cost trend rates have a significant effect on the reported amounts for CenterPoint Energy’s postretirement benefit plans. A 1% change in the assumed healthcare cost trend rate would have the following effects:
		1%				1%
		Increase				Decrease
		(in millions)
	Effect on the postretirement benefit obligation	$	19			$	16
	Effect on total of service and interest cost	1				1
Target Allocation of Plan Assets [Table Text Block]	As part of the investment strategy discussed above, CenterPoint Energy maintained the following weighted average allocation targets for its benefit plans as of December 31, 2014:
		Pension		Postretirement
		Benefits		Benefits
	U.S. equity	12 – 28%		14 – 24%
	International developed market equity	7 – 17%		3 – 13%
	Emerging market equity	3 – 13%		—
	Fixed income	54 – 66%		68 – 78%
	Cash	0 – 2%		0 – 2%
Schedule of Allocation of Plan Assets [Table Text Block]	The following tables set forth by level, within the fair value hierarchy (see Note 8), CenterPoint Energy’s pension plan assets at fair value as of December 31, 2014 and 2013:
		Fair Value Measurements at December 31, 2014
		(in millions)
		Total				Quoted Prices in				Significant				Significant
						Active Markets for				Observable Inputs				Unobservable
						Identical Assets				(Level 2)				Inputs
						(Level 1)								(Level 3)
	Cash	$	6			$	6			$	—			$	—
	Common collective trust funds (1)	1,108				—				1,108				—
	Corporate bonds:
	Investment grade or above	368				—				368				—
	Equity securities:
	International companies	49				49				—				—
	U.S. companies	83				83				—				—
	Cash received as collateral from securities lending	86				86				—				—
	U.S. treasuries	47				47				—				—
	Mortgage backed securities	4				—				4				—
	Asset backed securities	4				—				4				—
	Municipal bonds	79				—				79				—
	Mutual funds (2)	161				161				—				—
	International government bonds	15				—				15				—
	Real estate	1				—				—				1
	Obligation to return cash received as collateral from securities lending	(86		)		(86		)		—				—
	Total	$	1,925			$	346			$	1,578			$	1
	-1	61% of the amount invested in common collective trust funds is in fixed income securities, 14% is in U.S. equities, 22% is in international equities and 3% is in emerging market equities.
	-2	57% of the amount invested in mutual funds is in international equities, 30% is in emerging market equities and 13% is in U.S. equities.
		Fair Value Measurements at December 31, 2013
		(in millions)
		Total				Quoted Prices in				Significant				Significant
						Active Markets for				Observable Inputs				Unobservable
						Identical Assets				(Level 2)				Inputs
						(Level 1)								(Level 3)
	Cash	$	11			$	11			$	—			$	—
	Common collective trust funds (1)	1,107				—				1,107				—
	Corporate bonds:
	Investment grade or above	256				—				256				—
	Equity securities:
	International companies	75				75				—				—
	U.S. companies	77				77				—				—
	Cash received as collateral from securities lending	71				71				—				—
	U.S. government backed agencies bonds	1				1				—				—
	U.S. treasuries	18				18				—				—
	Mortgage backed securities	7				—				7				—
	Asset backed securities	6				—				6				—
	Municipal bonds	61				—				61				—
	Mutual funds (2)	172				172				—				—
	International government bonds	11				—				11				—
	Real estate	1				—				—				1
	Obligation to return cash received as collateral from securities lending	(71		)		(71		)		—				—
	Total	$	1,803			$	354			$	1,448			$	1
	-1	50% of the amount invested in common collective trust funds is in fixed income securities, 20% is in U.S. equities, 25% is in international equities and 5% is in emerging market equities.
	-2	58% of the amount invested in mutual funds is in international equities, 30% is in emerging market equities and 12% is in U.S. equities.
	The pension plan utilized both exchange traded and over-the-counter financial instruments such as futures, interest rate options and swaps that were marked to market daily with the gains/losses settled in the cash accounts. The pension plan did not include any holdings of CenterPoint Energy common stock as of December 31, 2014 or 2013.
	The changes in the fair value of the pension plan’s level 3 investments for the years ended December 31, 2014 and 2013 were not material.
	The following tables present by level, within the fair value hierarchy, CenterPoint Energy’s postretirement plan assets at fair value as of December 31, 2014 and 2013, by asset category:
		Fair Value Measurements at December 31, 2014
		(in millions)
		Total				Quoted Prices				Significant				Significant
						in Active				Observable				Unobservable
						Markets for				Inputs				Inputs
						Identical Assets				(Level 2)				(Level 3)
						(Level 1)
	Mutual funds (1)	$	141			$	141			$	—			$	—
	Total	$	141			$	141			$	—			$	—
-1	73% of the amount invested in mutual funds is in fixed income securities, 19% is in U.S. equities and 8% is in international equities.
	Fair Value Measurements at December 31, 2013
	(in millions)
	Total				Quoted Prices				Significant				Significant
					in Active				Observable				Unobservable
					Markets for				Inputs				Inputs
					Identical Assets				(Level 2)				(Level 3)
					(Level 1)
Mutual funds (1)	$	140			$	140			$	—			$	—
Total	$	140			$	140			$	—			$	—
-1	72% of the amount invested in mutual funds is in fixed income securities, 20% is in U.S. equities and 8% is in international equities.
Schedule of Expected Benefit Payments [Table Text Block]	The following benefit payments are expected to be paid by the pension and postretirement benefit plans (in millions):
						Postretirement Benefit Plan
		Pension				Benefit				Medicare
		Benefits				Payments				Subsidy
										Receipts
	2015	$	223			$	35			$	(4	)
	2016	143				36				(4		)
	2017	147				38				(5		)
	2018	154				40				(5		)
	2019	152				42				(6		)
	2020-2024	785				228				(39		)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	CenterPoint Energy’s changes in accumulated comprehensive loss related to defined benefit, postretirement and other postemployment plans are as follows (in millions):
			Year Ended December 31,
			2014				2013
	Beginning Balance		$	(88	)		$	(132	)
	Other comprehensive income (loss) before reclassifications (1)		(3		)		52
	Amounts reclassified from accumulated other comprehensive income:
	Prior service cost (2)		2				3
	Actuarial losses (2)		9				14
	Total reclassifications from accumulated other comprehensive income		11				17
	Tax expense		(5		)		(25		)
	Net current period other comprehensive income		3				44
	Ending Balance		$	(85	)		$	(88	)
	________________
	-1	Total other comprehensive income (loss) related to the re-measurement of pension, postretirement and other postemployment plans.
	-2	These accumulated other comprehensive components are included in the computation of net periodic cost.
	Amounts recognized in accumulated other comprehensive loss consist of the following:
		December 31,
		2014								2013
		Pension				Postretirement				Pension				Postretirement
		Benefits				Benefits				Benefits				Benefits
		(in millions)
	Unrecognized actuarial loss	$	113			$	14			$	126			$	7
	Unrecognized prior service cost	4				2				12				1
	Net amount recognized in accumulated other comprehensive loss	$	117			$	16			$	138			$	8

Derivative_Instruments_Tables

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments
	Fair Value of Derivative Instruments
			December 31, 2013
	Total derivatives not designated		Balance Sheet		Derivative				Derivative
	as hedging instruments		Location		Assets				Liabilities
					Fair Value				Fair Value
					(in millions)
	Natural gas derivatives (1) (2) (3)		Current Assets: Non-trading derivative assets		$	28			$	4
	Natural gas derivatives (1) (2)		Other Assets: Non-trading derivative assets		10				—
	Natural gas derivatives (1) (2)		Current Liabilities: Non-trading derivative liabilities		4				21
	Natural gas derivatives (1) (2)		Other Liabilities: Non-trading derivative liabilities		1				5
	Indexed debt securities derivative		Current Liabilities		—				455
	Total				$	43			$	485
	-1	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 607 Bcf or a net 46 Bcf long position.  Of the net long position, basis swaps constitute 99 Bcf.
	-2	Natural gas contracts are presented on a net basis in the Consolidated Balance Sheets. Natural gas contracts are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $13 million asset as shown on CenterPoint Energy’s Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, offset by collateral netting of less than $1 million.
	-3	The $28 million Derivative Current Asset includes $1 million related to physical forwards purchased from Enable.
	The following tables present information about CenterPoint Energy’s derivative instruments and hedging activities. The first two tables provide a balance sheet overview of CenterPoint Energy’s Derivative Assets and Liabilities as of December 31, 2014 and 2013, while the last table provides a breakdown of the related income statement impacts for the years ending December 31, 2014 and 2013.
	Fair Value of Derivative Instruments
			December 31, 2014
	Total derivatives not designated		Balance Sheet		Derivative				Derivative
	as hedging instruments		Location		Assets				Liabilities
					Fair Value				Fair Value
					(in millions)
	Natural gas derivatives (1) (2) (3)		Current Assets: Non-trading derivative assets		$	101			$	1
	Natural gas derivatives (1) (2) (3)		Other Assets: Non-trading derivative assets		32				—
	Natural gas derivatives (1) (2) (3)		Current Liabilities: Non-trading derivative liabilities		14				83
	Natural gas derivatives (1) (2) (3)		Other Liabilities: Non-trading derivative liabilities		2				18
	Indexed debt securities derivative		Current Liabilities		—				541
	Total				$	149			$	643
	-1	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 804 billion cubic feet (Bcf) or a net 60 Bcf long position.  Of the net long position, basis swaps constitute 127 Bcf.
	-2	Natural gas contracts are presented on a net basis in the Consolidated Balance Sheets. Natural gas contracts are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $111 million asset as shown on CenterPoint Energy’s Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above offset by collateral netting of $64 million.
	-3	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
Offsetting of Natural Gas Derivative Assets and Liabilities [Table Text Block]
	Offsetting of Natural Gas Derivative Assets and Liabilities
			December 31, 2014
			Gross Amounts Recognized (1)				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amount Presented in the Consolidated Balance Sheets (2)
			(in millions)
	Current Assets: Non-trading derivative assets		$	115			$	(16	)		$	99
	Other Assets: Non-trading derivative assets		34				(2		)		32
	Current Liabilities: Non-trading derivative liabilities		(84		)		65				(19		)
	Other Liabilities: Non-trading derivative liabilities		(18		)		17				(1		)
	Total		$	47			$	64			$	111
	________________
	-1	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.
	-2	The derivative assets and liabilities on the Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
	Offsetting of Natural Gas Derivative Assets and Liabilities
			December 31, 2013
			Gross Amounts Recognized (1)				Gross Amounts Offset in the Consolidated Balance Sheets				Net Amount Presented in the Consolidated Balance Sheets (2)
			(in millions)
	Current Assets: Non-trading derivative assets		$	32			$	(8	)		$	24
	Other Assets: Non-trading derivative assets		11				(1		)		10
	Current Liabilities: Non-trading derivative liabilities		(25		)		8				(17		)
	Other Liabilities: Non-trading derivative liabilities		(5		)		1				(4		)
	Total		$	13			$	—			$	13
	________________
	-1	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.
	-2	The derivative assets and liabilities on the Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
Income Statement Impact of Derivative Activity
	Income Statement Impact of Derivative Activity
					Year Ended December 31,
	Total derivatives not designated		Income Statement Location		2014				2013				2011
	as hedging instruments
					(in millions)
	Natural gas derivatives		Gains (Losses) in Revenue		$	35			$	11			$	43
	Natural gas derivatives (1) (2)		Gains (Losses) in Expense: Natural Gas		11				10				(63		)
	Indexed debt securities derivative		Gains (Losses) in Other Income (Expense)		(86		)		(193		)		(71		)
	Total				$	(40	)		$	(172	)		$	(91	)
	-1	The Gains (Losses) in Expense: Natural Gas includes $2 million and $(2) million during the years ended December 31, 2014 and 2013, respectively, related to physical forwards purchased from Enable.
	-2	The Gains (Losses) in Expense: Natural Gas includes $-0-, $-0- and $(38) million of costs in 2014, 2013 and 2012, respectively, associated with price stabilization activities of the Natural Gas Distribution business segment that will be ultimately recovered through purchased gas adjustments.
Credit Quality of Counterparties	In addition to the risk associated with price movements, credit risk is also inherent in CenterPoint Energy’s non-trading derivative activities. Credit risk relates to the risk of loss resulting from non-performance of contractual obligations by a counterparty. The following table shows the composition of counterparties to the non-trading derivative assets of CenterPoint Energy as of December 31, 2014 and 2013 (in millions):
		December 31, 2014								December 31, 2013
		Investment				Total				Investment				Total
		Grade(1)								Grade(1)
	Energy marketers	$	2			$	4			$	1			$	4
	Financial institutions	—				—				1				9
	End users (2)	2				127				1				21
	Total	$	4			$	131			$	3			$	34
	-1	“Investment grade” is primarily determined using publicly available credit ratings and considers credit support (including parent company guarantees) and collateral (including cash and standby letters of credit). For unrated counterparties, CenterPoint Energy determines a synthetic credit rating by performing financial statement analysis and considers contractual rights and restrictions and collateral.
	-2	End users are comprised primarily of customers who have contracted to fix the price of a portion of their physical gas requirements for future periods.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on a Recurring Basis	The following tables present information about CenterPoint Energy’s assets and liabilities (including derivatives that are presented net) measured at fair value on a recurring basis as of December 31, 2014 and 2013, and indicate the fair value hierarchy of the valuation techniques utilized by CenterPoint Energy to determine such fair value.
		Quoted Prices in			Significant Other			Significant			Netting			Balance at December 31, 2014
		Active Markets			Observable			Unobservable			Adjustments (1)
		for Identical Assets			Inputs			Inputs
		(Level 1)			(Level 2)			(Level 3)
		(in millions)
	Assets
	Corporate equities	$	932		$	—		$	—		$	—		$	932
	Investments, including money market funds	54			—			—			—			54
	Natural gas derivatives (2)	7			122			20			(18		)	131
	Total assets	$	993		$	122		$	20		$	(18	)	$	1,117
	Liabilities
	Indexed debt securities derivative	$	—		$	541		$	—		$	—		$	541
	Natural gas derivatives (2)	22			77			3			(82		)	20
	Total liabilities	$	22		$	618		$	3		$	(82	)	$	561
	-1	Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy to settle positive and negative positions and also include cash collateral of $64 million posted with the same counterparties.
	-2	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.
		Quoted Prices in			Significant Other			Significant			Netting			Balance at December 31, 2013
		Active Markets			Observable			Unobservable			Adjustments (1)
		for Identical Assets			Inputs			Inputs
		(Level 1)			(Level 2)			(Level 3)
		(in millions)
	Assets
	Corporate equities	$	770		$	—		$	—		$	—		$	770
	Investments, including money market funds	61			—			—			—			61
	Natural gas derivatives (2)	5			33			5			(9		)	34
	Total assets	$	836		$	33		$	5		$	(9	)	$	865
	Liabilities
	Indexed debt securities derivative	$	—		$	455		$	—		$	—		$	455
	Natural gas derivatives	1			27			2			(9		)	21
	Total liabilities	$	1		$	482		$	2		$	(9	)	$	476
	-1	Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy to settle positive and negative positions and also include cash collateral of less than $1 million posted with the same counterparties.
	-2	The (Level 2) Natural gas derivative assets of $33 million include $1 million related to physical forwards purchased from Enable.
Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs	The following tables present additional information about assets or liabilities, including derivatives that are measured at fair value on a recurring basis for which CenterPoint Energy has utilized Level 3 inputs to determine fair value:
		Fair Value Measurements Using Significant
		Unobservable Inputs (Level 3)
		Derivative assets and liabilities, net
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Beginning balance	$	3		$	2		$	6
	Total gains	14			3			3
	Total settlements	1			(3		)	(6		)
	Transfers out of Level 3	—			—			(1		)
	Transfers into Level 3	(1		)	1			—
	Ending balance (1)	$	17		$	3		$	2
	The amount of total gains for the period included in earnings	$	16		$	2		$	1
	attributable to the change in unrealized gains or losses relating
	to assets still held at the reporting date
	-1	During 2014, 2013 and 2012, CenterPoint Energy did not have significant Level 3 purchases or sales.
Estimated Fair Value of Financial Instruments, Debt Instruments
		December 31, 2014						December 31, 2013
		Carrying			Fair			Carrying			Fair
		Amount			Value			Amount			Value
		(in millions)
	Financial assets:
	Notes receivable - affiliated companies	$	363		$	362		$	363		$	363
	Financial liabilities:
	Long-term debt	$	8,652		$	9,427		$	8,171		$	8,670

Unconsolidated_Affiliates_Tabl

Unconsolidated Affiliates (Tables)	12 Months Ended
	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity Method Investments [Table Text Block]	Investment in Unconsolidated Affiliates:
			Year Ended December 31,
			2014			2013
			(in millions)
	Enable		$	4,520		$	4,319
	SESH (1)		1			199
	Total		$	4,521		$	4,518
	-1	On May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
	Equity in Earnings of Unconsolidated Affiliates, net:
			Year Ended December 31,
			2014			2013			2012
			(in millions)
	Enable (1)		$	303		$	173		$	—
	SESH (2)		5			15			26
	Waskom (3)		—			—			5
	Total		$	308		$	188		$	31
	-1	On May 1, 2013, CenterPoint Energy formed Enable with OGE and ArcLight.
	-2	On each of May 1, 2013 and May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
	-3	On July 31, 2012, Waskom became a wholly owned subsidiary of CenterPoint Energy. Beginning on August 1, 2012, Waskom’s operating results are consolidated on the Statements of Consolidated Income. On May 1, 2013, CenterPoint Energy contributed Waskom to Enable.
	Summarized consolidated income information for Enable is as follows:
			Year Ended December 31,
			2014			2013 (1)
			(in millions)
	Operating revenues		$	3,367		$	2,123
	Cost of sales, excluding depreciation and amortization		1,914			1,241
	Operating income		586			322
	Net income attributable to Enable		530			289
	CenterPoint Energy’s approximate interest		$	298		$	168
	Basis difference accretion		5			5
	CenterPoint Energy’s equity in earnings, net		$	303		$	173
	-1	The amounts included in this column represent the eight month period from formation of Enable on May 1, 2013 through December 31, 2013.
	Summarized consolidated balance sheet information for Enable is as follows:
			December 31,
			2014			2013
			(in millions)
	Current assets		$	438		$	549
	Non-current assets		11,399			10,683
	Current liabilities		671			720
	Non-current liabilities		2,343			2,331
	Non-controlling interest		31			33
	Enable partners’ capital		8,792			8,148
	CenterPoint Energy’s ownership interest in Enable’s partner capital		$	4,869		$	4,753
	CenterPoint Energy’s basis difference attributable to goodwill (1)		(217		)	(229		)
	CenterPoint Energy’s accretable basis difference (2)		(132		)	(205		)
	CenterPoint Energy’s total basis difference		(349		)	(434		)
	CenterPoint Energy’s investment in Enable		$	4,520		$	4,319
	-1	The difference relates to CenterPoint Energy’s proportionate share of Enable’s goodwill arising from its acquisition of Enogex, and therefore will be recognized by CenterPoint Energy upon dilution or disposition of its interest in Enable.
	-2	The difference will be recognized by CenterPoint Energy over 30 years beginning May 1, 2013. CenterPoint Energy will also adjust the accretable basis difference for dilution or disposition of its interest in Enable.
	Enable concluded that the formation of Enable is considered a business combination, and CenterPoint Midstream is the acquirer for accounting purposes.  Under this method, the fair value of the consideration paid by CenterPoint Midstream for Enogex was allocated to the assets acquired and liabilities assumed on the Closing Date based on their fair value.  Enogex’s assets, liabilities and equity were accordingly adjusted to estimated fair value as of May 1, 2013.  Determining the fair value of assets and liabilities is judgmental in nature and involves the use of significant estimates and assumptions.  Enable used appraisers to assist in the determination of the estimated fair value of certain assets and liabilities contributed by Enogex.
	Distributions Received from Unconsolidated Affiliates:
			Year Ended December 31,
			2014			2013			2012
			(in millions)
	Enable (1)		$	298		$	106		$	—
	SESH (2)		7			23			32
	Waskom (3)		—			—			7
	Total		$	305		$	129		$	39
	-1	On May 1, 2013, CenterPoint Energy formed Enable with OGE and ArcLight.
	-2	On each of May 1, 2013 and May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
	-3	On July 31, 2012, Waskom became a wholly owned subsidiary of CenterPoint Energy. Beginning on August 1, 2012, Waskom’s operating results are consolidated on the Statements of Consolidated Income. On May 1, 2013, CenterPoint Energy contributed Waskom to Enable.

Indexed_Debt_Securities_ZENS_a1

Indexed Debt Securities (ZENS) and Securities Related to ZENS (Tables)	12 Months Ended
	Dec. 31, 2014
Indexed Debt Securities [Abstract]
Summarized Financial Information on Investment in Time Warner Securities and Indexed Debt Security Obligation	The following table sets forth summarized financial information regarding CenterPoint Energy’s investment in TW Securities and each component of CenterPoint Energy’s ZENS obligation (in millions).
		TW			Debt			Derivative
		Securities			Component			Component
					of ZENS			of ZENS
	Balance at December 31, 2011	$	386		$	131		$	197
	Accretion of debt component of ZENS	—			24			—
	2% interest paid	—			(17		)	—
	Loss on indexed debt securities	—			—			71
	Gain on TW Securities	154			—			—
	Balance at December 31, 2012	540			138			268
	Accretion of debt component of ZENS	—			24			—
	2% interest paid	—			(17		)	—
	Sale of TW Securities	(9		)	—			—
	Redemption of indexed debt securities	—			(2		)	(6		)
	Loss on indexed debt securities	—			—			193
	Gain on TW Securities	236			—			—
	Balance at December 31, 2013	767			143			455
	Accretion of debt component of ZENS	—			26			—
	2% interest paid	—			(17		)	—
	Loss on indexed debt securities	—			—			86
	Gain on TW Securities	163			—			—
	Balance at December 31, 2014	$	930		$	152		$	541

Short_Term_Borrowings_and_Long1

Short Term Borrowings and Long Term Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of Short-term Borrowings and Long-term Debt
		December 31,					December 31,
		2014					2013
		Long-Term			Current(1)		Long-Term			Current(1)
		(in millions)
	Short-term borrowings:
	Inventory financing	$	—		$	53	$	—		$	43
	Total short-term borrowings	—			53		—			43
	Long-term debt:
	CenterPoint Energy:
	ZENS (2)	—			152		—			143
	Senior notes 5.95% to 6.85% due 2015 to 2018	550			200		750			—
	Pollution control bonds 4.90% to 5.125% due 2015 to 2028 (3)	118			69		187			—
	Commercial paper (4)	191			—		—			—
	Other	2			2		—			—
	CenterPoint Houston:
	First mortgage bonds 9.15% due 2021	102			—		102			—
	General mortgage bonds 2.25% to 6.95% due 2022 to 2044	1,912			—		1,312			—
	Pollution control bonds 4.25% to 5.60% due 2017 to 2027	—			—		183			—
	System restoration bonds 1.833% to 4.243% due 2015 to 2022	415			48		463			47
	Transition bonds 0.90% to 5.302% due 2015 to 2024	2,259			324		2,583			307
	Other	1			—		—			—
	CERC Corp.:
	Senior notes 4.50% to 6.625% due 2016 to 2041	2,168			—		2,168			—
	Commercial paper (4)	341			—		118			—
	Other	—			—		1			—
	Unamortized discount and premium, net	(50		)	—		(50		)	—
	Total long-term debt	8,009			795		7,817			497
	Total debt	$	8,009		$	848	$	7,817		$	540
	-1	Includes amounts due or exchangeable within one year of the date noted.
	-2	CenterPoint Energy’s ZENS obligation is bifurcated into a debt component and an embedded derivative component. For additional information regarding ZENS, see Note 10(b). As ZENS are exchangeable for cash at any time at the option of the holders, these notes are classified as a current portion of long-term debt.
	-3	$118 million of these series of debt were secured by general mortgage bonds of CenterPoint Houston at both December 31, 2014 and 2013.
	-4	Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted.
Schedule of Revolving Credit Facilities and Utilization of Such Facilities	As of December 31, 2014 and 2013, CenterPoint Energy, CenterPoint Houston and CERC Corp. had the following revolving credit facilities and utilization of such facilities (in millions):
					December 31, 2014							December 31, 2013
		Size of			Loans		Letters			Commercial		Loans		Letters		Commercial
		Facility					of Credit			Paper				of Credit		Paper
	CenterPoint Energy	$	1,200		$	—	$	6		$	191	$	—	$	6	$	—
	CenterPoint Houston	300			—		4			—		—		4		—
	CERC Corp.	600			—		—			341		—		—		118
	Total	$	2,100		$	—	$	10		$	532	$	—	$	10	$	118

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Expense	The components of CenterPoint Energy’s income tax expense were as follows:
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Current income tax expense (benefit):
	Federal	$	(20	)	$	91		$	—
	State	14			23			12
	Total current expense (benefit)	(6		)	114			12
	Deferred income tax expense (benefit):
	Federal	273			370			280
	State	7			(14		)	48
	Total deferred expense	280			356			328
	Total income tax expense	$	274		$	470		$	340
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,
		2014			2013			2012
		(in millions)
	Income before income taxes	$	885		$	781		$	757
	Federal statutory income tax rate	35		%	35		%	35		%
	Expected federal income tax expense	310			273			265
	Increase (decrease) in tax expense resulting from:
	State income tax expense, net of federal income tax	16			21			39
	Amortization of investment tax credit	—			—			(2		)
	Tax effect related to the formation of Enable	—			196			—
	Decrease in settled and uncertain income tax positions	—			(9		)	(33		)
	Goodwill impairment	—			—			88
	Tax basis balance sheet adjustments	(29		)	—			—
	Other, net	(23		)	(11		)	(17		)
	Total	(36		)	197			75
	Total income tax expense	$	274		$	470		$	340
	Effective tax rate	31		%	60.2		%	44.9		%
Tax Assets and Liabilities	The tax effects of temporary differences that give rise to significant portions of deferred tax assets and liabilities were as follows:
		December 31,
		2014			2013
		(in millions)
	Deferred tax assets:
	Current:
	Allowance for doubtful accounts	$	10		$	11
	Deferred gas costs	—			7
	Other	13			12
	Total current deferred tax assets	23			30
	Non-current:
	Loss and credit carryforwards	69			51
	Employee benefits	327			258
	Other	89			76
	Total non-current deferred tax assets before valuation allowance	485			385
	Valuation allowance	(2		)	(2		)
	Total non-current deferred tax assets, net of valuation allowance	483			383
	Total deferred tax assets, net of valuation allowance	506			413
	Deferred tax liabilities:
	Current:
	Unrealized gain on indexed debt securities	636			541
	Unrealized gain on TW securities	65			97
	Deferred gas costs	6			—
	Total current deferred tax liabilities	707			638
	Non-current:
	Depreciation	2,201			1,908
	Regulatory assets, net	1,228			1,308
	Investment in unconsolidated affiliates	1,789			1,590
	Other	21			119
	Total non-current deferred tax liabilities	5,239			4,925
	Total deferred tax liabilities	5,946			5,563
	Accumulated deferred income taxes, net	$	5,440		$	5,150
Rollforward of Unrecognized Tax Benefits	Uncertain Income Tax Positions. The following table reconciles the beginning and ending balance of CenterPoint Energy’s unrecognized tax benefits (expenses):
		December 31,
		2014			2013			2012
		(in millions)
	Balance, beginning of year	$	—		$	(23	)	$	51
	Tax Positions related to prior years:
	Reductions	—			(1		)	(75		)
	Tax Positions related to current year:
	Settlements	—			24			1
	Balance, end of year	$	—		$	—		$	(23	)

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Lease Commitments	The following table sets forth information concerning CenterPoint Energy’s obligations under non-cancelable long-term operating leases at December 31, 2014, which primarily consist of rental agreements for building space, data processing equipment, compression equipment and rights of way (in millions):
	2015	$	5
	2016	4
	2017	3
	2018	2
	2019	2
	2020 and beyond	7
	Total	$	23

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Basic and Diluted Earnings Per Share	The following table reconciles numerators and denominators of CenterPoint Energy’s basic and diluted earnings per share calculations:
		For the Year Ended December 31,
		2014		2013		2012
		(in millions, except per share and share amounts)
	Net income	$	611	$	311	$	417
	Basic weighted average shares outstanding	429,634,000		428,466,000		427,189,000
	Plus: Incremental shares from assumed conversions:
	Stock options	—		41,000		152,000
	Restricted stock	2,034,000		2,423,000		2,453,000
	Diluted weighted average shares	431,668,000		430,930,000		429,794,000
	Basic earnings per share	$	1.42	$	0.73	$	0.98
	Diluted earnings per share	$	1.42	$	0.72	$	0.97

Unaudited_Quarterly_Informatio1

Unaudited Quarterly Information (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	Summarized quarterly financial data is as follows:
		Year Ended December 31, 2014
		First		Second			Third		Fourth
		Quarter		Quarter			Quarter		Quarter (3)
		(in millions, except per share amounts)
	Revenues	$	3,163	$	1,884		$	1,807	$	2,372
	Operating income	295		186			233		221
	Net income	185		107			143		176
	Basic earnings per share(1)	$	0.43	$	0.25		$	0.33	$	0.41
	Diluted earnings per share(1)	$	0.43	$	0.25		$	0.33	$	0.41
		Year Ended December 31, 2013
		First		Second			Third		Fourth
		Quarter		Quarter (2)			Quarter		Quarter
		(in millions, except per share amounts)
	Revenues	$	2,388	$	1,894		$	1,640	$	2,184
	Operating income	332		223			244		211
	Net income (loss)	$	147	$	(100	)	$	151	$	113
	Basic earnings (loss) per share(1)	$	0.34	$	(0.23	)	$	0.35	$	0.26
	Diluted earnings (loss) per share(1)	$	0.34	$	(0.23	)	$	0.35	$	0.26
	-1	Quarterly earnings per common share are based on the weighted average number of shares outstanding during the quarter, and the sum of the quarters may not equal annual earnings per common share.
	-2	Effective May 1, 2013, CenterPoint Energy contributed CenterPoint Midstream to Enable.  See Note 2(b) and Note 9 for further discussion on the formation of Enable and CenterPoint Energy’s investment in Enable, respectively.
	-3	CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.

Reportable_Business_Segments_T

Reportable Business Segments (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Financial Data for Business Segments	Financial data for business segments and products and services are as follows (in millions):
		Revenues				Intersegment			Depreciation			Operating			Total				Expenditures
		from				Revenues			and			Income (Loss)			Assets				for Long-Lived
		External							Amortization										Assets
		Customers
	As of and for the year ended December 31, 2014:
	Electric Transmission & Distribution	$	2,845		-1	$	—		$	768		$	595		$	10,066			$	818
	Natural Gas Distribution	3,271				30			201			287			5,464				525
	Energy Services	3,095				84			5			52			978				3
	Midstream Investments (2)	—				—			—			—			4,521				—
	Other	15				—			39			1			3,368			-3	56
	Reconciling Eliminations	—				(114		)	—			—			(1,197		)		—
	Consolidated	$	9,226			$	—		$	1,013		$	935		$	23,200			$	1,402
	As of and for the year ended December 31, 2013:
	Electric Transmission & Distribution	$	2,570		-1	$	—		$	685		$	607		$	9,605			$	759
	Natural Gas Distribution	2,837				26			185			263			4,976				430
	Energy Services	2,374				27			5			13			895				3
	Interstate Pipelines (4) (6)	133				53			20			72			—				29
	Field Services (5) (6)	178				18			20			73			—				16
	Midstream Investments (2)	—				—			—			—			4,518				—
	Other	14				—			39			(18		)	3,026			-3	35
	Reconciling Eliminations	—				(124		)	—			—			(1,150		)		—
	Consolidated	$	8,106			$	—		$	954		$	1,010		$	21,870			$	1,272
	As of and for the year ended December 31, 2012:
	Electric Transmission & Distribution	$	2,540		-1	$	—		$	729		$	639		$	11,174			$	599
	Natural Gas Distribution	2,320				22			173			226			4,775				359
	Energy Services	1,758				26			6			(250		)	839				6
	Interstate Pipelines (4)	356				146			56			207			4,004				132
	Field Services (5)	467				39			50			214			2,453				52
	Other	11				—			36			2			2,600			-3	40
	Reconciling Eliminations	—				(233		)	—			—			(2,974		)		—
	Consolidated	$	7,452			$	—		$	1,050		$	1,038		$	22,871			$	1,188
	-1	Sales to affiliates of NRG in 2014, 2013 and 2012 represented approximately $735 million, $658 million and $648 million, respectively, of CenterPoint Houston’s transmission and distribution revenues. Sales to affiliates of Energy Future Holdings Corp. in 2014, 2013 and 2012 represented approximately $189 million, $167 million and $162 million, respectively, of CenterPoint Houston’s transmission and distribution revenues.
	-2	Midstream Investments reported equity earnings of $303 million from Enable and $5 million of equity earnings from CenterPoint Energy’s interest in SESH for the year ended December 31, 2014. Midstream Investments reported equity earnings of $173 million from Enable and $8 million of equity earnings from CenterPoint Energy’s interest in SESH for the eight months ended December 31, 2013. Included in total assets of Midstream Investments as of December 31, 2014 and 2013 is $4,520 million and $4,319 million, respectively, related to CenterPoint Energy’s investment in Enable and $1 million and $199 million related to CenterPoint Energy’s retained interest in SESH, respectively.
	-3	Included in total assets of Other Operations as of December 31, 2014, 2013 and 2012, are pension and other postemployment related regulatory assets of $795 million, $627 million and $832 million, respectively.
	-4	Interstate Pipelines recorded equity income of $7 million and $26 million in the years ended December 31, 2013 and 2012, respectively, from its interest in SESH, a jointly-owned pipeline. These amounts are included in Equity in earnings of unconsolidated affiliates under the Other Income (Expense) caption.  Interstate Pipelines’ investment in SESH was $404 million as of December 31, 2012, and is included in Investment in unconsolidated affiliates. As discussed above, effective May 1, 2013, CenterPoint Energy reports equity earnings associated with its interest in Enable and equity earnings associated with its interest in SESH under its Midstream Investments segment, and no longer has an Interstate Pipelines reporting segment prospectively.
	-5	Field Services recorded equity income of $5 million for the year ended December 31, 2012 from its interest in Waskom. This amount is included in Equity in earnings of unconsolidated affiliates under the Other Income (Expense) caption. Beginning on August 1, 2012, financial results for Waskom are included in operating income due to the July 31, 2012 purchase of the 50% interest in Waskom that CenterPoint Energy did not already own. CenterPoint Energy contributed 100% interest in Waskom to Enable on May 1, 2013. Effective May 1, 2013, CenterPoint Energy reports equity earnings associated with its interest in Enable under its Midstream Investments segment, and no longer has a Field Services reporting segment prospectively.
	-6	Results reflected in the year ended December 31, 2013 represent only January 2013 through April 2013.
Revenues by Products and Services
			Year Ended December 31,
	Revenues by Products and Services:		2014				2013			2012
	Electric delivery		$	2,845			$	2,570		$	2,540
	Retail gas sales		5,049				4,150			3,328
	Wholesale gas sales		1,159				913			613
	Gas transportation and processing		38				345			847
	Energy products and services		135				128			124
	Total		$	9,226			$	8,106		$	7,452

Background_Details

Background (Details) (Enable Midstream Partners [Member])	Dec. 31, 2014	30-May-14	Mar. 31, 2014
Enable Midstream Partners [Member]
Equity Method Investment, Ownership Percentage	55.40%	54.70%	58.30%

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended					0 Months Ended	3 Months Ended		0 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	Jul. 31, 2012	Dec. 31, 2014		1-May-13	Dec. 31, 2011	30-May-14
Significant Accounting Policies [Line Items]
Investment in unconsolidated affiliates	$4,521,000,000		$4,518,000,000				4,521,000,000
Acquisitions, net of cash acquired	0		0		360,000,000
Step Acquisition, Equity Interest in Acquiree, Percentage	0		0		136,000,000
Amount of removal costs recognized as a component of depreciation expense recorded as a regulatory liability	1,206,000,000		1,152,000,000				1,206,000,000
Capitalized Interest Costs, Including Allowance for Funds Used During Construction	11,000,000		11,000,000		9,000,000
Provision for doubtful accounts	22,000,000		21,000,000		16,000,000
Inventory	379,000,000		285,000,000				379,000,000
Cash and cash equivalents	298,000,000		208,000,000		646,000,000		298,000,000			220,000,000
Inventory Write-down	8,000,000		4,000,000		4,000,000
Variable Interest Entity, Primary Beneficiary [Member]
Significant Accounting Policies [Line Items]
Cash and cash equivalents	290,000,000		207,000,000				290,000,000
Waskom Plus Gathering and Related Assets [Member]
Significant Accounting Policies [Line Items]
Acquisitions, net of cash acquired						273,000,000
Waskom Gas Processing Company [Member]
Significant Accounting Policies [Line Items]
Percentage of Ownership in Affiliate 2 Acquired						50.00%
Step Acquisition, Equity Interest in Acquiree, Percentage						136,000,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage						50.00%
Enable Midstream Partners [Member]
Significant Accounting Policies [Line Items]
Incentive Distribution Right, Maximum							50.00%
Enable Midstream Partners [Member] | OGE [Member]
Significant Accounting Policies [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	26.30%
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	50.00%
Incentive Distribution Right							60.00%
Enable Midstream Partners [Member] | CERC Corp [Member]
Significant Accounting Policies [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	55.40%
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	50.00%
Incentive Distribution Right							40.00%
Enable Midstream Partners [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Incentive Distribution, Distribution Per Unit							0.2875
Enable Midstream Partners [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Incentive Distribution, Distribution Per Unit							0.330625
Prepaid Expenses and Other Current Assets [Member]
Significant Accounting Policies [Line Items]
Restricted cash accounts	47,000,000		41,000,000				47,000,000
Materials And Supplies [Member]
Significant Accounting Policies [Line Items]
Inventory	168,000,000		140,000,000				168,000,000
Public Utilities, Inventory, Natural Gas [Member]
Significant Accounting Policies [Line Items]
Inventory	211,000,000		145,000,000				211,000,000
Other Income [Member]
Significant Accounting Policies [Line Items]
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity	14,000,000		8,000,000		6,000,000
Removal Costs [Member]
Significant Accounting Policies [Line Items]
Amount of removal costs recognized as a component of depreciation expense recorded as a regulatory liability	958,000,000		941,000,000				958,000,000
Enogex LLC [Member] | OGE ARCLIGHT [Member]
Significant Accounting Policies [Line Items]
Equity Interest Contributed, Percentage									100.00%
Southeast Supply Header LLC [Member]
Significant Accounting Policies [Line Items]
Equity Method Investment, Additional Contribution of Ownership Percentage									24.95%		24.95%
Investment in unconsolidated affiliates	1,000,000	[1]	199,000,000	[1]			1,000,000	[1]
Southeast Supply Header LLC [Member] | CERC Corp [Member]
Significant Accounting Policies [Line Items]
Equity Interest Contributed, Percentage									24.95%
Enable Midstream Partners [Member]
Significant Accounting Policies [Line Items]
Contributed Assets									5,800,000,000
Contributed Assets, Plant, Property and Equipments									4,700,000,000
Goodwill, Transfers									629,000,000
Contributed Liabilities									1,500,000,000
Debt repayment by affiliate									1,050,000,000
Debt of Affiliate									363,000,000
Investment in unconsolidated affiliates	4,520,000,000		4,319,000,000				4,520,000,000		4,300,000,000
Southeast Supply Header LLC [Member] | Enable Midstream Partners [Member]
Significant Accounting Policies [Line Items]
Contributed Assets, Equity Method Investment									197,000,000
Equity Method Investment, Additional Contribution of Ownership Percentage									24.95%
[1]	On May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.

Property_Plant_and_Equipment_D

Property, Plant and Equipment (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment, Net, by Type [Abstract]
Total	$15,358	$14,138
Total accumulated depreciation and amortization	4,856	4,545
Property, plant and equipment, net	10,502	9,593
Depreciation and Amortization [Abstract]
Depreciation expense	521	531	562
Amortization	492	423	488
Total depreciation and amortization expense	1,013	954	1,050
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	134	164
Accretion expense	5	5
Revisions in estimates of cash flows	37	-35
Ending balance	176	134	164
Electric Transmission & Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	9,393	8,741
Total accumulated depreciation and amortization	3,050	2,907
Depreciation and Amortization [Abstract]
Total depreciation and amortization expense	768	685	729
Natural Gas Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	5,235	4,694
Total accumulated depreciation and amortization	1,493	1,324
Depreciation and Amortization [Abstract]
Total depreciation and amortization expense	201	185	173
Energy Services [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	84	82
Total accumulated depreciation and amortization	31	28
Depreciation and Amortization [Abstract]
Total depreciation and amortization expense	5	5	6
Other property [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total	646	621
Total accumulated depreciation and amortization	282	286
Depreciation and Amortization [Abstract]
Total depreciation and amortization expense	$39	$39	$36
Weighted Average [Member] | Electric Transmission & Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives	31 years
Weighted Average [Member] | Natural Gas Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives	33 years
Weighted Average [Member] | Energy Services [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives	27 years
Weighted Average [Member] | Other property [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives	22 years

Goodwill_Details

Goodwill (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Goodwill [Line Items]
Goodwill	$840		$840
Goodwill impairment	0		0		252
Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill	746		746
Energy Services [Member]
Goodwill [Line Items]
Goodwill	83	[1]	83	[1]	83
Goodwill impairment					252
Other [Member]
Goodwill [Line Items]
Goodwill	$11		$11
[1]	Amounts presented are net of accumulated goodwill impairment charge of $252 million

Regulatory_Accounting_Regulato

Regulatory Accounting (Regulatory Assets and Liabilities) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Schedule of Regulatory Assets and Liabilities [Line Items]
Unrecognized equity return (1)	($442)	[1]	($508)	[1]
Total regulatory assets	3,527		3,726
Regulatory liabilities	1,206		1,152
Total regulatory assets and liabilities, net	2,321		2,574
Amount of allowed equity return on the true-up balance that was recognized in the period	68		45		47
Removal Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities	958		941
Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities	248		211
Pension and Other Postretirement Plans Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided	0		5
Securitized regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	2,738		3,179
Unamortized loss on reacquired debt
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	104		111
Pension and postretirement-related regulatory asset (2)
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	922	[2]	732	[2]
Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$205	[3]	$212	[3]
[1]	As of December 31, 2014, CenterPoint Energy has not recognized an allowed equity return of $442 million because such return will be recognized as it is recovered in rates through 2024. During the years ended December 31, 2014, 2013 and 2012, CenterPoint Houston recognized approximately $68 million, $45 million and $47 million, respectively, of the allowed equity return. The timing of CenterPoint Energy’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]	CenterPoint Houston’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates is being deferred for rate making purposes. Deferred pension and other postemployment expenses of $-0- and $5 million as of December 31, 2014 and 2013, respectively, were not earning a return.
[3]	Other regulatory assets that are not earning a return were not material as of December 31, 2014 and 2013.

StockBased_Incentive_Compensat2

Stock-Based Incentive Compensation Plans and Employee Benefit Plans (Stock Based Incentive Compensation) (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance under long-term incentive plans (in shares)	14,000,000
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Income tax benefit recognized related to LTIPs	$7	$7	$7
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	0	0	0
Actual tax benefit realized for tax deductions related to LTIPs	13	13	14
Changes in shares outstanding under all long-term incentive plans, additional disclosures [Abstract]
Number of options outstanding, beginning balance (in shares)	120,000
Number of options exercised (in shares)	-120,000
Number of options outstanding, ending balance (in shares)	0	120,000
Number of exercisable options (in shares)	0
Weighted average exercise price per option, outstanding, beginning of period (in dollars per share)	$10.93
Weighted average exercise price per option exercised (in dollars per share)	$10.93
Weighted average exercise price per option, outstanding, end of period (in dollars per share)		$10.93
Cash received from options exercised	1	3	3
valuation data [Abstract]
Total intrinsic value of stock options exercised in the period	2	4	6
Total grant date fair values of performance and stock awards which vested during the period	21	19	19
Performance Shares [Member]
Summary of nonvested shares [Roll Forward]
Nonvested, beginning of period (in shares)	2,703,000
Granted (in shares)	1,198,000
Forfeited or cancelled (in shares)	-515,000
Vested and released to participants (in shares)	-926,000
Nonvested, end of period (in shares)	2,460,000	2,703,000
Weighted average grant date fair value, nonvested, beginning of period (in dollars per share)	$18.17
Weighted average grant date fair values of awards granted (in dollars per share)	$23.70	$20.67	$18.79
Weighted average grant date fair value, forfeited or cancelled (in dollars per share)	$21.09
Weighted average grant date fair value, vested and released to participants (in dollars per share)	$15.50
Weighted average grant date fair value, nonvested, end of period (in dollars per share)	$21.26	$18.17
Remaining average contractual life of nonvested shares outstanding (in years)	1 year 1 month
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested	40
valuation data [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested	24	20	24
Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Dividends declared during the vesting period (in dollars per share)		$2.49	$2.43
Summary of nonvested shares [Roll Forward]
Nonvested, beginning of period (in shares)	898,000
Granted (in shares)	322,000
Forfeited or cancelled (in shares)	-122,000
Vested and released to participants (in shares)	-375,000
Nonvested, end of period (in shares)	723,000	898,000
Weighted average grant date fair value, nonvested, beginning of period (in dollars per share)	$18.72
Weighted average grant date fair values of awards granted (in dollars per share)	$23.89	$21.53	$18.96
Weighted average grant date fair value, forfeited or cancelled (in dollars per share)	$21.60
Weighted average grant date fair value, vested and released to participants (in dollars per share)	$17.03
Weighted average grant date fair value, nonvested, end of period (in dollars per share)	$21.41	$18.72
Remaining average contractual life of nonvested shares outstanding (in years)	1 year 0 months
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested	17
valuation data [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested	10	10	9
Performance and Stock Awards [Member]
valuation data [Abstract]
Unrecognized compensation cost related to non-vested performance and stock awards	17
Weighted average period of recognition (in years)	1 year 7 months
Operation And Maintenance Expense Member
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
LTIP compensation expense	$18	$19	$18

StockBased_Incentive_Compensat3

Stock-Based Incentive Compensation Plans and Employee Benefit Plans (Pension and Postretirement Benefits) (Details) (USD $)	0 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Pension and Postretirement Benefits [Abstract]
New percentage of eligible earnings used to determine retirement benefits (in hundredths)	5.00%		5.00%
Percent vested			100.00%
Pension plan minimum vesting period (in years)			3 years
Approximate amortization period of transition obligation (in years)			20 years
Amounts recognized in balance sheets
Other liabilities-benefit obligations	($953)	($802)	($953)		($802)
Annualized individual discount rates based on time period, minimum			6 months
Annualized individual discount rates based on time period, maximum			99 years
Amounts reclassified from accumulated other comprehensive income: [Abstract]
Beginning Balance			-88		-132
Other comprehensive income (loss) before reclassifications (1)			-3	[1]	52	[1]
Amounts reclassified from accumulated other comprehensive income:
Amortization of prior service credit			2	[2]	3	[2]
Actuarial losses (2)			9	[2]	14	[2]
Total reclassifications from accumulated other comprehensive income			11		17
Tax expense			-5		-25		-2
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent			3		44		-2
Ending Balance	-85	-88	-85		-88		-132
Changes in plan assets and benefit obligations recognized in other comprehensive income
Amortization of prior service credit			2	[2]	3	[2]
Effect of a one-percentage point change in assumed health care cost trend rates
Effect of a one-percentage point increase on post-retirement benefit obligation			19
Effect of a one-percentage point decrease on post-retirement benefit obligation			16
Effect of a one-percentage point increase on total service and interest cost			1
Effect of a one-percentage point decrease on total service and interest cost			1
Postretirement Benefits [Member]
Components of net periodic costs [Abstract]
Service cost			2		2		1
Interest cost			22		20		23
Expected return on plan assets			-7		-7		-7
Amortization of prior service cost (credit)			-1		1		3
Amortization of net loss			1		6		4
Amortization of transition obligation			5		7		7
Benefit enhancement			0		0		1
Curtailment (1)			0	[3]	0	[3]	0	[3]
Net periodic cost			22		29		32
Assumptions used to determine net periodic benefit (income) cost
Discount rate			4.75%		3.90%		4.80%
Expected return on plan assets	5.20%	5.50%	5.50%		5.50%		5.50%
Rate of increase in compensation levels			0.00%		0.00%		0.00%
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year	529	476	476		538
Service cost			2		2		1
Interest cost			22		20		23
Participant contributions			7		7
Benefits paid			-32		-34
Actuarial (gain) loss			52		-60
Medicare reimbursement			3		3
Plan amendment			1		0
Curtailment			-2		0
Benefit obligation, end of year	529	476	529		476		538
Change in plan assets [Rollforward]
Fair value of plan assets, beginning of year	141	140	140		139
Employer contributions			18		19
Participant contributions			7		7
Benefits paid			-32		-34
Actual investment return			8		9
Fair value of plan assets, end of year	141	140	141		140		139
Funded status of plan
Funded status, end of year	-388	-336	-388		-336
Amounts recognized in balance sheets
Current liabilities-other	-9	-9	-9		-9
Other liabilities-benefit obligations	-379	-327	-379		-327
Net liability, end of year	-388	-336	-388		-336
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.90%	4.75%	3.90%		4.75%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	5.20%	5.50%	5.50%		5.50%		5.50%
Defined Benefit Plan Prescription Drug Cost Trend Rate Assumed For Next Fiscal Year			6.50%		7.00%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate			5.00%		5.50%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2024	2018	2024		2018
Defined Benefit Plan Year That Prescription Drug Rate Reaches Ultimate Trend Rate			2024		2018
Amounts reclassified from accumulated other comprehensive income:
Amortization of prior service credit			-1
Total expense recognized in net periodic cost and other comprehensive income			30
Amounts recognized in accumulated other comprehensive loss
Unrecognized actuarial loss	14	7	14		7
Unrecognized prior service cost	2	1	2		1
Net amount recognized in accumulated other comprehensive loss	16	8	16		8
Changes in plan assets and benefit obligations recognized in other comprehensive income
Net gain (loss)			-6
Amortization of net loss (gain)			-1
Amortization of prior service credit			-1
Total recognized in comprehensive income			-8
Amounts that will be amortized from accumulated other comprehensive loss in next fiscal year
Unrecognized actuarial loss			1
Unrecognized prior service cost			0
Amounts in accumulated comprehensive loss to be recognized in net periodic cost in 2015			1
Pension Plan [Member]
Components of net periodic costs [Abstract]
Service cost			42		44		35
Interest cost			100		90		100
Expected return on plan assets			-125		-135		-121
Amortization of prior service cost (credit)			10		10		8
Amortization of net loss			44		63		60
Amortization of transition obligation			0		0		0
Benefit enhancement			0		0		0
Curtailment (1)			6	[3]	0	[3]	0	[3]
Net periodic cost			77		72		82
Assumptions used to determine net periodic benefit (income) cost
Discount rate			4.80%		4.00%		4.90%
Expected return on plan assets	6.50%	7.00%	7.00%		8.00%		8.00%
Rate of increase in compensation levels			3.90%		4.00%		4.20%
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year	2,403	2,153	2,153		2,316
Service cost			42		44		35
Interest cost			100		90		100
Participant contributions			0		0
Benefits paid			-156		-142
Actuarial (gain) loss			264		-155
Medicare reimbursement			0		0
Plan amendment			0		0
Curtailment			0		0
Benefit obligation, end of year	2,403	2,153	2,403		2,153		2,316
Change in plan assets [Rollforward]
Fair value of plan assets, beginning of year	1,925	1,803	1,803		1,698
Employer contributions			97		91
Participant contributions			0		0
Benefits paid			-156		-142
Actual investment return			181		156
Fair value of plan assets, end of year	1,925	1,803	1,925		1,803		1,698
Funded status of plan
Funded status, end of year	-478	-350	-478		-350
Amounts recognized in balance sheets
Current liabilities-other	-31	-9	-31		-9
Other liabilities-benefit obligations	-447	-341	-447		-341
Net liability, end of year	-478	-350	-478		-350
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.05%	4.80%	4.05%		4.80%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	6.50%	7.00%	7.00%		8.00%		8.00%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	4.00%	3.90%	4.00%		3.90%
Accumulated benefit obligation for all defined benefit pension plans	2,371	2,123	2,371		2,123
Amounts reclassified from accumulated other comprehensive income:
Amortization of prior service credit			2
Total expense recognized in net periodic cost and other comprehensive income			56
Amounts recognized in accumulated other comprehensive loss
Unrecognized actuarial loss	113	126	113		126
Unrecognized prior service cost	4	12	4		12
Net amount recognized in accumulated other comprehensive loss	117	138	117		138
Changes in plan assets and benefit obligations recognized in other comprehensive income
Net gain (loss)			10
Amortization of net loss (gain)			9
Amortization of prior service credit			2
Total recognized in comprehensive income			21
Amounts that will be amortized from accumulated other comprehensive loss in next fiscal year
Unrecognized actuarial loss			12
Unrecognized prior service cost			1
Amounts in accumulated comprehensive loss to be recognized in net periodic cost in 2015			13
Pension Plan Qualified [Member]
Change in plan assets [Rollforward]
Employer contributions			87
Pension benefits that have accumulated benefit obligations in excess of plan assets
Accumulated benefit obligation	2,273	2,031	2,273		2,031
Projected benefit obligation	2,304	2,061	2,304		2,061
Fair value of plan assets	1,925	1,803	1,925		1,803
Pension Plan Non Qualified [Member]
Change in plan assets [Rollforward]
Employer contributions			10
Pension benefits that have accumulated benefit obligations in excess of plan assets
Accumulated benefit obligation	98	92	98		92
Projected benefit obligation	98	92	98		92
Fair value of plan assets	$0	$0	$0		$0
Age Pre 65 [Member] | Postretirement Benefits [Member]
Amounts recognized in balance sheets
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year			7.25%		7.00%
Age Post 65 [Member] | Postretirement Benefits [Member]
Amounts recognized in balance sheets
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year			8.50%		7.50%
[1]	Total other comprehensive income (loss) related to the re-measurement of pension, postretirement and other postemployment plans.
[2]	These accumulated other comprehensive components are included in the computation of net periodic cost.
[3]	During the fourth quarter of 2014, CenterPoint Energy recognized a curtailment pension loss of $6 million related to employees seconded to Enable. Substantially all of the seconded employees became employees of Enable effective January 1, 2015.

StockBased_Incentive_Compensat4

Stock-Based Incentive Compensation Plans and Employee Benefit Plans (Plan Assets) (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Savings Plan [Abstract]
Maximum percentage of eligible compensation employees may contribute to the savings plan (in hundredths)	50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%
Number of Common stock held by the savings plan (in shares)	17,497,676
Percentage of investment in common stocks (in hundredths)	20.00%
Defined Contribution Plan, Cost Recognized	$39		$38		$36
Postemployment Benefits [Abstract]
Postemployment Benefits, Period Expense	3		4		8
Other Non-Qualified Plans [Abstract]
Benefit expense related to deferred compensation plans	5		5		5
Pension Plan [Member]
Pension plan assets, fair value	1,925		1,803		1,698
Obligation To Return Cash Received As Collateral From Securities Lending,	-86		-71
Total contributions to the plans during the period	97		91
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2015	223
Pension benefit payments 2016	143
Pension benefit payments 2017	147
Pension benefit payments 2018	154
Pension benefit payments 2019	152
Pension benefit payments 2020 - 2024	785
Postretirement Benefits [Member]
Pension plan assets, fair value	141		140		139
Total contributions to the plans during the period	18		19
Estimated future contributions in the next fiscal year	17
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2015	35
Pension benefit payments 2016	36
Pension benefit payments 2017	38
Pension benefit payments 2018	40
Pension benefit payments 2019	42
Pension benefit payments 2020 - 2024	228
Medicare subsidy receipts - 2015	-4
Medicare subsidy receipts - 2016	-4
Medicare subsidy receipts - 2017	-5
Medicare subsidy receipts - 2018	-5
Medicare subsidy receipts - 2019	-6
Medicare subsidy receipts - 2020 - 2024	-39
Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	346		354
Obligation To Return Cash Received As Collateral From Securities Lending,	-86		-71
Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]
Pension plan assets, fair value	141		140
Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	1,578		1,448
Obligation To Return Cash Received As Collateral From Securities Lending,	0		0
Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]
Pension plan assets, fair value	0		0
Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	1		1
Obligation To Return Cash Received As Collateral From Securities Lending,	0		0
Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]
Pension plan assets, fair value	0		0
U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	12.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	28.00%
Pension plan assets, fair value	83		77
U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	14.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	24.00%
U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	83		77
U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
International Developed Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	7.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	17.00%
International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	3.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	13.00%
Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	3.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	13.00%
Emerging Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	0.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	0.00%
Fixed Income [Member] | Pension Plan [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	54.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	66.00%
Fixed Income [Member] | Postretirement Benefits [Member]
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] | Pension Plan [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	0.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	2.00%
Pension plan assets, fair value	6		11
Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	0.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	2.00%
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	6		11
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Common Collective Trust Funds [Member] | Pension Plan [Member]
Pension plan assets, fair value	1,108	[1]	1,107	[2]
Common Collective Trust Funds [Member] | International Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	22.00%		25.00%
Common Collective Trust Funds [Member] | Fixed Income Funds [Member] | Pension Plan [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	61.00%		50.00%
Common Collective Trust Funds [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	14.00%		20.00%
Common Collective Trust Funds [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	3.00%		5.00%
Common Collective Trust Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0	[1]	0	[2]
Common Collective Trust Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	1,108	[1]	1,107	[2]
Common Collective Trust Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0	[1]	0	[2]
Investment grade or above [Member] | Pension Plan [Member]
Pension plan assets, fair value	368		256
Investment grade or above [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Investment grade or above [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	368		256
Investment grade or above [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
International equities [Member] | Pension Plan [Member]
Pension plan assets, fair value	49		75
International equities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	49		75
International equities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
International equities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Cash received as collateral from securities [Member] | Pension Plan [Member]
Pension plan assets, fair value	86		71
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	86		71
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
US Government Agencies Debt Securities [Member] | Pension Plan [Member]
Pension plan assets, fair value			1
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value			1
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value			0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value			0
U.S. treasuries [Member] | Pension Plan [Member]
Pension plan assets, fair value	47		18
U.S. treasuries [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	47		18
U.S. treasuries [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
U.S. treasuries [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Mortgage backed securities [Member] | Pension Plan [Member]
Pension plan assets, fair value	4		7
Mortgage backed securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Mortgage backed securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	4		7
Mortgage backed securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Asset backed securities [Member] | Pension Plan [Member]
Pension plan assets, fair value	4		6
Asset backed securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Asset backed securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	4		6
Asset backed securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Municipal bonds [Member] | Pension Plan [Member]
Pension plan assets, fair value	79		61
Municipal bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Municipal bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	79		61
Municipal bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Mutual funds [Member] | Pension Plan [Member]
Pension plan assets, fair value	161	[3]	172	[4]
Mutual funds [Member] | Postretirement Benefits [Member]
Pension plan assets, fair value	141	[5]	140	[6]
Mutual funds [Member] | International Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	57.00%		58.00%
Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	8.00%		8.00%
Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	73.00%		72.00%
Mutual funds [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	13.00%		12.00%
Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	19.00%		20.00%
Mutual funds [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Actual Plan Asset Allocations	30.00%		30.00%
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	161	[3]	172	[4]
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]
Pension plan assets, fair value	141	[5]	140	[6]
Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0	[3]	0	[4]
Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]
Pension plan assets, fair value	0	[5]	0	[6]
Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0	[3]	0	[4]
Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]
Pension plan assets, fair value	0	[5]	0	[6]
International government bonds [Member] | Pension Plan [Member]
Pension plan assets, fair value	15		11
International government bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
International government bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	15		11
International government bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Real estate [Member] | Pension Plan [Member]
Pension plan assets, fair value	1		1
Real estate [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Real estate [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Pension plan assets, fair value	0		0
Real estate [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Pension plan assets, fair value	1		1
Benefit Obligation [Member]
Postemployment Benefits [Abstract]
Postemployment benefit obligations	28		30
Other Non-Qualified Plans [Abstract]
Other non-qualified plans benefit obligations deferred compensation	60		64
Benefit obligations related to split-dollar life insurance arrangements	33		28
Pension Plan Qualified [Member]
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Accumulated Benefit Obligation	2,273		2,031
Total contributions to the plans during the period	87
Estimated future contributions in the next fiscal year	35
Pension Plan Non Qualified [Member]
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Accumulated Benefit Obligation	98		92
Total contributions to the plans during the period	10
Estimated future contributions in the next fiscal year	$31
[1]	61% of the amount invested in common collective trust funds is in fixed income securities, 14% is in U.S. equities, 22% is in international equities and 3% is in emerging market equities.
[2]	50% of the amount invested in common collective trust funds is in fixed income securities, 20% is in U.S. equities, 25% is in international equities and 5% is in emerging market equities.
[3]	57% of the amount invested in mutual funds is in international equities, 30% is in emerging market equities and 13% is in U.S. equities.
[4]	58% of the amount invested in mutual funds is in international equities, 30% is in emerging market equities and 12% is in U.S. equities.
[5]	73% of the amount invested in mutual funds is in fixed income securities, 19% is in U.S. equities and 8% is in international equities.
[6]	72% of the amount invested in mutual funds is in fixed income securities, 20% is in U.S. equities and 8% is in international equities.

StockBased_Incentive_Compensat5

Stock-Based Incentive Compensation Plans and Employee Benefit Plans (Change in Control Agreements and Other Employee Matters) (Details)	12 Months Ended
	Dec. 31, 2014
Concentration Risk [Line Items]
Maximum Number Of Times Annual Salary Included In Severance Benefits	3
Number of Employees, Total [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	31.00%
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	8.00%

Derivative_Instruments_Details

Derivative Instruments (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Weather Hedges [Abstract]
Term of normal weather used as the basis for weather hedges (in years)	10
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset, Fair Value, Gross Asset	$149		$43
Derivative Liability, Fair Value, Gross Liability	643		485
Income Statement Impact of Derivative Activity [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-40		-172		-91
Derivative, Credit Risk Related Contingent Features [Abstract]
Total fair value of the derivative instruments that contain credit risk contingent features that are in a net liability position	2		1
The aggregate fair value of assets already posted as collateral	1		1
Credit Risk Contingent Features assets	2		1
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total	131		34
Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative, Nonmonetary Notional Amount, Volume	804,000		607,000
Derivative Assets (Liabilities), at Fair Value, Net	111	[1]	13	[1]
Collateral netting	64		1
Derivative, Fair Value, Net	47	[2]	13	[2]
Derivative, fair value, offsets, net	64		0
Energy Related Derivative [Member] | Gains (Losses) in Revenue [Member]
Income Statement Impact of Derivative Activity [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	35		11		43
Energy Related Derivative [Member] | Gains (Losses) in Expense: Natural Gas [Member]
Income Statement Impact of Derivative Activity [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	11	[3],[4]	10	[3],[4]	-63	[3],[4]
Energy Related Derivative [Member] | Current Assets [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	115	[2]	32	[2]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	-16		-8
Natural gas derivatives (2)	99	[1]	24	[1]
Energy Related Derivative [Member] | Other Noncurrent Assets [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	34	[2]	11	[2]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	-2		-1
Natural gas derivatives (2)	32	[1]	10	[1]
Energy Related Derivative [Member] | Current Liabilities [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	-84	[2]	-25	[2]
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	65		8
Derivative Liability	-19	[1]	-17	[1]
Energy Related Derivative [Member] | Other Noncurrent Liabilities [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	-18	[2]	-5	[2]
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	17		1
Derivative Liability	-1	[1]	-4	[1]
Energy Related Derivative [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Current Assets [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset, Fair Value, Gross Asset	101	[5],[6],[7]	28	[10],[8],[9]
Derivative Liability, Fair Value, Gross Liability	1	[5],[6],[7]	4	[10],[8],[9]
Energy Related Derivative [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Other Noncurrent Assets [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset, Fair Value, Gross Asset	32	[5],[6],[7]	10	[10],[8]
Derivative Liability, Fair Value, Gross Liability	0	[5],[6],[7]	0	[10],[8]
Energy Related Derivative [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Current Liabilities [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset, Fair Value, Gross Asset	14	[5],[6],[7]	4	[10],[8]
Derivative Liability, Fair Value, Gross Liability	83	[5],[6],[7]	21	[10],[8]
Energy Related Derivative [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Other Noncurrent Liabilities [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset, Fair Value, Gross Asset	2	[5],[6],[7]	1	[10],[8]
Derivative Liability, Fair Value, Gross Liability	18	[5],[6],[7]	5	[10],[8]
Weather Hedge Swaps [Member] | Gains (Losses) in Revenue [Member]
Weather Hedges [Abstract]
Gain (loss) recognized from weather hedges	-11		-22		8
IDS Derivative [Member] | Nonoperating Income (Expense) [Member]
Income Statement Impact of Derivative Activity [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-86		-193		-71
IDS Derivative [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Current Liabilities [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset, Fair Value, Gross Asset	0		0
Derivative Liability, Fair Value, Gross Liability	541		455
Electric Transmission & Distribution [Member]
Weather Hedges [Abstract]
Weather Hedge, Amount, maximum	8		8
Long [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative, Nonmonetary Notional Amount, Volume	60,000		46,000
Energy Marketers [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total	4		4
Financial Institutions [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total	0		9
Retail End Users [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total	127	[11]	21	[11]
Swap [Member] | Long [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative, Nonmonetary Notional Amount, Volume	127,000		99,000
Price Stabilization Activities [Member] | Natural Gas Distribution [Member] | Energy Related Derivative [Member] | Gains (Losses) in Expense: Natural Gas [Member]
Income Statement Impact of Derivative Activity [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0		0		-38
External Credit Rating, Investment Grade [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total	4	[12]	3	[12]
External Credit Rating, Investment Grade [Member] | Energy Marketers [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total	2	[12]	1	[12]
External Credit Rating, Investment Grade [Member] | Financial Institutions [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total	0	[12]	1	[12]
External Credit Rating, Investment Grade [Member] | Retail End Users [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total	2	[11],[12]	1	[11],[12]
Enable Midstream Partners [Member] | Forward Contracts [Member] | Energy Related Derivative [Member] | Gains (Losses) in Expense: Natural Gas [Member]
Income Statement Impact of Derivative Activity [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	2		-2
Enable Midstream Partners [Member] | Forward Contracts [Member] | Energy Related Derivative [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Current Assets [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset, Fair Value, Gross Asset			1
2012To2013 [Member] | Natural Gas Distribution [Member]
Derivative [Line Items]
Weather Hedge, Bilateral Cap Amount	15
2013To2014 [Member] | Natural Gas Distribution [Member]
Derivative [Line Items]
Weather Hedge, Bilateral Cap Amount	16
2014To2015 [Member] | Natural Gas Distribution [Member]
Derivative [Line Items]
Weather Hedge, Bilateral Cap Amount	$16
[1]	The derivative assets and liabilities on the Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
[2]	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.
[3]	The Gains (Losses) in Expense: Natural Gas includes $-0-, $-0- and $(38) million of costs in 2014, 2013 and 2012, respectively, associated with price stabilization activities of the Natural Gas Distribution business segment that will be ultimately recovered through purchased gas adjustments.
[4]	The Gains (Losses) in Expense: Natural Gas includes $2 million and $(2) million during the years ended December 31, 2014 and 2013, respectively, related to physical forwards purchased from Enable.
[5]	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
[6]	Natural gas contracts are presented on a net basis in the Consolidated Balance Sheets. Natural gas contracts are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $111 million asset as shown on CenterPoint Energy’s Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above offset by collateral netting of $64 million.
[7]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 804 billion cubic feet (Bcf) or a net 60 Bcf long position. Of the net long position, basis swaps constitute 127 Bcf.
[8]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 607 Bcf or a net 46 Bcf long position. Of the net long position, basis swaps constitute 99 Bcf.
[9]	The $28 million Derivative Current Asset includes $1 million related to physical forwards purchased from Enable.
[10]	Natural gas contracts are presented on a net basis in the Consolidated Balance Sheets. Natural gas contracts are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $13 million asset as shown on CenterPoint Energy’s Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, offset by collateral netting of less than $1 million.
[11]	End users are comprised primarily of customers who have contracted to fix the price of a portion of their physical gas requirements for future periods.
[12]	“Investment grade” is primarily determined using publicly available credit ratings and considers credit support (including parent company guarantees) and collateral (including cash and standby letters of credit). For unrated counterparties, CenterPoint Energy determines a synthetic credit rating by performing financial statement analysis and considers contractual rights and restrictions and collateral.

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Fair Value, assets and liabilities measured on recurring basis, financial statement captions
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	$0
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	0
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount	0
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount	0
ASSETS
Derivative Asset, Fair Value, Gross Liability	-18,000,000	[1]	-9,000,000	[2]
Total assets	1,117,000,000		865,000,000
Liabilities
Derivative Liability, Fair Value, Gross Asset	-82,000,000	[1]	-9,000,000	[2]
Total liabilities	561,000,000		476,000,000
Cash collateral posted with counterparties	64,000,000		1,000,000
Derivative Asset, Fair Value, Gross Asset	149,000,000		43,000,000
Fair value measurement using significant unobservable input (level 3) reconciliation [Roll Forward]
Beginning balance	3,000,000	[3]	2,000,000	[3]	6,000,000
Total gains	14,000,000		3,000,000		3,000,000
Total settlements	1,000,000		-3,000,000		-6,000,000
Transfers out of Level 3	0		0		-1,000,000
Transfers into Level 3	-1,000,000		1,000,000		0
Ending balance (1)	17,000,000	[3]	3,000,000	[3]	2,000,000	[3]
The amount of total gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	16,000,000		2,000,000		1,000,000
Fair value [Member]
Fair value measurement using significant unobservable input (level 3) reconciliation [Roll Forward]
Notes receivable - affiliated companies	362,000,000		363,000,000
Long-term debt	9,427,000,000		8,670,000,000
Carrying amount [Member]
Fair value measurement using significant unobservable input (level 3) reconciliation [Roll Forward]
Notes receivable - affiliated companies	363,000,000		363,000,000
Long-term debt	8,652,000,000		8,171,000,000
Fair Value, Inputs, Level 1 [Member]
ASSETS
Total assets	993,000,000		836,000,000
Liabilities
Total liabilities	22,000,000		1,000,000
Fair Value, Inputs, Level 2 [Member]
ASSETS
Total assets	122,000,000		33,000,000
Liabilities
Total liabilities	618,000,000		482,000,000
Fair Value, Inputs, Level 3 [Member]
ASSETS
Total assets	20,000,000		5,000,000
Liabilities
Total liabilities	3,000,000		2,000,000
Fair Value, Measurements, Recurring [Member]
ASSETS
Corporate equities	932,000,000		770,000,000
Investments, including money market funds	54,000,000		61,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
ASSETS
Corporate equities	932,000,000		770,000,000
Investments, including money market funds	54,000,000		61,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
ASSETS
Corporate equities	0		0
Investments, including money market funds	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
ASSETS
Corporate equities	0		0
Investments, including money market funds	0		0
Energy Related Derivative [Member] | Fair Value, Measurements, Recurring [Member]
ASSETS
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	-18,000,000	[1],[4]	-9,000,000	[2],[5]
Natural gas derivatives (2)	131,000,000	[4]	34,000,000	[5]
Liabilities
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	-82,000,000	[1],[4]	-9,000,000	[2]
Natural gas derivatives (2)	20,000,000	[4]	21,000,000
Energy Related Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
ASSETS
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	7,000,000	[4]	5,000,000	[5]
Liabilities
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	22,000,000	[4]	1,000,000
Energy Related Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
ASSETS
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	122,000,000	[4]	33,000,000	[5]
Liabilities
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	77,000,000	[4]	27,000,000
Energy Related Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
ASSETS
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	20,000,000	[4]	5,000,000	[5]
Liabilities
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	3,000,000	[4]	2,000,000
IDS Derivative [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	0	[1]	0	[2]
Natural gas derivatives (2)	541,000,000		455,000,000
IDS Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0		0
IDS Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	541,000,000		455,000,000
IDS Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0		0
Forward Contracts [Member] | Enable Midstream Partners [Member] | Energy Related Derivative [Member]
Liabilities
Derivative Asset, Fair Value, Gross Asset			$1,000,000
Minimum [Member] | Forward Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, assets and liabilities measured on recurring basis, financial statement captions
Illiquid forward price low range	1.6
Minimum [Member] | Options Held [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, assets and liabilities measured on recurring basis, financial statement captions
Option volatilities low range	0.00%
Maximum [Member] | Forward Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, assets and liabilities measured on recurring basis, financial statement captions
Illiquid forward price low range	4.23
Maximum [Member] | Options Held [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, assets and liabilities measured on recurring basis, financial statement captions
Option volatilities low range	88.00%
[1]	Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy to settle positive and negative positions and also include cash collateral of $64 million posted with the same counterparties.
[2]	Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy to settle positive and negative positions and also include cash collateral of less than $1 million posted with the same counterparties.
[3]	During 2014, 2013 and 2012, CenterPoint Energy did not have significant Level 3 purchases or sales.
[4]	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.
[5]	The (Level 2) Natural gas derivative assets of $33 million include $1 million related to physical forwards purchased from Enable.

Unconsolidated_Affiliates_Deta

Unconsolidated Affiliates (Details) (USD $)	12 Months Ended						0 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Apr. 16, 2014	Jan. 23, 2015	30-May-14	Mar. 31, 2014	1-May-13	Jun. 01, 2015	Jan. 29, 2015
Equity in earnings of unconsolidated affiliates	$308,000,000		$188,000,000		$31,000,000
CenterPoint Energy's approximate 58.3% interest	4,869,000,000		4,753,000,000
Equity Method Investment_Basis Difference_Goodwill	-217,000,000	[1]	-229,000,000	[1]
Equity Method Investment_Basis Difference To Be Accreted	-132,000,000	[2]	-205,000,000	[2]
CenterPoint Energy's basis difference	-349,000,000		-434,000,000
Equity Method Investments Underlying Equity in Net Assets, Net of Basis Difference	4,520,000,000		4,319,000,000
Proceeds from Equity Method Investment, Dividends or Distributions	305,000,000		129,000,000		39,000,000
Investment in unconsolidated affiliates	4,521,000,000		4,518,000,000
Enable Midstream Partners [Member]
Notes receivable - affiliated companies	363,000,000
Share Price	$19.39
Southeast Supply Header LLC [Member]
Equity Method Investment, Ownership Percentage	0.10%									25.05%
Equity Method Investment, Additional Contribution of Ownership Percentage									24.95%		24.95%
equity method investment, Additional Contribution of ownership, value									196,000,000
Equity in earnings of unconsolidated affiliates	5,000,000	[3]	15,000,000	[3]	26,000,000	[3]
Proceeds from Equity Method Investment, Dividends or Distributions	7,000,000	[3]	23,000,000	[3]	32,000,000	[3]
Investment in unconsolidated affiliates	1,000,000	[4]	199,000,000	[4]
Waskom Gas Processing Company [Member]
Equity in earnings of unconsolidated affiliates	0	[5]	0	[5]	5,000,000	[5]
Proceeds from Equity Method Investment, Dividends or Distributions	0	[5]	0	[5]	7,000,000	[5]
Enable Midstream Partners [Member]
Partners' Capital Account, Units, Sold in Public Offering							28,750,000
Share Price							$20
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	-14,000,000
Proceeds from Issuance Initial Public Offering							464,000,000
Equity Method Investment, Ownership Percentage	55.40%								54.70%	58.30%
Investment Owned, Restricted, Carrying Value Per Unit at Date of Balance Sheet	$19.33
Equity in earnings of unconsolidated affiliates	303,000,000	[6]	173,000,000	[6]	0	[6]
Operating revenues	3,367,000,000		2,123,000,000	[7]
Cost of sales, excluding depreciation and amortization	1,914,000,000		1,241,000,000	[7]
Operating income	586,000,000		322,000,000	[7]
Net income attributable to Enable	530,000,000		289,000,000	[7]
CenterPoint Energy's approximate 58.3% interest	298,000,000		168,000,000	[7]
Basis difference accretion gain	5,000,000		5,000,000	[7]
CenterPoint Energy’s equity in earnings, net	303,000,000		173,000,000	[7]
Current assets	438,000,000		549,000,000
Non-current assets	11,399,000,000		10,683,000,000
Current liabilities	671,000,000		720,000,000
Non-current liabilities	2,343,000,000		2,331,000,000
Noncontrolling interest	31,000,000		33,000,000
Enable Partners' Capital	8,792,000,000		8,148,000,000
Proceeds from Equity Method Investment, Dividends or Distributions	298,000,000	[6]	106,000,000	[6]	0	[6]
Investment in unconsolidated affiliates	4,520,000,000		4,319,000,000								4,300,000,000
Enable Midstream Partners [Member] | ArcLight [Member]
Partners' Capital Account, Units, Sold in Public Offering							3,750,000
Enable Guaranteed Senior Notes [Member] | CERC Corp [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	1,100,000,000
Enable Midstream Partners [Member]
Interest Income, Related Party	8,000,000		5,000,000
Due from Related Parties, Current	4,000,000		4,000,000
Transitional Service [Member] | Enable Midstream Partners [Member]
Reimbursement Revenue	163,000,000		119,000,000
Accounts Receivable, Related Parties	28,000,000		21,000,000
Common Stock [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares	94,126,366								6,322,457
Subordinated Units [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares	139,704,916
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Affiliate Costs	130,000,000		123,000,000
Accounts payable - subsidiaries	23,000,000		22,000,000
Subsequent Event [Member] | Enable Midstream Partners [Member]
Proceeds from Equity Method Investment, Dividends or Distributions								72,000,000
Subsequent Event [Member] | Common Stock [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares												25,341
Scenario, Forecast [Member] | Enable Midstream Partners [Member]
Share Price													$17.34
Scenario, Forecast [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Decrease in Carrying Value													465,000,000
Enable Midstream Partners [Member] | Enable Guaranteed Senior Notes [Member] | CERC Corp [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	$1,100,000,000
Indebtedness to CERC Corp. [Member] | Enable Midstream Partners [Member]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum (in hundredths)	2.10%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	2.45%
[1]	The difference relates to CenterPoint Energy’s proportionate share of Enable’s goodwill arising from its acquisition of Enogex, and therefore will be recognized by CenterPoint Energy upon dilution or disposition of its interest in Enable.
[2]	The difference will be recognized by CenterPoint Energy over 30 years beginning May 1, 2013. CenterPoint Energy will also adjust the accretable basis difference for dilution or disposition of its interest in Enable.
[3]	On each of May 1, 2013 and May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
[4]	On May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
[5]	On July 31, 2012, Waskom became a wholly owned subsidiary of CenterPoint Energy. Beginning on August 1, 2012, Waskom’s operating results are consolidated on the Statements of Consolidated Income. On May 1, 2013, CenterPoint Energy contributed Waskom to Enable.
[6]	On May 1, 2013, CenterPoint Energy formed Enable with OGE and ArcLight.
[7]	The amounts included in this column represent the eight month period from formation of Enable on May 1, 2013 through December 31, 2013.

Indexed_Debt_Securities_ZENS_a2

Indexed Debt Securities (ZENS) and Securities Related to ZENS (Details) (USD $)	12 Months Ended
Share data in Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 13, 2014
TW Securities
TW Securities	$767,000,000
Proceeds from Sale and Maturity of Marketable Securities	0	-9,000,000	0
Gain on TW Securities	163,000,000	236,000,000	154,000,000
TW Securities	930,000,000	767,000,000
Debt component of ZENS
Debt Component of ZENS	143,000,000	138,000,000	131,000,000
Accretion of debt component of ZENS	26,000,000	24,000,000	24,000,000
2 % interest paid	-17,000,000	-17,000,000	-17,000,000
Redemption of Indexed Debt Securities		-2,000,000
Debt Component of ZENS	152,000,000	143,000,000	138,000,000
Derivative component of ZENS
Derivative Component of ZENS	455,000,000	268,000,000	197,000,000
Redemption of Derivative Indexed Debt Securities		-6,000,000
Loss (gain) on indexed debt securities	86,000,000	193,000,000	71,000,000
Derivative Component of ZENS	541,000,000	455,000,000	268,000,000
TW Common [Member]
Schedule of Trading Securities [Line Items]
Number of shares of common stock held by subsidiary of CenterPoint Energy (in shares)	7.1
TWC Common [Member]
Schedule of Trading Securities [Line Items]
Number of shares of common stock held by subsidiary of CenterPoint Energy (in shares)	1.8
AOL Common [Member]
Schedule of Trading Securities [Line Items]
Number of shares of common stock held by subsidiary of CenterPoint Energy (in shares)	0.6
Time Common [Member]
Schedule of Trading Securities [Line Items]
Number of shares of common stock held by subsidiary of CenterPoint Energy (in shares)	0.9
TW Securities [Member]
TW Securities
TW Securities	767,000,000	540,000,000	386,000,000
Proceeds from Sale and Maturity of Marketable Securities		-9,000,000
Gain on TW Securities	163,000,000	236,000,000	154,000,000
TW Securities	930,000,000	767,000,000	540,000,000
Subordinated Debt ZENS Member
Zero Premium Exchangeable Subordinated Notes [Abstract]
Original principal amount of Zero Premium Exchangeable Subordinated Notes issued by CenterPoint Energy in September 1999	1,000,000,000
Long-term Debt, Gross	828,000,000
Percentage of market value of referenced shares of Time Warner Common each zero premium exchangeable subordinated note could be exchanged for cash (in hundredths)	95.00%
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)	2.00%
Referenced common shares
Target annual yield from interest and cash dividends on referenced shares before principal amount of indexed debt securities is increased or decreased (in hundredths)	2.31%
Contingent principal amount of indexed debt securities issued by CenterpPoint Energy in September 1999 and outstanding and exchangeable	751,000,000
The cash exchange amount from referenced shares per $1,000 face amount of individual notes	1,067
Face amount of each indexed debt security notes issued by CenterPoint Energy in September 1999	$1,000
The accretion rate for interest charges on bifurcated debt component of indexed debt securities (in hundredths)	17.30%
Subordinated Debt ZENS Member | TW Common [Member]
Referenced common shares
The referenced shares of common stock for each zero premium exchangeable subordinated note (in shares)	0.5
Subordinated Debt ZENS Member | TWC Common [Member]
Referenced common shares
The referenced shares of common stock for each zero premium exchangeable subordinated note (in shares)	0.125505
Subordinated Debt ZENS Member | AOL Common [Member]
Referenced common shares
The referenced shares of common stock for each zero premium exchangeable subordinated note (in shares)	0.045455
Subordinated Debt ZENS Member | Time Common [Member]
Referenced common shares
The referenced shares of common stock for each zero premium exchangeable subordinated note (in shares)	0.0625
Subordinated Debt ZENS Member | Comcast Common [Member]
Referenced common shares
The referenced shares of common stock for each zero premium exchangeable subordinated note (in shares)				0.360827
Conversion ratio of shares referenced in exchangeable subordinated note				2.875

Equity_Details

Equity (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Capital stock shares authorized (in shares)	1,020,000,000
Common stock shares authorized (in shares)	1,000,000,000	1,000,000,000	1,000,000,000
Common stock shares par value (in dollars per share)	$0.01	$0.01	$0.01
Cumulative preferred stock shares authorized (in shares)	20,000,000	20,000,000	20,000,000
Cumulative preferred stock par value (in dollars per share)	$0.01	$0.01	$0.01
Dividends Declared Per Share	$0.95	$0.83	$0.81
Enable Midstream Partners [Member]
Retained Earnings, Undistributed Earnings from Equity Method Investees	$71	$67

Short_Term_Borrowings_and_Long2

Short Term Borrowings and Long Term Debt (Schedule of Debt) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Short term borrowings:
Total short-term borrowings	$53,000,000	[1]	$43,000,000	[1]
Long-term debt:
Unamortized Discount (Premium), Net	-50,000,000		-50,000,000
Long-term Debt, Excluding Current Maturities	8,009,000,000		7,817,000,000
Long-term Debt, Current Maturities	795,000,000	[1]	497,000,000	[1]
Debt, Current	848,000,000	[1]	540,000,000	[1]
Size of Facility	2,100,000,000		2,100,000,000
ZENS (2)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)	2.00%
Other Debt [Member]
Long-term debt:
Long-Term	0	[2]	1,000,000	[2]
Current	0	[1],[2]	0	[1],[2]
Parent Company [Member]
Long-term debt:
Capital Lease Obligations, Noncurrent	2,000,000		0
Capital Lease Obligations, Current	2,000,000	[1]	0	[1]
Long-term Debt, Excluding Current Maturities	858,000,000		936,000,000
Size of Facility	1,200,000,000		1,200,000,000
Parent Company [Member] | ZENS (2)
Long-term debt:
Long-Term	0	[3]	0	[3]
Current	152,000,000	[1],[3]	143,000,000	[1],[3]
Parent Company [Member] | Senior notes 5.95% to 6.85% due 2015 to 2018
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum (in hundredths)	5.95%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum (in hundredths)	6.85%
Long-term debt:
Long-Term	550,000,000		750,000,000
Current	200,000,000	[1]	0	[1]
Parent Company [Member] | Pollution control bonds 4.90% to 5.125% due 2015 to 2028 (3)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum (in hundredths)	4.90%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum (in hundredths)	5.13%
Long-term debt:
Long-Term	118,000,000	[4]	187,000,000	[4]
Current	69,000,000	[1],[4]	0	[1],[4]
Amount of debt secured by general mortgage bonds	118,000,000		118,000,000
Parent Company [Member] | Commercial paper (4)
Long-term debt:
Long-Term	191,000,000	[2]	0	[2]
Current	0	[1],[2]	0	[1],[2]
CenterPoint Houston [Member]
Long-term debt:
Capital Lease Obligations, Noncurrent	1,000,000		0
Capital Lease Obligations, Current	0	[1]	0	[1]
Size of Facility	300,000,000		300,000,000
CenterPoint Houston [Member] | First mortgage bonds 9.15% due 2021
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)	9.15%
Long-term debt:
Long-Term	102,000,000		102,000,000
Current	0	[1]	0	[1]
Amount of debt secured by general mortgage bonds	102,000,000
CenterPoint Houston [Member] | General mortgage bonds 2.25% to 6.95% due 2022 to 2044
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum (in hundredths)	2.25%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum (in hundredths)	6.95%
Long-term debt:
Long-Term	1,912,000,000		1,312,000,000
Current	0	[1]	0	[1]
Amount of debt secured by general mortgage bonds	2,400,000,000
CenterPoint Houston [Member] | Pollution control bonds 4.25% to 5.60% due 2017 to 2027
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum (in hundredths)	4.25%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum (in hundredths)	5.60%
Long-term debt:
Long-Term	0		183,000,000
Current	0	[1]	0	[1]
CenterPoint Houston [Member] | System restoration bonds 1.833% to 4.243% due 2015 to 2022
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum (in hundredths)	1.83%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum (in hundredths)	4.24%
Long-term debt:
Long-Term	415,000,000		463,000,000
Current	48,000,000	[1]	47,000,000	[1]
CenterPoint Houston [Member] | Transition bonds 0.90% to 5.302% due 2015 to 2024
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum (in hundredths)	0.90%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum (in hundredths)	5.30%
Long-term debt:
Long-Term	2,259,000,000		2,583,000,000
Current	324,000,000	[1]	307,000,000	[1]
CERC Corp [Member]
Long-term debt:
Size of Facility	600,000,000		600,000,000
CERC Corp [Member] | Commercial paper (4)
Long-term debt:
Long-Term	341,000,000	[2]	118,000,000	[2]
Current	0	[1],[2]	0	[1],[2]
CERC Corp [Member] | Senior notes 4.50% to 6.625% due 2016 to 2041
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum (in hundredths)	4.50%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum (in hundredths)	6.63%
Long-term debt:
Long-Term	2,168,000,000		2,168,000,000
Current	0	[1]	0	[1]
Product Financing Arrangement [Member]
Short term borrowings:
Total short-term borrowings	$53,000,000	[1]	$43,000,000	[1]
[1]	Includes amounts due or exchangeable within one year of the date noted.
[2]	Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted.
[3]	CenterPoint Energy’s ZENS obligation is bifurcated into a debt component and an embedded derivative component. For additional information regarding ZENS, see Note 10(b). As ZENS are exchangeable for cash at any time at the option of the holders, these notes are classified as a current portion of long-term debt.
[4]	$118 million of these series of debt were secured by general mortgage bonds of CenterPoint Houston at both December 31, 2014 and 2013.

Short_Term_Borrowings_and_Long3

Short Term Borrowings and Long Term Debt (Long-term Debt) (Details) (USD $)	12 Months Ended		0 Months Ended
	Dec. 31, 2014		Jun. 02, 2014	Mar. 03, 2014	Dec. 31, 2013		Mar. 17, 2014
Debt Instrument [Line Items]
Debt, Current	$848,000,000	[1]			$540,000,000	[1]
Long-term Debt, Excluding Current Maturities	8,009,000,000				7,817,000,000
Long-term Debt, Current Maturities	795,000,000	[1]			497,000,000	[1]
Total short-term borrowings	53,000,000	[1]			43,000,000	[1]
Line of Credit Facility [Abstract]
Size of Facility	2,100,000,000				2,100,000,000
Long term Debt Excluding ZENS [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
2015	641,000,000
2016	716,000,000
2017	911,000,000
2018	1,100,000,000
2019	1,000,000,000
Transition And System Restoration Bonds [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
2015	372,000,000
2016	391,000,000
2017	411,000,000
2018	434,000,000
2019	458,000,000
CenterPoint Houston [Member]
Debt Instrument [Line Items]
Capital Lease Obligations, Noncurrent	1,000,000				0
Capital Lease Obligations, Current	0	[1]			0	[1]
Line of Credit Facility [Abstract]
Size of Facility	300,000,000				300,000,000
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
CenterPoint Houston [Member] | First mortgage bonds 9.15% due 2021
Debt Instrument [Line Items]
Long-Term	102,000,000				102,000,000
Current	0	[1]			0	[1]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)	9.15%
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Secured debt amount with asset liens	102,000,000
Replacement fund requirements to be satisfied in 2015	209,000,000
Sinking fund requirements to be satisfied in 2015	1,600,000
CenterPoint Houston [Member] | General mortgage bonds 2.25% to 6.95% due 2022 to 2044
Debt Instrument [Line Items]
Long-Term	1,912,000,000				1,312,000,000
Current	0	[1]			0	[1]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Secured debt amount with asset liens	2,400,000,000
Parent Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities	858,000,000				936,000,000
Capital Lease Obligations, Noncurrent	2,000,000				0
Capital Lease Obligations, Current	2,000,000	[1]			0	[1]
Line of Credit Facility [Abstract]
Size of Facility	1,200,000,000				1,200,000,000
Parent Company [Member] | Commercial paper (4)
Debt Instrument [Line Items]
Long-Term	191,000,000	[2]			0	[2]
Current	0	[1],[2]			0	[1],[2]
CERC Corp [Member]
Line of Credit Facility [Abstract]
Size of Facility	600,000,000				600,000,000
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
CERC Corp [Member] | Commercial paper (4)
Debt Instrument [Line Items]
Long-Term	341,000,000	[2]			118,000,000	[2]
Current	0	[1],[2]			0	[1],[2]
Bonds General Mortgage Due 2044 [Member] | CenterPoint Houston [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							600,000,000
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)							4.50%
Bonds Pollution Control Due2017 [Member] | CenterPoint Houston [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)			4.25%	4.25%
Extinguishment of Debt, Amount			84,000,000	44,000,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed			100.00%	101.00%
Bonds Pollution Control Due2027 [Member] | CenterPoint Houston [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)				5.60%
Debt Instrument, Repurchase Amount				56,000,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed				101.00%
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Loans	0				0
Revolving Credit Facility [Member] | CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Loans	0				0
Revolving Credit Facility [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Loans	0				0
Revolving Credit Facility [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Loans	0				0
Line of Credit [Member] | CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Line of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)	70.00%
System restoration costs threshold for increase in permitted debt to EBITDA covenant ratio	100,000,000
Consecutive Period for System Restoration Costs to Exceed $100 million (in months)	12
Line of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member] | CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.13%
Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Letter of Credit [Member]
Line of Credit Facility [Abstract]
Loans	10,000,000				10,000,000
Letter of Credit [Member] | CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Loans	4,000,000				4,000,000
Letter of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Loans	6,000,000				6,000,000
Letter of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Loans	0				0
Commercial paper (4)
Line of Credit Facility [Abstract]
Loans	532,000,000				118,000,000
Commercial paper (4) | CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Loans	0				0
Commercial paper (4) | Parent Company [Member]
Line of Credit Facility [Abstract]
Loans	191,000,000				0
Commercial paper (4) | CERC Corp [Member]
Line of Credit Facility [Abstract]
Loans	$341,000,000				$118,000,000
[1]	Includes amounts due or exchangeable within one year of the date noted.
[2]	Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted.

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Tax Carryforward [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	$885	$781	$757
Current income tax expense (benefit):
Federal	-20	91	0
State	14	23	12
Total current expense (benefit)	-6	114	12
Deferred income tax expense (benefit):
Federal	273	370	280
State	7	-14	48
Total deferred expense	280	356	328
Total income tax expense	274	470	340
Income tax reconciliation [Abstract]
Federal statutory income tax rate	35.00%	35.00%	35.00%
Expected federal income tax expense	310	273	265
Increase (decrease) in tax expense resulting from:
State income tax expense, net of federal income tax	16	21	39
Amortization of investment tax credit	0	0	-2
Tax effect related to the formation of Enable	0	196	0
Decrease in settled and uncertain income tax positions	0	-9	-33
Goodwill impairment	0	0	88
Tax basis balance sheet adjustments	-29	0	0
Other, net	-23	-11	-17
Total	-36	197	75
Total income tax expense	274	470	340
Effective tax rate (in hundredths)	31.00%	60.20%	44.90%
Increase (Decrease) in Deferred Income Taxes	32
Increase (Decrease) in Accrued Taxes Payable	5
Increase (Decrease) in Income Taxes	8
Deferred Tax Liabilities, Goodwill and Intangible Assets		225
Income tax expense (benefit) resulting from IRS settlement		-8	33
Goodwill impairment	0	0	252
Other Tax Expense (Benefit)			88
Current:
Allowance for doubtful accounts	10	11
Deferred gas costs	0	7
Other	13	12
Total current deferred tax assets	23	30
Non-current:
Loss and credit carryforwards	69	51
Employee benefits	327	258
Other	89	76
Total non-current deferred tax assets before valuation allowance	485	385
Valuation allowance	-2	-2
Total non-current deferred tax assets, net of valuation allowance	483	383
Total deferred tax assets, net of valuation allowance	506	413
Current:
Unrealized gain on indexed debt securities	636	541
Unrealized gain on TW securities	65	97
Deferred gas costs	6	0
Total current deferred tax liabilities	707	638
Non-current:
Depreciation	2,201	1,908
Regulatory assets, net	1,228	1,308
Investment in unconsolidated affiliates	1,789	1,590
Other	21	119
Total non-current deferred tax liabilities	5,239	4,925
Total deferred tax liabilities	5,946	5,563
Accumulated deferred income taxes, net	5,440	5,150
Unrecognized tax expense, beginning of year	0	-23
Balance, beginning of year			51
Tax Positions related to prior years:
Reductions	0	-1	-75
Tax Positions related to current year:
Settlements	0	24	1
Unrecognized tax expense, end of year	0	0	-23
Income Tax Expense (Benefit) Related To Interest On Income Tax Positions	3	-3	-7
Interest receivable on income tax positions at the end of the year		5
Federal [Member]
Non-current:
Deferred Tax Assets, Capital Loss Carryforwards	9
Expiration date of state capital loss carryforwards	31-Dec-17
State capital loss carryforwards, valuation allowance net of federal tax	2
Federal [Member] | General Business Tax Credit Carryforward [Member]
Non-current:
Tax carryforward	4
State and Local Jurisdiction [Member]
Non-current:
Net operating loss carryforwards	725
Deferred Tax Assets, Capital Loss Carryforwards	244
Enable Midstream Partners [Member]
Deferred income tax expense (benefit):
Total deferred expense		($29)
Year From [Member] | State and Local Jurisdiction [Member]
Non-current:
Net operating loss carryforwards expiration dates	31-Dec-15
Year To [Member] | State and Local Jurisdiction [Member]
Non-current:
Net operating loss carryforwards expiration dates	31-Dec-34

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leases, Future Minimum Payments Due [Abstract]
2015	$5
2016	4
2017	3
2018	2
2019	2
2020 and beyond	7
Total	23
Total lease expense for all operating leases	11	21	27
Gas Market Manipulation Cases [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Loss Contingency, Pending Claims, Number	1
Loss Contingency, Amicus Briefs filed, number	4
GenOn Demand Charges Transportation Contracts [Member] | CERC Corp [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Undiscounted maximum potential payout of demand charges	42
CenterPoint Midstream Guarantees [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Undiscounted maximum potential payout of demand charges	100
Enable Guaranteed Senior Notes [Member] | CERC Corp [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Undiscounted maximum potential payout of demand charges	1,100
Minnesota Service Territory [Member] | CERC Corp [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Number of remaining sites in the Minnesota service territory (in number of sites)	7
Number of the remaining sites in the Minnesota service territory where the company believes it has no liability (in number of sites)	2
Number of sites where remediation is complete, other than ongoing operations (in number of sites)	2
Amount accrued for remediation of Minnesota sites (in number of sites)	7
Amount collected from insurance companies to be used for future environmental remediation	4
Natural Gas Supply Commitments [Member]
Long-term Purchase Commitment [Line Items]
2015	696
2016	605
2017	551
2018	507
2019	255
After 2019	114
Maximum [Member] | Minnesota Service Territory [Member] | CERC Corp [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Minimum estimated remediation costs for the Minnesota sites	29
Minimum years of remediation for the Minnesota sites (in years)	50
Minimum [Member] | Minnesota Service Territory [Member] | CERC Corp [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Minimum estimated remediation costs for the Minnesota sites	$5
Minimum years of remediation for the Minnesota sites (in years)	30

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended																12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income	$176	[1]	$143		$107		$185		$113		$151		($100)	[2]	$147		$611	$311	$417
Weighted Average Number of Shares Outstanding, Basic																	429,634,000	428,466,000	427,189,000
Plus: Incremental shares from assumed conversions:
Diluted weighted average shares (in shares)																	431,668,000	430,930,000	429,794,000
Basic earnings per share:
Basic earnings per share	$0.41	[1],[3]	$0.33	[3]	$0.25	[3]	$0.43	[3]	$0.26	[3]	$0.35	[3]	($0.23)	[2],[3]	$0.34	[3]	$1.42	$0.73	$0.98
Diluted earnings per share:
Diluted earnings per share	$0.41	[1],[3]	$0.33	[3]	$0.25	[3]	$0.43	[3]	$0.26	[3]	$0.35	[3]	($0.23)	[2],[3]	$0.34	[3]	$1.42	$0.72	$0.97
Employee Stock Option [Member]
Plus: Incremental shares from assumed conversions:
Stock options (in shares)																	0	41,000	152,000
Restricted Stock [Member]
Plus: Incremental shares from assumed conversions:
Stock options (in shares)																	2,034,000	2,423,000	2,453,000
[1]	CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.
[2]	Effective May 1, 2013, CenterPoint Energy contributed CenterPoint Midstream to Enable. See Note 2(b) and Note 9 for further discussion on the formation of Enable and CenterPoint Energy’s investment in Enable, respectively.
[3]	Quarterly earnings per common share are based on the weighted average number of shares outstanding during the quarter, and the sum of the quarters may not equal annual earnings per common share.

Unaudited_Quarterly_Informatio2

Unaudited Quarterly Information (Details) (USD $)	3 Months Ended																12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Selected Quarterly Financial Information [Abstract]
Revenues	$2,372	[1]	$1,807		$1,884		$3,163		$2,184		$1,640		$1,894	[2]	$2,388		$9,226	$8,106	$7,452
Operating income	221	[1]	233		186		295		211		244		223	[2]	332		935	1,010	1,038
Net Income	176	[1]	143		107		185		113		151		-100	[2]	147		611	311	417
Basic Earnings Per Share:
Basic earnings per share	$0.41	[1],[3]	$0.33	[3]	$0.25	[3]	$0.43	[3]	$0.26	[3]	$0.35	[3]	($0.23)	[2],[3]	$0.34	[3]	$1.42	$0.73	$0.98
Diluted Earnings Per Share:
Diluted earnings per share	$0.41	[1],[3]	$0.33	[3]	$0.25	[3]	$0.43	[3]	$0.26	[3]	$0.35	[3]	($0.23)	[2],[3]	$0.34	[3]	$1.42	$0.72	$0.97
Tax basis balance sheet adjustments																	($29)	$0	$0
[1]	CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.
[2]	Effective May 1, 2013, CenterPoint Energy contributed CenterPoint Midstream to Enable. See Note 2(b) and Note 9 for further discussion on the formation of Enable and CenterPoint Energy’s investment in Enable, respectively.
[3]	Quarterly earnings per common share are based on the weighted average number of shares outstanding during the quarter, and the sum of the quarters may not equal annual earnings per common share.

Reportable_Business_Segments_D

Reportable Business Segments (Details) (USD $)	3 Months Ended											12 Months Ended						8 Months Ended		0 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2013		1-May-13	30-May-14	Jul. 31, 2012
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues	$2,372	[1]	$1,807	$1,884	$3,163	$2,184		$1,640	$1,894	[2]	$2,388	$9,226		$8,106		$7,452
Depreciation and Amortization												1,013		954		1,050
Operating Income (Loss)	221	[1]	233	186	295	211		244	223	[2]	332	935		1,010		1,038
Total Assets	23,200					21,870						23,200		21,870		22,871		21,870
Expenditures for Long-Lived Assets												1,402		1,272		1,188
Equity income												308		188		31
Investment in unconsolidated affiliates	4,521					4,518						4,521		4,518				4,518
Enable Midstream Partners [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	55.40%				58.30%							55.40%									54.70%
Equity income												303	[3]	173	[3]	0	[3]
Investment in unconsolidated affiliates	4,520					4,319						4,520		4,319				4,319		4,300
Southeast Supply Header LLC [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	0.10%				25.05%							0.10%
Equity income												5	[4]	15	[4]	26	[4]
Investment in unconsolidated affiliates	1	[5]				199	[5]					1	[5]	199	[5]			199	[5]
Waskom Gas Processing Company [Member]
Segment Reporting Information [Line Items]
Equity income												0	[6]	0	[6]	5	[6]
Electric Transmission & Distribution [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												2,845	[7]	2,570	[7]	2,540	[7]
Depreciation and Amortization												768		685		729
Operating Income (Loss)												595		607		639
Expenditures for Long-Lived Assets												818		759		599
Electric Transmission & Distribution [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												735		658		648
Electric Transmission & Distribution [Member] | Affiliates of Energy Future Holdings Corp. [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												189		167		162
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												3,271		2,837		2,320
Depreciation and Amortization												201		185		173
Operating Income (Loss)												287		263		226
Expenditures for Long-Lived Assets												525		430		359
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												3,095		2,374		1,758
Depreciation and Amortization												5		5		6
Operating Income (Loss)												52		13		-250
Expenditures for Long-Lived Assets												3		3		6
Interstate Pipelines [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues														133	[8],[9]	356	[8]
Depreciation and Amortization														20	[8],[9]	56	[8]
Operating Income (Loss)														72	[8],[9]	207	[8]
Expenditures for Long-Lived Assets														29	[8],[9]	132	[8]
Interstate Pipelines [Member] | Southeast Supply Header LLC [Member]
Segment Reporting Information [Line Items]
Equity income														7		26
Investment in unconsolidated affiliates																404
Field Services [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues														178	[10],[9]	467	[10]
Depreciation and Amortization														20	[10],[9]	50	[10]
Operating Income (Loss)														73	[10],[9]	214	[10]
Expenditures for Long-Lived Assets														16	[10],[9]	52	[10]
Field Services [Member] | Waskom Gas Processing Company [Member]
Segment Reporting Information [Line Items]
Equity income																5
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												0	[11]	0	[11]
Depreciation and Amortization												0	[11]	0	[11]
Operating Income (Loss)												0	[11]	0	[11]
Expenditures for Long-Lived Assets												0	[11]	0	[11]
Midstream Investments [Member] | Enable Midstream Partners [Member]
Segment Reporting Information [Line Items]
Equity income												303						173
Midstream Investments [Member] | Southeast Supply Header LLC [Member]
Segment Reporting Information [Line Items]
Equity income												5						8
Other [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												15		14		11
Depreciation and Amortization												39		39		36
Operating Income (Loss)												1		-18		2
Expenditures for Long-Lived Assets												56		35		40
Operating Segments [Member] | Electric Transmission & Distribution [Member]
Segment Reporting Information [Line Items]
Total Assets	10,066					9,605						10,066		9,605		11,174		9,605
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Total Assets	5,464					4,976						5,464		4,976		4,775		4,976
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Total Assets	978					895						978		895		839		895
Operating Segments [Member] | Interstate Pipelines [Member]
Segment Reporting Information [Line Items]
Total Assets						0	[8],[9]							0	[8],[9]	4,004	[8]	0	[8],[9]
Operating Segments [Member] | Field Services [Member]
Segment Reporting Information [Line Items]
Total Assets						0	[10],[9]							0	[10],[9]	2,453	[10]	0	[10],[9]
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Total Assets	4,521	[11]				4,518	[11]					4,521	[11]	4,518	[11]			4,518	[11]
Operating Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Total Assets	3,368	[12]				3,026	[12]					3,368	[12]	3,026	[12]	2,600	[12]	3,026	[12]
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												-114		-124		-233
Total Assets	-1,197					-1,150						-1,197		-1,150		-2,974		-1,150
Intersegment Eliminations [Member] | Electric Transmission & Distribution [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												0		0		0
Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												-30		-26		-22
Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												-84		-27		-26
Intersegment Eliminations [Member] | Interstate Pipelines [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues														-53	[8],[9]	-146	[8]
Intersegment Eliminations [Member] | Field Services [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues														-18	[10],[9]	-39	[10]
Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												0	[11]	0	[11]
Intersegment Eliminations [Member] | Other [Member]
Segment Reporting Information [Line Items]
Revenues from External Customers and Intersegment Revenues												0		0		0
Pension and Other Postretirement Plans Costs [Member] | Other [Member]
Segment Reporting Information [Line Items]
Total regulatory assets	$795					$627						$795		$627		$832		$627
Waskom Gas Processing Company [Member]
Segment Reporting Information [Line Items]
Percentage of Ownership in Affiliate 2 Acquired																						50.00%
Waskom Gas Processing Company [Member] | Enable Midstream Partners [Member]
Segment Reporting Information [Line Items]
Equity Interest Contributed, Percentage																				100.00%
[1]	CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.
[2]	Effective May 1, 2013, CenterPoint Energy contributed CenterPoint Midstream to Enable. See Note 2(b) and Note 9 for further discussion on the formation of Enable and CenterPoint Energy’s investment in Enable, respectively.
[3]	On May 1, 2013, CenterPoint Energy formed Enable with OGE and ArcLight.
[4]	On each of May 1, 2013 and May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
[5]	On May 30, 2014, CenterPoint Energy contributed a 24.95% interest in SESH to Enable, leaving CenterPoint Energy with a 0.1% interest in SESH as of December 31, 2014.
[6]	On July 31, 2012, Waskom became a wholly owned subsidiary of CenterPoint Energy. Beginning on August 1, 2012, Waskom’s operating results are consolidated on the Statements of Consolidated Income. On May 1, 2013, CenterPoint Energy contributed Waskom to Enable.
[7]	Sales to affiliates of NRG in 2014, 2013 and 2012 represented approximately $735 million, $658 million and $648 million, respectively, of CenterPoint Houston’s transmission and distribution revenues. Sales to affiliates of Energy Future Holdings Corp. in 2014, 2013 and 2012 represented approximately $189 million, $167 million and $162 million, respectively, of CenterPoint Houston’s transmission and distribution revenues.
[8]	Interstate Pipelines recorded equity income of $7 million and $26 million in the years ended December 31, 2013 and 2012, respectively, from its interest in SESH, a jointly-owned pipeline. These amounts are included in Equity in earnings of unconsolidated affiliates under the Other Income (Expense) caption. Interstate Pipelines’ investment in SESH was $404 million as of December 31, 2012, and is included in Investment in unconsolidated affiliates. As discussed above, effective May 1, 2013, CenterPoint Energy reports equity earnings associated with its interest in Enable and equity earnings associated with its interest in SESH under its Midstream Investments segment, and no longer has an Interstate Pipelines reporting segment prospectively.
[9]	Results reflected in the year ended December 31, 2013 represent only January 2013 through April 2013.
[10]	Field Services recorded equity income of $5 million for the year ended December 31, 2012 from its interest in Waskom. This amount is included in Equity in earnings of unconsolidated affiliates under the Other Income (Expense) caption. Beginning on August 1, 2012, financial results for Waskom are included in operating income due to the July 31, 2012 purchase of the 50% interest in Waskom that CenterPoint Energy did not already own. CenterPoint Energy contributed 100% interest in Waskom to Enable on May 1, 2013. Effective May 1, 2013, CenterPoint Energy reports equity earnings associated with its interest in Enable under its Midstream Investments segment, and no longer has a Field Services reporting segment prospectively.
[11]	Midstream Investments reported equity earnings of $303 million from Enable and $5 million of equity earnings from CenterPoint Energy’s interest in SESH for the year ended December 31, 2014. Midstream Investments reported equity earnings of $173 million from Enable and $8 million of equity earnings from CenterPoint Energy’s interest in SESH for the eight months ended December 31, 2013. Included in total assets of Midstream Investments as of December 31, 2014 and 2013 is $4,520 million and $4,319 million, respectively, related to CenterPoint Energy’s investment in Enable and $1 million and $199 million related to CenterPoint Energy’s retained interest in SESH, respectively.
[12]	Included in total assets of Other Operations as of December 31, 2014, 2013 and 2012, are pension and other postemployment related regulatory assets of $795 million, $627 million and $832 million, respectively.

Reportable_Business_Segments_R

Reportable Business Segments (Revenues by Products and Services) (Details) (USD $)

3 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Revenues by Products and Services:

Revenues

$2,372

[1]

$1,807

$1,884

$3,163

$2,184

$1,640

$1,894

[2]

$2,388

$9,226

$8,106

$7,452

Electric Delivery [Member]

Revenues by Products and Services:

Revenues

2,845

2,570

2,540

Retail Gas Sales [Member]

Revenues by Products and Services:

Revenues

5,049

4,150

3,328

Wholesale Gas Sales [Member]

Revenues by Products and Services:

Revenues

1,159

913

613

Gas Transportation and Processing [Member]

Revenues by Products and Services:

Revenues

38

345

847

Energy Products Or Services [Member]

Revenues by Products and Services:

Revenues

135

128

124

Interstate Pipelines [Member]

Revenues by Products and Services:

Revenues

$133

[3],[4]

$356

[3]

[1]

CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.

[2]

Effective May 1, 2013, CenterPoint Energy contributed CenterPoint Midstream to Enable. See Note 2(b) and Note 9 for further discussion on the formation of Enable and CenterPoint Energy’s investment in Enable, respectively.

[3]

Interstate Pipelines recorded equity income of $7 million and $26 million in the years ended December 31, 2013 and 2012, respectively, from its interest in SESH, a jointly-owned pipeline. These amounts are included in Equity in earnings of unconsolidated affiliates under the Other Income (Expense) caption. Interstate Pipelines’ investment in SESH was $404 million as of December 31, 2012, and is included in Investment in unconsolidated affiliates. As discussed above, effective May 1, 2013, CenterPoint Energy reports equity earnings associated with its interest in Enable and equity earnings associated with its interest in SESH under its Midstream Investments segment, and no longer has an Interstate Pipelines reporting segment prospectively.

[4]

Results reflected in the year ended December 31, 2013 represent only January 2013 through April 2013.

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	12 Months Ended						0 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Jan. 22, 2015	Jan. 23, 2015
Subsequent Event [Line Items]
Quarterly Cash Dividend Declared	$0.95		$0.83		$0.81
Expected Cash Distribution	$305		$129		$39
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared							22-Jan-15
Quarterly Cash Dividend Declared							$0.25
Dividends Payable, Date to be Paid							10-Mar-15
Dividends Payable, Date of Record							13-Feb-15
Enable Midstream Partners [Member]
Subsequent Event [Line Items]
Expected Cash Distribution	298	[1]	106	[1]	0	[1]
Enable Midstream Partners [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared								23-Jan-15
Quarterly Cash Dividend Declared								$0.31
Expected Cash Distribution								$72
[1]	On May 1, 2013, CenterPoint Energy formed Enable with OGE and ArcLight.

Schedule_I_Financial_Informati1

Schedule I: Financial Information of CenterPoint Energy, Inc. (Parent Company) (Statements of Income) (Details) (USD $)	3 Months Ended										12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Income (Expense):
Other Income (Expense)											$36	$24	$38
Loss on Indexed Debt Securities											-86	-193	-71
Interest Expense											-353	-351	-422
Total											-50	-229	-281
Income Tax Benefit											-274	-470	-340
Net Income	176	[1]	143	107	185	113	151	-100	[2]	147	611	311	417
CenterPoint Energy [Member]
Expenses:
Operation and Maintenance Expenses											-22	-13	-20
Total											-22	-13	-20
Other Income (Expense):
Interest Income from Subsidiaries											0	8	10
Other Income (Expense)											-1	-5	6
Loss on Indexed Debt Securities											-86	-193	-71
Interest Expense to Subsidiaries											0	-24	-25
Interest Expense											-103	-104	-112
Total											-190	-318	-192
Loss Before Income Taxes, Equity in Subsidiaries											-212	-331	-212
Income Tax Benefit											115	137	87
Loss Before Equity in Subsidiaries											-97	-194	-125
Equity Income of Subsidiaries											708	505	542
Net Income											$611	$311	$417
[1]	CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.
[2]	Effective May 1, 2013, CenterPoint Energy contributed CenterPoint Midstream to Enable. See Note 2(b) and Note 9 for further discussion on the formation of Enable and CenterPoint Energy’s investment in Enable, respectively.

Schedule_I_Financial_Informati2

Schedule I: Financial Information of CenterPoint Energy, Inc. (Parent Company) (Statements of Comprehensive Income) (Details) (USD $)	3 Months Ended										12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Statement of Income Captions [Line Items]
Net Income	$176	[1]	$143	$107	$185	$113	$151	($100)	[2]	$147	$611	$311	$417
Adjustment to pension and other postretirement plans (net of tax of $5, $25 and $2, respectively)											3	44	-2
Reclassification of deferred loss from cash flow hedges realized in net income (net of tax)											1	1	0
Other comprehensive income (loss)											4	45	-2
Comprehensive income											615	356	415
CenterPoint Houston [Member]
Condensed Statement of Income Captions [Line Items]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)											65.00%
CenterPoint Energy [Member]
Condensed Statement of Income Captions [Line Items]
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax											5	25	2
Net Income											611	311	417
Adjustment to pension and other postretirement plans (net of tax of $5, $25 and $2, respectively)											3	44	-2
Reclassification of deferred loss from cash flow hedges realized in net income (net of tax)											1	1	0
Other comprehensive income (loss)											4	45	-2
Comprehensive income											$615	$356	$415
[1]	CenterPoint Energy recognized a $29 million deferred income tax benefit upon completion of its tax basis balance sheet review.
[2]	Effective May 1, 2013, CenterPoint Energy contributed CenterPoint Midstream to Enable. See Note 2(b) and Note 9 for further discussion on the formation of Enable and CenterPoint Energy’s investment in Enable, respectively.

Schedule_I_Financial_Informati3

Schedule I: Financial Information of CenterPoint Energy, Inc. (Parent Company) (Balance Sheets) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, unless otherwise specified
Current Assets:
Cash and cash equivalents	$298	$208	$646	$220
Total current assets	3,268	2,658
Other Assets:
Other assets	147	162
Total other assets	9,430	9,619
Total Assets	23,200	21,870	22,871
Current Liabilities:
Indexed debt	152	143	138	131
Current portion of other long-term debt	271	0
Indexed debt securities derivative	541	455	268	197
Taxes accrued	161	184
Interest accrued	124	124
Other	383	402
Total current liabilities	3,475	3,019
Other Liabilities:
Accumulated deferred tax liabilities	4,757	4,542
Benefit obligations	953	802
Other	251	205
Total other liabilities	7,168	6,705
Long-Term Debt	8,009	7,817
Shareholders' Equity:
Total shareholders’ equity	4,548	4,329	4,301
Total Liabilities and Shareholders’ Equity	23,200	21,870
CenterPoint Energy [Member]
Current Assets:
Cash and cash equivalents	0	0	0	0
Notes receivable — subsidiaries	227	88
Accounts receivable — subsidiaries	230	116
Other assets	87	21
Total current assets	544	225
Other Assets:
Investment in subsidiaries	6,529	6,142
Other assets	811	649
Total other assets	7,340	6,791
Total Assets	7,884	7,016
Current Liabilities:
Notes payable — subsidiaries	142	11
Indexed debt	152	143
Current portion of other long-term debt	269	0
Indexed debt securities derivative	541	455
Accounts payable - subsidiaries	80	35
Other	2	5
Taxes accrued	575	517
Interest accrued	13	13
Other	22	0
Total current liabilities	1,796	1,179
Other Liabilities:
Accumulated deferred tax liabilities	240	232
Benefit obligations	441	340
Other	1	0
Total other liabilities	682	572
Long-Term Debt	858	936
Shareholders' Equity:
Common stock	4	4
Additional paid-in capital	4,169	4,157
Retained earnings	461	258
Accumulated other comprehensive loss	-86	-90
Total shareholders’ equity	4,548	4,329
Total Liabilities and Shareholders’ Equity	$7,884	$7,016

Schedule_I_Financial_Informati4

Schedule I: Financial Information of CenterPoint Energy, Inc. (Parent Company) (Statements of Cash Flows) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flows from Operating Activities:
Net Income	$611	$311	$417
Non-cash items included in net income:
Deferred income tax expense	280	356	328
Amortization of debt issuance costs	28	30	32
Loss on indexed debt securities	86	193	71
Changes in working capital:
Accounts payable	-3	152	-6
Other current assets	1	-2	-12
Other current liabilities	-20	21	18
Other	13	24	17
Net cash provided by operating activities	1,397	1,613	1,860
Investing Activities:
Net cash used in investing activities	-1,384	-1,300	-1,603
Financing Activities:
Proceeds from (payments of) commercial paper, net	414	118	-285
Payments of long-term debt	-537	-1,573	-1,590
Debt issuance costs	-8	-3	-16
Common stock dividends paid	-408	-355	-346
Proceeds from issuance of common stock, net	1	4	4
Redemption of indexed debt securities	0	-8	0
Other, net	6	18	0
Net cash provided by (used in) financing activities	77	-751	169
Net Increase (Decrease) in Cash and Cash Equivalents	90	-438	426
Cash and Cash Equivalents at Beginning of Year	208	646	220
Cash and Cash Equivalents at End of Year	298	208	646
CenterPoint Energy [Member]
Cash Flows from Operating Activities:
Net Income	611	311	417
Non-cash items included in net income:
Equity income of subsidiaries	-708	-505	-542
Deferred income tax expense	86	6	113
Amortization of debt issuance costs	4	4	4
Loss on indexed debt securities	86	193	71
Changes in working capital:
Accounts receivable/(payable) from subsidiaries, net	-7	47	39
Accounts payable	-3	5	0
Other current assets	0	0	26
Other current liabilities	-83	42	-63
Common stock dividends received from subsidiaries	315	766	1,700
Other	-76	-70	-72
Net cash provided by operating activities	225	799	1,693
Investing Activities:
Decrease (increase) in notes receivable from subsidiaries	-139	868	-398
Net cash used in investing activities	-139	868	-398
Financing Activities:
Proceeds from (payments of) commercial paper, net	191	0	0
Payments of long-term debt	0	-151	-375
Debt issuance costs	-1	-2	0
Common stock dividends paid	-408	-355	-346
Proceeds from issuance of common stock, net	1	4	4
Short-term notes payable to subsidiaries	131	-1,173	-578
Redemption of indexed debt securities	0	-8	0
Other, net	0	18	0
Net cash provided by (used in) financing activities	-86	-1,667	-1,295
Net Increase (Decrease) in Cash and Cash Equivalents	0	0	0
Cash and Cash Equivalents at Beginning of Year	0	0	0
Cash and Cash Equivalents at End of Year	$0	$0	$0

Schedule_I_Financial_Informati5

Schedule I: Financial Information of CenterPoint Energy, Inc. (Parent Company) (Note Disclosures) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Notes to Financial Statements of Parent, Long-Term Debt:
Maximum amount of credit facility	$2,100	$2,100
CERC Corp [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Maximum amount of credit facility	600	600
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
CenterPoint Energy [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Maximum amount of credit facility	1,200	1,200
CenterPoint Houston [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Maximum amount of credit facility	300	300
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Revolving Credit Facility [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	0	0
Revolving Credit Facility [Member] | CERC Corp [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	0	0
Revolving Credit Facility [Member] | CenterPoint Energy [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	0	0
Revolving Credit Facility [Member] | CenterPoint Houston [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	0	0
Letter of Credit [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	10	10
Letter of Credit [Member] | CERC Corp [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	0	0
Letter of Credit [Member] | CenterPoint Energy [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	6	6
Letter of Credit [Member] | CenterPoint Houston [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	4	4
Commercial Paper [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	532	118
Commercial Paper [Member] | CERC Corp [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	341	118
Commercial Paper [Member] | CenterPoint Energy [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	191	0
Commercial Paper [Member] | CenterPoint Houston [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Borrowings from credit facility	0	0
Line of Credit [Member] | CERC Corp [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Line of Credit [Member] | CenterPoint Energy [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)	70.00%
Restoration Cost Expected Cost	100
Consecutive Period for System Restoration Costs to Exceed $100 million (in months)	12
Line of Credit [Member] | CenterPoint Houston [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
London Interbank Offered Rate (LIBOR) [Member] | Line of Credit [Member] | CERC Corp [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Debt Instrument, Basis Spread on Variable Rate	1.50%
London Interbank Offered Rate (LIBOR) [Member] | Line of Credit [Member] | CenterPoint Energy [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Debt Instrument, Basis Spread on Variable Rate	1.25%
London Interbank Offered Rate (LIBOR) [Member] | Line of Credit [Member] | CenterPoint Houston [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Debt Instrument, Basis Spread on Variable Rate	1.13%
CenterPoint Midstream Guarantees [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Guarantor Obligations, Maximum Exposure, Undiscounted	100
Long term Debt Excluding Indexed Debt Securities [Member] | CenterPoint Energy [Member]
Notes to Financial Statements of Parent, Long-Term Debt:
Debt Maturities in 2015	269
Debt Maturities in 2016	0
Debt Maturities in 2017	250
Debt Maturities in 2018	350
Debt Maturities in 2019	$191

Schedule_II_Valuation_and_Qual1

Schedule II - Valuation and Qualifying Accounts (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Uncollectible accounts receivable [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$28		$25		$25
Additions Charged to Income	22		21		16
Additions Charged to Other Accounts	2		1		1
Deductions From Reserves	26	[1]	19	[1]	17	[1]
Balance at End of Period	26		28		25
Deferred tax asset valuation allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	2		2		4
Additions Charged to Income	0		0
Additions Charged to Other Accounts	0		0
Deductions From Reserves	0	[1]	0	[1]	0	[1]
Valuation Allowances and Reserves Deducted From Cost and Expense					-1
Valuation Allowances and Reserves, Addition to Other Accounts					-1
Balance at End of Period	$2		$2		$2
[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.