CenterPoint Energy (CNP) 10-Q 4 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	3 Months Ended
	Mar. 31, 2018	Apr. 24, 2018	Jun. 30, 2017
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, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		431,473,292
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 11,722,467,012

CONDENSED STATEMENTS OF CONSOLI

CONDENSED STATEMENTS OF CONSOLIDATED INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Utility revenues	$ 1,894	$ 1,546
Non-utility revenues	1,261	1,189
Total	3,155	2,735
Expenses:
Utility natural gas	637	450
Non-utility natural gas	1,273	1,129
Operation and maintenance	569	543
Depreciation and amortization	314	226
Taxes other than income taxes	111	96
Total	2,904	2,444
Operating Income	251	291	[1]
Other Income (Expense):
Gain on marketable securities	1	44
Loss on indexed debt securities	(18)	(10)
Interest and other finance charges	(78)	(78)
Interest on Securitization Bonds	(16)	(20)
Equity in earnings of unconsolidated affiliate, net	69	72
Other, net	3	0
Total	(39)	8
Income Before Income Taxes	212	299
Income tax expense	47	107
Net Income	$ 165	$ 192
Basic Earnings Per Share	$ 0.38	$ 0.45
Diluted Earnings Per Share	0.38	0.44
Dividends Declared Per Share	$ 0	$ 0.2675
Weighted Average Shares Outstanding, Basic	431,231,000	430,794,000
Weighted Average Shares Outstanding, Diluted	434,008,000	433,348,000
[1]	Amounts for 2017 have been restated to reflect the adoption of ASU 2017-07.

CONDENSED STATEMENTS OF CONSOL3

CONDENSED STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 165	$ 192
Other comprehensive income:
Adjustment to pension and other postretirement plans (net of tax of $1 and $1)	1	1
Net deferred gain (loss) from cash flow hedges (net of tax of $1 and $-0-)	4	(1)
Total	5	0
Comprehensive income	$ 170	$ 192

CONDENSED STATEMENTS OF CONSOL4

CONDENSED STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Parentheticals) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Tax benefit (expense) on adjustment related to pension and postretirement plans	$ (1)	$ (1)
Tax expense (benefit) on net deferred loss from cash flow hedges	$ 1	$ 0

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents ($181 and $230 related to VIEs, respectively)	$ 219	$ 260
Investment in marketable securities	944	960
Accounts receivable ($86 and $73 related to VIEs, respectively), less bad debt reserve of $23 and $19, respectively	1,081	1,000
Accrued unbilled revenues	275	427
Natural gas inventory	81	222
Materials and supplies	176	175
Non-trading derivative assets	84	110
Prepaid expenses and other current assets ($37 and $35 related to VIEs, respectively)	189	241
Total current assets	3,049	3,395
Property, Plant and Equipment:
Property, plant and equipment	19,294	19,031
Less: accumulated depreciation and amortization	6,089	5,974
Property, plant and equipment, net	13,205	13,057
Other Assets:
Goodwill	867	867
Regulatory assets ($1,455 and $1,590 related to VIEs, respectively)	2,213	2,347
Non-trading derivative assets	52	44
Investment in unconsolidated affiliate	2,467	2,472
Preferred units – unconsolidated affiliate	363	363
Other	194	191
Total other assets	6,156	6,284
Total Assets	22,410	22,736
Current Liabilities:
Short-term borrowings	0	39
Current portion of VIE Securitization Bonds long-term debt	444	434
Indexed debt, net	119	122
Current portion of other long-term debt	50	50
Indexed debt securities derivative	674	668
Accounts payable	712	963
Taxes accrued	176	181
Interest accrued	77	104
Dividends accrued	0	120
Non-trading derivative liabilities	21	20
Other	343	368
Total current liabilities	2,616	3,069
Other Liabilities:
Deferred income taxes, net	3,160	3,174
Non-trading derivative liabilities	12	4
Benefit obligations	723	785
Regulatory liabilities	2,505	2,464
Other	361	357
Total other liabilities	6,761	6,784
Long-term Debt:
VIE Securitization Bonds, net	1,260	1,434
Other long-term debt, net	6,916	6,761
Total long-term debt, net	8,176	8,195
Commitments and Contingencies (Note 13)
Shareholders’ Equity:
Cumulative preferred stock, $0.01 par value, 20,000,000 shares authorized, none issued or outstanding	0	0
Common stock, $0.01 par value, 1,000,000,000 shares authorized, 431,471,369 shares and 431,044,845 shares outstanding, respectively	4	4
Additional paid-in capital	4,208	4,209
Retained earnings	708	543
Accumulated other comprehensive loss	(63)	(68)
Total shareholders’ equity	4,857	4,688
Total Liabilities and Shareholders’ Equity	$ 22,410	$ 22,736

CONDENSED CONSOLIDATED BALANCE6

CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Cash and cash equivalents ($181 and $230 related to VIEs, respectively)	$ 219	$ 260
Accounts receivable, net	1,081	1,000
Bad debt reserve	23	19
Prepaid expenses and other current assets	189	241
Regulatory assets	$ 2,213	$ 2,347
Cumulative preferred stock par value (in dollars per share)	$ 0.01	$ 0.01
Cumulative preferred stock authorized (in shares)	20,000,000	20,000,000
Cumulative preferred stock outstanding (in shares)	0	0
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	1,000,000,000	1,000,000,000
Common stock outstanding (in shares)	431,471,369	431,044,845
Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents ($181 and $230 related to VIEs, respectively)	$ 181	$ 230
Accounts receivable, net	86	73
Prepaid expenses and other current assets	37	35
Regulatory assets	$ 1,455	$ 1,590

CONDENSED STATEMENTS OF CONSOL7

CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOW (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash Flows from Operating Activities:
Net income	$ 165	$ 192
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	314	226
Amortization of deferred financing costs	6	6
Deferred income taxes	(17)	85
Unrealized gain on marketable securities	(1)	(44)
Loss on indexed debt securities	18	10
Write-down of natural gas inventory	1	0
Equity in earnings of unconsolidated affiliate, net of distributions	(9)	(72)
Pension contributions	(62)	(2)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	39	114
Inventory	139	74
Taxes receivable	0	16
Accounts payable	(209)	(122)
Fuel cost recovery	64	(6)
Non-trading derivatives, net	64	(32)
Margin deposits, net	(28)	(46)
Interest and taxes accrued	(32)	(82)
Net regulatory assets and liabilities	42	15
Other current assets	(15)	(5)
Other current liabilities	1	(27)
Other assets	(3)	(4)
Other liabilities	5	15
Other, net	2	6
Net Cash Provided by (Used in) Operating Activities	484	317
Cash Flows from Investing Activities:
Capital expenditures	(362)	(312)
Acquisitions, net of cash acquired	0	(132)
Distributions from unconsolidated affiliate in excess of cumulative earnings	14	74
Proceeds from sale of marketable securities	16	0
Other, net	1	(2)
Net Cash Provided by (Used in) Investing Activities	(331)	(372)
Cash Flows from Financing Activities:
Decrease in short-term borrowings, net	(39)	(35)
Proceeds from (payments of) commercial paper, net	(837)	227
Proceeds from long-term debt, net	997	298
Payments of long-term debt	(165)	(405)
Debt issuance costs	(7)	(2)
Payment of dividends on common stock	(120)	(115)
Distribution to ZENS note holders	(16)	0
Other, net	(5)	(4)
Net Cash Provided by (Used in) Financing Activities	(192)	(36)
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(39)	(91)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	296	381
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 257	$ 290

Background and Basis of Present

Background and Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation [Text Block]	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 2017 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 and natural gas distribution facilities, supply natural gas to commercial and industrial customers and electric and natural gas utilities and own interests in Enable as described below. CenterPoint Energy’s indirect, wholly-owned subsidiaries include: • Houston Electric, which engages in the electric transmission and distribution business in the Texas Gulf Coast area that includes the city of Houston; • CERC Corp., which owns and operates natural gas distribution systems in six states; and • CES, which obtains and offers competitive variable and fixed-price physical natural gas supplies and services primarily to commercial and industrial customers and electric and natural gas utilities in 33 states. As of March 31, 2018 , CenterPoint Energy also owned an aggregate of 14,520,000 Series A Preferred Units in Enable, which owns, operates and develops natural gas and crude oil infrastructure assets, and CERC Corp. owned approximately 54.0% of the common units representing limited partner interests in Enable. As of March 31, 2018 , CenterPoint Energy had VIEs consisting of the Bond Companies, which it consolidates. The consolidated VIEs are wholly-owned, bankruptcy-remote, special purpose entities that were formed specifically for the purpose of securitizing transition and system restoration-related property. Creditors of CenterPoint Energy have no recourse to any assets or revenues of the 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, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements [Text Block]	New Accounting Pronouncements The following table provides an overview of recently adopted or issued accounting pronouncements applicable to CenterPoint Energy. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2014-09- Revenue from Contracts with Customers (Topic 606) and related amendments This standard provides a comprehensive new revenue recognition model that requires revenue to be recognized in a manner that depicts the transfer of goods or services to a customer at an amount that reflects the consideration expected to be received in exchange for those goods or services. Transition method: modified retrospective January 1, 2018 CenterPoint Energy added a revenue recognition footnote (Note 3) to address the disclosure requirements, and it did not identify significant changes to revenue recognition. A substantial amount of CenterPoint Energy’s revenues are tariff and derivative based, which were not significantly impacted by these ASUs. ASU 2017-05- Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets This standard clarifies when and how to apply ASC 610-20, which was issued as part of ASU 2014-09. It amends or supersedes the guidance in ASC 350 and ASC 360 on determining a gain or loss recognized upon the derecognition of nonfinancial assets. Transition method: modified retrospective January 1, 2018 ASU 2017-05 eliminates industry specific guidance, including ASC 360-20 Property, Plant, and Equipment - Real Estate Sales, for the recognition of gains or losses upon the sale of in-substance real estate. CenterPoint Energy elected to apply the practical expedient upon adoption to only evaluate transactions that were not determined to be complete as of the date of adoption. Subsequent to adoption, gains or losses on sales or dilution events in CenterPoint Energy’s investment in Enable may result in gains or losses recognized in earnings. See Note 8 for further discussion. ASU 2016-01-Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ASU 2018-03-Technical Corrections and Improvements to Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This standard 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. It also changes certain disclosure requirements and other aspects related to recognition and measurement of financial assets and financial liabilities. Transition method: cumulative-effect adjustment to beginning retained earnings, and two features prospective January 1, 2018 The adoption of this standard did not have an impact on CenterPoint Energy’s financial position, results of operations or cash flows. CenterPoint Energy elected the practicability exception for investments without a readily determinable fair value to be measured at cost for the Series A Preferred Units in Enable, which were previously accounted for under the cost method. See Note 8 for further discussion. ASU 2016-15- Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments This standard provides clarifying guidance on the classification of certain cash receipts and payments in the statement of cash flows and eliminates the variation in practice related to such classifications. Transition method: retrospective January 1, 2018 The adoption did not have a material impact on CenterPoint Energy’s financial position, results of operations or disclosures. However, the statement of cash flows reflects an increase in investing activities and a corresponding decrease in operating activities of $-0- and $2 million for the three months ended March 31, 2018 and 2017, respectively, due to the requirement that cash proceeds from COLI policies be classified as cash inflows from investing activity. ASU 2016-18- Statement of Cash Flows (Topic 230): Restricted Cash This standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. Transition method: retrospective January 1, 2018 The adoption of this standard did not have an impact on CenterPoint Energy’s financial position, results of operations or disclosures. However, the statement of cash flows is reconciled to cash, cash equivalents and restricted cash, resulting in a decrease in investing activities of $2 million and an increase in investing activities of $4 million for the three months ended March 31, 2018 and 2017, respectively. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2017-01- Business Combinations (Topic 805): Clarifying the Definition of a Business This standard revises the definition of a business. If substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, then under ASU 2017-01, the asset or group of assets is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs to be more closely aligned with how outputs are described in ASC 606. Transition method: prospective January 1, 2018 The adoption of this revised definition will reduce the number of transactions that are accounted for as a business combination, and therefore may have a potential impact on CenterPoint Energy’s accounting for future acquisitions. ASU 2017-04- Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This standard eliminates Step 2 of the goodwill impairment test, which required a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s future calculation of goodwill impairments if an impairment is identified. ASU 2017-07- Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This standard requires an employer to report the service cost component of the net periodic pension cost and postretirement benefit cost in the same line item(s) as other employee compensation costs arising from services rendered during the period; all other components will be presented separately from the line item(s) that includes the service cost and outside of any subtotal of operating income. In addition, only the service cost component will be eligible for capitalization in assets. Transition method: retrospective for the presentation of the service cost component and other components; prospective for the capitalization of the service cost component January 1, 2018 The adoption of this standard did not have a material impact on CenterPoint Energy’s financial position, results of operations, cash flows or disclosures; however, it resulted in an increase to operating income and a corresponding decrease to other income of $14 million and $17 million in the three months ended March 31, 2018 and 2017, respectively. Other components previously capitalized in assets will be recorded as regulatory assets in CenterPoint Energy’s rate-regulated businesses, prospectively. ASU No. 2017-09- Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting This standard clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. Entities will apply the modification accounting guidance if the value, vesting conditions or classification of the award changes. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s accounting for future changes to share-based payment awards. Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2016-02- Leases (Topic 842) and related amendments ASU 2018-01- Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842 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. Transition method : modified retrospective ASU 2018-01 allows entities to elect not to assess whether existing land easements that were not previously accounted for in accordance with ASC 840 Leases under ASC 842 Leases when transitioning to the new leasing standard. January 1, 2019 Early adoption is permitted CenterPoint Energy will elect the practical expedient on existing easements provided by ASU 2018-01 and is evaluating other available transitional practical expedients. CenterPoint Energy is in the process of reviewing contracts to identify leases as defined in ASU 2016-02 and expects to recognize on the statements of financial position right-of-use assets and lease liabilities for the majority of its leases that are currently classified as operating leases. CenterPoint Energy is continuing to assess the impact that adoption of these standards will have on its financial position, results of operations, cash flows and disclosures. ASU 2017-12- Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities This standard expands an entity’s ability to hedge nonfinancial and financial risk components and reduce complexity in fair value hedges of interest rate risk. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness, eases certain documentation and assessment requirements and updates the presentation and disclosure requirements. Transition method: cumulative-effect adjustment for elimination of the separate measurement of ineffectiveness; prospective for presentation and disclosure January 1, 2019 Early adoption is permitted CenterPoint Energy is currently assessing the impact that adoption of this standard will have on its financial position, results of operations, cash flows and disclosures. Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2018-02-Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA and requires entities to provide certain disclosures regarding stranded tax effects. Transition method: either in the period of adoption or retrospective January 1, 2019 Early adoption is permitted The adoption of this standard will allow CenterPoint Energy to reclass stranded deferred tax adjustments primarily related to benefit plans from other comprehensive income to retained earnings. CenterPoint Energy is currently assessing the impact that adoption of this standard will have on its financial position and disclosures. Management believes that other recently adopted standards and recently issued standards that are not yet effective will not have a material impact on CenterPoint Energy’s financial position, results of operations or cash flows upon adoption.

Revenue Recognition

Revenue Recognition	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition [Text Block]	Revenue Recognition CenterPoint Energy adopted ASC 606 and all related amendments on January 1, 2018 using the modified retrospective method for those contracts that were not completed as of the date of adoption. Application of the new revenue standard did not result in a cumulative effect adjustment to the opening balance of retained earnings. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. The adoption of the new standard did not have a material impact on CenterPoint Energy’s financial position, results of operations or cash flows. In accordance with ASC 606, revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which CenterPoint Energy expects to be entitled to receive in exchange for these goods or services. Contract assets and liabilities are not material. The following tables disaggregate revenues by major source: Three Months Ended March 31, 2018 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 761 $ 1,186 $ 178 $ 1 $ 2,126 Derivatives income (4 ) — 1,107 — 1,103 Other (3) (6 ) (33 ) — 3 (36 ) Eliminations — (10 ) (28 ) — (38 ) Total revenues $ 751 $ 1,143 $ 1,257 $ 4 $ 3,155 Three Months Ended March 31, 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy (2) Other Operations (2) Total (in millions) Revenue from contracts $ 644 $ 925 $ 142 $ 1 $ 1,712 Derivatives income 1 — 1,054 — 1,055 Other (3) (6 ) (9 ) — 3 (12 ) Eliminations — (9 ) (11 ) — (20 ) Total revenues $ 639 $ 907 $ 1,185 $ 4 $ 2,735 (1) Reflected in Utility revenues in the Condensed Statements of Consolidated Income. (2) Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income. (3) Primarily consists of income from ARPs and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. CenterPoint Energy recognizes ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period. Revenues from Contracts with Customers Electric Transmission & Distribution. Houston Electric distributes electricity to customers over time and customers consume the electricity when delivered. Revenue, consisting of both volumetric and fixed tariff rates set by the PUCT, is recognized as electricity is delivered and represents amounts both billed and unbilled. Discretionary services requested by customers are provided at a point in time with control transferring upon the completion of the service. Revenue for discretionary services is recognized upon completion of service based on the tariff rates set by the PUCT. Payments for electricity distribution and discretionary services are aggregated and received on a monthly basis. Houston Electric performs transmission services over time as a stand-ready obligation to provide a reliable network of transmission systems. Revenue is recognized upon time elapsed, and the monthly tariff rate set by the PUCT. Payments are received on a monthly basis. Natural Gas Distribution. CERC distributes and transports natural gas to customers over time, and customers consume the natural gas when delivered. Revenue, consisting of both volumetric and fixed tariff rates set by the state governing agency for that service area, is recognized as natural gas is delivered and represents amounts both billed and unbilled. Discretionary services requested by the customer are satisfied at a point in time and revenue is recognized upon completion of service and the tariff rates set by the applicable state regulator. Payments of natural gas distribution, transportation and discretionary services are aggregated and received on a monthly basis. Energy Services. The majority of CES natural gas sales contracts are considered a derivative, as the contracts typically have a stated minimum or contractual volume of delivery. For contracts in which CES delivers the full requirement of the natural gas needed by the customer and a volume is not stated, a contract as defined under ASC 606 is created upon the customer’s exercise of its option to take natural gas. CES supplies natural gas to retail customers over time as customers consume the natural gas when delivered. For wholesale customers, CES supplies natural gas at a point in time because the wholesale customer is presumed to have storage capabilities. Control is transferred to both types of customers upon delivery of natural gas. Revenue is recognized on a monthly basis based on the estimated volume of natural gas delivered and the price agreed upon with the customer. Payments are received on a monthly basis. AMAs are natural gas sales contracts under which CES also assumes management of a customer’s physical storage and/or transportation capacity. AMAs have two distinct performance obligations, which consist of natural gas sales and natural gas delivery because delivery could occur separate from the sale of natural gas (e.g., from storage to customer premises). Most AMAs’ natural gas sales performance obligations are accounted for as embedded derivatives. The transaction price is allocated between the sale of natural gas and the delivery based on the stand-alone selling price as stated in the contract. CES performs natural gas delivery over time as customers take delivery of the natural gas and recognizes revenue on an aggregated monthly basis based on the volume of natural gas delivered and the fees stated within the contract. Payments are received on a monthly basis. Practical Expedients and Exemption. Sales taxes and other similar taxes collected from customers are excluded from the transaction price.

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans [Text Block]	Employee Benefit Plans CenterPoint Energy’s net periodic cost, before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes, includes the following components relating to pension and post retirement benefits: Three Months Ended March 31, 2018 2017 Pension Postretirement Pension Postretirement (in millions) Service cost (1) $ 9 $ — $ 9 $ — Interest cost (2) 20 3 22 4 Expected return on plan assets (2) (27 ) (1 ) (24 ) (1 ) Amortization of prior service cost (credit) (2) 2 (1 ) 2 (1 ) Amortization of net loss (2) 11 — 14 — Net periodic cost $ 15 $ 1 $ 23 $ 2 (1) Included in Operation and maintenance expense in the Condensed Statements of Consolidated Income. (2) Included in Other, net in the Condensed Statements of Consolidated Income. CenterPoint Energy’s changes in accumulated other comprehensive loss related to defined benefit and postretirement plans are as follows: Three Months Ended March 31, 2018 2017 (in millions) Beginning Balance $ (66 ) $ (72 ) Amounts reclassified from accumulated other comprehensive loss: Actuarial losses (1) 2 2 Tax expense (1 ) (1 ) Net current period other comprehensive income 1 1 Ending Balance $ (65 ) $ (71 ) (1) These accumulated other comprehensive components are included in the computation of net periodic cost. CenterPoint Energy expects to contribute a minimum of approximately $67 million to its pension plans in 2018 , of which approximately $62 million was contributed during the three months ended March 31, 2018 . CenterPoint Energy expects to contribute a total of approximately $16 million to its postretirement benefit plan in 2018 , of which approximately $4 million was contributed during the three months ended March 31, 2018 .

Regulatory Accounting

Regulatory Accounting	3 Months Ended
	Mar. 31, 2018
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Regulatory Accounting [Text Block]	Regulatory Accounting The following is a list of regulatory assets and liabilities reflected on CenterPoint Energy’s Condensed Consolidated Balance Sheets: March 31, December 31, 2017 (in millions) Regulatory Assets: Current regulatory assets (1) $ 65 $ 130 Non-current regulatory assets: Securitized regulatory assets 1,455 1,590 Unrecognized equity return (2) (266 ) (287 ) Unamortized loss on reacquired debt 74 75 Pension and postretirement-related regulatory asset (3) 636 646 Hurricane Harvey restoration costs (4) 64 64 Regulatory assets related to TCJA (5) 48 48 Other long-term regulatory assets (6) 202 211 Total non-current regulatory assets 2,213 2,347 Total regulatory assets 2,278 2,477 Regulatory Liabilities: Current regulatory liabilities (7) 43 24 Non-current regulatory liabilities: Regulatory liabilities related to TCJA (5) 1,373 1,354 Estimated removal costs 882 878 Other long-term regulatory liabilities 250 232 Total non-current regulatory liabilities 2,505 2,464 Total regulatory liabilities 2,548 2,488 Total regulatory assets and liabilities, net $ (270 ) $ (11 ) (1) Current regulatory assets are included in Prepaid expenses and other current assets in CenterPoint Energy’s Condensed Consolidated Balance Sheets. (2) The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended March 31, 2018 and 2017, Houston Electric recognized approximately $21 million and $7 million , respectively, of the allowed equity return. The timing of CenterPoint Energy’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months. (3) Includes a portion of NGD’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates that is being deferred for rate making purposes. Deferred pension and other postemployment expenses of $6 million and $7 million as of March 31, 2018 and December 31, 2017 , respectively, were not earning a return. (4) CenterPoint Energy is not earning a return on its Hurricane Harvey restoration costs. (5) The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities. (6) Other long-term regulatory assets that are not earning a return were not material as of March 31, 2018 and December 31, 2017 . (7) Current regulatory liabilities are included in Other current liabilities in CenterPoint Energy’s Condensed Consolidated Balance Sheets.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments [Text Block]	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, weather and interest rates 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 normal sale if the intent is to physically receive or deliver the product for use or sale in the normal course of business. CenterPoint Energy has a Risk Oversight Committee composed of corporate and business segment officers that oversees 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 commercial risk management policy and procedures and limits established by CenterPoint Energy’s Board of Directors. CenterPoint Energy’s policies prohibit the use of leveraged financial instruments. A leveraged financial instrument, for this purpose, is a transaction involving a derivative whose financial impact will be based on an amount other than the notional amount or volume of the instrument. (a) Non-Trading Activities Derivative Instruments. CenterPoint Energy enters into certain derivative instruments to mitigate the effects of commodity price movements. Certain financial instruments used to hedge portions of the natural gas inventory of the Energy Services business segment are designated as fair value hedges for accounting purposes. All other 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 electric operations’ results in its service territory. CenterPoint Energy enters into winter season weather hedges from time to time for certain NGD jurisdictions and electric operations’ service territory to mitigate the effect of fluctuations from normal weather on results of operations and cash flows. These weather hedges are based on heating degree days at 10 -year normal weather. The table below summarizes CenterPoint Energy’s current weather hedge activity: Three Months Ended March 31, Jurisdiction Winter Season Bilateral Cap 2018 2017 (in millions) Certain NGD jurisdictions 2017 – 2018 $ 8 $ — $ — Electric operations’ service territory 2017 – 2018 9 (4 ) — Electric operations’ service territory 2016 – 2017 9 — 1 Total (1) $ (4 ) $ 1 (1) Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income. Hedging of Interest Expense for Future Debt Issuances. In January and February 2018, Houston Electric entered into forward interest rate agreements with multiple counterparties, having an aggregate notional amount of $200 million . These agreements were executed to hedge, in part, volatility in the 30-year U.S. treasury rate by reducing Houston Electric’s exposure to variability in cash flows related to interest payments of Houston Electric’s $400 million issuance of fixed rate debt in February 2018. These forward interest rate agreements were designated as cash flow hedges. Accordingly, the effective portion of realized gains associated with the forward interest rate agreements, which totaled approximately $5 million , is a component of accumulated other comprehensive income in 2018 and will be amortized over the life of the fixed rate debt. In March 2018, CERC Corp. entered into forward interest rate agreements with multiple counterparties, having an aggregate notional amount of $450 million . These agreements were executed to hedge, in part, volatility in the 5-year and 10-year U.S. treasury rates by reducing CERC Corp.’s exposure to variability in cash flows related to interest payments of CERC Corp.’s $600 million issuance of fixed rate debt in March 2018. These forward interest rate agreements were designated as cash flow hedges. Accordingly, the effective portion of realized losses associated with the forward interest rate agreements, which totaled less than $1 million , is a component of accumulated other comprehensive income in 2018 and will be amortized over the life of the fixed rate debt. (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, while the last table provides a breakdown of the related income statement impacts. Fair Value of Derivative Instruments March 31, 2018 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivatives designated as fair value hedges: (in millions) Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities $ 1 $ 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 86 2 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 52 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 18 70 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 9 42 Indexed debt securities derivative Current Liabilities — 674 Total $ 166 $ 789 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,735 Bcf or a net 437 Bcf long position. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure. (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 natural gas derivative assets and liabilities was a $103 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, impacted by collateral netting of $52 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, 2018 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 $ 105 $ (21 ) $ 84 Other Assets: Non-trading derivative assets 61 (9 ) 52 Current Liabilities: Non-trading derivative liabilities (73 ) 52 (21 ) Other Liabilities: Non-trading derivative liabilities (42 ) 30 (12 ) Total $ 51 $ 52 $ 103 (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, 2017 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivatives designated as fair value hedges: (in millions) Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities $ 13 $ 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 114 4 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 44 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 38 78 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 9 24 Indexed debt securities derivative Current Liabilities — 668 Total $ 218 $ 775 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,795 Bcf or a net 224 Bcf long position. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure. (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 natural gas derivative assets and liabilities was a $130 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, impacted by collateral netting of $19 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, 2017 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 $ 165 $ (55 ) $ 110 Other Assets: Non-trading derivative assets 53 (9 ) 44 Current Liabilities: Non-trading derivative liabilities (83 ) 63 (20 ) Other Liabilities: Non-trading derivative liabilities (24 ) 20 (4 ) Total $ 111 $ 19 $ 130 (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 natural gas derivatives are recognized in the Condensed Statements of Consolidated Income as revenue for physical sales derivative contracts and as natural gas expense for financial natural gas derivatives and physical purchase 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. Hedge ineffectiveness is recorded as a component of natural gas expense and primarily results from differences in the location of the derivative instrument and the hedged item. Basis ineffectiveness arises from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the hedge instruments. The impact of natural gas derivatives designated as fair value hedges, the related hedged item, and natural gas derivatives not designated as hedging instruments are presented in the table below. Income Statement Impact of Derivative Activity Three Months Ended March 31, Income Statement Location 2018 2017 Derivatives designated as fair value hedges: (in millions) Natural gas derivatives Gains (Losses) in Expenses: Natural Gas $ — $ 3 Fair value adjustments for natural gas inventory designated as the hedged item Gains (Losses) in Expenses: Natural Gas (2 ) (4 ) Total increase in Expenses: Natural Gas (1) $ (2 ) $ (1 ) Derivatives not designated as hedging instruments: Natural gas derivatives Gains (Losses) in Revenues $ 57 $ 96 Natural gas derivatives Gains (Losses) in Expenses: Natural Gas (69 ) (67 ) Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (18 ) (10 ) Total - derivatives not designated as hedging instruments $ (30 ) $ 19 (1) Hedge ineffectiveness results from the basis ineffectiveness discussed above, and excludes the impact to natural gas expense from timing ineffectiveness. Timing ineffectiveness arises due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity. As the commodity contract nears the settlement date, spot-to-forward price differences should converge, which should reduce or eliminate the impact of this ineffectiveness on natural gas expense. (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 as of both March 31, 2018 and December 31, 2017 was $2 million . CenterPoint Energy posted no assets as collateral toward derivative instruments that contain credit risk contingent features as of either March 31, 2018 or December 31, 2017 . If all derivative contracts (in a net liability position) containing credit risk contingent features were triggered as of both March 31, 2018 and December 31, 2017 , $2 million of additional assets would be required to be posted as collateral.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements [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, as well as natural gas inventory that has been designated as the hedged item in a fair value hedge. 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. As of March 31, 2018 , CenterPoint Energy’s Level 3 assets and liabilities are comprised of physical natural gas forward contracts and options and its indexed debt securities. Level 3 physical natural gas forward contracts and options are valued using a discounted cash flow model which includes illiquid forward price curve locations (ranging from $1.36 to $3.26 per MMBtu) as an unobservable input. CenterPoint Energy’s Level 3 physical natural gas forward contracts and options derivative assets and liabilities consist of both long and short positions (forwards and options) and their fair value is sensitive to forward prices. If forward prices decrease, CenterPoint Energy’s long forwards and options lose value whereas its short forwards and options gain in value. CenterPoint Energy’s Level 3 indexed debt securities are valued using a Black-Scholes option model and a discounted cash flow model, which use option volatility ( 19% ) and a projected dividend growth rate ( 6% ) as unobservable inputs. An increase in either volatilities or projected dividends will increase the value of the indexed debt securities, and a decrease in either the volatilities or projected dividends will decrease the value of the indexed debt securities. 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, 2018 , 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 and indicate the fair value hierarchy of the valuation techniques utilized by CenterPoint Energy to determine such fair value. March 31, 2018 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 (in millions) Assets Corporate equities $ 946 $ — $ — $ — $ 946 Investments, including money market funds (2) 70 — — — 70 Natural gas derivatives (3) — 147 19 (30 ) 136 Total assets $ 1,016 $ 147 $ 19 $ (30 ) $ 1,152 Liabilities Indexed debt securities derivative $ — $ — $ 674 $ — $ 674 Natural gas derivatives (3) — 108 7 (82 ) 33 Hedged portion of natural gas inventory 8 — — — 8 Total liabilities $ 8 $ 108 $ 681 $ (82 ) $ 715 (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 $52 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. December 31, 2017 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 (in millions) Assets Corporate equities $ 963 $ — $ — $ — $ 963 Investments, including money market funds (2) 68 — — — 68 Natural gas derivatives (3) — 161 57 (64 ) 154 Hedged portion of natural gas inventory 14 — — — 14 Total assets $ 1,045 $ 161 $ 57 $ (64 ) $ 1,199 Liabilities Indexed debt securities derivative $ — $ — $ 668 $ — $ 668 Natural gas derivatives (3) — 96 11 (83 ) 24 Total liabilities $ — $ 96 $ 679 $ (83 ) $ 692 (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 $19 million posted with the same counterparties. (2) Amounts are included in Prepaid expenses and other current assets and Other 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, 2018 2017 (in millions) Beginning balance $ (622 ) $ (704 ) Total gains (losses) (4 ) 6 Total settlements (34 ) (4 ) Transfers into Level 3 — 1 Transfers out of Level 3 (2 ) 1 Ending balance (1) $ (662 ) $ (700 ) The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date $ (5 ) $ 5 (1) CenterPoint Energy did not have significant Level 3 sales or purchases during either of the three months ended March 31, 2018 or 2017 . 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 a combination of historical trading prices and comparable issue data. These 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 2 in the fair value hierarchy. March 31, 2018 December 31, 2017 Carrying Fair Carrying Amount Fair Value (in millions) Financial liabilities: Long-term debt $ 8,670 $ 9,008 $ 8,679 $ 9,220

Unconsolidated Affiliate

Unconsolidated Affiliate	3 Months Ended
	Mar. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Unconsolidated Affiliate [Text Block]	Unconsolidated Affiliate CenterPoint Energy has the ability to significantly influence the operating and financial policies of Enable, a publicly traded MLP, and, accordingly, accounts for its investment in Enable’s common units using the equity method of accounting for in-substance real estate. Upon the adoption of ASU 2014-09 and ASU 2017-05 on January 1, 2018, CenterPoint Energy evaluated transactions in its investment in Enable that occurred prior to January 1, 2018 (the effective date) and concluded a cumulative effect adjustment to the opening balance of retained earnings was not required. See Note 2 for further discussion. 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, its Series A Preferred Unit investment and its outstanding current accounts receivable from Enable. Limited Partner Interest and Units Held in Enable: March 31, 2018 Limited Partner Interest (1) Common Units Series A Preferred Units (2) CenterPoint Energy 54.0 % 233,856,623 14,520,000 OGE 25.6 % 110,982,805 — Public unitholders 20.4 % 88,232,573 — Total units outstanding 100.0 % 433,072,001 14,520,000 (1) Excluding the Series A Preferred Units owned by CenterPoint Energy. (2) The carrying amount of the Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on the Condensed Consolidated Balance Sheets, was $363 million as of both March 31, 2018 and December 31, 2017. No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion. Generally, sales to any person or entity (including a series of sales to the same person or entity) of more than 5% of the aggregate of the common units CenterPoint Energy owns in Enable or sales to any person or entity (including a series of sales to the same person or entity) by OGE of more than 5% of the aggregate of the common units it owns in Enable are subject to mutual rights of first offer and first refusal set forth in Enable’s Agreement of Limited Partnership. Enable is controlled jointly by CERC Corp. and OGE, and each own 50% of the management rights in the general partner of Enable. Sale of CenterPoint Energy’s or OGE’s ownership interests in Enable’s general partner to a third party is subject to mutual rights of first offer and first refusal, and CenterPoint Energy is not permitted to dispose of less than all of its interest in Enable’s general partner. Distributions Received from Enable: Three Months Ended March 31, 2018 2017 (in millions) Investment in Enable common units $ 74 $ 74 Investment in Enable Series A Preferred Units 9 9 Total $ 83 $ 83 As of March 31, 2018 , CERC Corp. and OGE also owned 40% and 60% , respectively, of the incentive distribution rights held by the general partner of Enable. Enable is expected to pay a minimum quarterly distribution of $0.2875 per common unit on its outstanding common units to the extent it has sufficient cash from operations after establishment of cash reserves and payment of fees and expenses, including payments to its general partner and its affiliates, within 60 days after the end of each quarter. If cash distributions to Enable’s unitholders exceed $0.330625 per common unit in any quarter, the general partner will receive increasing percentages or incentive distributions rights, up to 50% , of the cash Enable distributes in excess of that amount. In certain circumstances the general partner of Enable will have the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election. To date, no incentive distributions have been made. Transactions with Enable: Three Months Ended March 31, 2018 2017 (in millions) Reimbursement of transition services (1) $ 2 $ 2 Natural gas expenses, including transportation and storage costs 37 33 (1) Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement. March 31, 2018 December 31, 2017 (in millions) Accounts receivable for amounts billed for transition services $ 1 $ 1 Accounts payable for natural gas purchases from Enable 11 13 Summarized unaudited consolidated income information for Enable is as follows: Three Months Ended March 31, 2018 2017 (in millions) Operating revenues $ 748 $ 666 Cost of sales, excluding depreciation and amortization 375 308 Operating income 139 140 Net income attributable to Enable 105 111 Reconciliation of Equity in Earnings, net: CenterPoint Energy’s interest $ 57 $ 60 Basis difference amortization (1) 12 12 CenterPoint Energy’s equity in earnings, net $ 69 $ 72 (1) Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s share of Enable’s earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s original investment in Enable and its underlying equity in Enable’s net assets. The basis difference is amortized over approximately 31 years, the average life of the assets to which the basis difference is attributed. Summarized unaudited consolidated balance sheet information for Enable is as follows: March 31, December 31, 2017 (in millions) Current assets $ 413 $ 416 Non-current assets 11,274 11,177 Current liabilities 1,404 1,279 Non-current liabilities 2,664 2,660 Non-controlling interest 11 12 Preferred equity 362 362 Enable partners’ equity 7,246 7,280 Reconciliation of Investment in Enable: CenterPoint Energy’s ownership interest in Enable partners’ equity $ 3,913 $ 3,935 CenterPoint Energy’s basis difference (1,446 ) (1,463 ) CenterPoint Energy’s equity method investment in Enable $ 2,467 $ 2,472

Goodwill and Other Intangibles

Goodwill and Other Intangibles	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles [Text Block]	Goodwill and Other Intangibles Goodwill by reportable business segment as of both March 31, 2018 and December 31, 2017 is as follows: (in millions) Natural Gas Distribution $ 746 Energy Services 110 (1) Other Operations 11 Total $ 867 (1) Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012. The tables below present information on CenterPoint Energy’s other intangible assets recorded in Other non-current assets on the Condensed Consolidated Balance Sheets. March 31, 2018 December 31, 2017 Useful Lives Gross Carrying Amount Accumulated Amortization Net Balance Gross Carrying Amount Accumulated Amortization Net Balance (in years) (in millions) Customer relationships 15 $ 86 $ (23 ) $ 63 $ 86 $ (21 ) $ 65 Covenants not to compete 4 4 (2 ) 2 4 (2 ) 2 Other Various 15 (9 ) 6 15 (8 ) 7 Total $ 105 $ (34 ) $ 71 $ 105 $ (31 ) $ 74 Three Months Ended March 31, 2018 2017 (in millions) Amortization expense of intangible assets $ 3 $ 2

Indexed Debt Securities (ZENS)

Indexed Debt Securities (ZENS) and Securities Related to ZENS	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Indexed Debt Securities [Text Block]	Indexed Debt Securities (ZENS) and Securities Related to ZENS (a) Investment in Securities Related to ZENS In 1995, CenterPoint Energy sold a cable television subsidiary to TW and received certain TW securities as partial consideration. A subsidiary of CenterPoint Energy holds shares of certain securities detailed in the table below, 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 Condensed Statements of Consolidated Income. Shares Held March 31, 2018 December 31, 2017 TW Common 7,107,130 7,107,130 Time Common — 888,392 Charter Common 872,503 872,503 (b) ZENS In September 1999, CenterPoint Energy issued ZENS having an original principal amount of $1 billion of which $828 million remain outstanding as of March 31, 2018 . Each ZENS 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 are adjusted for certain corporate events. On October 22, 2016, AT&T announced that it had entered into a definitive agreement to acquire TW in a stock and cash transaction. On February 15, 2017, TW shareholders approved the announced transaction with AT&T. Pursuant to the merger agreement, upon closing of the merger, TW shareholders would receive for each of their shares of TW Common an estimated implied value of $107.50 , comprised of $53.75 per share in cash and $53.75 per share in AT&T Common. The stock portion will be subject to a collar such that TW shareholders will receive 1.437 shares of AT&T Common if AT&T Common’s average stock price is below $37.411 at closing and 1.3 shares of AT&T Common if AT&T Common’s average stock price is above $41.349 at closing. Cash received for the TW Common reference shares would subsequently be distributed to ZENS holders, which is expected to reduce the contingent principal balance, and reference shares would consist of Charter Common, Time Common and AT&T Common. In November 2017, the U.S. Department of Justice filed a civil antitrust lawsuit to block AT&T’s acquisition of TW. AT&T has announced it does not expect the outcome of this matter to prohibit the acquisition. Such proceedings began March 19, 2018 and the judge’s ruling is expected by June 12, 2018. On November 26, 2017, Meredith announced that it had entered into a definitive merger agreement with Time. Pursuant to the merger agreement, upon closing of the merger, a subsidiary of Meredith would purchase for cash all outstanding Time Common shares for $18.50 per share. The transaction was consummated on January 31, 2018. CenterPoint Energy elected to make a reference share offer adjustment and distribute additional interest, if any, in accordance with the terms of its ZENS rather than electing to increase the early exchange ratio to 100% . CenterPoint Energy’s distribution of additional interest in connection with the reference share offer was proportionate to the percentage of eligible shares that were validly tendered by Time stockholders in Meredith’s tender offer. CenterPoint Energy received $18.50 for each share of Time Common held, resulting in cash proceeds of approximately $16 million . In accordance with the terms of the ZENS, CenterPoint Energy distributed additional interest of approximately $16 million to ZENS holders on March 6, 2018, which reduced the contingent principal amount. As a result, CenterPoint Energy recorded the following during the three months ended March 31, 2018: (in millions) Cash payment to ZENS holders $ 16 Indexed debt – reduction (4 ) Indexed debt securities derivative – reduction (1 ) Loss on indexed debt securities $ 11 The reference shares for each ZENS consisted of the following: March 31, 2018 December 31, 2017 (in shares) TW Common 0.5 0.5 Time Common — 0.0625 Charter Common 0.061382 0.061382 As of March 31, 2018 , the contingent principal balance was $486 million .

Short-Term Borrowings and Long-

Short-Term Borrowings and Long-term Debt	3 Months Ended
	Mar. 31, 2018
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 AMAs associated with its utility distribution service in Arkansas, Louisiana, Mississippi, Oklahoma and Texas. In March 2018, NGD’s third party AMAs in Arkansas, Louisiana and Oklahoma expired, and NGD entered into new AMAs with CES effective April 1, 2018 in these states. The AMAs have varying terms, the longest of which expires in 2021. 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 an inventory financing and had an associated principal obligation of $-0- and $39 million as of March 31, 2018 and December 31, 2017 , respectively. (b) Long-term Debt Debt Issuances. During the three months ended March 31, 2018 , Houston Electric and CERC Corp. issued the following debt instruments: Issuance Date Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) Houston Electric February 2018 General mortgage bonds $ 400 3.95% 2048 CERC Corp. March 2018 Unsecured senior notes 300 3.55% 2023 CERC Corp. March 2018 Unsecured senior notes 300 4.00% 2028 The proceeds from these issuances were used for general limited liability company and corporate purposes, as applicable, including to repay portions of outstanding commercial paper and borrowings under CenterPoint Energy’s money pool. CenterPoint Energy, Houston Electric and CERC Corp. had the following revolving credit facilities and utilization of such facilities: March 31, 2018 December 31, 2017 Size of Loans Letters Commercial Loans Letters Commercial (in millions) CenterPoint Energy $ 1,700 $ — $ 6 $ 189 (1) $ — $ 6 $ 855 (1) Houston Electric 300 — 4 — — 4 — CERC Corp. 900 — 1 726 (2) — 1 898 (2) Total $ 2,900 $ — $ 11 $ 915 $ — $ 11 $ 1,753 (1) Weighted average interest rate was 2.24% and 1.88% as of March 31, 2018 and December 31, 2017 , respectively. (2) Weighted average interest rate was 2.34% and 1.72% as of March 31, 2018 and December 31, 2017 , respectively. Execution Date Company Size of Facility Draw Rate of LIBOR plus (1) Financial Covenant Limit on Debt for Borrowed Money to Capital Ratio Debt for Borrowed Money to Capital Ratio as of March 31, 2018 (2) Termination Date (in millions) March 3, 2016 CenterPoint Energy $ 1,700 1.250% 65% (3) 52.6% March 3, 2022 March 3, 2016 Houston Electric 300 1.125% 65% (3) 51.2% March 3, 2022 March 3, 2016 CERC Corp. 900 1.250% 65% 38.7% March 3, 2022 (1) Based on current credit ratings. (2) As defined in the revolving credit facility agreement, excluding Securitization Bonds. (3) 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 12 -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. CenterPoint Energy, Houston Electric and CERC Corp. were in compliance with all financial debt covenants as of March 31, 2018 .

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes [Text Block]	Income Taxes The effective tax rate reported for the three months ended March 31, 2018 was 22% compared to 36% for the same period in 2017. The lower effective tax rate for the three months ended March 31, 2018 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. CenterPoint Energy reported no uncertain tax liability as of March 31, 2018 and expects no significant changes to the uncertain tax liability over the next twelve months. Tax years through 2015 have been audited and settled with the IRS. For the 2016 through 2018 tax years, CenterPoint Energy is a participant in the IRS’s Compliance Assurance Process.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies [Text Block]	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, 2018 and December 31, 2017 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, 2018 , minimum payment obligations for natural gas supply commitments are approximately: (in millions) Remaining nine months of 2018 $ 289 2019 311 2020 170 2021 81 2022 51 2023 and beyond 125 (b) Legal, Environmental and Other 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. 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 such cases. CES, a subsidiary of CERC Corp., was a defendant in a case now pending in federal court in Nevada alleging a conspiracy to inflate Wisconsin natural gas prices in 2000–2002. On May 24, 2016, the district court granted CES’s motion for summary judgment, dismissing CES from the case. The plaintiffs have appealed that ruling. CenterPoint Energy and CES intend to continue vigorously defending against the plaintiffs’ claims. In June 2017, GenOn and various affiliates filed for protection under Chapter 11 of the U.S. Bankruptcy Code. In December 2017, GenOn received court approval of a restructuring plan and is expected to emerge from Chapter 11 in mid-2018. CenterPoint Energy, CERC, and CES submitted proofs of claim in the bankruptcy proceedings to protect their indemnity rights. If GenOn were unable to meet its indemnity obligations or satisfy a liability that has been assumed in the gas market manipulation litigation, then CenterPoint Energy, Houston Electric or CERC could incur liability and be responsible for satisfying the liability. CenterPoint Energy does not expect the ultimate outcome of the case against CES to have a material adverse effect on its financial condition, results of operations or cash flows. Minnehaha Academy. On August 2, 2017, a natural gas explosion occurred at the Minnehaha Academy in Minneapolis, Minnesota, resulting in the deaths of two school employees, serious injuries to others and significant property damage to the school. CenterPoint Energy, certain of its subsidiaries, and the contractor company working in the school have been named in litigation arising out of this incident. Additionally, CenterPoint Energy is cooperating with the ongoing investigation conducted by the National Transportation Safety Board. Further, CenterPoint Energy is contesting approximately $200,000 in fines imposed by the Minnesota Office of Pipeline Safety. In early 2018, the Minnesota Occupational Safety and Health Administration concluded its investigation without any adverse findings against CenterPoint Energy. CenterPoint Energy’s general and excess liability insurance policies provide coverage for third party bodily injury and property damage claims. Environmental Matters MGP 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, 2018 , 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 $5 million to $30 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 EPA 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 in interest 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 during its operations or on property where its predecessor companies have conducted operations. Other such sites involving contaminants may be identified in the future. CenterPoint Energy has and expects to continue to remediate any identified sites consistent with its state and federal legal obligations. From time to time CenterPoint Energy has received notices, and may receive notices in the future, 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, or may be, 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 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.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	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, 2018 2017 (in millions, except share and per share amounts) Net income $ 165 $ 192 Basic weighted average shares outstanding 431,231,000 430,794,000 Plus: Incremental shares from assumed conversions: Restricted stock 2,777,000 2,554,000 Diluted weighted average shares 434,008,000 433,348,000 Basic earnings per share Net income $ 0.38 $ 0.45 Diluted earnings per share Net income $ 0.38 $ 0.44

Reportable Business Segments

Reportable Business Segments	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Reportable Business Segments [Text Block]	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 other than Midstream Investments, where it uses equity in earnings. 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 (Houston Electric) 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 equity investment in Enable (excluding the Series A Preferred Units). 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, 2018 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Total Assets as of March 31, 2018 (in millions) Electric Transmission & Distribution $ 751 (1) $ — $ 115 $ 10,358 Natural Gas Distribution 1,143 10 156 6,438 Energy Services 1,257 28 (26 ) 1,329 Midstream Investments (2) — — — 2,467 Other Operations 4 — 6 2,500 (3) Eliminations — (38 ) — (682 ) Consolidated $ 3,155 $ — $ 251 $ 22,410 For the Three Months Ended March 31, 2017 Revenues from Net Operating (4) Total Assets as of December 31, 2017 (in millions) Electric Transmission & Distribution $ 639 (1) $ — $ 86 $ 10,292 Natural Gas Distribution 907 9 168 6,608 Energy Services 1,185 11 35 1,521 Midstream Investments (2) — — — 2,472 Other Operations 4 — 2 2,497 (3) Eliminations — (20 ) — (654 ) Consolidated $ 2,735 $ — $ 291 $ 22,736 (1) Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended March 31, 2018 2017 (in millions) Affiliates of NRG $ 161 $ 152 Affiliates of Vistra Energy Corp. 54 47 (2) Midstream Investments’ equity earnings, net are as follows: Three Months Ended March 31, 2018 2017 (in millions) Enable $ 69 $ 72 (3) Included in total assets of Other Operations as of March 31, 2018 and December 31, 2017 are pension and other postemployment-related regulatory assets of $588 million and $600 million , respectively. (4) Amounts for 2017 have been restated to reflect the adoption of ASU 2017-07.

Supplemental Disclosure of Cash

Supplemental Disclosure of Cash Flow Information	3 Months Ended
	Mar. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Cash Flow, Supplemental Disclosures [Text Block]	Supplemental Disclosure of Cash Flow Information The table below provides supplemental disclosure of cash flow information: Three Months Ended March 31, 2018 2017 (in millions) Cash Payments/Receipts: Interest, net of capitalized interest $ 116 $ 112 Income tax refunds, net (4 ) (2 ) Non-cash transactions: Accounts payable related to capital expenditures 102 73 The table below provides a reconciliation of cash, cash equivalents and restricted cash reported in the Condensed Consolidated Balance Sheets to the amount reported in the Condensed Statements of Consolidated Cash Flows: March 31, 2018 December 31, 2017 (in millions) Cash and cash equivalents $ 219 $ 260 Restricted cash included in Prepaid expenses and other current assets 37 35 Restricted cash included in Other 1 1 Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows $ 257 $ 296

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Proposed Merger with Vectren On April 21, 2018, CenterPoint Energy entered into the Merger Agreement. Under the terms of the Merger Agreement, CenterPoint Energy will acquire Vectren for approximately $6 billion in cash. Upon closing, Vectren will become a wholly-owned subsidiary of CenterPoint Energy. Pursuant to the Merger Agreement, upon the closing of the Merger, each share of Vectren common stock issued and outstanding immediately prior to the closing will be converted automatically into the right to receive $72.00 in cash per share. CenterPoint Energy expects to finance the Merger with a combination of debt, equity-linked and equity issuances and has obtained a $5 billion 364-day bridge facility commitment to provide flexibility for the timing of the long-term acquisition financing and fund, in part, amounts payable by CenterPoint Energy in connection with the Merger. All outstanding debt held by Vectren and its subsidiaries will be assumed by CenterPoint Energy at the closing of the Merger. It is forecasted that Vectren and its subsidiaries will have approximately $2.5 billion of outstanding short-term and long-term debt as of December 31, 2018. As of March 31, 2018, Vectren and its subsidiaries had outstanding $288 million of short-term debt and $1.8 billion of long-term debt, including current maturities. Consummation of the Merger is conditioned upon approval by federal and state regulatory commissions, expiration or termination of the applicable Hart-Scott-Rodino waiting period and approval of the Merger by Vectren shareholders. The Merger Agreement contains termination rights for both CenterPoint Energy and Vectren, and provides that, upon termination of the Merger Agreement under specified circumstances, CenterPoint Energy would be required to pay a termination fee of $210 million to Vectren and Vectren would be required to pay CenterPoint Energy a termination fee of $150 million . Subject to receipt of required regulatory approvals and satisfaction and/or waiver of the closing conditions, CenterPoint Energy and Vectren target closing the Merger in the first quarter of 2019. CenterPoint Energy Dividend Declaration On April 26, 2018 , CenterPoint Energy’s Board of Directors declared a regular quarterly cash dividend of $0.2775 per share of common stock payable on June 14, 2018 , to shareholders of record as of the close of business on May 17, 2018 . Enable Distributions Declarations On May 1, 2018 , Enable declared a quarterly cash distribution of $0.318 per unit on all of its outstanding common units for the quarter ended March 31, 2018 . Accordingly, CERC Corp. expects to receive a cash distribution of approximately $74 million from Enable in the second quarter of 2018 to be made with respect to CERC Corp.’s investment in common units of Enable for the first quarter of 2018. On May 1, 2018 , Enable declared a quarterly cash distribution of $0.625 per Series A Preferred Unit for the quarter ended March 31, 2018 . Accordingly, CenterPoint Energy expects to receive a cash distribution of approximately $9 million from Enable in the second quarter of 2018 to be made with respect to CenterPoint Energy’s investment in Series A Preferred Units of Enable for the first quarter of 2018.

New Accounting Pronouncements (

New Accounting Pronouncements (Tables)	3 Months Ended
	Mar. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	The following table provides an overview of recently adopted or issued accounting pronouncements applicable to CenterPoint Energy. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2014-09- Revenue from Contracts with Customers (Topic 606) and related amendments This standard provides a comprehensive new revenue recognition model that requires revenue to be recognized in a manner that depicts the transfer of goods or services to a customer at an amount that reflects the consideration expected to be received in exchange for those goods or services. Transition method: modified retrospective January 1, 2018 CenterPoint Energy added a revenue recognition footnote (Note 3) to address the disclosure requirements, and it did not identify significant changes to revenue recognition. A substantial amount of CenterPoint Energy’s revenues are tariff and derivative based, which were not significantly impacted by these ASUs. ASU 2017-05- Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets This standard clarifies when and how to apply ASC 610-20, which was issued as part of ASU 2014-09. It amends or supersedes the guidance in ASC 350 and ASC 360 on determining a gain or loss recognized upon the derecognition of nonfinancial assets. Transition method: modified retrospective January 1, 2018 ASU 2017-05 eliminates industry specific guidance, including ASC 360-20 Property, Plant, and Equipment - Real Estate Sales, for the recognition of gains or losses upon the sale of in-substance real estate. CenterPoint Energy elected to apply the practical expedient upon adoption to only evaluate transactions that were not determined to be complete as of the date of adoption. Subsequent to adoption, gains or losses on sales or dilution events in CenterPoint Energy’s investment in Enable may result in gains or losses recognized in earnings. See Note 8 for further discussion. ASU 2016-01-Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ASU 2018-03-Technical Corrections and Improvements to Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This standard 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. It also changes certain disclosure requirements and other aspects related to recognition and measurement of financial assets and financial liabilities. Transition method: cumulative-effect adjustment to beginning retained earnings, and two features prospective January 1, 2018 The adoption of this standard did not have an impact on CenterPoint Energy’s financial position, results of operations or cash flows. CenterPoint Energy elected the practicability exception for investments without a readily determinable fair value to be measured at cost for the Series A Preferred Units in Enable, which were previously accounted for under the cost method. See Note 8 for further discussion. ASU 2016-15- Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments This standard provides clarifying guidance on the classification of certain cash receipts and payments in the statement of cash flows and eliminates the variation in practice related to such classifications. Transition method: retrospective January 1, 2018 The adoption did not have a material impact on CenterPoint Energy’s financial position, results of operations or disclosures. However, the statement of cash flows reflects an increase in investing activities and a corresponding decrease in operating activities of $-0- and $2 million for the three months ended March 31, 2018 and 2017, respectively, due to the requirement that cash proceeds from COLI policies be classified as cash inflows from investing activity. ASU 2016-18- Statement of Cash Flows (Topic 230): Restricted Cash This standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. Transition method: retrospective January 1, 2018 The adoption of this standard did not have an impact on CenterPoint Energy’s financial position, results of operations or disclosures. However, the statement of cash flows is reconciled to cash, cash equivalents and restricted cash, resulting in a decrease in investing activities of $2 million and an increase in investing activities of $4 million for the three months ended March 31, 2018 and 2017, respectively. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2017-01- Business Combinations (Topic 805): Clarifying the Definition of a Business This standard revises the definition of a business. If substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, then under ASU 2017-01, the asset or group of assets is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs to be more closely aligned with how outputs are described in ASC 606. Transition method: prospective January 1, 2018 The adoption of this revised definition will reduce the number of transactions that are accounted for as a business combination, and therefore may have a potential impact on CenterPoint Energy’s accounting for future acquisitions. ASU 2017-04- Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This standard eliminates Step 2 of the goodwill impairment test, which required a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s future calculation of goodwill impairments if an impairment is identified. ASU 2017-07- Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This standard requires an employer to report the service cost component of the net periodic pension cost and postretirement benefit cost in the same line item(s) as other employee compensation costs arising from services rendered during the period; all other components will be presented separately from the line item(s) that includes the service cost and outside of any subtotal of operating income. In addition, only the service cost component will be eligible for capitalization in assets. Transition method: retrospective for the presentation of the service cost component and other components; prospective for the capitalization of the service cost component January 1, 2018 The adoption of this standard did not have a material impact on CenterPoint Energy’s financial position, results of operations, cash flows or disclosures; however, it resulted in an increase to operating income and a corresponding decrease to other income of $14 million and $17 million in the three months ended March 31, 2018 and 2017, respectively. Other components previously capitalized in assets will be recorded as regulatory assets in CenterPoint Energy’s rate-regulated businesses, prospectively. ASU No. 2017-09- Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting This standard clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. Entities will apply the modification accounting guidance if the value, vesting conditions or classification of the award changes. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s accounting for future changes to share-based payment awards. Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2016-02- Leases (Topic 842) and related amendments ASU 2018-01- Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842 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. Transition method : modified retrospective ASU 2018-01 allows entities to elect not to assess whether existing land easements that were not previously accounted for in accordance with ASC 840 Leases under ASC 842 Leases when transitioning to the new leasing standard. January 1, 2019 Early adoption is permitted CenterPoint Energy will elect the practical expedient on existing easements provided by ASU 2018-01 and is evaluating other available transitional practical expedients. CenterPoint Energy is in the process of reviewing contracts to identify leases as defined in ASU 2016-02 and expects to recognize on the statements of financial position right-of-use assets and lease liabilities for the majority of its leases that are currently classified as operating leases. CenterPoint Energy is continuing to assess the impact that adoption of these standards will have on its financial position, results of operations, cash flows and disclosures. ASU 2017-12- Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities This standard expands an entity’s ability to hedge nonfinancial and financial risk components and reduce complexity in fair value hedges of interest rate risk. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness, eases certain documentation and assessment requirements and updates the presentation and disclosure requirements. Transition method: cumulative-effect adjustment for elimination of the separate measurement of ineffectiveness; prospective for presentation and disclosure January 1, 2019 Early adoption is permitted CenterPoint Energy is currently assessing the impact that adoption of this standard will have on its financial position, results of operations, cash flows and disclosures. Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2018-02-Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA and requires entities to provide certain disclosures regarding stranded tax effects. Transition method: either in the period of adoption or retrospective January 1, 2019 Early adoption is permitted The adoption of this standard will allow CenterPoint Energy to reclass stranded deferred tax adjustments primarily related to benefit plans from other comprehensive income to retained earnings. CenterPoint Energy is currently assessing the impact that adoption of this standard will have on its financial position and disclosures.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	The following tables disaggregate revenues by major source: Three Months Ended March 31, 2018 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 761 $ 1,186 $ 178 $ 1 $ 2,126 Derivatives income (4 ) — 1,107 — 1,103 Other (3) (6 ) (33 ) — 3 (36 ) Eliminations — (10 ) (28 ) — (38 ) Total revenues $ 751 $ 1,143 $ 1,257 $ 4 $ 3,155 Three Months Ended March 31, 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy (2) Other Operations (2) Total (in millions) Revenue from contracts $ 644 $ 925 $ 142 $ 1 $ 1,712 Derivatives income 1 — 1,054 — 1,055 Other (3) (6 ) (9 ) — 3 (12 ) Eliminations — (9 ) (11 ) — (20 ) Total revenues $ 639 $ 907 $ 1,185 $ 4 $ 2,735 (1) Reflected in Utility revenues in the Condensed Statements of Consolidated Income. (2) Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income. (3) Primarily consists of income from ARPs and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. CenterPoint Energy recognizes ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Schedule of Defined Benefit Plans Disclosures [Table Text Block]	CenterPoint Energy’s net periodic cost, before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes, includes the following components relating to pension and post retirement benefits: Three Months Ended March 31, 2018 2017 Pension Postretirement Pension Postretirement (in millions) Service cost (1) $ 9 $ — $ 9 $ — Interest cost (2) 20 3 22 4 Expected return on plan assets (2) (27 ) (1 ) (24 ) (1 ) Amortization of prior service cost (credit) (2) 2 (1 ) 2 (1 ) Amortization of net loss (2) 11 — 14 — Net periodic cost $ 15 $ 1 $ 23 $ 2 (1) Included in Operation and maintenance expense in the Condensed Statements of Consolidated Income. (2) Included in Other, net in the Condensed Statements of Consolidated Income.
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	CenterPoint Energy’s changes in accumulated other comprehensive loss related to defined benefit and postretirement plans are as follows: Three Months Ended March 31, 2018 2017 (in millions) Beginning Balance $ (66 ) $ (72 ) Amounts reclassified from accumulated other comprehensive loss: Actuarial losses (1) 2 2 Tax expense (1 ) (1 ) Net current period other comprehensive income 1 1 Ending Balance $ (65 ) $ (71 ) (1) These accumulated other comprehensive components are included in the computation of net periodic cost.

Regulatory Accounting (Tables)

Regulatory Accounting (Tables)	3 Months Ended
	Mar. 31, 2018
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Schedule of Regulatory Assets and Liabilities [Table Text Block]	The following is a list of regulatory assets and liabilities reflected on CenterPoint Energy’s Condensed Consolidated Balance Sheets: March 31, December 31, 2017 (in millions) Regulatory Assets: Current regulatory assets (1) $ 65 $ 130 Non-current regulatory assets: Securitized regulatory assets 1,455 1,590 Unrecognized equity return (2) (266 ) (287 ) Unamortized loss on reacquired debt 74 75 Pension and postretirement-related regulatory asset (3) 636 646 Hurricane Harvey restoration costs (4) 64 64 Regulatory assets related to TCJA (5) 48 48 Other long-term regulatory assets (6) 202 211 Total non-current regulatory assets 2,213 2,347 Total regulatory assets 2,278 2,477 Regulatory Liabilities: Current regulatory liabilities (7) 43 24 Non-current regulatory liabilities: Regulatory liabilities related to TCJA (5) 1,373 1,354 Estimated removal costs 882 878 Other long-term regulatory liabilities 250 232 Total non-current regulatory liabilities 2,505 2,464 Total regulatory liabilities 2,548 2,488 Total regulatory assets and liabilities, net $ (270 ) $ (11 ) (1) Current regulatory assets are included in Prepaid expenses and other current assets in CenterPoint Energy’s Condensed Consolidated Balance Sheets. (2) The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended March 31, 2018 and 2017, Houston Electric recognized approximately $21 million and $7 million , respectively, of the allowed equity return. The timing of CenterPoint Energy’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months. (3) Includes a portion of NGD’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates that is being deferred for rate making purposes. Deferred pension and other postemployment expenses of $6 million and $7 million as of March 31, 2018 and December 31, 2017 , respectively, were not earning a return. (4) CenterPoint Energy is not earning a return on its Hurricane Harvey restoration costs. (5) The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities. (6) Other long-term regulatory assets that are not earning a return were not material as of March 31, 2018 and December 31, 2017 . (7) Current regulatory liabilities are included in Other current liabilities in CenterPoint Energy’s Condensed Consolidated Balance Sheets.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The table below summarizes CenterPoint Energy’s current weather hedge activity: Three Months Ended March 31, Jurisdiction Winter Season Bilateral Cap 2018 2017 (in millions) Certain NGD jurisdictions 2017 – 2018 $ 8 $ — $ — Electric operations’ service territory 2017 – 2018 9 (4 ) — Electric operations’ service territory 2016 – 2017 9 — 1 Total (1) $ (4 ) $ 1 (1) Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income.
Fair Value of Derivative Instruments [Table Text Block]	Fair Value of Derivative Instruments December 31, 2017 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivatives designated as fair value hedges: (in millions) Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities $ 13 $ 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 114 4 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 44 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 38 78 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 9 24 Indexed debt securities derivative Current Liabilities — 668 Total $ 218 $ 775 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,795 Bcf or a net 224 Bcf long position. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure. (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 natural gas derivative assets and liabilities was a $130 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, impacted by collateral netting of $19 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, while the last table provides a breakdown of the related income statement impacts. Fair Value of Derivative Instruments March 31, 2018 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivatives designated as fair value hedges: (in millions) Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities $ 1 $ 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 86 2 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 52 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 18 70 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 9 42 Indexed debt securities derivative Current Liabilities — 674 Total $ 166 $ 789 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,735 Bcf or a net 437 Bcf long position. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure. (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 natural gas derivative assets and liabilities was a $103 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, impacted by collateral netting of $52 million . (3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
Offsetting of Natural Gas Derivative Assets and Liabilities [Table Text Block]	Offsetting of Natural Gas Derivative Assets and Liabilities December 31, 2017 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 $ 165 $ (55 ) $ 110 Other Assets: Non-trading derivative assets 53 (9 ) 44 Current Liabilities: Non-trading derivative liabilities (83 ) 63 (20 ) Other Liabilities: Non-trading derivative liabilities (24 ) 20 (4 ) Total $ 111 $ 19 $ 130 (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, 2018 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 $ 105 $ (21 ) $ 84 Other Assets: Non-trading derivative assets 61 (9 ) 52 Current Liabilities: Non-trading derivative liabilities (73 ) 52 (21 ) Other Liabilities: Non-trading derivative liabilities (42 ) 30 (12 ) Total $ 51 $ 52 $ 103 (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 [Table Text Block]	Hedge ineffectiveness is recorded as a component of natural gas expense and primarily results from differences in the location of the derivative instrument and the hedged item. Basis ineffectiveness arises from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the hedge instruments. The impact of natural gas derivatives designated as fair value hedges, the related hedged item, and natural gas derivatives not designated as hedging instruments are presented in the table below. Income Statement Impact of Derivative Activity Three Months Ended March 31, Income Statement Location 2018 2017 Derivatives designated as fair value hedges: (in millions) Natural gas derivatives Gains (Losses) in Expenses: Natural Gas $ — $ 3 Fair value adjustments for natural gas inventory designated as the hedged item Gains (Losses) in Expenses: Natural Gas (2 ) (4 ) Total increase in Expenses: Natural Gas (1) $ (2 ) $ (1 ) Derivatives not designated as hedging instruments: Natural gas derivatives Gains (Losses) in Revenues $ 57 $ 96 Natural gas derivatives Gains (Losses) in Expenses: Natural Gas (69 ) (67 ) Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (18 ) (10 ) Total - derivatives not designated as hedging instruments $ (30 ) $ 19 (1) Hedge ineffectiveness results from the basis ineffectiveness discussed above, and excludes the impact to natural gas expense from timing ineffectiveness. Timing ineffectiveness arises due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity. As the commodity contract nears the settlement date, spot-to-forward price differences should converge, which should reduce or eliminate the impact of this ineffectiveness on natural gas expense.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair value, assets and liabilities measured on a recurring basis [Table Text Block]	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 and indicate the fair value hierarchy of the valuation techniques utilized by CenterPoint Energy to determine such fair value. March 31, 2018 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 (in millions) Assets Corporate equities $ 946 $ — $ — $ — $ 946 Investments, including money market funds (2) 70 — — — 70 Natural gas derivatives (3) — 147 19 (30 ) 136 Total assets $ 1,016 $ 147 $ 19 $ (30 ) $ 1,152 Liabilities Indexed debt securities derivative $ — $ — $ 674 $ — $ 674 Natural gas derivatives (3) — 108 7 (82 ) 33 Hedged portion of natural gas inventory 8 — — — 8 Total liabilities $ 8 $ 108 $ 681 $ (82 ) $ 715 (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 $52 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. December 31, 2017 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 (in millions) Assets Corporate equities $ 963 $ — $ — $ — $ 963 Investments, including money market funds (2) 68 — — — 68 Natural gas derivatives (3) — 161 57 (64 ) 154 Hedged portion of natural gas inventory 14 — — — 14 Total assets $ 1,045 $ 161 $ 57 $ (64 ) $ 1,199 Liabilities Indexed debt securities derivative $ — $ — $ 668 $ — $ 668 Natural gas derivatives (3) — 96 11 (83 ) 24 Total liabilities $ — $ 96 $ 679 $ (83 ) $ 692 (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 $19 million posted with the same counterparties. (2) Amounts are included in Prepaid expenses and other current assets and Other 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 [Table Text Block]	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, 2018 2017 (in millions) Beginning balance $ (622 ) $ (704 ) Total gains (losses) (4 ) 6 Total settlements (34 ) (4 ) Transfers into Level 3 — 1 Transfers out of Level 3 (2 ) 1 Ending balance (1) $ (662 ) $ (700 ) The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date $ (5 ) $ 5 (1) CenterPoint Energy did not have significant Level 3 sales or purchases during either of the three months ended March 31, 2018 or 2017 .
Estimated fair value of financial instruments, debt instruments [Table Text Block]	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 a combination of historical trading prices and comparable issue data. These 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 2 in the fair value hierarchy. March 31, 2018 December 31, 2017 Carrying Fair Carrying Amount Fair Value (in millions) Financial liabilities: Long-term debt $ 8,670 $ 9,008 $ 8,679 $ 9,220

Unconsolidated Affiliate (Table

Unconsolidated Affiliate (Tables)	3 Months Ended
	Mar. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments [Table Text Block]	Limited Partner Interest and Units Held in Enable: March 31, 2018 Limited Partner Interest (1) Common Units Series A Preferred Units (2) CenterPoint Energy 54.0 % 233,856,623 14,520,000 OGE 25.6 % 110,982,805 — Public unitholders 20.4 % 88,232,573 — Total units outstanding 100.0 % 433,072,001 14,520,000 (1) Excluding the Series A Preferred Units owned by CenterPoint Energy. (2) The carrying amount of the Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on the Condensed Consolidated Balance Sheets, was $363 million as of both March 31, 2018 and December 31, 2017. No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion. Summarized unaudited consolidated income information for Enable is as follows: Three Months Ended March 31, 2018 2017 (in millions) Operating revenues $ 748 $ 666 Cost of sales, excluding depreciation and amortization 375 308 Operating income 139 140 Net income attributable to Enable 105 111 Reconciliation of Equity in Earnings, net: CenterPoint Energy’s interest $ 57 $ 60 Basis difference amortization (1) 12 12 CenterPoint Energy’s equity in earnings, net $ 69 $ 72 (1) Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s share of Enable’s earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s original investment in Enable and its underlying equity in Enable’s net assets. The basis difference is amortized over approximately 31 years, the average life of the assets to which the basis difference is attributed. Summarized unaudited consolidated balance sheet information for Enable is as follows: March 31, December 31, 2017 (in millions) Current assets $ 413 $ 416 Non-current assets 11,274 11,177 Current liabilities 1,404 1,279 Non-current liabilities 2,664 2,660 Non-controlling interest 11 12 Preferred equity 362 362 Enable partners’ equity 7,246 7,280 Reconciliation of Investment in Enable: CenterPoint Energy’s ownership interest in Enable partners’ equity $ 3,913 $ 3,935 CenterPoint Energy’s basis difference (1,446 ) (1,463 ) CenterPoint Energy’s equity method investment in Enable $ 2,467 $ 2,472 Distributions Received from Enable: Three Months Ended March 31, 2018 2017 (in millions) Investment in Enable common units $ 74 $ 74 Investment in Enable Series A Preferred Units 9 9 Total $ 83 $ 83 Transactions with Enable: Three Months Ended March 31, 2018 2017 (in millions) Reimbursement of transition services (1) $ 2 $ 2 Natural gas expenses, including transportation and storage costs 37 33 (1) Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement. March 31, 2018 December 31, 2017 (in millions) Accounts receivable for amounts billed for transition services $ 1 $ 1 Accounts payable for natural gas purchases from Enable 11 13

Goodwill and Other Intangibles

Goodwill and Other Intangibles (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	Goodwill by reportable business segment as of both March 31, 2018 and December 31, 2017 is as follows: (in millions) Natural Gas Distribution $ 746 Energy Services 110 (1) Other Operations 11 Total $ 867 (1) Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012.
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The tables below present information on CenterPoint Energy’s other intangible assets recorded in Other non-current assets on the Condensed Consolidated Balance Sheets. March 31, 2018 December 31, 2017 Useful Lives Gross Carrying Amount Accumulated Amortization Net Balance Gross Carrying Amount Accumulated Amortization Net Balance (in years) (in millions) Customer relationships 15 $ 86 $ (23 ) $ 63 $ 86 $ (21 ) $ 65 Covenants not to compete 4 4 (2 ) 2 4 (2 ) 2 Other Various 15 (9 ) 6 15 (8 ) 7 Total $ 105 $ (34 ) $ 71 $ 105 $ (31 ) $ 74
Finite-lived Intangible Assets Amortization Expense [Table Text Block]	Three Months Ended March 31, 2018 2017 (in millions) Amortization expense of intangible assets $ 3 $ 2

Indexed Debt Securities (ZENS33

Indexed Debt Securities (ZENS) and Securities Related to ZENS (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Indexed Debt Securities and Marketable Securities [Table Text Block]	In 1995, CenterPoint Energy sold a cable television subsidiary to TW and received certain TW securities as partial consideration. A subsidiary of CenterPoint Energy holds shares of certain securities detailed in the table below, 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 Condensed Statements of Consolidated Income. Shares Held March 31, 2018 December 31, 2017 TW Common 7,107,130 7,107,130 Time Common — 888,392 Charter Common 872,503 872,503 The reference shares for each ZENS consisted of the following: March 31, 2018 December 31, 2017 (in shares) TW Common 0.5 0.5 Time Common — 0.0625 Charter Common 0.061382 0.061382 As a result, CenterPoint Energy recorded the following during the three months ended March 31, 2018: (in millions) Cash payment to ZENS holders $ 16 Indexed debt – reduction (4 ) Indexed debt securities derivative – reduction (1 ) Loss on indexed debt securities $ 11

Short-Term Borrowings and Lon34

Short-Term Borrowings and Long-term Debt (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt [Table Text Block]	Debt Issuances. During the three months ended March 31, 2018 , Houston Electric and CERC Corp. issued the following debt instruments: Issuance Date Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) Houston Electric February 2018 General mortgage bonds $ 400 3.95% 2048 CERC Corp. March 2018 Unsecured senior notes 300 3.55% 2023 CERC Corp. March 2018 Unsecured senior notes 300 4.00% 2028
Schedule of Line of Credit Facilities [Table Text Block]	CenterPoint Energy, Houston Electric and CERC Corp. had the following revolving credit facilities and utilization of such facilities: March 31, 2018 December 31, 2017 Size of Loans Letters Commercial Loans Letters Commercial (in millions) CenterPoint Energy $ 1,700 $ — $ 6 $ 189 (1) $ — $ 6 $ 855 (1) Houston Electric 300 — 4 — — 4 — CERC Corp. 900 — 1 726 (2) — 1 898 (2) Total $ 2,900 $ — $ 11 $ 915 $ — $ 11 $ 1,753 (1) Weighted average interest rate was 2.24% and 1.88% as of March 31, 2018 and December 31, 2017 , respectively. (2) Weighted average interest rate was 2.34% and 1.72% as of March 31, 2018 and December 31, 2017 , respectively. Execution Date Company Size of Facility Draw Rate of LIBOR plus (1) Financial Covenant Limit on Debt for Borrowed Money to Capital Ratio Debt for Borrowed Money to Capital Ratio as of March 31, 2018 (2) Termination Date (in millions) March 3, 2016 CenterPoint Energy $ 1,700 1.250% 65% (3) 52.6% March 3, 2022 March 3, 2016 Houston Electric 300 1.125% 65% (3) 51.2% March 3, 2022 March 3, 2016 CERC Corp. 900 1.250% 65% 38.7% March 3, 2022 (1) Based on current credit ratings. (2) As defined in the revolving credit facility agreement, excluding Securitization Bonds. (3) 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 12 -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.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Long-term Purchase Commitment [Table Text Block]	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, 2018 and December 31, 2017 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, 2018 , minimum payment obligations for natural gas supply commitments are approximately: (in millions) Remaining nine months of 2018 $ 289 2019 311 2020 170 2021 81 2022 51 2023 and beyond 125

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
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, 2018 2017 (in millions, except share and per share amounts) Net income $ 165 $ 192 Basic weighted average shares outstanding 431,231,000 430,794,000 Plus: Incremental shares from assumed conversions: Restricted stock 2,777,000 2,554,000 Diluted weighted average shares 434,008,000 433,348,000 Basic earnings per share Net income $ 0.38 $ 0.45 Diluted earnings per share Net income $ 0.38 $ 0.44

Reportable Business Segments (T

Reportable Business Segments (Tables)	3 Months Ended
	Mar. 31, 2018
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, 2018 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Total Assets as of March 31, 2018 (in millions) Electric Transmission & Distribution $ 751 (1) $ — $ 115 $ 10,358 Natural Gas Distribution 1,143 10 156 6,438 Energy Services 1,257 28 (26 ) 1,329 Midstream Investments (2) — — — 2,467 Other Operations 4 — 6 2,500 (3) Eliminations — (38 ) — (682 ) Consolidated $ 3,155 $ — $ 251 $ 22,410 For the Three Months Ended March 31, 2017 Revenues from Net Operating (4) Total Assets as of December 31, 2017 (in millions) Electric Transmission & Distribution $ 639 (1) $ — $ 86 $ 10,292 Natural Gas Distribution 907 9 168 6,608 Energy Services 1,185 11 35 1,521 Midstream Investments (2) — — — 2,472 Other Operations 4 — 2 2,497 (3) Eliminations — (20 ) — (654 ) Consolidated $ 2,735 $ — $ 291 $ 22,736 (1) Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended March 31, 2018 2017 (in millions) Affiliates of NRG $ 161 $ 152 Affiliates of Vistra Energy Corp. 54 47 (2) Midstream Investments’ equity earnings, net are as follows: Three Months Ended March 31, 2018 2017 (in millions) Enable $ 69 $ 72 (3) Included in total assets of Other Operations as of March 31, 2018 and December 31, 2017 are pension and other postemployment-related regulatory assets of $588 million and $600 million , respectively. (4) Amounts for 2017 have been restated to reflect the adoption of ASU 2017-07.
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, 2018 2017 (in millions) Affiliates of NRG $ 161 $ 152 Affiliates of Vistra Energy Corp. 54 47
Midstream Investments [Table Text Block]	Midstream Investments’ equity earnings, net are as follows: Three Months Ended March 31, 2018 2017 (in millions) Enable $ 69 $ 72

Supplemental Disclosure of Ca38

Supplemental Disclosure of Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]	The table below provides supplemental disclosure of cash flow information: Three Months Ended March 31, 2018 2017 (in millions) Cash Payments/Receipts: Interest, net of capitalized interest $ 116 $ 112 Income tax refunds, net (4 ) (2 ) Non-cash transactions: Accounts payable related to capital expenditures 102 73 The table below provides a reconciliation of cash, cash equivalents and restricted cash reported in the Condensed Consolidated Balance Sheets to the amount reported in the Condensed Statements of Consolidated Cash Flows: March 31, 2018 December 31, 2017 (in millions) Cash and cash equivalents $ 219 $ 260 Restricted cash included in Prepaid expenses and other current assets 37 35 Restricted cash included in Other 1 1 Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows $ 257 $ 296

Background and Basis of Prese39

Background and Basis of Presentation (Details)	Mar. 31, 2018stateshares
Enable Midstream Partners [Member]
Ownership percentage of equity method investment	54.00%	[1]
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Preferred units held | shares	14,520,000	[2]
Natural Gas Distribution [Member]
Number of states in which entity operates	6
Energy Services [Member]
Number of states in which entity operates	33
[1]	Excluding the Series A Preferred Units owned by CenterPoint Energy.
[2]	The carrying amount of the Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on the Condensed Consolidated Balance Sheets, was $363 million as of both March 31, 2018 and December 31, 2017. No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion.

New Accounting Pronouncements40

New Accounting Pronouncements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounting Standards Update 2016-15 [Member]
Effect of change on cash flow activities due to adoption of new ASU	$ 0	$ 2
Accounting Standards Update 2016-18 [Member]
Effect of change on cash flow activities due to adoption of new ASU	(2)	4
Accounting Standards Update 2017-07 [Member]
Increase to operating income and corresponding decrease to other net income from the adoption of ASU 2017-07	$ 14	$ 17

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from contracts		$ 2,126	$ 1,712
Derivatives income		1,103	1,055
Other (1)	[1]	(36)	(12)
Revenues		3,155	2,735
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues		(38)	(20)
Electric Transmission and Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues	[2]	751	639
Electric Transmission and Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues		0	0
Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues		1,143	907
Natural Gas Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues		(10)	(9)
Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenues		1,257	1,185
Energy Services [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues		(28)	(11)
Other Operations [Member]
Disaggregation of Revenue [Line Items]
Revenues		4	4
Other Operations [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues		0	0
Reportable Subsegments [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	(10)	(9)
Derivatives income	[4]	(28)	(11)
Revenues		(38)	(20)
Reportable Subsegments [Member] | Electric Transmission and Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	761	644
Derivatives income	[3]	(4)	1
Other (1)	[1],[3]	(6)	(6)
Revenues	[3]	751	639
Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	1,186	925
Derivatives income	[3]	0	0
Other (1)	[1],[3]	(33)	(9)
Revenues	[3]	1,143	907
Reportable Subsegments [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]	178	142
Derivatives income	[4]	1,107	1,054
Other (1)	[1],[4]	0	0
Revenues	[4]	1,257	1,185
Reportable Subsegments [Member] | Other Operations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]	1	1
Derivatives income	[4]	0	0
Other (1)	[1],[4]	3	3
Revenues	[4]	$ 4	$ 4
[1]	Primarily consists of income from ARPs and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. CenterPoint Energy recognizes ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period.
[2]	Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended March 31, 2018 2017 (in millions)Affiliates of NRG $161 $152Affiliates of Vistra Energy Corp. 54 47
[3]	Reflected in Utility revenues in the Condensed Statements of Consolidated Income.
[4]	Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income.

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan, Change in Accumulated Comprehensive Loss [Roll Forward]
Beginning Balance		$ (66)	$ (72)
Amounts reclassified from accumulated other comprehensive loss:
Actuarial losses (1)	[1]	2	2
Tax expense		(1)	(1)
Net current period other comprehensive income		1	1
Ending Balance		(65)	(71)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost		15	23
Total contributions expected in current year		67
Total contributions to the plans during the period		62
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost		1	2
Total contributions expected in current year		16
Total contributions to the plans during the period		4
Operation and maintenance expense [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	9	9
Operation and maintenance expense [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	0	0
Other, net [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	20	22
Expected return on plan assets (2)	[3]	(27)	(24)
Amortization of prior service cost (credit) (2)	[3]	2	2
Amortization of net loss (2)	[3]	11	14
Other, net [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	3	4
Expected return on plan assets (2)	[3]	(1)	(1)
Amortization of prior service cost (credit) (2)	[3]	(1)	(1)
Amortization of net loss (2)	[3]	$ 0	$ 0
[1]	These accumulated other comprehensive components are included in the computation of net periodic cost.
[2]	Included in Operation and maintenance expense in the Condensed Statements of Consolidated Income.
[3]	Included in Other, net in the Condensed Statements of Consolidated Income.

Regulatory Accounting (Details)

Regulatory Accounting (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Securitized regulatory assets		$ 1,455		$ 1,590
Unrecognized equity return (2)	[1]	(266)		(287)
Unamortized loss on reacquired debt		74		75
Net regulatory asset		2,213		2,347
Total regulatory assets		2,278		2,477
Regulatory liabilities		2,505		2,464
Total regulatory liabilities		2,548		2,488
Total regulatory assets and liabilities, net		(270)		(11)
CenterPoint Houston [Member]
Amount of allowed equity return on the true-up balance that was recognized in the period		21	$ 7
Hurricane Harvey [Member]
Net regulatory asset	[2]	64		64
Prepaid expenses and other current assets [Member]
Current regulatory assets (1)	[3]	65		130
Other current liabilities [Member]
Current regulatory liabilities (7)	[4]	43		24
Pension and Other Postretirement Plans Costs [Member]
Net regulatory asset	[5]	636		646
Amounts related to TCJA [Member]
Net regulatory asset	[6]	48		48
Other Regulatory Assets (Liabilities) [Member]
Net regulatory asset	[7]	202		211
Amounts related to TCJA [Member]
Regulatory liabilities	[6]	1,373		1,354
Removal Costs [Member]
Regulatory liabilities		882		878
Other Regulatory Assets (Liabilities) [Member]
Regulatory liabilities		250		232
Natural Gas Distribution [Member] | Pension and Other Postretirement Plans Costs [Member]
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		$ 6		$ 7
[1]	The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended March 31, 2018 and 2017, Houston Electric recognized approximately $21 million and $7 million, respectively, of the allowed equity return. The timing of CenterPoint Energy’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months.
[2]	CenterPoint Energy is not earning a return on its Hurricane Harvey restoration costs.
[3]	Current regulatory assets are included in Prepaid expenses and other current assets in CenterPoint Energy’s Condensed Consolidated Balance Sheets.
[4]	Current regulatory liabilities are included in Other current liabilities in CenterPoint Energy’s Condensed Consolidated Balance Sheets.
[5]	Includes a portion of NGD’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates that is being deferred for rate making purposes. Deferred pension and other postemployment expenses of $6 million and $7 million as of March 31, 2018 and December 31, 2017, respectively, were not earning a return.
[6]	The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities.
[7]	Other long-term regulatory assets that are not earning a return were not material as of March 31, 2018 and December 31, 2017.

Derivative Instruments Derivati

Derivative Instruments Derivatives and hedging (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Mar. 26, 2018	Feb. 28, 2018
Derivatives, Fair Value [Line Items]
Weather hedges term		10 years
Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges	[1]	$ (4)	$ 1
Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0
Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		(4)	$ 1
2017 to 2018 [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount		8
2017 to 2018 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount		9
2016to2017 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount		9
CenterPoint Houston [Member] | January thru February [Member] | Treasury Lock [Member]
Derivatives, Fair Value [Line Items]
Aggregate notional amount		200
Effective portion of realized gains (losses)		5
CERC Corp [Member] | March [Member] | Treasury Lock [Member]
Derivatives, Fair Value [Line Items]
Aggregate notional amount		450
Effective portion of realized gains (losses)		$ (1)
General Mortgage Bonds Due 2048 [Member] | CenterPoint Houston [Member]
Derivatives, Fair Value [Line Items]
Principal amount of debt issued					$ 400
Senior Notes [Member] | CERC Corp [Member]
Derivatives, Fair Value [Line Items]
Principal amount of debt issued				$ 600
[1]	Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income.

Derivative Instruments Deriva45

Derivative Instruments Derivative Fair Values (Details)		3 Months Ended			12 Months Ended
		Mar. 31, 2018USD ($)Bcf		Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)Bcf
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		$ 166,000,000			$ 218,000,000
Derivative Liabilities Fair Value		789,000,000			775,000,000
Gain (loss) on derivative instruments not designated as hedging instruments		(30,000,000)		$ 19,000,000
Total fair value of the derivative instruments that contain credit risk contingent features that are in a net liability position		2,000,000			2,000,000
The aggregate fair value of assets already posted as collateral		0			0
Credit risk contingent features assets		2,000,000			$ 2,000,000
Gains (Losses) in Expense: Natural Gas [Member]
Derivatives, Fair Value [Line Items]
Change in unrealized gain (loss) on hedged item in fair value hedge		(2,000,000)		(4,000,000)
Gain (loss) on fair value hedges recognized in earnings	[1]	$ (2,000,000)		(1,000,000)
Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative gross volume notional amount (in Bcf) | Bcf		1,735			1,795
Net amount presented in the consolidated balance sheets	[2]	$ 103,000,000			$ 130,000,000
Gross Amounts Recognized	[3]	51,000,000			111,000,000
Gross Amounts Offset in the Consolidated Balance Sheets		52,000,000			19,000,000
Energy Related Derivative [Member] | Gains (Losses) in Revenue [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments not designated as hedging instruments		57,000,000		96,000,000
Energy Related Derivative [Member] | Gains (Losses) in Expense: Natural Gas [Member]
Derivatives, Fair Value [Line Items]
Change in unrealized gain (loss) on fair value hedging instruments		0		3,000,000
Gain (loss) on derivative instruments not designated as hedging instruments		(69,000,000)		(67,000,000)
Energy Related Derivative [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[3]	105,000,000			165,000,000
Gross Amounts Offset		(21,000,000)			(55,000,000)
Derivative Asset	[2]	84,000,000			110,000,000
Energy Related Derivative [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[3]	61,000,000			53,000,000
Gross Amounts Offset		(9,000,000)			(9,000,000)
Derivative Asset	[2]	52,000,000			44,000,000
Energy Related Derivative [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[3]	(73,000,000)			(83,000,000)
Gross Amounts Offset		52,000,000			63,000,000
Derivative Liability	[2]	(21,000,000)			(20,000,000)
Energy Related Derivative [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[3]	(42,000,000)			(24,000,000)
Gross Amounts Offset		30,000,000			20,000,000
Derivative Liability	[2]	(12,000,000)			(4,000,000)
Energy Related Derivative [Member] | Designated as Fair Value Hedge [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4]	1,000,000	[5],[6]		13,000,000	[7],[8]
Derivative Liabilities Fair Value	[4]	1,000,000	[5],[6]		1,000,000	[7],[8]
Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4]	86,000,000	[5],[6]		114,000,000	[7],[8]
Derivative Liabilities Fair Value	[4]	2,000,000	[5],[6]		4,000,000	[7],[8]
Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4]	52,000,000	[5],[6]		44,000,000	[7],[8]
Derivative Liabilities Fair Value	[4]	0	[5],[6]		0	[7],[8]
Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4]	18,000,000	[5],[6]		38,000,000	[7],[8]
Derivative Liabilities Fair Value	[4]	70,000,000	[5],[6]		78,000,000	[7],[8]
Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4]	9,000,000	[5],[6]		9,000,000	[7],[8]
Derivative Liabilities Fair Value	[4]	$ 42,000,000	[5],[6]		$ 24,000,000	[7],[8]
Energy Related Derivative [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
Derivative gross volume notional amount (in Bcf) | Bcf		437			224
IDS Derivative [Member] | Gains (losses) in Other Income (Expense) [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments not designated as hedging instruments		$ (18,000,000)		$ (10,000,000)
IDS Derivative [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		0			$ 0
Derivative Liabilities Fair Value		$ 674,000,000			$ 668,000,000
[1]	Hedge ineffectiveness results from the basis ineffectiveness discussed above, and excludes the impact to natural gas expense from timing ineffectiveness. Timing ineffectiveness arises due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity. As the commodity contract nears the settlement date, spot-to-forward price differences should converge, which should reduce or eliminate the impact of this ineffectiveness on natural gas expense.
[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]	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.
[4]	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
[5]	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 natural gas derivative assets and liabilities was a $103 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, impacted by collateral netting of $52 million.
[6]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,735 Bcf or a net 437 Bcf long position. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure.
[7]	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 natural gas derivative assets and liabilities was a $130 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, impacted by collateral netting of $19 million.
[8]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,795 Bcf or a net 224 Bcf long position. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure.

Fair Value Measurements (Detail

Fair Value Measurements (Details)		3 Months Ended
		Mar. 31, 2018USD ($)		Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair value amount of Level 1 to Level 2 assets transferred		$ 0
Fair value amount of Level 2 to Level 1 assets transferred		0
Fair value amount of Level 1 to Level 2 liabilities transferred		0
Fair value amount of Level 2 to Level 1 liabilities transferred		0
Assets
Total derivative assets, netting adjustment		(30,000,000)	[1]		$ (64,000,000)	[2]
Total assets		1,152,000,000			1,199,000,000
Liabilities
Total derivative liabilities, netting adjustment		(82,000,000)	[1]		(83,000,000)	[2]
Total liabilities		715,000,000			692,000,000
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		(622,000,000)		$ (704,000,000)
Total gains (losses)		(4,000,000)		6,000,000
Total settlements		(34,000,000)		(4,000,000)
Transfers into Level 3		0		1,000,000
Transfers out of Level 3		(2,000,000)		1,000,000
Ending balance (1)	[3]	(662,000,000)		(700,000,000)
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date (3)		(5,000,000)		$ 5,000,000
Carrying Value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt		8,670,000,000			8,679,000,000
Fair Value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt		9,008,000,000			9,220,000,000
Natural gas derivatives [Member]
Assets
Derivative fair value offsets, net		52,000,000			19,000,000
Fair Value, Inputs, Level 1 [Member]
Assets
Total assets		1,016,000,000			1,045,000,000
Liabilities
Total liabilities		8,000,000			0
Fair Value, Inputs, Level 2 [Member]
Assets
Total assets		147,000,000			161,000,000
Liabilities
Total liabilities		108,000,000			96,000,000
Fair Value, Inputs, Level 3 [Member]
Assets
Total assets		19,000,000			57,000,000
Liabilities
Total liabilities		$ 681,000,000			679,000,000
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair value inputs (price per MMBtu)		1.36
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair value inputs (price per MMBtu)		3.26
Fair Value, Inputs, Level 3 [Member] | IDS Derivative [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair value options volatility rate		19.00%
Fair value projected dividend growth rate		6.00%
Fair Value, Measurements, Recurring [Member]
Assets
Corporate equities		$ 946,000,000			963,000,000
Investments, including money market funds (2)	[4]	70,000,000			68,000,000
Fair Value Hedge Assets					14,000,000
Liabilities
Hedged portion of natural gas inventory		8,000,000
Fair Value, Measurements, Recurring [Member] | IDS Derivative [Member]
Liabilities
Derivative liabilities, netting adjustment		0	[1]		0	[2]
Derivative liabilities		674,000,000			668,000,000
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member]
Assets
Derivative asset, netting adjustment	[5]	(30,000,000)	[1]		(64,000,000)	[2]
Derivative assets	[5]	136,000,000			154,000,000
Liabilities
Derivative liabilities, netting adjustment	[5]	(82,000,000)	[1]		(83,000,000)	[2]
Derivative liabilities	[5]	33,000,000			24,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Corporate equities		946,000,000			963,000,000
Investments, including money market funds (2)	[4]	70,000,000			68,000,000
Fair Value Hedge Assets					14,000,000
Liabilities
Hedged portion of natural gas inventory		8,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | IDS Derivative [Member]
Liabilities
Derivative liability		0			0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Natural gas derivatives [Member]
Assets
Derivative asset	[5]	0			0
Liabilities
Derivative liability	[5]	0			0
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 Hedge Assets					0
Liabilities
Hedged portion of natural gas inventory		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | IDS Derivative [Member]
Liabilities
Derivative liability		0			0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Natural gas derivatives [Member]
Assets
Derivative asset	[5]	147,000,000			161,000,000
Liabilities
Derivative liability	[5]	108,000,000			96,000,000
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 Hedge Assets					0
Liabilities
Hedged portion of natural gas inventory		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | IDS Derivative [Member]
Liabilities
Derivative liability		674,000,000			668,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Natural gas derivatives [Member]
Assets
Derivative asset	[5]	19,000,000			57,000,000
Liabilities
Derivative liability	[5]	$ 7,000,000			$ 11,000,000
[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 $52 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 $19 million posted with the same counterparties.
[3]	CenterPoint Energy did not have significant Level 3 sales or purchases during either of the three months ended March 31, 2018 or 2017.
[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 Affiliate (Detai

Unconsolidated Affiliate (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Enable Units [Abstract]
Preferred units – unconsolidated affiliate		$ 363	$ 363	$ 363
Percentage of sales that trigger right of first refusal		5.00%
Enable Distributions [Abstract]
Total distributions received from Enable		$ 83	83
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
CenterPoint Energy’s equity in earnings, net		69	72
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s equity method investment in Enable		$ 2,467		2,472
OGE [Member]
Enable Units [Abstract]
Percentage of sales that trigger right of first refusal		5.00%
Enable Midstream Partners [Member]
Enable Partnership Interest [Abstract]
Equity Method Investment, Ownership Percentage	[1]	54.00%
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
Operating revenues		$ 748	666
Cost of sales, excluding depreciation and amortization		375	308
Operating income		139	140
Net income attributable to Enable		105	111
CenterPoint Energy’s interest		57	60
Basis difference amortization (1)	[2]	12	12
CenterPoint Energy’s equity in earnings, net		$ 69	72
Basis difference amortization period		31 years
Equity Method Investment, Summarized Financial Information, Assets and Liabilities [Abstract]
Current assets		$ 413		416
Non-current assets		11,274		11,177
Current liabilities		1,404		1,279
Non-current liabilities		2,664		2,660
Non-controlling interest		11		12
Preferred equity		362		362
Enable partners’ equity		7,246		7,280
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s ownership interest in Enable partners’ equity		3,913		3,935
CenterPoint Energy’s basis difference		(1,446)		(1,463)
CenterPoint Energy’s equity method investment in Enable		2,467		2,472
Enable Midstream Partners [Member] | Common Units [Member]
Enable Distributions [Abstract]
Distributions received from Enable equity method investment		74	74
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Enable Distributions [Abstract]
Distributions received from Enable cost method investment		$ 9	9
Enable Midstream Partners [Member]
Enable Partnership Interest [Abstract]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	[1]	100.00%
Enable Distributions [Abstract]
Maximum incentive distribution right		50.00%
Enable Midstream Partners [Member] | CERC Corp [Member]
Enable Units [Abstract]
Management rights ownership percentage		50.00%
Enable Distributions [Abstract]
Incentive distribution right		40.00%
Enable Midstream Partners [Member] | OGE [Member]
Enable Partnership Interest [Abstract]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	[1]	25.60%
Enable Units [Abstract]
Management rights ownership percentage		50.00%
Enable Distributions [Abstract]
Incentive distribution right		60.00%
Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Partnership Interest [Abstract]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	[1]	20.40%
Enable Midstream Partners [Member] | Minimum [Member]
Enable Distributions [Abstract]
Incentive distribution per unit		$ 0.2875
Enable Midstream Partners [Member] | Maximum [Member]
Enable Distributions [Abstract]
Incentive distribution per unit		$ 0.330625
Common Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Equity Method Investment, Ownership, Shares		233,856,623
Common Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Variable Interest Entity, Ownership, Shares		433,072,001
Common Units [Member] | Enable Midstream Partners [Member] | OGE [Member]
Enable Units [Abstract]
Variable Interest Entity, Ownership, Shares		110,982,805
Common Units [Member] | Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Units [Abstract]
Variable Interest Entity, Ownership, Shares		88,232,573
Series A Preferred Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Preferred Units Held	[3]	14,520,000
Transitional Service [Member] | Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Reimbursement of transition services (1)	[4]	$ 2	2
Accounts receivable for amounts billed for transition services		1		1
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Natural gas expenses, including transportation and storage costs		37	$ 33
Accounts payable for natural gas purchases from Enable		$ 11		$ 13
[1]	Excluding the Series A Preferred Units owned by CenterPoint Energy.
[2]	Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s share of Enable’s earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s original investment in Enable and its underlying equity in Enable’s net assets. The basis difference is amortized over approximately 31 years, the average life of the assets to which the basis difference is attributed.
[3]	The carrying amount of the Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on the Condensed Consolidated Balance Sheets, was $363 million as of both March 31, 2018 and December 31, 2017. No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion.
[4]	Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement.

Goodwill and Other Intangible48

Goodwill and Other Intangibles (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Goodwill [Line Items]
Goodwill		$ 867		$ 867
Intangible assets gross carrying amount		105		105
Intangible assets accumulated amortization		(34)		(31)
Net intangible assets		71		74
Amortization expense of intangible assets		3	$ 2
Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill		746		746
Energy Services [Member]
Goodwill [Line Items]
Goodwill	[1]	110		110
Accumulated goodwill impairment charge recorded in 2012		252
Other Operations [Member]
Goodwill [Line Items]
Goodwill		$ 11		11
Customer Relationships [Member]
Goodwill [Line Items]
Intangible asset useful lives		15 years
Intangible assets gross carrying amount		$ 86		86
Intangible assets accumulated amortization		(23)		(21)
Net intangible assets		$ 63		65
Noncompete Agreements [Member]
Goodwill [Line Items]
Intangible asset useful lives		4 years
Intangible assets gross carrying amount		$ 4		4
Intangible assets accumulated amortization		(2)		(2)
Net intangible assets		2		2
Other Intangible Assets [Member]
Goodwill [Line Items]
Intangible assets gross carrying amount		15		15
Intangible assets accumulated amortization		(9)		(8)
Net intangible assets		$ 6		$ 7
[1]	Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012.

Indexed Debt Securities (ZENS49

Indexed Debt Securities (ZENS) and Securities Related to ZENS (Details) $ / shares in Units, $ in Millions	Feb. 15, 2017$ / sharesshares	Mar. 31, 2018USD ($)shares	Mar. 31, 2017USD ($)	Jan. 31, 2018$ / shares	Dec. 31, 2017shares	Nov. 26, 2017$ / shares
Distribution To ZENS holders | $		$ 16	$ 0
Indexed debt – reduction | $		(4)
Indexed debt securities derivative – reduction | $		(1)
Loss on indexed debt securities | $		11
Subordinated Debt ZENS [Member]
Principal amount of debt issued | $		1,000
Outstanding debt balance | $		$ 828
Subordinated note cash exchangeable percentage of fair value		95.00%
Contingent principal amount outstanding | $		$ 486
TW Common [Member]
Balance of investment owned (in shares) | shares		7,107,130			7,107,130
TW Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares		0.5			0.5
Time Common [Member]
Balance of investment owned (in shares) | shares					888,392
ZENS early exchange ratio				100.00%
Time Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares					0.0625
Charter Common [Member]
Balance of investment owned (in shares) | shares		872,503			872,503
Charter Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares		0.061382			0.061382
AT&T To Acquire Time Warner [Member]
Implied value of consideration received by TW common stock shareholders, net | $ / shares	$ 107.50
Implied value of consideration received by TW common stock shareholders, Cash | $ / shares	53.75
Implied value of consideration received by TW common stock shareholders, Noncash | $ / shares	$ 53.75
Lower range of shares received by TW common shareholders | shares	1.437
Price of AT&T common stock, lower range | $ / shares	$ 37.411
Upper range of shares received by TW Common shareholders | shares	1.3
Price of AT&T common stock, upper range | $ / shares	$ 41.349
Meredith to acquire Time [Member] | Time Common [Member]
Cash paid per share of Time Common | $ / shares				$ 18.50		$ 18.50
Cash proceeds received for Time Common shares | $		$ 16

Short-Term Borrowings and Lon50

Short-Term Borrowings and Long-term Debt (Details)		Mar. 26, 2018USD ($)	Feb. 28, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Short-term Debt [Line Items]
Short-term borrowings				$ 0	$ 39,000,000
Line of Credit Facility [Abstract]
Size of credit facility				2,900,000,000	2,900,000,000
Parent Company [Member]
Line of Credit Facility [Abstract]
Size of credit facility				1,700,000,000	1,700,000,000
CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Size of credit facility				300,000,000	300,000,000
CERC Corp [Member]
Line of Credit Facility [Abstract]
Size of credit facility				900,000,000	900,000,000
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				0	0
Revolving Credit Facility [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				0	0
Revolving Credit Facility [Member] | CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				0	0
Revolving Credit Facility [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 0	0
Line of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant	[1]			65.00%
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)				70.00%
Ratio of indebtedness to net capital	[2]			0.526
System restoration costs threshold for increase in permitted debt to EBITDA covenant ratio				$ 100,000,000
Consecutive period for system restoration costs to exceed $100 million (in months)				12
Line of Credit [Member] | Parent Company [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[3]			1.25%
Line of Credit [Member] | CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant	[1]			65.00%
Ratio of indebtedness to net capital	[2]			0.512
Line of Credit [Member] | CenterPoint Houston [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[3]			1.125%
Line of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant				65.00%
Ratio of indebtedness to net capital	[2]			0.387
Line of Credit [Member] | CERC Corp [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[3]			1.25%
Letter of Credit [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 11,000,000	11,000,000
Letter of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				6,000,000	6,000,000
Letter of Credit [Member] | CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				4,000,000	4,000,000
Letter of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				1,000,000	1,000,000
Commercial Paper [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				915,000,000	1,753,000,000
Commercial Paper [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[4]			$ 189,000,000	$ 855,000,000
Weighted average interest rate of debt				2.24%	1.88%
Commercial Paper [Member] | CenterPoint Houston [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 0	$ 0
Commercial Paper [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[5]			$ 726,000,000	$ 898,000,000
Weighted average interest rate of debt				2.34%	1.72%
Product Financing Arrangement [Member]
Short-term Debt [Line Items]
Short-term borrowings				$ 0	$ 39,000,000
General Mortgage Bonds Due 2048 [Member] | CenterPoint Houston [Member]
Debt Instruments [Abstract]
Principal amount of debt issued			$ 400,000,000
Interest rate of debt issued			3.95%
Maturity date of debt issued			Mar. 1, 2048
Senior Notes Due 2023 [Member] | CERC Corp [Member]
Debt Instruments [Abstract]
Principal amount of debt issued		$ 300,000,000
Interest rate of debt issued		3.55%
Maturity date of debt issued		Apr. 1, 2023
Senior Notes Due 2028 [Member] | CERC Corp [Member]
Debt Instruments [Abstract]
Principal amount of debt issued		$ 300,000,000
Interest rate of debt issued		4.00%
Maturity date of debt issued		Apr. 1, 2028
[1]	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 12-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.
[2]	As defined in the revolving credit facility agreement, excluding Securitization Bonds.
[3]	Based on current credit ratings.
[4]	Weighted average interest rate was 2.24% and 1.88% as of March 31, 2018 and December 31, 2017, respectively.
[5]	Weighted average interest rate was 2.34% and 1.72% as of March 31, 2018 and December 31, 2017, respectively.

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate	22.00%	36.00%
Federal statutory income tax rate	21.00%	35.00%

Commitments and Contingencies52

Commitments and Contingencies (Details)	3 Months Ended
	Mar. 31, 2018USD ($)
CERC Corp [Member] | Minnesota Service Territory [Member]
Legal, Environmental and Other Matters
Liability recorded for remediation of Minnesota sites	$ 7,000,000
CERC Corp [Member] | Minnesota Service Territory [Member] | Minimum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 5,000,000
Years to resolve contingency	30 years
CERC Corp [Member] | Minnesota Service Territory [Member] | Maximum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 30,000,000
Years to resolve contingency	50 years
Natural Gas Supply Commitments [Member]
Natural Gas Supply Commitments
Remaining nine months of 2018	$ 289,000,000
2,019	311,000,000
2,020	170,000,000
2,021	81,000,000
2,022	51,000,000
2023 and beyond	125,000,000
Minnehaha Academy Gas Explosion [Member]
Legal, Environmental and Other Matters
Contested amount of fines imposed	$ 200,000

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net income	$ 165	$ 192
Basic weighted average shares outstanding	431,231,000	430,794,000
Plus: Incremental shares from assumed conversions:
Diluted weighted average shares	434,008,000	433,348,000
Basic earnings per share
Net income	$ 0.38	$ 0.45
Diluted earnings per share
Net income	$ 0.38	$ 0.44
Restricted Stock [Member]
Plus: Incremental shares from assumed conversions:
Restricted stock	2,777,000	2,554,000

Reportable Business Segments (D

Reportable Business Segments (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017		Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues		$ 3,155	$ 2,735
Operating Income (Loss)		251	291	[1]
Assets		22,410			$ 22,736
Enable		69	72
Total regulatory assets		2,278			2,477
Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	751	639
Operating Income (Loss)		115	86	[1]
Electric Transmission and Distribution [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues		161	152
Electric Transmission and Distribution [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues		54	47
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		1,143	907
Operating Income (Loss)		156	168	[1]
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		1,257	1,185
Operating Income (Loss)		(26)	35	[1]
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[3]	0	0
Operating Income (Loss)	[3]	0	0	[1]
Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		4	4
Operating Income (Loss)		6	2	[1]
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(38)	(20)
Assets		(682)			(654)
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		(10)	(9)
Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(28)	(11)
Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[3]	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		10,358			10,292
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		6,438			6,608
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		1,329			1,521
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets	[3]	2,467			2,472
Operating Segments [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Assets	[4]	2,500			2,497
Enable Midstream Partners [Member]
Segment Reporting Information [Line Items]
Enable		69	72
Enable Midstream Partners [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Enable		69	$ 72
Pension and Other Postretirement Plans Costs [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Total regulatory assets		$ 588			$ 600
[1]	Amounts for 2017 have been restated to reflect the adoption of ASU 2017-07.
[2]	Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended March 31, 2018 2017 (in millions)Affiliates of NRG $161 $152Affiliates of Vistra Energy Corp. 54 47
[3]	Midstream Investments’ equity earnings, net are as follows: Three Months Ended March 31, 2018 2017 (in millions)Enable $69 $72
[4]	Included in total assets of Other Operations as of March 31, 2018 and December 31, 2017 are pension and other postemployment-related regulatory assets of $588 million and $600 million, respectively.

Supplemental Disclosure of Ca55

Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Interest, net of capitalized interest	$ 116	$ 112
Income tax refunds, net	(4)	(2)
Accounts payable related to capital expenditures	102	73
Cash and cash equivalents	219		$ 260
Total Cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	257	$ 290	296	$ 381
Prepaid expenses and other current assets [Member]
Restricted cash	37		35
Other Noncurrent Assets [Member]
Restricted cash	$ 1		$ 1

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	May 01, 2018	Apr. 26, 2018	Apr. 21, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Short-term debt				$ 0			$ 39
Quarterly cash dividend/distribution declared per share				$ 0	$ 0.2675
Vectren [Member]
Subsequent Event [Line Items]
Short-term debt				$ 288
Long-term debt, including current maturities				$ 1,800
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends payable, date declared		Apr. 26, 2018
Quarterly cash dividend/distribution declared per share		$ 0.2775
Dividends payable, date to be paid		Jun. 14, 2018
Dividends payable, date of record		May 17, 2018
Subsequent Event [Member] | Enable Midstream Partners [Member] | Common Units [Member]
Subsequent Event [Line Items]
Dividends payable, date declared	May 1, 2018
Quarterly cash dividend/distribution declared per share	$ 0.318
Expected cash distribution from equity method investment	$ 74
Subsequent Event [Member] | Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Subsequent Event [Line Items]
Dividends payable, date declared	May 1, 2018
Preferred stock dividends declared per share	$ 0.625
Expected cash distribution from cost method investment	$ 9
Subsequent Event [Member] | Merger Agreement with Vectren [Member]
Subsequent Event [Line Items]
Amount of cash to be paid to acquire Vectren			$ 6,000
Cash to be paid per share of Vectren common stock prior to closing of Merger			$ 72
Subsequent Event [Member] | Merger Agreement with Vectren [Member] | CenterPoint Energy [Member]
Subsequent Event [Line Items]
Amount of bridge facility commitment to fund amounts payable in connection with the Merger			$ 5,000
Termination fee			210
Subsequent Event [Member] | Merger Agreement with Vectren [Member] | Vectren [Member]
Subsequent Event [Line Items]
Anticipated amount of combined short and long-term debt at closing of the Merger						$ 2,500
Termination fee			$ 150