CenterPoint Energy (CNP) 10-Q 10 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Supplementa

Document and Entity Supplemental Information Document - USD ($)	3 Months Ended
	Mar. 31, 2016	Apr. 20, 2016	Jun. 30, 2015
Entity Information [Line Items]
Entity Registrant Name	CENTERPOINT ENERGY INC.
Entity Central Index Key	1,130,310
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		430,619,432
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 8,146,639,191

Condensed Statements of Consoli

Condensed Statements of Consolidated Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Revenues	$ 1,984	$ 2,433
Expenses:
Natural gas	852	1,354
Operation and maintenance	521	498
Depreciation and amortization	260	217
Taxes other than income taxes	101	108
Total	1,734	2,177
Operating Income	250	256
Other Income (Expense):
Gain (loss) on marketable securities	90	(17)
Gain (loss) on indexed debt securities	(56)	24
Interest and other finance charges	(87)	(89)
Interest on securitization bonds	(24)	(28)
Equity in earnings of unconsolidated affiliate, net	60	52
Other, net	7	11
Total	(10)	(47)
Income Before Income Taxes	240	209
Income tax expense	86	78
Net Income	$ 154	$ 131
Basic Earnings Per Share	$ 0.36	$ 0.30
Diluted Earnings Per Share	0.36	0.30
Dividends Declared Per Share	$ 0.2575	$ 0.2475
Weighted Average Shares Outstanding, Basic	430,407,000	429,955,000
Weighted Average Shares Outstanding, Diluted	432,594,000	431,183,000

Condensed Statements of Consol3

Condensed Statements of Consolidated Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 154	$ 131
Other comprehensive income:
Adjustment related to pension and other postretirement plans (net of tax of $1 and $2)	1	2
Total	1	2
Comprehensive income	$ 155	$ 133

Comprehensive Income Parentheti

Comprehensive Income Parentheticals - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income, Pension and Other Postretirement Benefit Plans, Tax	$ 1	$ 2

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents ($205 and $264 related to VIEs, respectively)	$ 218	$ 264
Investment in marketable securities	894	805
Accounts receivable ($63 and $64 related to VIEs, respectively), less bad debt reserve of $25 and $20, respectively	577	593
Accrued unbilled revenues	207	279
Natural gas inventory	58	168
Materials and supplies	176	179
Non-trading derivative assets	75	89
Taxes receivable	3	172
Prepaid expenses and other current assets ($39 and $35 related to VIEs, respectively)	127	140
Total current assets	2,335	2,689
Property, Plant and Equipment:
Property, plant and equipment	16,900	16,650
Less: accumulated depreciation and amortization	5,182	5,113
Property, plant and equipment, net	11,718	11,537
Other Assets:
Goodwill	840	840
Regulatory assets ($2,279 and $2,373 related to VIEs, respectively)	3,031	3,129
Notes receivable – unconsolidated affiliate	0	363
Non-trading derivative assets	28	36
Investment in unconsolidated affiliate	2,580	2,594
Preferred units – unconsolidated affiliate	363	0
Other	109	102
Total other assets	6,951	7,064
Total Assets	21,004	21,290
Current Liabilities:
Short-term borrowings	0	40
Current portion of VIE securitization bonds long-term debt	400	391
Indexed debt	148	145
Current portion of other long-term debt	576	328
Indexed debt securities derivative	498	442
Accounts payable	378	483
Taxes accrued	101	158
Interest accrued	108	117
Non-trading derivative liabilities	8	11
Other	317	343
Total current liabilities	2,534	2,458
Other Liabilities:
Deferred income taxes, net	5,116	5,047
Non-trading derivative liabilities	3	5
Benefit obligations	909	904
Regulatory liabilities	1,306	1,276
Other	276	273
Total other liabilities	7,610	7,505
Long-term Debt:
VIE securitization bonds	2,122	2,276
Other long-term debt	5,232	5,590
Total long-term debt	$ 7,354	$ 7,866
Commitments and Contingencies (Note 13)
Shareholders’ Equity:
Common stock (430,614,900 shares and 430,262,703 shares outstanding, respectively)	$ 4	$ 4
Additional paid-in capital	4,180	4,180
Accumulated deficit	(613)	(657)
Accumulated other comprehensive loss	(65)	(66)
Total shareholders’ equity	3,506	3,461
Total Liabilities and Shareholders’ Equity	$ 21,004	$ 21,290

Balance Sheets Parentheticals

Balance Sheets Parentheticals - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Cash and cash equivalents	$ 218	$ 264
Bad Debt Reserve	25	20
Accounts receivable, net	577	593
Prepaid expenses and other current assets	127	140
Regulatory assets	$ 3,031	$ 3,129
Total common stock outstanding (in shares)	430,614,900	430,262,703
Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents	$ 205	$ 264
Accounts receivable, net	63	64
Prepaid expenses and other current assets	39	35
Regulatory assets	$ 2,279	$ 2,373

Condensed Statements of Consol7

Condensed Statements of Consolidated Cash Flow Statement - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net income	$ 154	$ 131
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	260	217
Amortization of deferred financing costs	6	7
Deferred income taxes	65	7
Unrealized loss (gain) on marketable securities	(90)	17
Loss (gain) on indexed debt securities	56	(24)
Write-down of natural gas inventory	1	2
Equity in (earnings) losses of unconsolidated affiliate, net of distributions	(60)	20
Pension contributions	(3)	(23)
Changes in other assets and liabilities:
Accounts receivable and unbilled revenues, net	67	57
Inventory	112	179
Taxes receivable	169	190
Accounts payable	(82)	(208)
Fuel cost recovery	(3)	86
Non-trading derivatives, net	8	1
Margin deposits, net	27	(4)
Interest and taxes accrued	(66)	(27)
Net regulatory assets and liabilities	2	58
Other current assets	2	17
Other current liabilities	(2)	(41)
Other assets	0	6
Other liabilities	8	(1)
Other, net	3	(1)
Net cash provided by operating activities	634	666
Cash Flows from Investing Activities:
Capital expenditures	(332)	(341)
Decrease in notes receivable – unconsolidated affiliate	363	0
Investment in preferred units – unconsolidated affiliate	(363)	0
Distributions from unconsolidated affiliate in excess of cumulative earnings	74	0
Decrease (increase) in restricted cash of Bond Companies	(4)	5
Other, net	(7)	(1)
Net cash used in investing activities	(269)	(337)
Cash Flows from Financing Activities:
Decrease in short-term borrowings, net	(40)	(53)
Payments of commercial paper, net	(111)	(96)
Payments of long-term debt	(147)	(139)
Debt issuance costs	(4)	0
Payment of common stock dividends	(110)	(106)
Other, net	1	1
Net cash used in financing activities	(411)	(393)
Net Decrease in Cash and Cash Equivalents	(46)	(64)
Cash and Cash Equivalents at Beginning of Period	264	298
Cash and Cash Equivalents at End of Period	218	234
Cash Payments:
Interest, net of capitalized interest	113	115
Income tax refunds, net	(158)	(166)
Non-cash transactions:
Accounts payable related to capital expenditures	$ 72	$ 72

Background and Basis of Present

Background and Basis of Presentation	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation	Background and Basis of Presentation General. Included in this Form 10-Q are the Interim Condensed Financial Statements of CenterPoint Energy. The Interim Condensed Financial Statements are unaudited, omit certain financial statement disclosures and should be read with the 2015 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 both CenterPoint Energy and its operating subsidiaries own interests in Enable as described in Note 7 . As of March 31, 2016 , CenterPoint Energy’s indirect, wholly-owned subsidiaries included: • Houston Electric, which engages in the electric transmission and distribution business in the Texas Gulf Coast area that includes the city of Houston; and • CERC Corp. (together with its subsidiaries), 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, 2016 , 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, 2016 , CenterPoint Energy had VIEs consisting of 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 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 15 .

New Accounting Pronouncements

New Accounting Pronouncements	3 Months Ended
	Mar. 31, 2016
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 FASB issued ASU 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 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. CenterPoint Energy adopted ASU 2015-02 on January 1, 2016, which CenterPoint Energy determined did not have a material impact on its financial position, results of operations, cash flows and disclosures. In April 2015, the FASB issued ASU 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 adopted ASU 2015-03 retrospectively on January 1, 2016, which resulted in a reduction of other long-term assets, indexed debt and total long-term debt on its Condensed Consolidated Balance Sheets. CenterPoint Energy had debt issuance costs, excluding amounts related to credit facility arrangements, of $42 million and $44 million as of March 31, 2016 and December 31, 2015, respectively. In May 2015, the FASB issued ASU No. 2015-07, Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent) (ASU 2015-07). ASU 2015-07 removes the requirement to categorize within the fair value hierarchy investments for which fair values are measured at NAV using the practical expedient. Entities will be required to disclose the fair value of investments measured using the NAV practical expedient so that financial statement users can reconcile amounts reported in the fair value hierarchy table to amounts reported on the balance sheet. CenterPoint Energy adopted ASU 2015-07 on January 1, 2016, which will have an impact on its employee benefit plan disclosures, beginning with its annual report on Form 10-K for the year ended December 31, 2016. This standard did not have an impact on CenterPoint Energy’s financial position, results of operations or cash flows. In September 2015, the FASB issued ASU No. 2015-16, Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments (ASU 2015-16). ASU 2015-16 eliminates the requirement for an acquirer in a business combination to account for measurement-period adjustments retrospectively. Instead, an acquirer would recognize a measurement-period adjustment during the period in which the amount of the adjustment is determined. CenterPoint Energy adopted ASU 2015-16 on January 1, 2016, which did not have an impact on its financial position, results of operations or cash flows. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01). ASU 2016-01 requires equity investments that do not result in consolidation and are not accounted for under the equity method to be measured at fair value and to recognize any changes in fair value in net income unless the investments qualify for the new practicability exception. It does not change the guidance for classifying and measuring investments in debt securities and loans. ASU 2016-01 also changes certain disclosure requirements and other aspects related to recognition and measurement of financial assets and financial liabilities. ASU 2016-01 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. CenterPoint Energy is currently assessing the impact that this standard will have on its financial position, results of operations, cash flows and disclosures. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 provides a comprehensive new lease model that requires lessees to recognize assets and liabilities for most leases and would change certain aspects of lessor accounting. ASU 2016-02 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. CenterPoint Energy is currently assessing the impact that this standard will have on its financial position, results of operations, cash flows and disclosures. In March 2016, the FASB issued ASU No. 2016-05, Derivatives and Hedging (Topic 815): Effect of Derivative Contract Novation on Existing Hedge Accounting Relationships (ASU 2016-05). ASU 2016-05 clarifies that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument in an existing hedging relationship would not, in and of itself, be considered a termination of the derivative instrument or a change in a critical term of the hedging relationship. This clarification applies to both cash flow and fair value hedging relationships. CenterPoint Energy adopted ASU 2016-05 prospectively in the first quarter of 2016, which did not have an impact on its financial position, results of operations, cash flows and disclosures. In March and April 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (ASU 2016-08) and ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing (ASU 2016-10), respectively . ASU 2016-08 and ASU 2016-10 clarify certain aspects of ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09), which supersedes most current revenue recognition guidance. CenterPoint Energy is currently evaluating the impact that ASU 2016-08, ASU 2016-10, and ASU 2014-09 will have on its financial position, results of operations, cash flows and disclosures and expects to adopt the three ASUs on January 1, 2018. In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). ASU 2016-09 will change the accounting for certain aspects of share-based payments to employees, including the recognition of income tax effects of vested or settled awards in the income statement, instead of within additional paid in capital. It will also increase the amount an employer can withhold to cover income taxes on awards and still qualify for the exception to liability classification for shares used to satisfy the employer’s statutory income tax withholding obligations. ASU 2016-09 will allow companies to elect between two different methods to account for forfeitures of share-based payments. ASU 2016-09 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016, with early adoption permitted. CenterPoint Energy 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, 2016
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, 2016 2015 Pension Postretirement Pension Postretirement (in millions) Service cost $ 9 $ 1 $ 10 $ 1 Interest cost 23 4 23 5 Expected return on plan assets (25 ) (2 ) (30 ) (2 ) Amortization of prior service cost 2 — 3 — Amortization of net loss 16 — 14 1 Settlement cost (2) — — 9 — Net periodic cost $ 25 $ 3 $ 29 $ 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 amount of lump sum payment distributions 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’s changes in accumulated comprehensive loss related to defined benefit and postretirement plans are as follows: Three Months Ended March 31, 2016 2015 Pension and Postretirement Plans (in millions) Beginning Balance $ (65 ) $ (85 ) Amounts reclassified from accumulated other comprehensive loss: Actuarial losses (1) 2 4 Total reclassifications from accumulated other comprehensive loss 2 4 Tax expense (1 ) (2 ) Net current period other comprehensive income 1 2 Ending Balance $ (64 ) $ (83 ) (1) These components are included in the computation of net periodic cost. CenterPoint Energy expects to contribute a total of approximately $8 million to its pension plans in 2016 , of which approximately $3 million was contributed during the three months ended March 31, 2016 . CenterPoint Energy expects to contribute a total of approximately $16 million to its postretirement benefit plan in 2016 , of which approximately $4 million was contributed during the three months ended March 31, 2016 .

Regulatory Accounting

Regulatory Accounting	3 Months Ended
	Mar. 31, 2016
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Regulatory Matters	Regulatory Accounting As of March 31, 2016 , CenterPoint Energy has not recognized an allowed equity return of $380 million because such return will be recognized as it is recovered in rates. During the three months ended March 31, 2016 and 2015 , Houston Electric recognized approximately $13 million and $9 million , respectively, of the allowed equity return not previously recognized.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2016
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 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 NGD in Arkansas, Louisiana, Mississippi, Minnesota and Oklahoma. NGD and electric operations in Texas do not have such mechanisms, although fixed customer charges are historically higher in Texas for NGD compared to CenterPoint Energy’s other jurisdictions. As a result, fluctuations from normal weather may have a positive or negative effect on NGD’s results in Texas and on Houston Electric’s results in its service territory. CenterPoint Energy has historically 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 2014–2015. However, NGD did not enter into heating-degree day swaps for the 2015–2016 winter season as a result of NGD’s Minnesota division implementing a full decoupling pilot in July 2015. CenterPoint Energy also entered into weather hedges for the Houston Electric service territory, which contained a bilateral dollar cap of $8 million for the 2014–2015 winter season and a bilateral dollar cap of $7 million for the 2015–2016 winter season. The swaps are based on 10 -year normal weather. During the three months ended March 31, 2016 and 2015 , CenterPoint Energy recognized gains of $3 million and losses of $10 million , respectively, related to these swaps. Weather hedge gains and losses are included in revenues in the Condensed Statements of Consolidated Income. Hedging of Future Debt Issuances. In April 2016, Houston Electric entered into Treasury Locks with several counterparties, having an aggregate notional amount of $150 million . These Treasury Locks were executed to hedge, in part, volatility in the 5-year U.S. treasury rate by reducing Houston Electric’s exposure to variability in cash flows relating to interest payments on a forecasted issuance of fixed rate debt in 2016. These Treasury Locks were designated as cash flow hedges. Accordingly, the effective portion of unrealized gains and losses associated with the Treasury Locks would be recorded as a component of accumulated other comprehensive income and the ineffective portion would be recorded in 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, 2016 and December 31, 2015 , while the last table provides a breakdown of the related income statement impacts for the three months ended March 31, 2016 and 2015 . Fair Value of Derivative Instruments March 31, 2016 Total derivatives not designated as hedging instruments Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value (in millions) Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets $ 75 $ — Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 28 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 10 57 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 4 15 Indexed debt securities derivative Current Liabilities — 498 Total $ 117 $ 570 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 751 Bcf or a net 139 Bcf long position. Of the net long position, basis swaps constitute 122 Bcf. (2) Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they 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 $92 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 $47 million . (3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable. Offsetting of Natural Gas Derivative Assets and Liabilities March 31, 2016 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 $ 85 $ (10 ) $ 75 Other Assets: Non-trading derivative assets 32 (4 ) 28 Current Liabilities: Non-trading derivative liabilities (57 ) 49 (8 ) Other Liabilities: Non-trading derivative liabilities (15 ) 12 (3 ) Total $ 45 $ 47 $ 92 (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, 2015 Total derivatives not designated as hedging instruments Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value (in millions) Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets $ 90 $ 2 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 36 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 10 60 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 4 25 Indexed debt securities derivative Current Liabilities — 442 Total $ 140 $ 529 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 767 Bcf or a net 112 Bcf long position. Of the net long position, basis swaps constitute 133 Bcf. (2) Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they 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 $109 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 $56 million . (3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable. Offsetting of Natural Gas Derivative Assets and Liabilities December 31, 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 $ 100 $ (11 ) $ 89 Other Assets: Non-trading derivative assets 40 (4 ) 36 Current Liabilities: Non-trading derivative liabilities (62 ) 51 (11 ) Other Liabilities: Non-trading derivative liabilities (25 ) 20 (5 ) Total $ 53 $ 56 $ 109 (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. Realized and 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 as hedging instruments Income Statement Location 2016 2015 (in millions) Natural gas derivatives Gains (Losses) in Revenues $ 20 $ (133 ) Natural gas derivatives Gains (Losses) in Expenses: Natural Gas (11 ) 132 Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (56 ) 24 Total $ (47 ) $ 23 (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 S&P or Moody’s 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, 2016 and December 31, 2015 was $2 million and $3 million , respectively. CenterPoint Energy posted no assets as collateral towards derivative instruments that contain credit risk contingent features at either March 31, 2016 or December 31, 2015 . If all derivative contracts (in a net liability position) containing credit risk contingent features were triggered at both March 31, 2016 and December 31, 2015 , $2 million of additional assets would be required to be posted as collateral.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2016
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, 2016 , CenterPoint Energy’s Level 3 assets and liabilities are comprised of physical forward contracts and options. Level 3 physical forward contracts are valued using a discounted cash flow model which includes illiquid forward price curve locations (ranging from $1.37 to $3.36 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 20% to 84% ) 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, 2016 , 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, 2016 and December 31, 2015 , and indicate the fair value hierarchy of the valuation techniques utilized by CenterPoint Energy to determine such fair value. Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustments (1) Balance as of March 31, 2016 (in millions) Assets Corporate equities $ 896 $ — $ — $ — $ 896 Investments, including money market funds (2) 53 — — — 53 Natural gas derivatives (3) 3 95 19 (14 ) 103 Total assets $ 952 $ 95 $ 19 $ (14 ) $ 1,052 Liabilities Indexed debt securities derivative $ — $ 498 $ — $ — $ 498 Natural gas derivatives (3) 8 60 4 (61 ) 11 Total liabilities $ 8 $ 558 $ 4 $ (61 ) $ 509 (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 $47 million posted with the same counterparties. (2) Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable. Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustments (1) Balance as of December 31, 2015 (in millions) Assets Corporate equities $ 807 $ — $ — $ — $ 807 Investments, including money market funds (2) 53 — — — 53 Natural gas derivatives (3) 4 115 21 (15 ) 125 Total assets $ 864 $ 115 $ 21 $ (15 ) $ 985 Liabilities Indexed debt securities derivative $ — $ 442 $ — $ — $ 442 Natural gas derivatives (3) 13 65 9 (71 ) 16 Total liabilities $ 13 $ 507 $ 9 $ (71 ) $ 458 (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 $56 million posted with the same counterparties. (2) Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable. 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, 2016 2015 (in millions) Beginning balance $ 12 $ 17 Total gains 4 — Total settlements (5 ) (3 ) Transfers into Level 3 5 — Transfers out of Level 3 (1 ) (1 ) Ending balance (1) $ 15 $ 13 The amount of total gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date $ 8 $ 2 (1) CenterPoint Energy did not have significant Level 3 purchases or sales during either of the three months ended March 31, 2016 and 2015 . 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 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, 2016 December 31, 2015 Carrying Fair Carrying Amount Fair Value (in millions) Financial assets: Notes receivable – unconsolidated affiliate $ — $ — $ 363 $ 356 Financial liabilities: Long-term debt $ 8,330 $ 8,927 $ 8,585 $ 9,067

Unconsolidated Affiliates (Note

Unconsolidated Affiliates (Notes)	3 Months Ended
	Mar. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments and Joint Ventures Disclosure [Text Block]	Unconsolidated Affiliate On May 1, 2013 (the Formation Date) CERC Corp., OGE and ArcLight 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’s common and subordinated units 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 and preferred unit investment as presented in the Condensed Consolidated Balance Sheet as of March 31, 2016 , the guarantees discussed in Note 13 , and outstanding current accounts receivable from Enable. On February 18, 2016, CenterPoint Energy purchased in a Private Placement an aggregate of 14,520,000 Series A Preferred Units from Enable for a total purchase price of $363 million , which is accounted for as a cost method investment. In connection with the Private Placement, Enable redeemed $363 million of notes owed to a wholly-owned subsidiary of CERC Corp., which bore interest at an annual rate of 2.10% to 2.45% . CenterPoint Energy recorded interest income of $1 million and $2 million during the three months ended March 31, 2016 and 2015 , respectively, and had interest receivable from Enable of $-0- and $4 million as of March 31, 2016 and December 31, 2015 , respectively, on its notes receivable. Effective on the Formation Date, CenterPoint Energy and Enable entered into Transition 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, which ended on April 30, 2016. CenterPoint Energy is providing certain services to Enable on a year-to-year basis unless terminated by Enable with at least 90 days’ notice prior to the end of the extension term. 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 billed Enable for reimbursement of transition services of $3 million and $5 million during the three months ended March 31, 2016 and 2015 , respectively, under the Transition Agreements. Actual transition services costs are recorded net of reimbursements received from Enable. CenterPoint Energy had accounts receivable from Enable of $3 million as of both March 31, 2016 and December 31, 2015 for amounts billed for transition services. CenterPoint Energy incurred natural gas expenses, including transportation and storage costs, of $33 million and $39 million during the three months ended March 31, 2016 and 2015 , respectively, for transactions with Enable. CenterPoint Energy had accounts payable to Enable of $11 million as of both March 31, 2016 and December 31, 2015 from such transactions. As of March 31, 2016 , CenterPoint Energy held an approximate 55.4% limited partner interest in Enable, consisting of 94,151,707 common units and 139,704,916 subordinated units. As of March 31, 2016 , CenterPoint Energy and OGE each own a 50% management interest in the general partner of Enable and a 40% and 60% interest, respectively, in the incentive distribution rights held by the general partner. Additionally, as of March 31, 2016 , CenterPoint Energy held 14,520,000 Series A Preferred Units in Enable. CenterPoint Energy evaluates its equity method investments and cost 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, 2016 , the carrying value of CenterPoint Energy’s equity method investment in Enable was $11.03 per unit, which includes limited partner common and subordinated units, a general partner interest and incentive distribution rights. On March 31, 2016 , Enable’s common unit price closed at $8.56 . On April 29, 2016, Enable’s common unit price closed at $11.87 . Based on an analysis of its equity method investment in Enable as of March 31, 2016 , CenterPoint Energy believes that the decline in the value of its investment is temporary, and that the carrying value of its investment of $2.6 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, to conclude that its equity method investment is not other than temporarily impaired as of March 31, 2016 . As there were no identified events or changes in circumstances that may have a significant adverse effect on the fair value of CenterPoint Energy’s cost method investment in Enable’s preferred units as of March 31, 2016, and the investment’s fair value is not readily determinable, an estimate of the fair value of the cost method investment was not performed. Summarized unaudited consolidated income information for Enable is as follows: Three Months Ended March 31, 2016 2015 (in millions) Operating revenues $ 509 $ 616 Cost of sales, excluding depreciation and amortization 195 292 Operating income 103 104 Net income attributable to Enable 86 91 Reconciliation of Equity in Earnings, net: CenterPoint Energy’s interest $ 48 $ 51 Basis difference amortization 12 1 CenterPoint Energy’s equity in earnings, net $ 60 $ 52 Summarized unaudited consolidated balance sheet information for Enable is as follows: March 31, December 31, 2015 (in millions) Current assets $ 380 $ 381 Non-current assets 10,869 10,857 Current liabilities 280 615 Non-current liabilities 3,122 3,092 Non-controlling interest 12 12 Preferred equity 362 — Enable partners’ equity 7,473 7,519 Reconciliation of Equity Method Investment in Enable: CenterPoint Energy’s ownership interest in Enable partners’ capital $ 4,138 $ 4,163 CenterPoint Energy’s basis difference (1,558 ) (1,569 ) CenterPoint Energy’s equity method investment in Enable $ 2,580 $ 2,594 Distributions Received from Unconsolidated Affiliate: Three Months Ended March 31, 2016 2015 (in millions) Enable $ 74 $ 72

Goodwill

Goodwill	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets Disclosure [Text Block]	Goodwill Goodwill by reportable business segment as of both March 31, 2016 and December 31, 2015 is as follows: (in millions) Natural Gas Distribution $ 746 Energy Services (1) 83 Other Operations 11 Total $ 840 (1) Amounts presented are net of accumulated goodwill impairment charge of $252 million .

Capital Stock

Capital Stock	3 Months Ended
	Mar. 31, 2016
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. As of March 31, 2016 , 430,615,066 shares of CenterPoint Energy, Inc. common stock were issued and 430,614,900 shares were outstanding. As of December 31, 2015 , 430,262,869 shares of CenterPoint Energy, Inc. common stock were issued and 430,262,703 shares were outstanding. Outstanding common shares exclude 166 treasury shares as of both March 31, 2016 and December 31, 2015 .

Indexed Debt Securities (ZENS)

Indexed Debt Securities (ZENS) and Securities Related to ZENS (Notes)	3 Months Ended
	Mar. 31, 2016
Indexed Debt Securities [Text Block]	Indexed Debt Securities (ZENS) and Securities Related to ZENS (a) Investment in Securities Related to ZENS In 1995, CenterPoint Energy sold a cable television subsidiary to TW and received TW securities as partial consideration. A subsidiary of CenterPoint Energy now holds 7.1 million shares of TW Common, 1.8 million shares of TWC Common and 0.9 million shares of Time Common, which are classified as trading securities and are expected to be held to facilitate CenterPoint Energy’s ability to meet its obligation under the ZENS. Unrealized gains and losses resulting from changes in the market value of the TW Securities are recorded in CenterPoint Energy’s Statements of Consolidated Income. (b) ZENS In September 1999, CenterPoint Energy issued ZENS having an original principal amount of $1 billion of which $828 million remain outstanding at March 31, 2016 . Each ZENS note was originally exchangeable at the holder’s option at any time for an amount of cash equal to 95% of the market value of the reference shares of TW Common attributable to such note. The number and identity of the reference shares attributable to each ZENS note are adjusted for certain corporate events. As of March 31, 2016 , the reference shares for each ZENS note consisted of 0.5 share of TW Common, 0.125505 share of TWC Common and 0.0625 share of Time Common, and the contingent principal balance was $701 million . On May 26, 2015, Charter announced that it had entered into a definitive merger agreement with TWC. On September 21, 2015, Charter shareholders approved the announced transaction with TWC. Pursuant to the merger agreement, upon closing of the merger, TWC Common shares would be exchanged for cash and Charter stock and as a result, reference shares would consist of Charter stock, TW Common and Time Common. The merger is expected to close in the second quarter of 2016.

Short-Term Borrowings and Long-

Short-Term Borrowings and Long-term Debt	3 Months Ended
	Mar. 31, 2016
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 2019. 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 had an associated principal obligation of $-0- and $40 million as of March 31, 2016 and December 31, 2015 , respectively. (b) Long-term Debt Credit Facilities. On March 4, 2016, CenterPoint Energy announced that it had refinanced its existing $2.1 billion revolving credit facilities, which would have expired in 2019, with new revolving credit facilities totaling an aggregate $2.5 billion . The credit agreements evidencing the new revolving credit facilities provide for five -year senior unsecured revolving credit facilities in amounts of $1.6 billion for CenterPoint Energy, $300 million for Houston Electric and $600 million for CERC Corp. As of March 31, 2016 and December 31, 2015 , CenterPoint Energy, Houston Electric and CERC Corp. had the following revolving credit facilities and utilization of such facilities: March 31, 2016 December 31, 2015 Size of Loans Letters Commercial Size of Loans Letters Commercial (in millions) CenterPoint Energy $ 1,600 $ — $ 6 $ 824 (1) $ 1,200 $ — $ 6 $ 716 (1) Houston Electric 300 200 (2) 4 — 300 200 (2) 4 — CERC Corp. 600 — 2 — 600 — 2 219 (3) Total $ 2,500 $ 200 $ 12 $ 824 $ 2,100 $ 200 $ 12 $ 935 (1) Weighted average interest rate was 0.898% and 0.79% as of March 31, 2016 and December 31, 2015 , respectively. (2) Weighted average interest rate was 1.56% and 1.637% as of March 31, 2016 and December 31, 2015 , respectively. (3) Weighted average interest rate was 0.81% as of December 31, 2015 . CenterPoint Energy’s $1.6 billion revolving credit facility, which is scheduled to terminate on March 3, 2021 , can be drawn at 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 (with certain exceptions, including but not limited to Securitization Bonds) to an amount not to exceed 65% of CenterPoint Energy’s consolidated capitalization. As of March 31, 2016 , CenterPoint Energy’s debt (excluding Securitization Bonds) to capital ratio, as defined in its credit facility agreement, was 54.2% . The financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive twelve -month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date 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. Houston Electric’s $300 million revolving credit facility, which is scheduled to terminate on March 3, 2021 , can be drawn at LIBOR plus 1.125% based on Houston Electric’s current credit ratings. The revolving credit facility contains a financial covenant which limits Houston Electric’s consolidated debt (with certain exceptions, including but not limited to Securitization Bonds) to an amount not to exceed 65% of Houston Electric’s consolidated capitalization. As of March 31, 2016 , Houston Electric’s debt (excluding Securitization Bonds) to capital ratio, as defined in its credit facility agreement, was 52.6% . The financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and Houston Electric certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive twelve -month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date Houston Electric delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of Houston Electric’s certification or (iii) the revocation of such certification. CERC Corp.’s $600 million revolving credit facility, which is scheduled to terminate on March 3, 2021 , can be drawn at LIBOR plus 1.25% 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. As of March 31, 2016 , CERC’s debt to capital ratio, as defined in its credit facility agreement, was 32.5% . CenterPoint Energy, Houston Electric and CERC Corp. were in compliance with all financial covenants as of March 31, 2016 .

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate reported for the three months ended March 31, 2016 was 36% compared to 37% for the same period in 2015. CenterPoint Energy reported no uncertain tax liability as of March 31, 2016 and expects no significant change to the uncertain tax liability over the next twelve months. Tax years through 2013 have been audited and settled with the IRS. For tax years 2014 through 2016, CenterPoint Energy is a participant in the IRS’s Compliance Assurance Process.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2016
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 Condensed Consolidated Balance Sheets as of March 31, 2016 and December 31, 2015 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, 2016 , minimum payment obligations for natural gas supply commitments are approximately $283 million for the remaining nine months in 2016, $449 million in 2017, $404 million in 2018, $217 million in 2019, $90 million in 2020 and $38 million after 2020. (b) Legal, Environmental and Other Regulatory Matters Legal Matters Gas Market Manipulation Cases . CenterPoint Energy, Houston Electric or their predecessor, Reliant Energy, and certain of their former subsidiaries have been named as defendants in certain lawsuits described below. Under a master separation agreement between CenterPoint Energy and a former subsidiary, RRI, CenterPoint Energy and its subsidiaries are entitled to be indemnified by RRI and its successors for any losses, including certain attorneys’ fees and other costs, arising out of these lawsuits. In May 2009, RRI sold its Texas retail business to a subsidiary of NRG and RRI changed its name to RRI Energy, Inc. In December 2010, Mirant Corporation merged with and became a wholly-owned subsidiary of RRI, and RRI changed its name to GenOn. In December 2012, NRG acquired GenOn through a merger in which GenOn became a wholly-owned subsidiary of NRG. None of the sale of the retail business, the merger with Mirant Corporation, or the acquisition of GenOn by NRG alters RRI’s (now GenOn’s) contractual obligations to indemnify CenterPoint Energy and its subsidiaries, including Houston Electric, for certain liabilities, including their indemnification obligations regarding the gas market manipulation litigation, 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. CES, a subsidiary of CERC Corp., is a defendant in a case now pending in federal court in Nevada alleging a conspiracy to inflate Wisconsin natural gas prices in 2000–2002. In July 2011, the court issued an order dismissing the plaintiffs’ claims against other defendants in the case, each of whom had demonstrated Federal Energy Regulatory Commission jurisdictional sales for resale during the relevant period, based on federal preemption, and stayed the remainder of the case pending outcome of the appeals. The plaintiffs appealed this ruling to the U.S. Court of Appeals for the Ninth Circuit, which reversed the trial court’s dismissal of the plaintiffs’ claims. On April 21, 2015, the U.S. Supreme Court affirmed the Ninth Circuit’s ruling and remanded the case to the district court for further proceedings, which are now underway. CenterPoint Energy and CES intend to continue vigorously defending against the plaintiffs’ claims. CenterPoint Energy does not expect the ultimate outcome of this matter to have a material adverse effect on its financial condition, results of operations or cash flows. Environmental Matters Manufactured Gas Plant Sites. CERC and its predecessors operated MGPs in the past. With respect to certain Minnesota MGP sites, CERC has completed state-ordered remediation and continues state-ordered monitoring and water treatment. As of March 31, 2016 , CERC had a recorded liability of $7 million for continued monitoring and any future remediation required by regulators in Minnesota. The estimated range of possible remediation costs for the sites for which CERC believes it may have responsibility was $4 million to $28 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 depend on the number of sites to be remediated, the participation of other PRPs, if any, and the remediation methods used. In addition to the Minnesota sites, the 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. CenterPoint Energy does not expect the ultimate outcome of these matters 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 or its predecessors contain or have contained asbestos insulation and other asbestos-containing materials. CenterPoint Energy and its subsidiaries are from time to time named, along with numerous others, as defendants in lawsuits filed by a number of individuals who claim injury due to exposure to asbestos, and CenterPoint Energy anticipates that additional claims may be asserted in the future. Although their ultimate outcome cannot be predicted at this time, CenterPoint Energy 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 and reasonably estimable 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 $24 million as of March 31, 2016 . Based on market conditions in the fourth quarter of 2015 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. In 2010, CenterPoint Energy provided a guarantee (the CenterPoint Midstream Guarantee) with respect to the performance of certain obligations of Enable under a long-term gas gathering and treating agreement with an indirect, wholly-owned subsidiary of Royal Dutch Shell plc. 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 Guarantee and to release CenterPoint Energy from such guarantee. As of March 31, 2016 , CenterPoint Energy had guaranteed Enable’s obligations up to an aggregate amount of $50 million under the CenterPoint Energy Midstream Guarantee. CERC Corp. had also provided a guarantee of collection of $1.1 billion of Enable’s senior notes due 2019 and 2024. This guarantee was subordinated to all senior debt of CERC Corp. and was automatically released on May 1, 2016. The fair value of these guarantees is not material.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2016
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, 2016 2015 (in millions, except share and per share amounts) Net income $ 154 $ 131 Basic weighted average shares outstanding 430,407,000 429,955,000 Plus: Incremental shares from assumed conversions: Restricted stock 2,187,000 1,228,000 Diluted weighted average shares 432,594,000 431,183,000 Basic earnings per share Net income $ 0.36 $ 0.30 Diluted earnings per share Net income $ 0.36 $ 0.30

Reportable Business Segments

Reportable Business Segments	3 Months Ended
	Mar. 31, 2016
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 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 of CenterPoint Energy’s investment in Enable. 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: For the Three Months Ended March 31, 2016 Revenues from External Customers Net Intersegment Revenues Operating Income Total Assets as of March 31, 2016 (in millions) Electric Transmission & Distribution $ 660 (1) $ — $ 83 $ 9,960 Natural Gas Distribution 888 7 160 5,661 Energy Services 432 7 6 844 Midstream Investments (2) — — — 2,580 Other Operations 4 — 1 2,953 (3) Eliminations — (14 ) — (994 ) Consolidated $ 1,984 $ — $ 250 $ 21,004 For the Three Months Ended March 31, 2015 Revenues from Net Operating Total Assets as of December 31, 2015 (in millions) Electric Transmission & Distribution $ 612 (1) $ — $ 96 $ 10,028 Natural Gas Distribution 1,185 8 146 5,657 Energy Services 632 18 13 857 Midstream Investments (2) — — — 2,594 Other Operations 4 — 1 2,879 (3) Eliminations — (26 ) — (725 ) Consolidated $ 2,433 $ — $ 256 $ 21,290 (1) Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended March 31, 2016 2015 (in millions) Affiliates of NRG $ 145 $ 184 Affiliates of Energy Future Holdings Corp. $ 45 $ 52 (2) Midstream Investments’ equity earnings are as follows: Three Months Ended March 31, 2016 2015 (in millions) Enable $ 60 $ 52 Midstream Investments’ total assets are as follows: March 31, 2016 December 31, 2015 (in millions) Enable $ 2,580 $ 2,594 (3) Included in total assets of Other Operations as of March 31, 2016 and December 31, 2015 are pension and other postemployment related regulatory assets of $798 million and $814 million , respectively.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2016
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events On April 1, 2016 , CES, an indirect, wholly-owned subsidiary of CenterPoint Energy, closed the previously announced agreement to acquire the retail commercial and industrial businesses of Continuum for $98.2 million , comprised of a purchase price of $77.5 million , less a $4.7 million purchase price adjustment, and working capital of $25.4 million . Due to the limited amount of time since the acquisition, the initial accounting for the acquisition is incomplete. CenterPoint Energy intends to provide additional business combination disclosures, if material, in its Form 10-Q for the second quarter of 2016. On April 28, 2016 , CenterPoint Energy’s board of directors declared a regular quarterly cash dividend of $0.2575 per share of common stock payable on June 10, 2016 , to shareholders of record as of the close of business on May 16, 2016 . On April 26, 2016 , Enable declared a quarterly cash distribution of $0.318 per unit on all of its outstanding common and subordinated units for the quarter ended March 31, 2016 . Accordingly, CERC Corp. expects to receive a cash distribution of approximately $74 million from Enable in the second quarter of 2016 to be made with respect to CERC Corp.’s investment in common and subordinated units in Enable for the first quarter of 2016. On April 26, 2016 , Enable declared a quarterly cash distribution of $0.2917 per Series A Preferred Unit for the period from February 18, 2016 to March 31, 2016. Accordingly, CenterPoint Energy expects to receive a cash distribution of approximately $4 million from Enable in the second quarter of 2016 to be made with respect to CenterPoint Energy’s investment in Series A Preferred Units of Enable for the first quarter of 2016.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2016
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, 2016 2015 Pension Postretirement Pension Postretirement (in millions) Service cost $ 9 $ 1 $ 10 $ 1 Interest cost 23 4 23 5 Expected return on plan assets (25 ) (2 ) (30 ) (2 ) Amortization of prior service cost 2 — 3 — Amortization of net loss 16 — 14 1 Settlement cost (2) — — 9 — Net periodic cost $ 25 $ 3 $ 29 $ 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 amount of lump sum payment distributions 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’s changes in accumulated comprehensive loss related to defined benefit and postretirement plans are as follows: Three Months Ended March 31, 2016 2015 Pension and Postretirement Plans (in millions) Beginning Balance $ (65 ) $ (85 ) Amounts reclassified from accumulated other comprehensive loss: Actuarial losses (1) 2 4 Total reclassifications from accumulated other comprehensive loss 2 4 Tax expense (1 ) (2 ) Net current period other comprehensive income 1 2 Ending Balance $ (64 ) $ (83 ) (1) These components are included in the computation of net periodic cost.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	Fair Value of Derivative Instruments December 31, 2015 Total derivatives not designated as hedging instruments Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value (in millions) Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets $ 90 $ 2 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 36 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 10 60 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 4 25 Indexed debt securities derivative Current Liabilities — 442 Total $ 140 $ 529 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 767 Bcf or a net 112 Bcf long position. Of the net long position, basis swaps constitute 133 Bcf. (2) Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they 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 $109 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 $56 million . (3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable. 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, 2016 and December 31, 2015 , while the last table provides a breakdown of the related income statement impacts for the three months ended March 31, 2016 and 2015 . Fair Value of Derivative Instruments March 31, 2016 Total derivatives not designated as hedging instruments Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value (in millions) Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets $ 75 $ — Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 28 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 10 57 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 4 15 Indexed debt securities derivative Current Liabilities — 498 Total $ 117 $ 570 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 751 Bcf or a net 139 Bcf long position. Of the net long position, basis swaps constitute 122 Bcf. (2) Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they 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 $92 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 $47 million . (3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
Offsetting of Natural Gas Derivative Assets and Liabilities	Offsetting of Natural Gas Derivative Assets and Liabilities December 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 $ 100 $ (11 ) $ 89 Other Assets: Non-trading derivative assets 40 (4 ) 36 Current Liabilities: Non-trading derivative liabilities (62 ) 51 (11 ) Other Liabilities: Non-trading derivative liabilities (25 ) 20 (5 ) Total $ 53 $ 56 $ 109 (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 March 31, 2016 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 $ 85 $ (10 ) $ 75 Other Assets: Non-trading derivative assets 32 (4 ) 28 Current Liabilities: Non-trading derivative liabilities (57 ) 49 (8 ) Other Liabilities: Non-trading derivative liabilities (15 ) 12 (3 ) Total $ 45 $ 47 $ 92 (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. Realized and 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 as hedging instruments Income Statement Location 2016 2015 (in millions) Natural gas derivatives Gains (Losses) in Revenues $ 20 $ (133 ) Natural gas derivatives Gains (Losses) in Expenses: Natural Gas (11 ) 132 Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (56 ) 24 Total $ (47 ) $ 23

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2016
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, 2016 and December 31, 2015 , and indicate the fair value hierarchy of the valuation techniques utilized by CenterPoint Energy to determine such fair value. Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustments (1) Balance as of March 31, 2016 (in millions) Assets Corporate equities $ 896 $ — $ — $ — $ 896 Investments, including money market funds (2) 53 — — — 53 Natural gas derivatives (3) 3 95 19 (14 ) 103 Total assets $ 952 $ 95 $ 19 $ (14 ) $ 1,052 Liabilities Indexed debt securities derivative $ — $ 498 $ — $ — $ 498 Natural gas derivatives (3) 8 60 4 (61 ) 11 Total liabilities $ 8 $ 558 $ 4 $ (61 ) $ 509 (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 $47 million posted with the same counterparties. (2) Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable. Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Netting Adjustments (1) Balance as of December 31, 2015 (in millions) Assets Corporate equities $ 807 $ — $ — $ — $ 807 Investments, including money market funds (2) 53 — — — 53 Natural gas derivatives (3) 4 115 21 (15 ) 125 Total assets $ 864 $ 115 $ 21 $ (15 ) $ 985 Liabilities Indexed debt securities derivative $ — $ 442 $ — $ — $ 442 Natural gas derivatives (3) 13 65 9 (71 ) 16 Total liabilities $ 13 $ 507 $ 9 $ (71 ) $ 458 (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 $56 million posted with the same counterparties. (2) Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable.
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, 2016 2015 (in millions) Beginning balance $ 12 $ 17 Total gains 4 — Total settlements (5 ) (3 ) Transfers into Level 3 5 — Transfers out of Level 3 (1 ) (1 ) Ending balance (1) $ 15 $ 13 The amount of total gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date $ 8 $ 2 (1) CenterPoint Energy did not have significant Level 3 purchases or sales during either of the three months ended March 31, 2016 and 2015 .
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 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, 2016 December 31, 2015 Carrying Fair Carrying Amount Fair Value (in millions) Financial assets: Notes receivable – unconsolidated affiliate $ — $ — $ 363 $ 356 Financial liabilities: Long-term debt $ 8,330 $ 8,927 $ 8,585 $ 9,067

Unconsolidated Affiliates (Tabl

Unconsolidated Affiliates (Tables)	3 Months Ended
	Mar. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments [Table Text Block]	Summarized unaudited consolidated income information for Enable is as follows: Three Months Ended March 31, 2016 2015 (in millions) Operating revenues $ 509 $ 616 Cost of sales, excluding depreciation and amortization 195 292 Operating income 103 104 Net income attributable to Enable 86 91 Reconciliation of Equity in Earnings, net: CenterPoint Energy’s interest $ 48 $ 51 Basis difference amortization 12 1 CenterPoint Energy’s equity in earnings, net $ 60 $ 52 Summarized unaudited consolidated balance sheet information for Enable is as follows: March 31, December 31, 2015 (in millions) Current assets $ 380 $ 381 Non-current assets 10,869 10,857 Current liabilities 280 615 Non-current liabilities 3,122 3,092 Non-controlling interest 12 12 Preferred equity 362 — Enable partners’ equity 7,473 7,519 Reconciliation of Equity Method Investment in Enable: CenterPoint Energy’s ownership interest in Enable partners’ capital $ 4,138 $ 4,163 CenterPoint Energy’s basis difference (1,558 ) (1,569 ) CenterPoint Energy’s equity method investment in Enable $ 2,580 $ 2,594 Distributions Received from Unconsolidated Affiliate: Three Months Ended March 31, 2016 2015 (in millions) Enable $ 74 $ 72

Goodwill (Tables)

Goodwill (Tables)	3 Months Ended
	Mar. 31, 2016
Goodwill [Line Items]
Schedule of Goodwill [Table Text Block]	Goodwill by reportable business segment as of both March 31, 2016 and December 31, 2015 is as follows: (in millions) Natural Gas Distribution $ 746 Energy Services (1) 83 Other Operations 11 Total $ 840 (1) Amounts presented are net of accumulated goodwill impairment charge of $252 million .

Short-Term Borrowings and Lon29

Short-Term Borrowings and Long-term Debt Credit Facilities (Tables)	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Schedule of Line of Credit Facilities [Table Text Block]	Credit Facilities. On March 4, 2016, CenterPoint Energy announced that it had refinanced its existing $2.1 billion revolving credit facilities, which would have expired in 2019, with new revolving credit facilities totaling an aggregate $2.5 billion . The credit agreements evidencing the new revolving credit facilities provide for five -year senior unsecured revolving credit facilities in amounts of $1.6 billion for CenterPoint Energy, $300 million for Houston Electric and $600 million for CERC Corp. As of March 31, 2016 and December 31, 2015 , CenterPoint Energy, Houston Electric and CERC Corp. had the following revolving credit facilities and utilization of such facilities: March 31, 2016 December 31, 2015 Size of Loans Letters Commercial Size of Loans Letters Commercial (in millions) CenterPoint Energy $ 1,600 $ — $ 6 $ 824 (1) $ 1,200 $ — $ 6 $ 716 (1) Houston Electric 300 200 (2) 4 — 300 200 (2) 4 — CERC Corp. 600 — 2 — 600 — 2 219 (3) Total $ 2,500 $ 200 $ 12 $ 824 $ 2,100 $ 200 $ 12 $ 935 (1) Weighted average interest rate was 0.898% and 0.79% as of March 31, 2016 and December 31, 2015 , respectively. (2) Weighted average interest rate was 1.56% and 1.637% as of March 31, 2016 and December 31, 2015 , respectively. (3) Weighted average interest rate was 0.81% as of December 31, 2015 .

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2016
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, 2016 2015 (in millions, except share and per share amounts) Net income $ 154 $ 131 Basic weighted average shares outstanding 430,407,000 429,955,000 Plus: Incremental shares from assumed conversions: Restricted stock 2,187,000 1,228,000 Diluted weighted average shares 432,594,000 431,183,000 Basic earnings per share Net income $ 0.36 $ 0.30 Diluted earnings per share Net income $ 0.36 $ 0.30

Reportable Business Segments (T

Reportable Business Segments (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Financial data for business segments is as follows: For the Three Months Ended March 31, 2016 Revenues from External Customers Net Intersegment Revenues Operating Income Total Assets as of March 31, 2016 (in millions) Electric Transmission & Distribution $ 660 (1) $ — $ 83 $ 9,960 Natural Gas Distribution 888 7 160 5,661 Energy Services 432 7 6 844 Midstream Investments (2) — — — 2,580 Other Operations 4 — 1 2,953 (3) Eliminations — (14 ) — (994 ) Consolidated $ 1,984 $ — $ 250 $ 21,004 For the Three Months Ended March 31, 2015 Revenues from Net Operating Total Assets as of December 31, 2015 (in millions) Electric Transmission & Distribution $ 612 (1) $ — $ 96 $ 10,028 Natural Gas Distribution 1,185 8 146 5,657 Energy Services 632 18 13 857 Midstream Investments (2) — — — 2,594 Other Operations 4 — 1 2,879 (3) Eliminations — (26 ) — (725 ) Consolidated $ 2,433 $ — $ 256 $ 21,290 (1) Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended March 31, 2016 2015 (in millions) Affiliates of NRG $ 145 $ 184 Affiliates of Energy Future Holdings Corp. $ 45 $ 52 (2) Midstream Investments’ equity earnings are as follows: Three Months Ended March 31, 2016 2015 (in millions) Enable $ 60 $ 52 Midstream Investments’ total assets are as follows: March 31, 2016 December 31, 2015 (in millions) Enable $ 2,580 $ 2,594 (3) Included in total assets of Other Operations as of March 31, 2016 and December 31, 2015 are pension and other postemployment related regulatory assets of $798 million and $814 million , respectively.
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended March 31, 2016 2015 (in millions) Affiliates of NRG $ 145 $ 184 Affiliates of Energy Future Holdings Corp. $ 45 $ 52
Midstream Investments [Table Text Block]	Midstream Investments’ equity earnings are as follows: Three Months Ended March 31, 2016 2015 (in millions) Enable $ 60 $ 52 Midstream Investments’ total assets are as follows: March 31, 2016 December 31, 2015 (in millions) Enable $ 2,580 $ 2,594

Background and Basis of Prese32

Background and Basis of Presentation (Details)	Mar. 31, 2016
Enable Midstream Partners [Member]
Equity Method Investment, Ownership Percentage	55.40%

New Accounting Pronouncements N

New Accounting Pronouncements New Accounting Pronouncements and Changes in Accounting Principles (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Unamortized Debt Issuance Expense	$ 42	$ 44

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan, Change in Accumulated Comprehensive Loss [Roll Forward]
Beginning Balance		$ (65)	$ (85)
Amounts reclassified from accumulated other comprehensive loss:
Actuarial losses (1)	[1]	2	4
Total reclassifications from accumulated other comprehensive loss		2	4
Tax expense		(1)	(2)
Net current period other comprehensive income		1	2
Ending Balance		(64)	(83)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[2]	9	10
Interest cost	[2]	23	23
Expected return on plan assets	[2]	(25)	(30)
Amortization of prior service cost	[2]	2	3
Amortization of net loss	[2]	16	14
Settlement cost (2)	[2],[3]	0	9
Net periodic cost	[2]	25	29
Total contributions to the plans during the period		3
Total contributions expected in 2016		8
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[2]	1	1
Interest cost	[2]	4	5
Expected return on plan assets	[2]	(2)	(2)
Amortization of prior service cost	[2]	0	0
Amortization of net loss	[2]	0	1
Settlement cost (2)	[2],[3]	0	0
Net periodic cost	[2]	3	$ 5
Total contributions to the plans during the period		4
Total contributions expected in 2016		$ 16
[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 amount of lump sum payment distributions 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.

Regulatory Accounting (Details)

Regulatory Accounting (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Amount of allowed equity return on the true-up balance that has not been recognized	$ 380
Amount of allowed equity return on the true-up balance that was recognized in the period	$ 13	$ 9

Derivative Instruments Derivati

Derivative Instruments Derivatives and hedging (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Treasury Lock [Member]
Derivatives, Fair Value [Line Items]
Aggregate Notional Amount	$ 150
Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	3	$ (10)
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
2015To2016 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather Hedge, Bilateral Cap Amount	$ 7
Weather Hedges Term	10 years

Derivative Fair Values (Details

Derivative Fair Values (Details) $ in Millions		3 Months Ended			12 Months Ended
		Mar. 31, 2016USD ($)Bcf		Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)Bcf
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative Asset, Fair Value		$ 117			$ 140
Indexed debt securities derivative		570			529
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		(47)		$ 23
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		2			3
The aggregate fair value of assets already posted as collateral		0			0
Credit Risk Contingent Features assets		$ 2			$ 2
Natural gas derivatives [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative, Nonmonetary Notional Amount, Volume | Bcf		751			767
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	[1]	$ 45			$ 53
Gross amounts offset, Net		47			56
Net Amount Presented in the Consolidated Balance Sheets	[2]	92			109
Collateral Netting		47			56
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		20		(133)
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		(11)		132
Natural gas derivatives [Member] | Current Assets [Member]
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	[1]	85			100
Gross amounts offset		(10)			(11)
Derivative Asset	[2]	75			89
Natural gas derivatives [Member] | Other Assets [Member]
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	[1]	32			40
Gross amounts offset		(4)			(4)
Derivative Asset	[2]	28			36
Natural gas derivatives [Member] | Current Liabilities [Member]
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	[1]	(57)			(62)
Gross amounts offset		49			51
Derivative Liability	[2]	(8)			(11)
Natural gas derivatives [Member] | Other Liabilities [Member]
Derivative, Fair Value, Net [Abstract]
Gross Amounts Recognized	[1]	(15)			(25)
Gross amounts offset		12			20
Derivative Liability	[2]	(3)			(5)
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		(56)		$ 24
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	[3]	75	[4],[5]		90	[6],[7]
Indexed debt securities derivative	[3]	0	[4],[5]		2	[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	[3]	28	[4],[5]		36	[6],[7]
Indexed debt securities derivative	[3]	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	[3]	10	[4],[5]		10	[6],[7]
Indexed debt securities derivative	[3]	57	[4],[5]		60	[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	[3]	4	[4],[5]		4	[6],[7]
Indexed debt securities derivative	[3]	15	[4],[5]		25	[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		$ 498			$ 442
Long [Member] | Natural gas derivatives [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative, Nonmonetary Notional Amount, Volume | Bcf		139			112
Swap [Member] | Long [Member] | Natural gas derivatives [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative, Nonmonetary Notional Amount, Volume | Bcf		122			133
[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]	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
[4]	Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they 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 $92 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 $47 million.
[5]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 751 Bcf or a net 139 Bcf long position. Of the net long position, basis swaps constitute 122 Bcf.
[6]	Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they 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 $109 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 $56 million.
[7]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 767 Bcf or a net 112 Bcf long position. Of the net long position, basis swaps constitute 133 Bcf.

Fair Value Measurements (Detail

Fair Value Measurements (Details)		3 Months Ended
		Mar. 31, 2016USD ($)		Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)
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		(14,000,000)	[1]		$ (15,000,000)	[2]
Total assets		1,052,000,000			985,000,000
Liabilities
Natural gas derivatives, netting adjustment		(61,000,000)	[1]		(71,000,000)	[2]
Total liabilities		509,000,000			458,000,000
Cash collateral posted with counterparties		47,000,000			56,000,000
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		12,000,000		$ 17,000,000
Total gains		4,000,000		0
Total settlements		(5,000,000)		(3,000,000)
Transfers into Level 3		5,000,000		0
Transfers out of Level 3		(1,000,000)		(1,000,000)
Ending balance (1)	[3]	15,000,000		13,000,000
The amount of total gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date		8,000,000		$ 2,000,000
Fair Value, Inputs, Level 1 [Member]
Assets
Total assets		952,000,000			864,000,000
Liabilities
Total liabilities		8,000,000			13,000,000
Fair Value, Inputs, Level 2 [Member]
Assets
Total assets		95,000,000			115,000,000
Liabilities
Total liabilities		558,000,000			507,000,000
Fair Value, Inputs, Level 3 [Member]
Assets
Total assets		19,000,000			21,000,000
Liabilities
Total liabilities		$ 4,000,000			9,000,000
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		1.37
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		3.36
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		20.00%
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		84.00%
Estimate of Fair Value Measurement [Member]
Estimated Fair Value of Financial Instruments
Notes receivable – unconsolidated affiliate		$ 0			356,000,000
Long-term debt		8,927,000,000			9,067,000,000
Reported Value Measurement [Member]
Estimated Fair Value of Financial Instruments
Notes receivable – unconsolidated affiliate		0			363,000,000
Long-term debt		8,330,000,000			8,585,000,000
Fair Value, Measurements, Recurring [Member]
Assets
Corporate equities		896,000,000			807,000,000
Investments, including money market funds (2)	[4]	53,000,000			53,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Corporate equities		896,000,000			807,000,000
Investments, including money market funds (2)	[4]	53,000,000			53,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Corporate equities		0			0
Investments, including money market funds (2)	[4]	0			0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Corporate equities		0			0
Investments, including money market funds (2)	[4]	0			0
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member]
Assets
Natural gas derivatives, netting adjustment	[5]	(14,000,000)	[1]		(15,000,000)	[2]
Derivative Asset	[5]	103,000,000			125,000,000
Liabilities
Natural gas derivatives, netting adjustment	[5]	(61,000,000)	[1]		(71,000,000)	[2]
Derivative Liabilities	[5]	11,000,000			16,000,000
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Natural gas derivatives (3)	[5]	3,000,000			4,000,000
Liabilities
Derivative Liability, Fair Value	[5]	8,000,000			13,000,000
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Natural gas derivatives (3)	[5]	95,000,000			115,000,000
Liabilities
Derivative Liability, Fair Value	[5]	60,000,000			65,000,000
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Natural gas derivatives (3)	[5]	19,000,000			21,000,000
Liabilities
Derivative Liability, Fair Value	[5]	4,000,000			9,000,000
Fair Value, Measurements, Recurring [Member] | IDS Derivative [Member]
Liabilities
Natural gas derivatives, netting adjustment		0	[1]		0	[2]
Derivative Liabilities		498,000,000			442,000,000
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		498,000,000			442,000,000
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 $47 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 $56 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, 2016 and 2015.
[4]	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.
[5]	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.

Unconsolidated Affiliates (Deta

Unconsolidated Affiliates (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 18, 2016	Mar. 31, 2016	Mar. 31, 2015	Apr. 29, 2016	Dec. 31, 2015
Preferred units – unconsolidated affiliate		$ 363			$ 0
Service Agreement Notice For Termination At Term End, Number of Days		90 days
Service Agreement, Termination With Board Approval, Number Of Days		180 days
Investment in unconsolidated affiliate		$ 2,580			2,594
Enable Midstream Partners [Member]
Equity Method Investment, Ownership Percentage		55.40%
Equity Method Investment, Carrying Value Per Unit		$ 11.03
Investment in unconsolidated affiliate		$ 2,580			2,594
Enable Midstream Partners [Member]
Share Price		$ 8.56
Series A Preferred Stock [Member] | Enable Midstream Partners [Member]
Purchase of Preferred Units, Price Per Unit	14,520,000
Purchase of Preferred Units, Number of Units Purchased		14,520,000
Preferred units – unconsolidated affiliate		$ 363
Common Stock [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares		94,151,707
Subordinated Units [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares		139,704,916
Enable Midstream Partners [Member]
Extinguishment of Debt, Amount	$ 363
Interest Income (Expense), Net		$ 1	$ 2
Interest Receivable		0			4
Transitional Service [Member] | Enable Midstream Partners [Member]
Reimbursement for Transitional Services		3	5
Transitional Service cost receivable		3			3
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Cost of natural gas purchases, affiliates		33	$ 39
Due to Affiliate		$ 11			$ 11
Enable Midstream Partners [Member] | CERC Corp [Member]
Management Rights Ownership Percentage		50.00%
Incentive Distribution Right		40.00%
Enable Midstream Partners [Member] | OGE [Member]
Management Rights Ownership Percentage		50.00%
Incentive Distribution Right		60.00%
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%
Subsequent Event [Member] | Enable Midstream Partners [Member]
Share Price				$ 11.87

Unconsolidated Affiliates Finan

Unconsolidated Affiliates Financial data (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s equity method investment in Enable	$ 2,580,000,000		$ 2,594,000,000
Enable Midstream Partners [Member]
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
Operating revenues	509,000,000	$ 616,000,000
Cost of sales, excluding depreciation and amortization	195,000,000	292,000,000
Operating income	103,000,000	104,000,000
Net income attributable to Enable	86,000,000	91,000,000
CenterPoint Energy’s interest	48,000,000	51,000,000
Basis difference amortization	12,000,000	1,000,000
CenterPoint Energy’s equity in earnings, net	60,000,000	52,000,000
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Current assets	380,000,000		381,000,000
Non-current assets	10,869,000,000		10,857,000,000
Current liabilities	280,000,000		615,000,000
Non-current liabilities	3,122,000,000		3,092,000,000
Non-controlling interest	12,000,000		12,000,000
Preferred equity	362,000,000		0
Enable partners’ equity	7,473,000,000		7,519,000,000
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s ownership interest in Enable partners’ capital	4,138,000,000		4,163,000,000
CenterPoint Energy’s basis difference	(1,558,000,000)		(1,569,000,000)
CenterPoint Energy’s equity method investment in Enable	2,580,000,000		$ 2,594,000,000
Proceeds from Equity Method Investment, Dividends or Distributions	$ 74,000,000	$ 72,000,000

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill		$ 840	$ 840
Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill		746	746
Energy Services [Member]
Goodwill [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss		252	252
Goodwill	[1]	83	83
Corporate and Other [Member]
Goodwill [Line Items]
Goodwill		$ 11	$ 11
[1]	Amounts presented are net of accumulated goodwill impairment charge of $252 million.

Capital Stock (Details)

Capital Stock (Details) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
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)	430,615,066	430,262,869
Total common stock outstanding (in shares)	430,614,900	430,262,703
Treasury stock (in shares)	166	166

Indexed Debt Securities (ZENS43

Indexed Debt Securities (ZENS) and Securities Related to ZENS (Details) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)shares
Subordinated Debt ZENS Member
Debt Instrument, Face Amount | $	$ 1,000
Long-term Debt, Gross | $	$ 828
Subordinated Note Cash Exchangeable Percentage Of Fair Value	95.00%
TW Common Member
Investment Owned, Balance, Shares | shares	7.1
TW Common Member | Subordinated Debt ZENS Member
Number Of Shares Referenced In Exchangeable Subordinated Note	0.5
TWC Common Member
Investment Owned, Balance, Shares | shares	1.8
TWC Common Member | Subordinated Debt ZENS Member
Number Of Shares Referenced In Exchangeable Subordinated Note	0.125505
Debt Instrument Contingent Principal Amount Outstanding | $	$ 701
Time Common [Member]
Investment Owned, Balance, Shares | shares	0.9
Time Common [Member] | Subordinated Debt ZENS Member
Number Of Shares Referenced In Exchangeable Subordinated Note	0.0625

Short-Term Borrowings and Lon44

Short-Term Borrowings and Long-term Debt (Details) $ in Millions		3 Months Ended
		Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Short-term Debt [Line Items]
Total short term borrowings		$ 0	$ 40
Credit Facilities [Abstract]
Total credit facility amount		2,500	2,100
CenterPoint Houston [Member]
Credit Facilities [Abstract]
Total credit facility amount		$ 300	300
Debt Instrument, Term		5 years
CERC Corp [Member]
Credit Facilities [Abstract]
Total credit facility amount		$ 600	600
Debt Instrument, Term		5 years
Parent Company [Member]
Credit Facilities [Abstract]
Total credit facility amount		$ 1,600	1,200
Debt Instrument, Term		5 years
Revolving Credit Facility [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		$ 200	200
Revolving Credit Facility [Member] | CenterPoint Houston [Member]
Credit Facilities [Abstract]
Long-term Line of Credit	[1]	$ 200	$ 200
Debt, Weighted Average Interest Rate		1.56%	1.637%
Revolving Credit Facility [Member] | CERC Corp [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		$ 0	$ 0
Revolving Credit Facility [Member] | Parent Company [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		$ 0	0
Line of Credit [Member] | CenterPoint Houston [Member]
Credit Facilities [Abstract]
Percentage on limitation of debt to total capitalization under covenant		65.00%
Ratio of Indebtedness to Net Capital		0.526
Percentage on limitation of debt to total capitalization under covenant amended		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] | CenterPoint Houston [Member] | London Interbank Offered Rate (LIBOR) [Member]
Credit Facilities [Abstract]
Basis Spread on LIBOR		1.125%
Line of Credit [Member] | CERC Corp [Member]
Credit Facilities [Abstract]
Percentage on limitation of debt to total capitalization under covenant		65.00%
Ratio of Indebtedness to Net Capital		0.325
Line of Credit [Member] | CERC Corp [Member] | London Interbank Offered Rate (LIBOR) [Member]
Credit Facilities [Abstract]
Basis Spread on LIBOR		1.25%
Line of Credit [Member] | Parent Company [Member]
Credit Facilities [Abstract]
Percentage on limitation of debt to total capitalization under covenant		65.00%
Ratio of Indebtedness to Net Capital		0.542
Percentage on limitation of debt to total capitalization under covenant amended		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%
Letter of Credit [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		$ 12	12
Letter of Credit [Member] | CenterPoint Houston [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		4	4
Letter of Credit [Member] | CERC Corp [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		2	2
Letter of Credit [Member] | Parent Company [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		6	6
Commercial Paper [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		824	935
Commercial Paper [Member] | CenterPoint Houston [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		0	0
Commercial Paper [Member] | CERC Corp [Member]
Credit Facilities [Abstract]
Long-term Line of Credit		0	$ 219	[2]
Debt, Weighted Average Interest Rate			0.81%
Commercial Paper [Member] | Parent Company [Member]
Credit Facilities [Abstract]
Long-term Line of Credit	[3]	$ 824	$ 716
Debt, Weighted Average Interest Rate		0.898%	0.79%
Product Financing Arrangement [Member]
Short-term Debt [Line Items]
Total short term borrowings		$ 0	$ 40
[1]	Weighted average interest rate was 1.56% and 1.637% as of March 31, 2016 and December 31, 2015, respectively.
[2]	Weighted average interest rate was 0.81% as of December 31, 2015.
[3]	Weighted average interest rate was 0.898% and 0.79% as of March 31, 2016 and December 31, 2015, respectively.

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Effective Income Tax Rate Reconciliation, Percent	36.00%	37.00%

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
GenOn Demand Charges Transportation Contracts [Member] | CERC Corp [Member]
Guarantees
Approximate amount of undiscounted maximum obligation under guarantee	$ 24
CenterPoint Midstream Guarantees [Member]
Guarantees
Approximate amount of undiscounted maximum obligation under guarantee	50
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
2,016	283
2,017	449
2,018	404
2,019	217
2,020	90
After 2,020	$ 38
Gas Market Manipulation Cases [Member]
Legal Matters
Loss Contingency, Pending Claims, Number	1
Minnesota Service Territory [Member] | CERC Corp [Member]
Environmental Matters
Liability recorded for remediation of Minnesota sites	$ 7
Minnesota Service Territory [Member] | CERC Corp [Member] | Minimum [Member]
Environmental Matters
Minimum estimated remediation costs for the Minnesota sites	$ 4
Site Contingency, Years to Resolve Contingency	30 years
Minnesota Service Territory [Member] | CERC Corp [Member] | Maximum [Member]
Environmental Matters
Minimum estimated remediation costs for the Minnesota sites	$ 28
Site Contingency, Years to Resolve Contingency	50 years

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net income	$ 154	$ 131
Basic weighted average shares outstanding	430,407,000	429,955,000
Plus: Incremental shares from assumed conversions:
Diluted weighted average shares	432,594,000	431,183,000
Basic earnings per share
Net income	$ 0.36	$ 0.30
Diluted earnings per share
Net income	$ 0.36	$ 0.30
Restricted Stock [Member]
Plus: Incremental shares from assumed conversions:
Restricted stock	2,187,000	1,228,000

Reportable Business Segments (D

Reportable Business Segments (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues		$ 1,984	$ 2,433
Operating Income		250	256
Assets		21,004		$ 21,290
Equity in earnings of unconsolidated affiliate, net		60	52
Investment in unconsolidated affiliate		2,580		2,594
Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	660	612
Operating Income		83	96
Electric Transmission and Distribution [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues		145	184
Electric Transmission and Distribution [Member] | Affiliates of Energy Future Holdings Corp. [Member]
Segment Reporting Information [Line Items]
Revenues		45	52
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		888	1,185
Operating Income		160	146
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		432	632
Operating Income		6	13
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0	0
Operating Income	[2]	0	0
Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		4	4
Operating Income		1	1
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(14)	(26)
Assets		(994)		(725)
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		(7)	(8)
Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(7)	(18)
Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0	0
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		9,960		10,028
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		5,661		5,657
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		844		857
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets	[2]	2,580		2,594
Operating Segments [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Assets	[3]	2,953		2,879
Enable Midstream Partners [Member]
Segment Reporting Information [Line Items]
Investment in unconsolidated affiliate		2,580		2,594
Enable Midstream Partners [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated affiliate, net		60	$ 52
Investment in unconsolidated affiliate		2,580		2,594
Pension and Other Postretirement Plans Costs [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Regulatory Assets		$ 798		$ 814
[1]	(1)Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended March 31, 2016 2015 (in millions)Affiliates of NRG $145 $184Affiliates of Energy Future Holdings Corp. $45 $52
[2]	(2)Midstream Investments’ equity earnings are as follows: Three Months Ended March 31, 2016 2015 (in millions)Enable $60 $52Midstream Investments’ total assets are as follows: March 31, 2016 December 31, 2015 (in millions)Enable $2,580 $2,594
[3]	Included in total assets of Other Operations as of March 31, 2016 and December 31, 2015 are pension and other postemployment related regulatory assets of $798 million and $814 million, respectively.

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 28, 2016	Apr. 26, 2016	Apr. 01, 2016	Mar. 31, 2016	Mar. 31, 2015
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Declared				$ 0.2575	$ 0.2475
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared	Apr. 28, 2016
Common Stock, Dividends, Per Share, Declared	$ 0.2575
Dividends Payable, Date to be Paid, Day, Month and Year	Jun. 10, 2016
Dividends Payable, Date of Record, Day, Month and Year	May 16, 2016
Enable Midstream Partners [Member]
Subsequent Event [Line Items]
Proceeds from Equity Method Investment, Dividends or Distributions				$ 74	$ 72
Common Stock [Member] | Enable Midstream Partners [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared		Apr. 26, 2016
Common Stock, Dividends, Per Share, Declared		$ 0.318
Proceeds from Equity Method Investment, Dividends or Distributions		$ 74
Redeemable Preferred Stock [Member] | Enable Midstream Partners [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared		Apr. 26, 2016
Preferred Stock, Dividends Per Share, Declared		$ 0.2917
Proceeds from Equity Method Investment, Dividends or Distributions		$ 4
Continuum Energy Services [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Business Acquisition, Effective Date of Acquisition			Apr. 1, 2016
Total Acquisition Cost			$ 98.2
Purchase Price			77.5
Purchase Price Adjustment			4.7
Working Capital			$ 25.4