CenterPoint Energy (CNP) 10-Q 11 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Supplement

Document and Entity Supplemental Information Document (USD $)	3 Months Ended
	Mar. 31, 2015	Apr. 20, 2015	Jun. 30, 2014
Entity Information [Line Items]
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-Q
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		430,207,011
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$10,907,234,073

Condensed_Statements_of_Consol

Condensed Statements of Consolidated Income (Unaudited) (USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenues	$2,433	$3,163
Expenses:
Natural gas	1,354	2,043
Operation and maintenance	498	479
Depreciation and amortization	217	235
Taxes other than income taxes	108	111
Total	2,177	2,868
Operating Income	256	295
Other Income (Expense):
Loss on marketable securities	-17	-30
Gain on indexed debt securities	24	43
Interest and other finance charges	-89	-84
Interest on transition and system restoration bonds	-28	-30
Equity in earnings of unconsolidated affiliates, net	52	91
Other, net	11	9
Total	-47	-1
Income Before Income Taxes	209	294
Income tax expense	78	109
Net Income	$131	$185
Basic Earnings Per Share	$0.30	$0.43
Diluted Earnings Per Share	$0.30	$0.43
Dividends Declared Per Share	$0.25	$0.24
Weighted Average Shares Outstanding, Basic	429,955,000	429,163,000
Weighted Average Shares Outstanding, Diluted	431,183,000	430,559,000

Condensed_Statements_of_Consol1

Condensed Statements of Consolidated Comprehensive Income (Unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$131	$185
Other comprehensive income:
Adjustment related to pension and other postretirement plans (net of tax of $2 and $1)	2	1
Total	2	1
Comprehensive income	$133	$186

Comprehensive_Income_Parenthet

Comprehensive Income Parentheticals (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income, Pension and Other Postretirement Benefit Plans, Tax	$2	$1

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Current Assets:
Cash and cash equivalents ($212 and $290 related to VIEs, respectively)	$234	$298
Investment in marketable securities	913	930
Accounts receivable ($55 and $58 related to VIEs, respectively), less bad debt reserve of $34 and $26, respectively	897	837
Accrued unbilled revenues	235	357
Natural gas inventory	37	211
Materials and supplies	161	168
Non-trading derivative assets	82	99
Taxes receivable	0	190
Prepaid expenses and other current assets ($43 and $47 related to VIEs, respectively)	132	178
Total current assets	2,691	3,268
Property, Plant and Equipment:
Property, plant and equipment	15,633	15,358
Less: accumulated depreciation and amortization	4,963	4,856
Property, plant and equipment, net	10,670	10,502
Other Assets:
Goodwill	840	840
Regulatory assets ($2,670 and $2,738 related to VIEs, respectively)	3,426	3,527
Notes receivable - affiliated companies	363	363
Non-trading derivative assets	35	32
Investment in unconsolidated affiliates	4,501	4,521
Other	144	147
Total other assets	9,309	9,430
Total Assets	22,670	23,200
Current Liabilities:
Short-term borrowings	0	53
Current portion of VIE transition and system restoration bonds long-term debt	380	372
Indexed debt	154	152
Current portion of other long-term debt	271	271
Indexed debt securities derivative	517	541
Accounts payable	476	716
Taxes accrued	142	161
Interest accrued	116	124
Non-trading derivative liabilities	9	19
Accumulated deferred income taxes, net	728	683
Other	394	383
Total current liabilities	3,187	3,475
Other Liabilities:
Accumulated deferred income taxes, net	4,716	4,757
Non-trading derivative liabilities	2	1
Benefit obligations	928	953
Regulatory liabilities	1,243	1,206
Other	253	251
Total other liabilities	7,142	7,168
Long-term Debt:
VIE transition and system restoration bonds	2,528	2,674
Other	5,239	5,335
Total long-term debt	7,767	8,009
Commitments and Contingencies (Note 12)
Shareholders’ Equity:
Common stock (430,206,636 shares and 429,795,830 shares outstanding, respectively)	4	4
Additional paid-in capital	4,168	4,169
Retained earnings	486	461
Accumulated other comprehensive loss	-84	-86
Total shareholders’ equity	4,574	4,548
Total Liabilities and Shareholders’ Equity	$22,670	$23,200

Balance_Sheets_Parentheticals

Balance Sheets Parentheticals (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, except Share data, unless otherwise specified
Cash and cash equivalents	$234	$298
Bad Debt Reserve	34	26
Accounts receivable, net	897	837
Prepaid expenses and other current assets	132	178
Regulatory assets	3,426	3,527
Total common stock outstanding (in shares)	430,206,636	429,795,830
Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents	212	290
Accounts receivable, net	55	58
Prepaid expenses and other current assets	43	47
Regulatory assets	$2,670	$2,738

Condensed_Statements_of_Consol2

Condensed Statements of Consolidated Cash Flows (Unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash Flows from Operating Activities:
Net income	$131	$185
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	217	235
Amortization of deferred financing costs	7	7
Deferred income taxes	7	4
Unrealized loss on marketable securities	17	30
Unrealized gain on indexed debt securities	-24	-43
Write-down of natural gas inventory	2	0
Equity in earnings of unconsolidated affiliates, net of distributions	20	-22
Pension contributions	-23	-3
Changes in other assets and liabilities:
Accounts receivable and unbilled revenues, net	57	-253
Inventory	179	113
Taxes receivable	190	0
Accounts payable	-208	128
Fuel cost recovery	86	-27
Non-trading derivatives, net	1	0
Margin deposits, net	-4	1
Interest and taxes accrued	-27	19
Net regulatory assets and liabilities	58	27
Other current assets	17	20
Other current liabilities	-41	-55
Other assets	6	9
Other liabilities	-1	13
Other, net	-1	-8
Net cash provided by operating activities	666	380
Cash Flows from Investing Activities:
Capital expenditures	-341	-301
Decrease (increase) in restricted cash of transition and system restoration bond companies	5	-2
Other, net	-1	-13
Net cash used in investing activities	-337	-316
Cash Flows from Financing Activities:
Decrease in short-term borrowings, net	-53	-43
Payments of commercial paper, net	-96	-118
Proceeds from long-term debt	0	600
Payments of long-term debt	-139	-231
Debt issuance costs	0	-5
Payment of common stock dividends	-106	-102
Proceeds from issuance of common stock, net	0	1
Other, net	1	5
Net cash provided by (used in) financing activities	-393	107
Net Increase (Decrease) in Cash and Cash Equivalents	-64	171
Cash and Cash Equivalents at Beginning of Period	298	208
Cash and Cash Equivalents at End of Period	234	379
Cash Payments:
Interest, net of capitalized interest	115	122
Income tax refunds, net	-166	-1
Non-cash transactions:
Accounts payable related to capital expenditures	$72	$59

Background_and_Basis_of_Presen

Background and Basis of Presentation	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation	Background and Basis of Presentation
	General. Included in this Quarterly Report on Form 10-Q (Form 10-Q) of CenterPoint Energy, Inc. are the condensed consolidated interim financial statements and notes (Interim Condensed Financial Statements) of CenterPoint Energy, Inc. and its subsidiaries (collectively, CenterPoint Energy). The Interim Condensed Financial Statements are unaudited, omit certain financial statement disclosures and should be read with the Annual Report on Form 10-K of CenterPoint Energy for the year ended December 31, 2014 (CenterPoint Energy Form 10-K).
	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 in Note 7. As of March 31, 2015, 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. 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 March 31, 2015, 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.
	As of March 31, 2015, CenterPoint Energy had variable interest entities (VIEs) consisting of transition and system restoration bond companies, which it consolidates. The consolidated VIEs are wholly owned bankruptcy remote special purpose entities that were formed specifically for the purpose of securitizing transition and system restoration related property. Creditors of CenterPoint 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.
	Basis of Presentation. The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	CenterPoint Energy’s Interim Condensed Financial Statements reflect all normal recurring adjustments that are, in the opinion of management, necessary to present fairly the financial position, results of operations and cash flows for the respective periods. Amounts reported in CenterPoint Energy’s Condensed Statements of Consolidated Income are not necessarily indicative of amounts expected for a full-year period due to the effects of, among other things, (a) seasonal fluctuations in demand for energy and energy services, (b) changes in energy commodity prices, (c) timing of maintenance and other expenditures and (d) acquisitions and dispositions of businesses, assets and other interests.
	For a description of CenterPoint Energy’s reportable business segments, see Note 14.

New_Accounting_Pronouncements

New Accounting Pronouncements	3 Months Ended
	Mar. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Description of New Accounting Pronouncements Not yet Adopted [Text Block]	New Accounting Pronouncements
	In February 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis (ASU 2015-02). ASU 2015-02 changes the analysis that reporting organizations must perform to evaluate whether they should consolidate certain legal entities, such as limited partnerships. The changes include, among others, modification of the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities and elimination of the presumption that a general partner should consolidate a limited partnership. ASU 2015-02 does not amend the related party guidance for situations in which power is shared between two or more entities that hold interests in a VIE. ASU 2015-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015. CenterPoint Energy will adopt ASU 2015-02 on January 1, 2016 and is currently assessing the impact, if any, that this standard will have on its financial position, results of operations, cash flows and disclosures.
	In April 2015, the FASB issued Accounting Standards Update No. 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost (ASU 2015-03). ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by ASU 2015-03. CenterPoint Energy will adopt ASU 2015-03 retrospectively on January 1, 2016, which will result in a reduction of both other long-term assets and long-term debt on its Condensed Consolidated Balance Sheets. CenterPoint Energy had debt issuance costs of $59 million and $61 million included in other long-term assets on its Condensed Consolidated Balance Sheets as of March 31, 2015 and December 31, 2014, respectively.
	In April 2015, the FASB issued Accounting Standards Update No. 2015-05, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40) (ASU 2015-05).  ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The guidance will not change a customer’s accounting for service contracts.  ASU 2015-05 is effective for fiscal years, and interim periods within the fiscal years, beginning after December 15, 2015 and may be adopted either prospectively or retrospectively.  CenterPoint Energy will adopt ASU 2015-05 on January 1, 2016 and is currently assessing the impact that this standard will have on its financial position, results of operations, cash flows and disclosures.
	Management believes that other recently issued standards, which are not yet effective, will not have a material impact on CenterPoint Energy’s consolidated financial position, results of operations or cash flows upon adoption.

Employee_Benefit_Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans	Employee Benefit Plans
	CenterPoint Energy’s net periodic cost includes the following components relating to pension and postretirement benefits:
		Three Months Ended March 31,
		2015						2014
		Pension			Postretirement			Pension			Postretirement
		Benefits (1)			Benefits			Benefits (1)			Benefits
		(in millions)
	Service cost	$	10		$	1		$	10		$	—
	Interest cost	23			5			25			6
	Expected return on plan assets	(30		)	(2		)	(31		)	(2		)
	Amortization of prior service cost	3			—			3			—
	Amortization of net loss	14			1			11			—
	Amortization of transition obligation	—			—			—			1
	Settlement cost (2)	9			—			—			—
	Net periodic cost	$	29		$	5		$	18		$	5
	________________
	-1	Net periodic cost in these tables is before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes.
	-2	A one-time, non-cash settlement charge is required when lump sum distributions or other settlements of plan benefit obligations during a plan year exceed the service cost and interest cost components of net periodic cost for that year.  Due to the distribution of lump sum payments from the non-qualified pension plan during the three months ended March 31, 2015, CenterPoint Energy recognized a non-cash settlement charge of $9 million.  This charge is an acceleration of costs that would otherwise be recognized in future periods.  CenterPoint Energy will continue to recognize incremental settlement costs in subsequent quarters as additional lump sum distributions are made under the non-qualified pension plan.  CenterPoint Energy currently estimates the additional settlement costs in the remaining nine months of 2015 to total approximately $1 million.
	CenterPoint Energy's changes in accumulated comprehensive loss related to defined benefit and postretirement plans are as follows:
		Three Months Ended March 31,
		2015			2014
		Pension and Postretirement Plans
		(in millions)
	Beginning Balance	$	(85	)	$	(88	)
	Amounts reclassified from accumulated other comprehensive loss:
	Actuarial losses (1)	4			2
	Total reclassifications from accumulated other comprehensive loss	4			2
	Tax expense	(2		)	(1		)
	Net current period other comprehensive income	2			1
	Ending Balance	$	(83	)	$	(87	)
	________________
	-1	These components are included in the computation of net periodic cost.
	CenterPoint Energy expects to contribute a total of approximately $66 million to its pension plans in 2015, of which approximately $23 million was contributed during the three months ended March 31, 2015.
	CenterPoint Energy expects to contribute a total of approximately $17 million to its postretirement benefits plan in 2015, of which approximately $5 million was contributed during the three months ended March 31, 2015.

Regulatory_Accounting

Regulatory Accounting	3 Months Ended
	Mar. 31, 2015
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Regulatory Matters	Regulatory Accounting
	As of March 31, 2015, CenterPoint Energy has not recognized an allowed equity return of $433 million because such return will be recognized as it is recovered in rates. During the three months ended March 31, 2015 and 2014, CenterPoint Houston recognized approximately $9 million and $15 million, respectively, of the allowed equity return not previously recognized.

Derivative_Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2015
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. Such derivatives are recognized in CenterPoint Energy’s Condensed 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 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, 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.
	(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 its natural gas distribution business (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 $16 million in both 2013 - 2014 and 2014 - 2015. CenterPoint Energy also entered into a winter weather hedge for the CenterPoint Houston service territory, which contained a bilateral dollar cap of $8 million in both 2013 - 2014 and 2014 - 2015. The swaps are based on ten-year normal weather. During the three months ended March 31, 2015 and 2014, CenterPoint Energy recognized losses of $10 million and $8 million, respectively, related to these swaps. Weather hedge gains and losses are included in revenues in the Condensed 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 four tables provide a balance sheet overview of CenterPoint Energy’s Derivative Assets and Liabilities as of March 31, 2015 and December 31, 2014, while the last table provides a breakdown of the related income statement impacts for the three months ended March 31, 2015 and 2014.
	Fair Value of Derivative Instruments
					March 31, 2015
	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)		Current Assets: Non-trading derivative assets		$	82			$	—
	Natural gas derivatives (1) (2)		Other Assets: Non-trading derivative assets		35				—
	Natural gas derivatives (1) (2)		Current Liabilities: Non-trading derivative liabilities		9				63
	Natural gas derivatives (1) (2)		Other Liabilities: Non-trading derivative liabilities		2				19
	Indexed debt securities derivative		Current Liabilities		—				517
	Total				$	128			$	599
	_____________
	-1	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 749 billion cubic feet (Bcf) or a net 126 Bcf long position.  Of the net long position, basis swaps constitute 125 Bcf.
	-2	Natural gas contracts are presented on a net basis in the Condensed 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 Condensed Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $106 million asset as shown on CenterPoint Energy’s Condensed 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 $60 million.
	Offsetting of Natural Gas Derivative Assets and Liabilities
			March 31, 2015
			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		$	91			$	(9	)		$	82
	Other Assets: Non-trading derivative assets		37				(2		)		35
	Current Liabilities: Non-trading derivative liabilities		(63		)		54				(9		)
	Other Liabilities: Non-trading derivative liabilities		(19		)		17				(2		)
	Total		$	46			$	60			$	106
	________________
	-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 Condensed 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, 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)		Current Assets: Non-trading derivative assets		$	101			$	1
	Natural gas derivatives (1) (2)		Other Assets: Non-trading derivative assets		32				—
	Natural gas derivatives (1) (2)		Current Liabilities: Non-trading derivative liabilities		14				83
	Natural gas derivatives (1) (2)		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 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 Condensed 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 Condensed Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $111 million asset as shown on CenterPoint Energy’s Condensed 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.
	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 Condensed 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.
Realized and unrealized gains and losses on derivatives are recognized in the Condensed 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 Condensed Statements of Consolidated Income.
Income Statement Impact of Derivative Activity
				Three Months Ended March 31,
Total derivatives not designated		Income Statement Location		2015				2014
as hedging instruments
				(in millions)
Natural gas derivatives		Gains (Losses) in Revenues		$	(133	)		$	(101	)
Natural gas derivatives (1)		Gains (Losses) in Expenses: Natural Gas		132				110
Indexed debt securities derivative		Gains (Losses) in Other Income (Expense)		24				43
Total				$	23			$	52
________________
-1	The Gains (Losses) in Expenses: Natural Gas includes $-0- and $2 million during the three months ended March 31, 2015 and 2014, respectively, related to physical forwards purchased from Enable.
(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 March 31, 2015 and December 31, 2014 was $3 million and $2 million, respectively.  The aggregate fair value of assets that were posted as collateral was less than $1 million at both March 31, 2015 and December 31, 2014.  If all derivative contracts (in a net liability position) containing credit risk contingent features were triggered at March 31, 2015 and December 31, 2014, $3 million and $2 million, respectively, of additional assets would be required to be posted as collateral.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	Fair Value Measurements
	Assets and liabilities that are recorded at fair value in the Condensed Consolidated Balance Sheets are categorized based upon the level of judgment associated with the inputs used to measure their value. Hierarchical levels, as defined below and directly related to the amount of subjectivity associated with the inputs to fair valuations of these assets and liabilities, are as follows:
	Level 1: Inputs are unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date. The types of assets carried at Level 1 fair value 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 March 31, 2015, 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 $2.26 to $3.84 per one million British thermal units) as an unobservable input. Level 3 options are valued through Black-Scholes (including forward start) option models which include option volatilities (ranging from 33% to 60%) 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 three months ended March 31, 2015, 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 March 31, 2015 and December 31, 2014, 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
		Active Markets			Observable			Unobservable		Adjustments (1)			as of
		for Identical Assets			Inputs			Inputs					31-Mar-15
		(Level 1)			(Level 2)			(Level 3)
		(in millions)
	Assets
	Corporate equities	$	915		$	—		$	—	$	—		$	915
	Investments, including money	32			—			—		—			32
	market funds (2)
	Natural gas derivatives	3			110			15		(11		)	117
	Total assets	$	950		$	110		$	15	$	(11	)	$	1,064
	Liabilities
	Indexed debt securities derivative	$	—		$	517		$	—	$	—		$	517
	Natural gas derivatives	15			65			2		(71		)	11
	Total liabilities	$	15		$	582		$	2	$	(71	)	$	528
	________________
	-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 $60 million posted with the same counterparties.
	-2	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.
		Quoted Prices in			Significant Other			Significant		Netting			Balance
		Active Markets			Observable			Unobservable		Adjustments (1)			as of
		for Identical Assets			Inputs			Inputs					31-Dec-14
		(Level 1)			(Level 2)			(Level 3)
		(in millions)
	Assets
	Corporate equities	$	932		$	—		$	—	$	—		$	932
	Investments, including money	54			—			—		—			54
	market funds (2)
	Natural gas derivatives	7			122			20		(18		)	131
	Total assets	$	993		$	122		$	20	$	(18	)	$	1,117
	Liabilities
	Indexed debt securities derivative	$	—		$	541		$	—	$	—		$	541
	Natural gas derivatives	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	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.
	The following table presents 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
		Three Months Ended March 31,
		2015			2014
		(in millions)
	Beginning balance	$	17		$	3
	Total losses	—			(2		)
	Total settlements	(3		)	1
	Transfers into Level 3	—			(1		)
	Transfers out of Level 3	(1		)	—
	Ending balance (1)	$	13		$	1
	The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	$	2		$	(2	)
	________________
	-1	CenterPoint Energy did not have significant Level 3 purchases or sales during either of the three months ended March 31, 2015 or 2014.
	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.
		March 31, 2015						December 31, 2014
		Carrying			Fair			Carrying		Fair
		Amount			Value			Amount		Value
	(in millions)
Financial assets:
Notes receivable - affiliated companies	$	363		$	364		$	363	$	362
Financial liabilities:
Long-term debt	$	8,418		$	9,275		$	8,652	$	9,427

Unconsolidated_Affiliates_Note

Unconsolidated Affiliates (Notes)	3 Months Ended
	Mar. 31, 2015
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. and ArcLight Capital Partners, LLC closed on the formation of Enable. CenterPoint Energy has the ability to significantly influence the operating and financial policies of Enable and, accordingly, accounts for its investment in Enable using the equity method of accounting.
	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 Condensed Consolidated Balance Sheet at March 31, 2015, 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 12, 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 $2 million during each of the three months ended March 31, 2015 and 2014 and had interest receivable from Enable of $6 million and $4 million as of March 31, 2015 and December 31, 2014, respectively, on its notes receivable.
	Effective on the Closing Date, CenterPoint Energy and Enable entered into a Services Agreement, Employee Transition Agreement, Transitional Seconding Agreement, and other agreements.  Under the Services Agreement, CenterPoint Energy agreed to provide certain support services to Enable such as accounting, legal, risk management and treasury functions for an initial term.  The initial term of the Services Agreement ends on April 30, 2016, after which date such services continue on a year-to-year basis unless terminated by Enable with at least 90 days’ notice.  Enable may terminate the Services Agreement, or the provision of any services thereunder, upon approval by its board of directors and at least 180 days’ notice.
	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 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.
	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 and (2) a 0.1% interest in SESH, which may be exercised no earlier than June 2015 for 25,341 common units in Enable.
	CenterPoint Energy billed Enable for reimbursement of transition services, including the costs of seconded employees, $5 million and $45 million during the three months ended March 31, 2015 and 2014, respectively, under the Transition Agreements for transition services. Actual transition services costs are recorded net of reimbursements received from Enable. CenterPoint Energy had accounts receivable from Enable of $3 million and $28 million as of March 31, 2015 and December 31, 2014, respectively, for amounts billed for transition services, including the cost of seconded employees.
	CenterPoint Energy incurred natural gas expenses, including transportation and storage costs, of $39 million and $47 million during the three months ended March 31, 2015 and 2014, respectively, for transactions with Enable. CenterPoint Energy had accounts payable to Enable of $11 million and $23 million at March 31, 2015 and December 31, 2014, respectively, from such transactions.
	As of March 31, 2015, 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.
	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, based on the excess of the carrying value over the best estimate of fair value of the investment, is recognized in earnings when an impairment is deemed to be other than temporary. Considerable judgment is used in determining if an impairment loss is other than temporary and the amount of any impairment. As of March 31, 2015, the carrying value of CenterPoint Energy’s investment in Enable was $19.24 per unit. On March 31, 2015, Enable’s common unit price closed at $16.40 (an aggregate of approximately $665 million below carrying value).
	Based on an analysis of its investment in Enable as of March 31, 2015, CenterPoint Energy believes that the decline in the value of its investment is temporary, and that the carrying value of its investment of $4.5 billion will be recovered. CenterPoint Energy considered the severity and duration of the impairment, management’s intent and ability to hold its investment to recovery, significant events and conditions of Enable, including its investment grade credit rating and planned expansion projects, along with other factors, to conclude that its investment is not other than temporarily impaired as of March 31, 2015.
	Investment in Unconsolidated Affiliates:
			March 31,			December 31, 2014
			2015
			(in millions)
	Enable		$	4,500		$	4,520
	SESH		1			1
	Total		$	4,501		$	4,521
	Equity in Earnings of Unconsolidated Affiliates, net:
			Three Months Ended March 31,
			2015			2014
			(in millions)
	Enable		$	52		$	88
	SESH		—			3
	Total		$	52		$	91
	Summarized unaudited consolidated income information for Enable is as follows:
			Three Months Ended March 31,
			2015			2014
			(in millions)
	Operating revenues		$	616		$	1,002
	Cost of sales, excluding depreciation and amortization		292			633
	Operating income		104			162
	Net income attributable to Enable		91			149
	CenterPoint Energy's interest		$	51		$	87
	Basis difference accretion		1			1
	CenterPoint Energy's equity in earnings, net		$	52		$	88
	Summarized unaudited consolidated balance sheet information for Enable is as follows:
			March 31,			December 31, 2014
			2015
			(in millions)
	Current assets		$	407		$	438
	Non-current assets		11,561			11,399
	Current liabilities		841			671
	Non-current liabilities		2,340			2,343
	Non-controlling interest		31			31
	Enable partners' capital		8,756			8,792
	CenterPoint Energy's ownership interest in Enable partners' capital		$	4,848		$	4,869
	CenterPoint Energy's basis difference attributable to goodwill (1)		(217		)	(217		)
	CenterPoint Energy's accretable basis difference (2)		(131		)	(132		)
	CenterPoint Energy's total basis difference		(348		)	(349		)
	CenterPoint Energy's investment in Enable		$	4,500		$	4,520
	-1	The difference relates to CenterPoint Energy’s proportionate share of Enable’s goodwill arising from its acquisition of Enogex LLC, 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.
	Distributions Received from Unconsolidated Affiliates:
			Three Months Ended March 31,
			2015			2014
			(in millions)
	Enable		$	72		$	67
	SESH		—			3
	Total		$	72		$	70

Goodwill

Goodwill	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets Disclosure [Text Block]	Goodwill
	Goodwill by reportable business segment as of both March 31, 2015 and December 31, 2014 is as follows (in millions):
	Natural Gas Distribution	$	746
	Energy Services	83
	Other Operations	11
	Total	$	840

Capital_Stock

Capital Stock	3 Months Ended
	Mar. 31, 2015
Class of Stock Disclosures [Abstract]
Capital Stock	Capital Stock
	CenterPoint Energy, Inc. 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. At March 31, 2015, 430,206,802 shares of CenterPoint Energy, Inc. common stock were issued and 430,206,636 shares were outstanding. At December 31, 2014, 429,795,996 shares of CenterPoint Energy, Inc. common stock were issued and 429,795,830 shares were outstanding. Outstanding common shares exclude 166 treasury shares at both March 31, 2015 and December 31, 2014.

ShortTerm_Borrowings_and_Longt

Short-Term Borrowings and Long-term Debt	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Short-term Borrowings and Long-term Debt [Text Block]	Short-term Borrowings and Long-term Debt
	(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 $-0- and $53 million as of March 31, 2015 and December 31, 2014, respectively.
	(b)	Long-term Debt
	Credit Facilities. As of March 31, 2015 and December 31, 2014, CenterPoint Energy, CenterPoint Houston and CERC Corp. had the following revolving credit facilities and utilization of such facilities (in millions):
				March 31, 2015						December 31, 2014
		Size of		Loans		Letters		Commercial		Loans		Letters		Commercial
		Facility				of Credit		Paper				of Credit		Paper
	CenterPoint Energy	$	1,200	$	—	$	6	$	157	$	—	$	6	$	191
	CenterPoint Houston	300		—		4		—		—		4		—
	CERC Corp.	600		—		—		279		—		—		341
	Total	$	2,100	$	—	$	10	$	436	$	—	$	10	$	532
	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 covenants as of March 31, 2015.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	The effective tax rate reported for both the three months ended March 31, 2015 and 2014 was 37%.
	CenterPoint Energy reported no uncertain tax liability as of March 31, 2015 and expects no significant change to the uncertain tax liability over the next twelve months.  Tax years through 2011 have been audited and settled with the Internal Revenue Service (IRS). The consolidated federal income tax returns for the years 2012 and 2013 are currently under audit by the IRS. For 2014 and 2015, CenterPoint Energy is a participant in the IRS’s Compliance Assurance Process.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
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 March 31, 2015 and December 31, 2014 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 March 31, 2015, minimum payment obligations for natural gas supply commitments are approximately $282 million for the remaining nine months in 2015, $471 million in 2016, $446 million in 2017, $400 million in 2018, $220 million in 2019 and $125 million after 2019.
	(b)	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. The Supreme Court heard arguments on January 12, 2015, and on April 21, 2015, affirmed the Ninth Circuit’s ruling and remanded the case to the district court for further proceedings. CenterPoint Energy and CES intend to continue vigorously defending against the plaintiffs’ claims on remand.  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 March 31, 2015, 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 $4 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 March 31, 2015, 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. 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.
	(c)	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 $40 million as of March 31, 2015.  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 March 31, 2015, 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	3 Months Ended
	Mar. 31, 2015
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:
		Three Months Ended March 31,
		2015		2014
		(in millions, except share and per share amounts)
	Net income	$	131	$	185
	Basic weighted average shares outstanding	429,955,000		429,163,000
	Plus: Incremental shares from assumed conversions:
	Restricted stock	1,228,000		1,396,000
	Diluted weighted average shares	431,183,000		430,559,000
	Basic earnings per share:
	Net income	$	0.3	$	0.43
	Diluted earnings per share:
	Net income	$	0.3	$	0.43

Reportable_Business_Segments

Reportable Business Segments	3 Months Ended
	Mar. 31, 2015
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.
	Financial data for business segments is as follows (in millions):
		For the Three Months Ended March 31, 2015
		Revenues from			Net			Operating		Total Assets as of March 31, 2015
		External			Intersegment			Income
		Customers			Revenues
	Electric Transmission & Distribution	$	612	(1)	$	—		$	96	$	9,788
	Natural Gas Distribution	1,185			8			146		5,335
	Energy Services	632			18			13		891
	Midstream Investments (2)	—			—			—		4,501
	Other Operations	4			—			1		3,153			(3)
	Eliminations	—			(26		)	—		(998		)
	Consolidated	$	2,433		$	—		$	256	$	22,670
		For the Three Months Ended March 31, 2014
		Revenues from			Net			Operating		Total Assets as of December 31, 2014
		External			Intersegment			Income
		Customers			Revenues
	Electric Transmission & Distribution	$	629	(1)	$	—		$	105	$	10,066
	Natural Gas Distribution	1,478			9			162		5,464
	Energy Services	1,052			32			26		978
	Midstream Investments (2)	—			—			—		4,521
	Other Operations	4			—			2		3,368			(3)
	Eliminations	—			(41		)	—		(1,197		)
	Consolidated	$	3,163		$	—		$	295	$	23,200
	________________
	-1	Sales to affiliates of NRG in the three months ended March 31, 2015 and 2014 represented approximately $184 million and $166 million, respectively, of CenterPoint Houston’s transmission and distribution revenues.  Sales to affiliates of Energy Future Holdings Corp. in the three months ended March 31, 2015 and 2014 represented approximately $52 million and $40 million, respectively, of CenterPoint Houston’s transmission and distribution revenues.
	-2	Midstream Investments reported equity earnings of $52 million from Enable and $-0- of equity earnings from CenterPoint Energy’s interest in SESH for the three months ended March 31, 2015. Midstream Investments reported equity earnings of $88 million from Enable and $3 million of equity earnings from CenterPoint Energy’s interest in SESH for the three months ended March 31, 2014. Included in total assets of Midstream Investments as of March 31, 2015 and December 31, 2014 is $4,500 million and $4,520 million, respectively, related to CenterPoint Energy’s investment in Enable and $1 million and $1 million, respectively, related to CenterPoint Energy’s retained interest in SESH.
	-3	Included in total assets of Other Operations as of March 31, 2015 and December 31, 2014 are pension and other postemployment related regulatory assets of $772 million and $795 million, respectively.

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events
	On April 23, 2015, CenterPoint Energy’s board of directors declared a regular quarterly cash dividend of $0.2475 per share of common stock payable on June 10, 2015, to shareholders of record as of the close of business on May 15, 2015.
	On April 24, 2015, Enable declared a quarterly cash distribution of $0.3125 per unit on all of its outstanding common and subordinated units for the quarter ended March 31, 2015. Accordingly, CERC Corp. expects to receive a cash distribution of approximately $73 million from Enable in the second quarter of 2015 to be made with respect to CERC Corp.’s limited partner interest in Enable for the first quarter of 2015.

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Schedule of Defined Benefit Plans Disclosures [Table Text Block]	CenterPoint Energy’s net periodic cost includes the following components relating to pension and postretirement benefits:
		Three Months Ended March 31,
		2015						2014
		Pension			Postretirement			Pension			Postretirement
		Benefits (1)			Benefits			Benefits (1)			Benefits
		(in millions)
	Service cost	$	10		$	1		$	10		$	—
	Interest cost	23			5			25			6
	Expected return on plan assets	(30		)	(2		)	(31		)	(2		)
	Amortization of prior service cost	3			—			3			—
	Amortization of net loss	14			1			11			—
	Amortization of transition obligation	—			—			—			1
	Settlement cost (2)	9			—			—			—
	Net periodic cost	$	29		$	5		$	18		$	5
	________________
	-1	Net periodic cost in these tables is before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes.
	-2	A one-time, non-cash settlement charge is required when lump sum distributions or other settlements of plan benefit obligations during a plan year exceed the service cost and interest cost components of net periodic cost for that year.  Due to the distribution of lump sum payments from the non-qualified pension plan during the three months ended March 31, 2015, CenterPoint Energy recognized a non-cash settlement charge of $9 million.  This charge is an acceleration of costs that would otherwise be recognized in future periods.  CenterPoint Energy will continue to recognize incremental settlement costs in subsequent quarters as additional lump sum distributions are made under the non-qualified pension plan.  CenterPoint Energy currently estimates the additional settlement costs in the remaining nine months of 2015 to total approximately $1 million.
	CenterPoint Energy's changes in accumulated comprehensive loss related to defined benefit and postretirement plans are as follows:
		Three Months Ended March 31,
		2015			2014
		Pension and Postretirement Plans
		(in millions)
	Beginning Balance	$	(85	)	$	(88	)
	Amounts reclassified from accumulated other comprehensive loss:
	Actuarial losses (1)	4			2
	Total reclassifications from accumulated other comprehensive loss	4			2
	Tax expense	(2		)	(1		)
	Net current period other comprehensive income	2			1
	Ending Balance	$	(83	)	$	(87	)
	________________
	-1	These components are included in the computation of net periodic cost.

Derivative_Instruments_Tables

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments
	Fair Value of Derivative Instruments
					March 31, 2015
	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)		Current Assets: Non-trading derivative assets		$	82			$	—
	Natural gas derivatives (1) (2)		Other Assets: Non-trading derivative assets		35				—
	Natural gas derivatives (1) (2)		Current Liabilities: Non-trading derivative liabilities		9				63
	Natural gas derivatives (1) (2)		Other Liabilities: Non-trading derivative liabilities		2				19
	Indexed debt securities derivative		Current Liabilities		—				517
	Total				$	128			$	599
	_____________
	-1	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 749 billion cubic feet (Bcf) or a net 126 Bcf long position.  Of the net long position, basis swaps constitute 125 Bcf.
	-2	Natural gas contracts are presented on a net basis in the Condensed 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 Condensed Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $106 million asset as shown on CenterPoint Energy’s Condensed 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 $60 million.
	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)		Current Assets: Non-trading derivative assets		$	101			$	1
	Natural gas derivatives (1) (2)		Other Assets: Non-trading derivative assets		32				—
	Natural gas derivatives (1) (2)		Current Liabilities: Non-trading derivative liabilities		14				83
	Natural gas derivatives (1) (2)		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 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 Condensed 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 Condensed Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $111 million asset as shown on CenterPoint Energy’s Condensed 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.
Offsetting of Natural Gas Derivative Assets and Liabilities
	Offsetting of Natural Gas Derivative Assets and Liabilities
			March 31, 2015
			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		$	91			$	(9	)		$	82
	Other Assets: Non-trading derivative assets		37				(2		)		35
	Current Liabilities: Non-trading derivative liabilities		(63		)		54				(9		)
	Other Liabilities: Non-trading derivative liabilities		(19		)		17				(2		)
	Total		$	46			$	60			$	106
	________________
	-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 Condensed 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, 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 Condensed 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	Realized and unrealized gains and losses on derivatives are recognized in the Condensed 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 Condensed Statements of Consolidated Income.
	Income Statement Impact of Derivative Activity
					Three Months Ended March 31,
	Total derivatives not designated		Income Statement Location		2015				2014
	as hedging instruments
					(in millions)
	Natural gas derivatives		Gains (Losses) in Revenues		$	(133	)		$	(101	)
	Natural gas derivatives (1)		Gains (Losses) in Expenses: Natural Gas		132				110
	Indexed debt securities derivative		Gains (Losses) in Other Income (Expense)		24				43
	Total				$	23			$	52
	________________
	-1	The Gains (Losses) in Expenses: Natural Gas includes $-0- and $2 million during the three months ended March 31, 2015 and 2014, respectively, related to physical forwards purchased from Enable.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
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 March 31, 2015 and December 31, 2014, 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
		Active Markets			Observable			Unobservable		Adjustments (1)			as of
		for Identical Assets			Inputs			Inputs					31-Mar-15
		(Level 1)			(Level 2)			(Level 3)
		(in millions)
	Assets
	Corporate equities	$	915		$	—		$	—	$	—		$	915
	Investments, including money	32			—			—		—			32
	market funds (2)
	Natural gas derivatives	3			110			15		(11		)	117
	Total assets	$	950		$	110		$	15	$	(11	)	$	1,064
	Liabilities
	Indexed debt securities derivative	$	—		$	517		$	—	$	—		$	517
	Natural gas derivatives	15			65			2		(71		)	11
	Total liabilities	$	15		$	582		$	2	$	(71	)	$	528
	________________
	-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 $60 million posted with the same counterparties.
	-2	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.
		Quoted Prices in			Significant Other			Significant		Netting			Balance
		Active Markets			Observable			Unobservable		Adjustments (1)			as of
		for Identical Assets			Inputs			Inputs					31-Dec-14
		(Level 1)			(Level 2)			(Level 3)
		(in millions)
	Assets
	Corporate equities	$	932		$	—		$	—	$	—		$	932
	Investments, including money	54			—			—		—			54
	market funds (2)
	Natural gas derivatives	7			122			20		(18		)	131
	Total assets	$	993		$	122		$	20	$	(18	)	$	1,117
	Liabilities
	Indexed debt securities derivative	$	—		$	541		$	—	$	—		$	541
	Natural gas derivatives	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	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.
Assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs	The following table presents 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
		Three Months Ended March 31,
		2015			2014
		(in millions)
	Beginning balance	$	17		$	3
	Total losses	—			(2		)
	Total settlements	(3		)	1
	Transfers into Level 3	—			(1		)
	Transfers out of Level 3	(1		)	—
	Ending balance (1)	$	13		$	1
	The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	$	2		$	(2	)
	________________
	-1	CenterPoint Energy did not have significant Level 3 purchases or sales during either of the three months ended March 31, 2015 or 2014.
Estimated fair value of financial instruments, debt instruments	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.
		March 31, 2015						December 31, 2014
		Carrying			Fair			Carrying		Fair
		Amount			Value			Amount		Value
		(in millions)
	Financial assets:
	Notes receivable - affiliated companies	$	363		$	364		$	363	$	362
	Financial liabilities:
	Long-term debt	$	8,418		$	9,275		$	8,652	$	9,427

Unconsolidated_Affiliates_Tabl

Unconsolidated Affiliates (Tables)	3 Months Ended
	Mar. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments [Table Text Block]	Investment in Unconsolidated Affiliates:
			March 31,			December 31, 2014
			2015
			(in millions)
	Enable		$	4,500		$	4,520
	SESH		1			1
	Total		$	4,501		$	4,521
	Equity in Earnings of Unconsolidated Affiliates, net:
			Three Months Ended March 31,
			2015			2014
			(in millions)
	Enable		$	52		$	88
	SESH		—			3
	Total		$	52		$	91
	Summarized unaudited consolidated income information for Enable is as follows:
			Three Months Ended March 31,
			2015			2014
			(in millions)
	Operating revenues		$	616		$	1,002
	Cost of sales, excluding depreciation and amortization		292			633
	Operating income		104			162
	Net income attributable to Enable		91			149
	CenterPoint Energy's interest		$	51		$	87
	Basis difference accretion		1			1
	CenterPoint Energy's equity in earnings, net		$	52		$	88
	Summarized unaudited consolidated balance sheet information for Enable is as follows:
			March 31,			December 31, 2014
			2015
			(in millions)
	Current assets		$	407		$	438
	Non-current assets		11,561			11,399
	Current liabilities		841			671
	Non-current liabilities		2,340			2,343
	Non-controlling interest		31			31
	Enable partners' capital		8,756			8,792
	CenterPoint Energy's ownership interest in Enable partners' capital		$	4,848		$	4,869
	CenterPoint Energy's basis difference attributable to goodwill (1)		(217		)	(217		)
	CenterPoint Energy's accretable basis difference (2)		(131		)	(132		)
	CenterPoint Energy's total basis difference		(348		)	(349		)
	CenterPoint Energy's investment in Enable		$	4,500		$	4,520
	-1	The difference relates to CenterPoint Energy’s proportionate share of Enable’s goodwill arising from its acquisition of Enogex LLC, 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.
	Distributions Received from Unconsolidated Affiliates:
			Three Months Ended March 31,
			2015			2014
			(in millions)
	Enable		$	72		$	67
	SESH		—			3
	Total		$	72		$	70

Goodwill_Tables

Goodwill (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	Goodwill by reportable business segment as of both March 31, 2015 and December 31, 2014 is as follows (in millions):
	Natural Gas Distribution	$	746
	Energy Services	83
	Other Operations	11
	Total	$	840

ShortTerm_Borrowings_and_Longt1

Short-Term Borrowings and Long-term Debt Credit Facilities (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule of Line of Credit Facilities [Table Text Block]	Credit Facilities. As of March 31, 2015 and December 31, 2014, CenterPoint Energy, CenterPoint Houston and CERC Corp. had the following revolving credit facilities and utilization of such facilities (in millions):
				March 31, 2015						December 31, 2014
		Size of		Loans		Letters		Commercial		Loans		Letters		Commercial
		Facility				of Credit		Paper				of Credit		Paper
	CenterPoint Energy	$	1,200	$	—	$	6	$	157	$	—	$	6	$	191
	CenterPoint Houston	300		—		4		—		—		4		—
	CERC Corp.	600		—		—		279		—		—		341
	Total	$	2,100	$	—	$	10	$	436	$	—	$	10	$	532

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table reconciles numerators and denominators of CenterPoint Energy’s basic and diluted earnings per share calculations:
		Three Months Ended March 31,
		2015		2014
		(in millions, except share and per share amounts)
	Net income	$	131	$	185
	Basic weighted average shares outstanding	429,955,000		429,163,000
	Plus: Incremental shares from assumed conversions:
	Restricted stock	1,228,000		1,396,000
	Diluted weighted average shares	431,183,000		430,559,000
	Basic earnings per share:
	Net income	$	0.3	$	0.43
	Diluted earnings per share:
	Net income	$	0.3	$	0.43

Reportable_Business_Segments_T

Reportable Business Segments (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Financial data for business segments is as follows (in millions):
		For the Three Months Ended March 31, 2015
		Revenues from			Net			Operating		Total Assets as of March 31, 2015
		External			Intersegment			Income
		Customers			Revenues
	Electric Transmission & Distribution	$	612	(1)	$	—		$	96	$	9,788
	Natural Gas Distribution	1,185			8			146		5,335
	Energy Services	632			18			13		891
	Midstream Investments (2)	—			—			—		4,501
	Other Operations	4			—			1		3,153			(3)
	Eliminations	—			(26		)	—		(998		)
	Consolidated	$	2,433		$	—		$	256	$	22,670
		For the Three Months Ended March 31, 2014
		Revenues from			Net			Operating		Total Assets as of December 31, 2014
		External			Intersegment			Income
		Customers			Revenues
	Electric Transmission & Distribution	$	629	(1)	$	—		$	105	$	10,066
	Natural Gas Distribution	1,478			9			162		5,464
	Energy Services	1,052			32			26		978
	Midstream Investments (2)	—			—			—		4,521
	Other Operations	4			—			2		3,368			(3)
	Eliminations	—			(41		)	—		(1,197		)
	Consolidated	$	3,163		$	—		$	295	$	23,200
	________________
	-1	Sales to affiliates of NRG in the three months ended March 31, 2015 and 2014 represented approximately $184 million and $166 million, respectively, of CenterPoint Houston’s transmission and distribution revenues.  Sales to affiliates of Energy Future Holdings Corp. in the three months ended March 31, 2015 and 2014 represented approximately $52 million and $40 million, respectively, of CenterPoint Houston’s transmission and distribution revenues.
	-2	Midstream Investments reported equity earnings of $52 million from Enable and $-0- of equity earnings from CenterPoint Energy’s interest in SESH for the three months ended March 31, 2015. Midstream Investments reported equity earnings of $88 million from Enable and $3 million of equity earnings from CenterPoint Energy’s interest in SESH for the three months ended March 31, 2014. Included in total assets of Midstream Investments as of March 31, 2015 and December 31, 2014 is $4,500 million and $4,520 million, respectively, related to CenterPoint Energy’s investment in Enable and $1 million and $1 million, respectively, related to CenterPoint Energy’s retained interest in SESH.
	-3	Included in total assets of Other Operations as of March 31, 2015 and December 31, 2014 are pension and other postemployment related regulatory assets of $772 million and $795 million, respectively.

Background_and_Basis_of_Presen1

Background and Basis of Presentation (Details) (Enable Midstream Partners [Member])	Mar. 31, 2015
Enable Midstream Partners [Member]
Equity Method Investment, Ownership Percentage	55.40%

Employee_Benefit_Plans_Details

Employee Benefit Plans (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Defined Benefit Plan, Change in Accumulated Comprehensive Loss [Roll Forward]
Beginning Balance	($85)		($88)
Amounts reclassified from accumulated other comprehensive loss:
Actuarial losses (1)	4	[1]	2	[1]
Total reclassifications from accumulated other comprehensive loss	4		2
Tax expense	-2		-1
Net current period other comprehensive income	2		1
Ending Balance	-83		-87
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	10	[2]	10	[2]
Interest cost	23	[2]	25	[2]
Expected return on plan assets	-30	[2]	-31	[2]
Amortization of prior service cost	3	[2]	3	[2]
Amortization of net loss	14	[2]	11	[2]
Amortization of transition obligation	0	[2]	0	[2]
Settlement cost (2)	9	[2],[3]	0	[2],[3]
Net periodic cost	29	[2]	18	[2]
Defined Benefit Plan, Additional Settlement Costs For Remainder of Year	1	[2],[3]
Total contributions to the plans during the period	23
Total contributions expected in 2014	66
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1		0
Interest cost	5		6
Expected return on plan assets	-2		-2
Amortization of prior service cost	0		0
Amortization of net loss	1		0
Amortization of transition obligation	0		1
Settlement cost (2)	0	[3]	0	[3]
Net periodic cost	5		5
Total contributions to the plans during the period	5
Total contributions expected in 2014	$17
[1]	These components are included in the computation of net periodic cost.
[2]	Net periodic cost in these tables is before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes.
[3]	A one-time, non-cash settlement charge is required when lump sum distributions or other settlements of plan benefit obligations during a plan year exceed the service cost and interest cost components of net periodic cost for that year. Due to the distribution of lump sum payments from the non-qualified pension plan during the three months ended March 31, 2015, CenterPoint Energy recognized a non-cash settlement charge of $9 million. This charge is an acceleration of costs that would otherwise be recognized in future periods. CenterPoint Energy will continue to recognize incremental settlement costs in subsequent quarters as additional lump sum distributions are made under the non-qualified pension plan. CenterPoint Energy currently estimates the additional settlement costs in the remaining nine months of 2015 to total approximately $1 million.

Regulatory_Accounting_Details

Regulatory Accounting (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Amount of allowed equity return on the true-up balance that has not been recognized	$433
Amount of allowed equity return on the true-up balance that was recognized in the period	$9	$15

Derivative_Instruments_Derivat

Derivative Instruments Derivatives and hedging (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivatives, Fair Value [Line Items]
Weather Hedges Term	10
Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	($10)	($8)
2014To2015 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather Hedge, Bilateral Cap Amount	8
2014To2015 [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather Hedge, Bilateral Cap Amount	16
2013To2014 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather Hedge, Bilateral Cap Amount	8
2013To2014 [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather Hedge, Bilateral Cap Amount	$16

Derivative_Fair_Values_Details

Derivative Fair Values (Details) (USD $)	3 Months Ended				12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
					MMcf
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Asset, Fair Value	$128				$149
Indexed debt securities derivative	599				643
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	23		52
Derivative, Fair Value, Net [Abstract]
Total fair value of the derivative instruments that contain credit risk contingent features that are in a net liability position	3				2
The aggregate fair value of assets already posted as collateral	1				1
Credit Risk Contingent Features assets	3				2
Natural gas derivatives [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative, Nonmonetary Notional Amount, Volume	749,000				804,000
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	46	[1]			47	[1]
Gross amounts offset, Net	60				64
Net Amount Presented in the Consolidated Balance Sheets	106	[2]			111	[2]
Collateral Netting	60				64
Natural gas derivatives [Member] | Gains (Losses) in Revenue [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-133		-101
Natural gas derivatives [Member] | Gains (Losses) in Expense: Natural Gas [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	132	[3]	110	[3]
Natural gas derivatives [Member] | Current Assets [Member]
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	91	[1]			115	[1]
Gross amounts offset	-9				-16
Derivative Asset	82	[2]			99	[2]
Natural gas derivatives [Member] | Other Assets [Member]
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	37	[1]			34	[1]
Gross amounts offset	-2				-2
Derivative Asset	35	[2]			32	[2]
Natural gas derivatives [Member] | Current Liabilities [Member]
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	-63	[1]			-84	[1]
Gross amounts offset	54				65
Derivative Liability	-9	[2]			-19	[2]
Natural gas derivatives [Member] | Other Liabilities [Member]
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	-19	[1]			-18	[1]
Gross amounts offset	17				17
Derivative Liability	-2	[2]			-1	[2]
Indexed debt securities derivative | Gains (losses) in Other Income (Expense) [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	24		43
Not Designated as Hedging Instrument [Member] | Natural gas derivatives [Member] | Current Assets [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Asset, Fair Value	82	[4],[5]			101	[6],[7]
Indexed debt securities derivative	0	[4],[5]			1	[6],[7]
Not Designated as Hedging Instrument [Member] | Natural gas derivatives [Member] | Other Assets [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Asset, Fair Value	35	[4],[5]			32	[6],[7]
Indexed debt securities derivative	0	[4],[5]			0	[6],[7]
Not Designated as Hedging Instrument [Member] | Natural gas derivatives [Member] | Current Liabilities [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Asset, Fair Value	9	[4],[5]			14	[6],[7]
Indexed debt securities derivative	63	[4],[5]			83	[6],[7]
Not Designated as Hedging Instrument [Member] | Natural gas derivatives [Member] | Other Liabilities [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Asset, Fair Value	2	[4],[5]			2	[6],[7]
Indexed debt securities derivative	19	[4],[5]			18	[6],[7]
Not Designated as Hedging Instrument [Member] | Indexed debt securities derivative | Current Liabilities [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Asset, Fair Value	0				0
Indexed debt securities derivative	517				541
Long [Member] | Natural gas derivatives [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative, Nonmonetary Notional Amount, Volume	126,000				60,000
Swap [Member] | Long [Member] | Natural gas derivatives [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative, Nonmonetary Notional Amount, Volume	125,000				127,000
Enable Midstream Partners [Member] | Forward Contracts [Member] | Natural gas derivatives [Member] | Gains (Losses) in Expense: Natural Gas [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$0		$2
[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 Condensed 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.
[3]	The Gains (Losses) in Expenses: Natural Gas includes $-0- and $2 million during the three months ended March 31, 2015 and 2014, respectively, related to physical forwards purchased from Enable.
[4]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 749 billion cubic feet (Bcf) or a net 126 Bcf long position. Of the net long position, basis swaps constitute 125 Bcf.
[5]	Natural gas contracts are presented on a net basis in the Condensed 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 Condensed Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $106 million asset as shown on CenterPoint Energy’s Condensed 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 $60 million
[6]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 804 Bcf or a net 60 Bcf long position. Of the net long position, basis swaps constitute 127 Bcf.
[7]	Natural gas contracts are presented on a net basis in the Condensed 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 Condensed Consolidated Balance Sheets. The net of total non-trading derivative assets and liabilities was a $111 million asset as shown on CenterPoint Energy’s Condensed 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

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
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
Natural gas derivatives, netting adjustment	-11,000,000	[1]			-18,000,000	[2]
Total assets	1,064,000,000				1,117,000,000
Liabilities
Natural gas derivatives, netting adjustment	-71,000,000	[1]			-82,000,000	[2]
Total liabilities	528,000,000				561,000,000
Cash collateral posted with counterparties	60,000,000				64,000,000
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	17,000,000		3,000,000
Total losses	0		-2,000,000
Total settlements	-3,000,000		1,000,000
Transfers into Level 3	0		-1,000,000
Transfers out of Level 3	-1,000,000		0
Ending balance (1)	13,000,000	[3]	1,000,000	[3]
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	2,000,000		-2,000,000
Fair Value, Inputs, Level 1 [Member]
Assets
Total assets	950,000,000				993,000,000
Liabilities
Total liabilities	15,000,000				22,000,000
Fair Value, Inputs, Level 2 [Member]
Assets
Total assets	110,000,000				122,000,000
Liabilities
Total liabilities	582,000,000				618,000,000
Fair Value, Inputs, Level 3 [Member]
Assets
Total assets	15,000,000				20,000,000
Liabilities
Total liabilities	2,000,000				3,000,000
Forward Contracts [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair Value Inputs, Price Per MMBtu	2.26
Forward Contracts [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair Value Inputs, Price Per MMBtu	3.84
Options Held [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair Value Assumptions, Expected Volatility Rate	33.00%
Options Held [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair Value Assumptions, Expected Volatility Rate	60.00%
Estimate of Fair Value Measurement [Member]
Estimated Fair Value of Financial Instruments
Notes Receivable, Fair Value Disclosure	364,000,000				362,000,000
Long-term Debt	9,275,000,000				9,427,000,000
Reported Value Measurement [Member]
Estimated Fair Value of Financial Instruments
Notes Receivable, Fair Value Disclosure	363,000,000				363,000,000
Long-term Debt	8,418,000,000				8,652,000,000
Fair Value, Measurements, Recurring [Member]
Assets
Corporate equities	915,000,000				932,000,000
Investments, including money market funds (2)	32,000,000	[4]			54,000,000	[4]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Corporate equities	915,000,000				932,000,000
Investments, including money market funds (2)	32,000,000	[4]			54,000,000	[4]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Corporate equities	0				0
Investments, including money market funds (2)	0	[4]			0	[4]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Corporate equities	0				0
Investments, including money market funds (2)	0	[4]			0	[4]
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member]
Assets
Natural gas derivatives, netting adjustment	-11,000,000	[1]			-18,000,000	[2]
Derivative Asset	117,000,000				131,000,000
Liabilities
Natural gas derivatives, netting adjustment	-71,000,000	[1]			-82,000,000	[2]
Derivative Liabilities	11,000,000				20,000,000
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Natural gas derivatives	3,000,000				7,000,000
Liabilities
Derivative Liability, Fair Value	15,000,000				22,000,000
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Natural gas derivatives	110,000,000				122,000,000
Liabilities
Derivative Liability, Fair Value	65,000,000				77,000,000
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Natural gas derivatives	15,000,000				20,000,000
Liabilities
Derivative Liability, Fair Value	2,000,000				3,000,000
Fair Value, Measurements, Recurring [Member] | IDS Derivative [Member]
Liabilities
Natural gas derivatives, netting adjustment	0				0
Derivative Liabilities	517,000,000				541,000,000
Fair Value, Measurements, Recurring [Member] | IDS Derivative [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities
Derivative Liability, Fair Value	0				0
Fair Value, Measurements, Recurring [Member] | IDS Derivative [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities
Derivative Liability, Fair Value	517,000,000				541,000,000
Fair Value, Measurements, Recurring [Member] | IDS Derivative [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities
Derivative Liability, Fair Value	$0				$0
[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 $60 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 $64 million posted with the same counterparties.
[3]	CenterPoint Energy did not have significant Level 3 purchases or sales during either of the three months ended March 31, 2015 or 2014.
[4]	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.

Unconsolidated_Affiliates_Deta

Unconsolidated Affiliates (Details) (USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	30-May-14	Jun. 01, 2015
Investment in unconsolidated affiliates	$4,501		$4,521
Southeast Supply Header LLC [Member]
Equity Method Investment, Ownership Percentage	0.10%	25.05%
Equity Method Investment, Contributed Ownership Percentage				24.95%
Investment in unconsolidated affiliates	1		1
Enable Midstream Partners [Member]
Equity Method Investment, Ownership Percentage	55.40%
Equity Method Investment, Carrying Value Per Unit	$19.24
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	665
Investment in unconsolidated affiliates	4,500		4,520
Enable Midstream Partners [Member]
Sale of Stock, Price Per Share	$16.40
Common Stock [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares	94,126,366
Subordinated Units [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares	139,704,916
Enable Midstream Partners [Member]
Indebtedness to CERC	363
Interest Income (Expense), Net	2	2
Interest Receivable	6		4
Enable Guaranteed Senior Notes [Member] | CERC Corp [Member]
Enable Senior Notes Due 2019 and 2024	1,100
Transitional Service [Member] | Enable Midstream Partners [Member]
Reimbursement for Transitional Services	5	45
Transitional Service cost receivable	3		28
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Cost of natural gas purchases, affiliates	39	47
Due to Affiliate	11		23
Subsequent Event [Member] | Common Stock [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares					25,341
Enable Midstream Partners [Member] | Enable Guaranteed Senior Notes [Member] | CERC Corp [Member]
Enable Senior Notes Due 2019 and 2024	$1,100
Indebtedness to CERC Corp. [Member] | Enable Midstream Partners [Member]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	2.10%
Debt Instrument, Interest Rate, Stated Percentage	2.45%

Unconsolidated_Affiliates_Fina

Unconsolidated Affiliates Financial data (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Investment in unconsolidated affiliates	$4,501		$4,521
Equity in earnings of unconsolidated affiliates, net	52	91
CenterPoint Energy's ownership interest in Enable partners' capital	4,848		4,869
CenterPoint Energy's basis difference attributable to goodwill (1)	-217		-217
CenterPoint Energy's accretable basis difference (2)	-131		-132
CenterPoint Energy's total basis difference	-348		-349
CenterPoint Energy's investment in Enable	4,500		4,520
Proceeds from Equity Method Investment, Dividends or Distributions	72	70
Southeast Supply Header LLC [Member]
Investment in unconsolidated affiliates	1		1
Equity in earnings of unconsolidated affiliates, net	0	3
Proceeds from Equity Method Investment, Dividends or Distributions	0	3
Enable Midstream Partners [Member]
Investment in unconsolidated affiliates	4,500		4,520
Equity in earnings of unconsolidated affiliates, net	52	88
Operating revenues	616	1,002
Cost of sales, excluding depreciation and amortization	292	633
Operating income	104	162
Net income attributable to Enable	91	149
CenterPoint Energy's approximate interest	51	87
Basis difference accretion	1	1
CenterPoint Energy's equity in earnings, net	52	88
Current assets	407		438
Non-current assets	11,561		11,399
Current liabilities	841		671
Non-current liabilities	2,340		2,343
Non-controlling interest	31		31
Enable partners' capital	8,756		8,792
Proceeds from Equity Method Investment, Dividends or Distributions	$72	$67

Goodwill_Details

Goodwill (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Goodwill [Line Items]
Goodwill	$840	$840
Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill	746	746
Energy Services [Member]
Goodwill [Line Items]
Goodwill	83	83
Corporate and Other [Member]
Goodwill [Line Items]
Goodwill	$11	$11

Capital_Stock_Details

Capital Stock (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Capital stock shares authorized (in shares)	1,020,000,000
Common stock shares authorized (in shares)	1,000,000,000
Common stock shares par value (in dollars per share)	$0.01
Cumulative preferred stock shares authorized (in shares)	20,000,000
Cumulative preferred stock par value (in dollars per share)	$0.01
Total common stock issued (in shares)	430,206,802	429,795,996
Total common stock outstanding (in shares)	430,206,636	429,795,830
Treasury stock (in shares)	166	166

ShortTerm_Borrowings_and_Longt2

Short-Term Borrowings and Long-term Debt (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Total short term borrowings	$0	$53
Credit Facilities [Abstract]
Total credit facility amount	2,100	2,100
Parent Company [Member]
Credit Facilities [Abstract]
Total credit facility amount	1,200	1,200
CenterPoint Houston [Member]
Credit Facilities [Abstract]
Total credit facility amount	300	300
CERC Corp [Member]
Credit Facilities [Abstract]
Total credit facility amount	600	600
Revolving Credit Facility [Member]
Credit Facilities [Abstract]
Amounts Outstanding	0	0
Revolving Credit Facility [Member] | Parent Company [Member]
Credit Facilities [Abstract]
Amounts Outstanding	0	0
Revolving Credit Facility [Member] | CenterPoint Houston [Member]
Credit Facilities [Abstract]
Amounts Outstanding	0	0
Revolving Credit Facility [Member] | CERC Corp [Member]
Credit Facilities [Abstract]
Amounts Outstanding	0	0
Line of Credit [Member] | Parent Company [Member]
Credit Facilities [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
Consecutive Period for System Restoration Costs to Exceed $100 million (in months)	12
Line of Credit [Member] | Parent Company [Member] | London Interbank Offered Rate (LIBOR) [Member]
Credit Facilities [Abstract]
Basis Spread on LIBOR	1.25%
Line of Credit [Member] | CenterPoint Houston [Member]
Credit Facilities [Abstract]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Line of Credit [Member] | CenterPoint Houston [Member] | London Interbank Offered Rate (LIBOR) [Member]
Credit Facilities [Abstract]
Basis Spread on LIBOR	1.13%
Line of Credit [Member] | CERC Corp [Member]
Credit Facilities [Abstract]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Line of Credit [Member] | CERC Corp [Member] | London Interbank Offered Rate (LIBOR) [Member]
Credit Facilities [Abstract]
Basis Spread on LIBOR	1.50%
Letter of Credit [Member]
Credit Facilities [Abstract]
Amounts Outstanding	10	10
Letter of Credit [Member] | Parent Company [Member]
Credit Facilities [Abstract]
Amounts Outstanding	6	6
Letter of Credit [Member] | CenterPoint Houston [Member]
Credit Facilities [Abstract]
Amounts Outstanding	4	4
Letter of Credit [Member] | CERC Corp [Member]
Credit Facilities [Abstract]
Amounts Outstanding	0	0
Commercial Paper [Member]
Credit Facilities [Abstract]
Amounts Outstanding	436	532
Commercial Paper [Member] | Parent Company [Member]
Credit Facilities [Abstract]
Amounts Outstanding	157	191
Commercial Paper [Member] | CenterPoint Houston [Member]
Credit Facilities [Abstract]
Amounts Outstanding	0	0
Commercial Paper [Member] | CERC Corp [Member]
Credit Facilities [Abstract]
Amounts Outstanding	279	341
Product Financing Arrangement [Member]
Short-term Debt [Line Items]
Total short term borrowings	$0	$53

Income_Taxes_Details

Income Taxes (Details)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Effective Income Tax Rate Reconciliation, Percent	37.00%	37.00%

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
GenOn Demand Charges Transportation Contracts [Member] | CERC Corp [Member]
Guarantees
Approximate amount of undiscounted maximum obligation under guarantee	$40
CenterPoint Midstream Guarantees [Member]
Guarantees
Approximate amount of undiscounted maximum obligation under guarantee	100
Enable Guaranteed Senior Notes [Member] | CERC Corp [Member]
Guarantees
Approximate amount of undiscounted maximum obligation under guarantee	1,100
Natural Gas Supply Commitments [Member]
Natural Gas Supply Commitments
2015	282
2016	471
2017	446
2018	400
2019	220
After 2019	125
Gas Market Manipulation Cases [Member]
Legal Matters
Loss Contingency, Pending Claims, Number	1
Minnesota Service Territory [Member] | CERC Corp [Member]
Environmental Matters
Number of MGP sites in the Minnesota service territory (in number of sites)	7
Number of MGP sites in the Minnesota service territory where the company believes it has no liability (in number of sites)	2
Number of MGP sites where remediation is complete, other than ongoing operations (in number of sites)	2
Liability recorded for remediation of Minnesota sites	7
Amount collected from insurance companies to be used for future environmental remediation	4
Minnesota Service Territory [Member] | CERC Corp [Member] | Minimum [Member]
Environmental Matters
Minimum estimated remediation costs for the Minnesota sites	4
Years of remediation for the Minnesota sites (in years)	30
Minnesota Service Territory [Member] | CERC Corp [Member] | Maximum [Member]
Environmental Matters
Minimum estimated remediation costs for the Minnesota sites	$29
Years of remediation for the Minnesota sites (in years)	50

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net income	$131	$185
Basic weighted average shares outstanding	429,955,000	429,163,000
Plus: Incremental shares from assumed conversions:
Diluted weighted average shares	431,183,000	430,559,000
Basic earnings per share:
Net income	$0.30	$0.43
Diluted earnings per share:
Net income	$0.30	$0.43
Restricted Stock [Member]
Plus: Incremental shares from assumed conversions:
Incremental shares from assumed conversions	1,228,000	1,396,000

Reportable_Business_Segments_D

Reportable Business Segments (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$2,433		$3,163
Operating Income (Loss)	256		295
Assets	22,670				23,200
Equity in earnings of unconsolidated affiliates, net	52		91
Investment in unconsolidated affiliates	4,501				4,521
Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Revenues	612	[1]	629	[1]
Operating Income (Loss)	96		105
Electric Transmission and Distribution [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues	184		166
Electric Transmission and Distribution [Member] | Affiliates of Energy Future Holdings Corp. [Member]
Segment Reporting Information [Line Items]
Revenues	52		40
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues	1,185		1,478
Operating Income (Loss)	146		162
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues	632		1,052
Operating Income (Loss)	13		26
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	0	[2]	0	[2]
Operating Income (Loss)	0	[2]	0	[2]
Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues	4		4
Operating Income (Loss)	1		2
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	-26		-41
Assets	-998				-1,197
Intersegment Eliminations [Member] | Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Revenues	0		0
Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues	-8		-9
Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues	-18		-32
Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	0	[2]	0	[2]
Intersegment Eliminations [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues	0		0
Operating Segments [Member] | Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Assets	9,788				10,066
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets	5,335				5,464
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets	891				978
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets	4,501	[2]			4,521	[2]
Operating Segments [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Assets	3,153	[3]			3,368	[3]
Southeast Supply Header LLC [Member]
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated affiliates, net	0		3
Investment in unconsolidated affiliates	1				1
Southeast Supply Header LLC [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated affiliates, net	0		3
Investment in unconsolidated affiliates	1				1
Enable Midstream Partners [Member]
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated affiliates, net	52		88
Investment in unconsolidated affiliates	4,500				4,520
Enable Midstream Partners [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated affiliates, net	52		88
Investment in unconsolidated affiliates	4,500				4,520
Pension and Other Postretirement Plans Costs [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Regulatory Assets	$772				$795
[1]	Sales to affiliates of NRG in the three months ended March 31, 2015 and 2014 represented approximately $184 million and $166 million, respectively, of CenterPoint Houston’s transmission and distribution revenues. Sales to affiliates of Energy Future Holdings Corp. in the three months ended March 31, 2015 and 2014 represented approximately $52 million and $40 million, respectively, of CenterPoint Houston’s transmission and distribution revenues.
[2]	Midstream Investments reported equity earnings of $52 million from Enable and $-0- of equity earnings from CenterPoint Energy’s interest in SESH for the three months ended March 31, 2015. Midstream Investments reported equity earnings of $88 million from Enable and $3 million of equity earnings from CenterPoint Energy’s interest in SESH for the three months ended March 31, 2014. Included in total assets of Midstream Investments as of March 31, 2015 and December 31, 2014 is $4,500 million and $4,520 million, respectively, related to CenterPoint Energy’s investment in Enable and $1 million and $1 million, respectively, related to CenterPoint Energy’s retained interest in SESH.
[3]	Included in total assets of Other Operations as of March 31, 2015 and December 31, 2014 are pension and other postemployment related regulatory assets of $772 million and $795 million, respectively.

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	3 Months Ended		0 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Apr. 23, 2015	Apr. 24, 2015
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Declared	$0.25	$0.24
Proceeds from Equity Method Investment, Dividends or Distributions	$72	$70
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared			23-Apr-15
Common Stock, Dividends, Per Share, Declared			$0.25
Dividends Payable, Date to be Paid, Day, Month and Year			10-Jun-15
Dividends Payable, Date of Record, Day, Month and Year			15-May-15
Enable Midstream Partners [Member]
Subsequent Event [Line Items]
Proceeds from Equity Method Investment, Dividends or Distributions	72	67
Enable Midstream Partners [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared				24-Apr-15
Common Stock, Dividends, Per Share, Declared				$0.31
Proceeds from Equity Method Investment, Dividends or Distributions				$73