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Document and Entity Information Document - USD ($)	9 Months Ended
Document and Entity Information Document - USD ($)	Sep. 30, 2016	Oct. 21, 2016	Jun. 30, 2015
Entity Information [Line Items]
Entity Registrant Name	CENTERPOINT ENERGY RESOURCES CORP
Entity Central Index Key	0001042773
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0

CONDENSED STATEMENTS OF CONSOLIDATED INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Revenues	$ 978	$ 799	$ 3,105	$ 3,440
Expenses:
Natural gas	683	527	2,031	2,410
Operation and maintenance	175	165	571	541
Depreciation and amortization	62	57	185	169
Taxes other than income taxes	32	32	108	115
Total	952	781	2,895	3,235
Operating Income	26	18	210	205
Other Income (Expense):
Interest and other finance charges	(29)	(34)	(93)	(103)
Equity in earnings (losses) of unconsolidated affiliate, net	73	(794)	164	(699)
Other, net	(1)	2	1	3
Total	43	(826)	72	(799)
Income (Loss) Before Income Taxes	69	(808)	282	(594)
Income tax expense (benefit)	26	(300)	113	(217)
Net Income (Loss)	$ 43	$ (508)	$ 169	$ (377)

CONDENSED STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 43	$ (508)	$ 169	$ (377)
Other comprehensive income, net of tax:
Adjustment to pension and other postretirement plans (net of tax of $1, $-0-, $-0- and $-0-)	1	0	2	0
Other comprehensive income	1	0	2	0
Comprehensive income (loss)	$ 44	$ (508)	$ 171	$ (377)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Comprehensive Income Parenthetical - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Comprehensive Income Parenthetical - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Tax expense on adjustment related to pension and postretirement plans	$ (1)	$ 0	$ 0	$ 0

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 0	$ 0
Accounts receivable, less bad debt reserve of $17 and $19, respectively	326	350
Accrued unbilled revenues	69	183
Accounts and notes receivable–affiliated companies	5	8
Materials and supplies	53	45
Natural gas inventory	160	168
Non-trading derivative assets	49	89
Prepaid expenses and other current assets	75	61
Total current assets	737	904
Property, Plant and Equipment:
Property, plant and equipment	6,228	5,898
Less: accumulated depreciation and amortization	1,751	1,640
Property, plant and equipment, net	4,477	4,258
Other Assets:
Goodwill	862	840
Non-trading derivative assets	24	36
Notes receivable–unconsolidated affiliate	0	363
Investment in unconsolidated affiliate	2,535	2,594
Other	191	146
Total other assets	3,612	3,979
Total Assets	8,826	9,141
Current Liabilities:
Short-term borrowings	43	40
Current portion of long-term debt	0	325
Accounts payable	266	307
Accounts and notes payable–affiliated companies	31	39
Taxes accrued	60	63
Interest accrued	31	36
Customer deposits	79	80
Non-trading derivative liabilities	19	11
Other	153	158
Total current liabilities	682	1,059
Other Liabilities:
Deferred income taxes, net	1,881	1,774
Non-trading derivative liabilities	4	5
Benefit obligations	94	89
Regulatory liabilities	759	734
Other	217	210
Total other liabilities	2,955	2,812
Long-Term Debt	2,263	2,016
Commitments and Contingencies (Note 11)
Stockholder’s Equity:
Common stock	0	0
Paid-in capital	2,489	2,417
Retained earnings	430	828
Accumulated other comprehensive income	7	9
Total stockholder’s equity	2,926	3,254
Total Liabilities and Stockholder’s Equity	$ 8,826	$ 9,141

Balance Sheets Parenthetical - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Allowance for Doubtful Accounts Receivable, Current	$ 17	$ 19

CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash Flows from Operating Activities:
Net income (loss)	$ 169	$ (377)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	185	169
Amortization of deferred financing costs	7	7
Deferred income taxes	108	(162)
Write-down of natural gas inventory	1	4
Equity in (earnings) losses of unconsolidated affiliate, net of distributions	(164)	843
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	220	532
Accounts receivable/payable–affiliated companies	(5)	(64)
Inventory	(1)	31
Accounts payable	(85)	(302)
Fuel cost recovery	(43)	71
Interest and taxes accrued	(8)	(3)
Non-trading derivatives, net	23	(6)
Margin deposits, net	65	20
Other current assets	(11)	13
Other current liabilities	15	(12)
Other assets	(5)	11
Other liabilities	1	(9)
Other, net	1	0
Net cash provided by operating activities	473	766
Cash Flows from Investing Activities:
Capital expenditures	(378)	(420)
Distribution from unconsolidated affiliate in excess of cumulative earnings	223	74
Decrease in notes receivable–unconsolidated affiliate	363	0
Acquisitions, net of cash acquired	(102)	0
Other, net	(1)	3
Net cash provided by (used in) investing activities	105	(343)
Cash Flows from Financing Activities:
Increase (decrease) in short-term borrowings, net	3	(4)
Proceeds from (payments of) commercial paper, net	240	(232)
Payments of long-term debt	(325)	0
Dividends to parent	(567)	0
Debt issuance costs	(1)	0
Decrease in notes payable–affiliated companies	0	(188)
Contribution from parent	73	0
Other, net	(1)	0
Net cash used in financing activities	(578)	(424)
Net Decrease in Cash and Cash Equivalents	0	(1)
Cash and Cash Equivalents at Beginning of Period	0	2
Cash and Cash Equivalents at End of Period	0	1
Cash Payments:
Interest, net of capitalized interest	90	90
Income taxes, net	3	7
Non-cash transactions:
Accounts payable related to capital expenditures	$ 32	$ 37

Background and Basis of Presentation	9 Months Ended
Background and Basis of Presentation	Sep. 30, 2016
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 CERC. The Interim Condensed Financial Statements are unaudited, omit certain financial statement disclosures and should be read with the 2015 Form 10-K. Background. CERC owns and operates natural gas distribution systems and owns interests in Enable as described in Note 7. A wholly-owned subsidiary of CERC Corp. offers variable and fixed-price physical natural gas supplies primarily to commercial and industrial customers and electric and natural gas utilities. As of September 30, 2016, CERC Corp. also owned approximately 55.4% of the limited partner interests in Enable, which owns, operates and develops natural gas and crude oil infrastructure assets. CERC Corp. is an indirect, wholly-owned subsidiary of CenterPoint Energy, Inc., a public utility holding company. 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. CERC’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 CERC’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 CERC’s reportable business segments, see Note 13.

New Accounting Pronouncements	9 Months Ended
New Accounting Pronouncements	Sep. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements [Text Block]	New Accounting Pronouncements In February 2015, the FASB issued ASU No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis (ASU 2015-02). ASU 2015-02 changes the analysis that reporting organizations must perform to evaluate whether they should consolidate certain legal entities, such as limited partnerships. The changes include, among others, modification of the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities and elimination of the presumption that a general partner should consolidate a limited partnership. ASU 2015-02 does not amend the related party guidance for situations in which power is shared between two or more entities that hold interests in a VIE. CERC adopted ASU 2015-02 on January 1, 2016, which CERC determined did not have a material impact on its financial position, results of operations, cash flows and disclosures. In April 2015, the FASB issued ASU No. 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost (ASU 2015-03). ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by ASU 2015-03. CERC adopted ASU 2015-03 retrospectively on January 1, 2016, which resulted in a reduction of other long-term assets and total long-term debt on its Condensed Consolidated Balance Sheets. CERC had debt issuance costs, excluding amounts related to credit facility arrangements, of $11 million and $12 million as of September 30, 2016 and December 31, 2015, respectively. In May 2015, the FASB issued ASU No. 2015-07, Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent) (ASU 2015-07). ASU 2015-07 removes the requirement to categorize within the fair value hierarchy investments for which fair values are measured at NAV using the practical expedient. Entities will be required to disclose the fair value of investments measured using the NAV practical expedient so that financial statement users can reconcile amounts reported in the fair value hierarchy table to amounts reported on the balance sheet. CERC adopted ASU 2015-07 on January 1, 2016, which will have an impact on its employee benefit plan disclosures, beginning with its annual report on Form 10-K for the year ended December 31, 2016. This standard did not have an impact on CERC’s financial position, results of operations or cash flows. In September 2015, the FASB issued ASU No. 2015-16, Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments (ASU 2015-16). ASU 2015-16 eliminates the requirement for an acquirer in a business combination to account for measurement-period adjustments retrospectively. Instead, an acquirer would recognize a measurement-period adjustment during the period in which the amount of the adjustment is determined. CERC adopted ASU 2015-16 on January 1, 2016, which did not have an impact on its financial position, results of operations or cash flows. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01). ASU 2016-01 requires equity investments that do not result in consolidation and are not accounted for under the equity method to be measured at fair value and to recognize any changes in fair value in net income unless the investments qualify for the new practicability exception. It does not change the guidance for classifying and measuring investments in debt securities and loans. ASU 2016-01 also changes certain disclosure requirements and other aspects related to recognition and measurement of financial assets and financial liabilities. ASU 2016-01 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. CERC is currently assessing the impact that this standard will have on its financial position, results of operations, cash flows and disclosures. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 provides a comprehensive new lease model that requires lessees to recognize assets and liabilities for most leases and would change certain aspects of lessor accounting. ASU 2016-02 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. CERC is currently assessing the impact that this standard will have on its financial position, results of operations, cash flows and disclosures. In March 2016, the FASB issued ASU No. 2016-05, Derivatives and Hedging (Topic 815): Effect of Derivative Contract Novation on Existing Hedge Accounting Relationships (ASU 2016-05). ASU 2016-05 clarifies that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument in an existing hedging relationship would not, in and of itself, be considered a termination of the derivative instrument or a change in a critical term of the hedging relationship. This clarification applies to both cash flow and fair value hedging relationships. CERC adopted ASU 2016-05 prospectively in the first quarter of 2016, which did not have an impact on its financial position, results of operations, cash flows and disclosures. In March, April, and May 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (ASU 2016-08), ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing (ASU 2016-10), and ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients (ASU 2016-12), respectively. ASU 2016-08, ASU 2016-10, and ASU 2016-12 clarify certain aspects of ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09), which supersedes most current revenue recognition guidance. CERC is currently evaluating the impact that ASU 2016-08, ASU 2016-10, ASU 2016-12, and ASU 2014-09 will have on its financial position, results of operations, cash flows and disclosures and expects to adopt these ASUs on January 1, 2018. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13). ASU 2016-13 requires a new model called the CECL model to estimate credit losses for financial assets subject to credit losses and measured at amortized cost and certain off-balance sheet credit exposures. This includes loans, held-to-maturity debt securities, loan commitments, financial guarantees, and net investments in leases, as well as reinsurance and trade receivables. Upon initial recognition of the exposure, the CECL model requires an entity to estimate the credit losses expected over the life of an exposure based on historical information, current information and reasonable and supportable forecasts, including estimates of prepayments. The update also amends the other-than-temporary impairment model for debt securities classified as available-for-sale. ASU 2016-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted beginning after December 15, 2018. CERC is currently assessing the impact that this standard will have on its financial position, results of operations, cash flows and disclosures. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230)-Classification of Certain Cash Receipts and Cash Payments (ASU 2016-15). ASU 2016-15 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. ASU 2016-15 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. CERC is currently assessing the impact that this standard will have on its statement of cash flows. Management believes that other recently issued standards, which are not yet effective, will not have a material impact on CERC’s consolidated financial position, results of operations or cash flows upon adoption.

Acquisition

9 Months Ended

Sep. 30, 2016

Business Combinations [Abstract]

Acquisition [Text Block]

Acquisition

On April 1, 2016, CES, a wholly-owned subsidiary of CERC, closed the previously announced agreement to acquire the retail energy services business and natural gas wholesale assets of Continuum for a preliminary purchase price of $98 million, including working capital. After working capital adjustments, the final purchase price was $102 million and allocated to identifiable assets acquired and liabilities assumed based on their estimated fair values on the acquisition date.

The following table summarizes the final purchase price allocation and the fair value amounts recognized for the assets acquired and liabilities assumed related to the acquisition:



	(in millions)
Total purchase price consideration	$	102
Receivables	$	76
Derivative assets	38
Property and equipment	1
Identifiable intangibles	38
Total assets acquired	153
Accounts payable	49
Derivative liabilities	24
Total liabilities assumed	73
Identifiable net assets acquired	80
Goodwill	22
Net assets acquired	$	102

The goodwill of $22 million resulting from the acquisition reflects the excess of the purchase price over the fair value of the net identifiable assets acquired. The goodwill recorded as part of the acquisition primarily reflects the value of the complementary operational and geographic footprints, along with the scale, geographic reach and expanded capabilities.

Identifiable intangible assets were recorded at estimated fair value as determined by management based on available information, which includes a valuation prepared by an independent third party. The significant assumptions used in arriving at the estimated identifiable intangible asset values included management’s estimates of future cash flows, the discount rate which is based on the weighted average cost of capital for comparable publicly traded guideline companies and projected customer attrition rates. The useful lives for the identifiable intangible assets were determined using methods that approximate the pattern of economic benefit provided by the utilization of the assets.

The estimated fair value of the identifiable intangible assets and related useful lives as included in the final purchase price allocation include:



	Estimate Fair Value		Estimate Useful Life
	(in millions)		(in years)
Customer relationships	$	34	15
Covenants not to compete	4		4
Total identifiable intangibles	$	38

Amortization expense related to the above identifiable intangible assets was $1 million and $2 million for the three and nine months ended September 30, 2016, respectively.

Revenues of approximately $170 million and $270 million, respectively, and operating income of approximately $2 million and $2 million, respectively, attributable to the acquisition are included in CERC’s Condensed Consolidated Statements of Income for the three and nine months ended September 30, 2016.

As Continuum was a non-public company that did not prepare interim financial information and the acquisition included the purchase of both businesses and assets, the historical financial information for the businesses and assets acquired was impracticable to obtain. As a result, pro forma results of the acquired businesses and assets are not presented.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

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+ Details

Employee Benefit Plans

9 Months Ended

Sep. 30, 2016

Compensation and Retirement Disclosure [Abstract]

Employee Benefits Plans [Text Block]

Employee Benefit Plans

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



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2016			2015			2016			2015
	(in millions)
Service cost	$	1		$	1		$	1		$	1
Interest cost on accumulated benefit obligation	1			2			3			4
Expected return on plan assets	(1		)	(1		)	(1		)	(1		)
Amortization of net loss	—			—			—			1
Net periodic cost	$	1		$	2		$	3		$	5

CERC expects to contribute approximately $6 million to its postretirement benefit plan in 2016, of which approximately $1 million and $4 million were contributed during the three and nine months ended September 30, 2016, respectively.

Derivative Instruments

9 Months Ended

Sep. 30, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments [Text Block]

Derivative Instruments

CERC is exposed to various market risks. These risks arise from transactions entered into in the normal course of business. CERC utilizes derivative instruments such as physical forward contracts, swaps and options to mitigate the impact of changes in commodity prices and weather on its operating results and cash flows. Such derivatives are recognized in CERC’s Condensed Consolidated Balance Sheets at their fair value unless CERC elects the normal purchase and sales exemption for qualified physical transactions. A derivative may be designated as a normal purchase or sale if the intent is to physically receive or deliver the product for use or sale in the normal course of business.

CenterPoint Energy has a Risk Oversight Committee composed of corporate and business segment officers that oversees commodity price, weather and credit risk activities, including CERC’s marketing, risk management services and hedging activities. The committee’s duties are to establish CERC’s commodity risk policies, allocate board-approved commercial risk limits, approve the use of new products and commodities, monitor positions and ensure compliance with CERC’s risk management policies, procedures and limits established by CenterPoint Energy’s board of directors.

CERC’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. CERC enters into certain derivative instruments to manage physical commodity price risk and does not engage in proprietary or speculative commodity trading. These financial instruments do not qualify or are not designated as cash flow or fair value hedges.

Weather Hedges. CERC has weather normalization or other rate mechanisms that mitigate the impact of weather on NGD in Arkansas, Louisiana, Mississippi, Minnesota and Oklahoma. NGD in Texas does not have such mechanisms, although fixed customer charges are historically higher in Texas for NGD compared to CERC’s other jurisdictions. As a result, fluctuations from normal weather may have a positive or negative effect on NGD’s results in Texas.

CERC has historically entered into heating-degree day swaps for certain NGD jurisdictions to mitigate the effect of fluctuations from normal weather on its results of operations and cash flows for the winter heating season, which contained a bilateral dollar cap of $16 million in 2014–2015. However, NGD did not enter into heating-degree day swaps for the 2015–2016 winter season as a result of NGD’s Minnesota division implementing a full decoupling pilot in July 2015. The swaps are based on 10-year normal weather. During both the three months ended September 30, 2016 and 2015, CERC recognized no gains or losses related to these swaps. During the nine months ended September 30, 2016 and 2015, CERC recognized losses of $-0- and $4 million, respectively, related to these swaps. Weather hedge gains and losses are included in revenues in the Condensed Statements of Consolidated Income.

(b) Derivative Fair Values and Income Statement Impacts

The following tables present information about CERC’s derivative instruments and hedging activities. The first four tables provide a balance sheet overview of CERC’s Derivative Assets and Liabilities as of September 30, 2016 and December 31, 2015, while the last two tables provide a breakdown of the related income statement impacts for the three and nine months ended September 30, 2016 and 2015.



Fair Value of Derivative Instruments
		September 30, 2016
Total derivatives not designated as hedging instruments	Balance Sheet Location	Derivative Assets Fair Value		Derivative Liabilities Fair Value
		(in millions)
Natural gas derivatives (1) (2) (3)	Current Assets: Non-trading derivative assets	$	51	$	2
Natural gas derivatives (1) (2) (3)	Other Assets: Non-trading derivative assets	24		—
Natural gas derivatives (1) (2) (3)	Current Liabilities: Non-trading derivative liabilities	19		41
Natural gas derivatives (1) (2) (3)	Other Liabilities: Non-trading derivative liabilities	4		11
Total		$	98	$	54


(1)	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,080 Bcf or a net 16 Bcf short position. Of the net short position, basis swaps constitute a net 128 Bcf long position.

(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 $50 million asset as shown on CERC’s Condensed Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, offset by collateral netting of $6 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
	September 30, 2016
	Gross Amounts Recognized (1)			Gross Amounts Offset in the Consolidated Balance Sheets			Net Amount Presented in the Consolidated Balance Sheets (2)
	(in millions)
Current Assets: Non-trading derivative assets	$	70		$	(21	)	$	49
Other Assets: Non-trading derivative assets	28			(4		)	24
Current Liabilities: Non-trading derivative liabilities	(43		)	24			(19		)
Other Liabilities: Non-trading derivative liabilities	(11		)	7			(4		)
Total	$	44		$	6		$	50


(1)	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.


(2)	The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.



Fair Value of Derivative Instruments
		December 31, 2015
Total derivatives not designated as hedging instruments	Balance Sheet Location	Derivative Assets Fair Value		Derivative Liabilities Fair Value
		(in millions)
Natural gas derivatives (1) (2) (3)	Current Assets: Non-trading derivative assets	$	90	$	2
Natural gas derivatives (1) (2) (3)	Other Assets: Non-trading derivative assets	36		—
Natural gas derivatives (1) (2) (3)	Current Liabilities: Non-trading derivative liabilities	10		60
Natural gas derivatives (1) (2) (3)	Other Liabilities: Non-trading derivative liabilities	4		25
Total		$	140	$	87


(1)	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 767 Bcf or a net 112 Bcf long position. Of the net long position, basis swaps constitute 133 Bcf.

(2)

Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $109 million asset as shown on CERC’s Condensed Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, offset by collateral netting of $56 million.


(3)	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.



Offsetting of Natural Gas Derivative Assets and Liabilities
	December 31, 2015
	Gross Amounts Recognized (1)			Gross Amounts Offset in the Consolidated Balance Sheets			Net Amount Presented in the Consolidated Balance Sheets (2)
	(in millions)
Current Assets: Non-trading derivative assets	$	100		$	(11	)	$	89
Other Assets: Non-trading derivative assets	40			(4		)	36
Current Liabilities: Non-trading derivative liabilities	(62		)	51			(11		)
Other Liabilities: Non-trading derivative liabilities	(25		)	20			(5		)
Total	$	53		$	56		$	109


(1)	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.


(2)	The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.

Realized and unrealized gains and losses on natural gas derivatives are recognized in the Condensed Statements of Consolidated Income as revenue for retail sales derivative contracts and as natural gas expense for financial natural gas derivatives and non-retail related physical natural gas derivatives.



Income Statement Impact of Derivative Activity
		Three Months Ended September 30,
Total derivatives not designated as hedging instruments	Income Statement Location	2016			2015
		(in millions)
Natural gas derivatives	Gains (Losses) in Revenues	$	31		$	39
Natural gas derivatives	Gains (Losses) in Expenses: Natural Gas	(13		)	(30		)
Total		$	18		$	9



Income Statement Impact of Derivative Activity
		Nine Months Ended September 30,
Total derivatives not designated as hedging instruments	Income Statement Location	2016		2015
		(in millions)
Natural gas derivatives	Gains (Losses) in Revenues	$	1	$	88
Natural gas derivatives	Gains (Losses) in Expenses: Natural Gas	35		(72		)
Total		$	36	$	16

CERC enters into financial derivative contracts containing material adverse change provisions. These provisions could require CERC to post additional collateral if the S&P or Moody’s credit ratings of CERC 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 September 30, 2016 and December 31, 2015 was $2 million and $3 million, respectively. CERC posted no assets as collateral towards derivative instruments that contain credit risk contingent features as of both September 30, 2016 and December 31, 2015. If all derivative contracts (in a net liability position) containing credit risk contingent features were triggered as of both September 30, 2016 and December 31, 2015, $2 million of additional assets would be required to be posted as collateral.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

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+ Details

Fair Value Measurements

9 Months Ended

Sep. 30, 2016

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.

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 CERC’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 CERC’s judgments about the assumptions market participants would use in pricing the asset or liability since limited market data exists. CERC develops these inputs based on the best information available, including CERC’s own data. A market approach is utilized to value CERC’s Level 3 assets or liabilities. As of September 30, 2016, CERC’s Level 3 assets and liabilities are comprised of physical forward contracts and options. Level 3 physical forward contracts are valued using a discounted cash flow model which includes illiquid forward price curve locations (ranging from $0.77 to $7.90 per one million British thermal units) as an unobservable input. Level 3 options are valued through Black-Scholes (including forward start) option models which include option volatilities (ranging from 0% to 73%) as an unobservable input. CERC’s Level 3 derivative assets and liabilities consist of both long and short positions (forwards and options) and their fair value is sensitive to forward prices and volatilities. If forward prices decrease, CERC’s long forwards lose value whereas its short forwards gain in value. If volatility decreases, CERC’s long options lose value whereas its short options gain in value.

CERC 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 nine months ended September 30, 2016, there were no transfers between Level 1 and 2. CERC 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 CERC’s assets and liabilities (including derivatives that are presented net) measured at fair value on a recurring basis as of September 30, 2016 and December 31, 2015, and indicate the fair value hierarchy of the valuation techniques utilized by CERC to determine such fair value.



	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Netting Adjustments (1)			Balance as of September 30, 2016
	(in millions)
Assets
Corporate equities	$	2	$	—	$	—	$	—		$	2
Investments, including money market funds (2)	10		—		—		—			10
Natural gas derivatives (3)	4		72		22		(25		)	73
Total assets	$	16	$	72	$	22	$	(25	)	$	85
Liabilities
Natural gas derivatives (3)	$	5	$	44	$	5	$	(31	)	$	23
Total liabilities	$	5	$	44	$	5	$	(31	)	$	23


(1)	Amounts represent the impact of legally enforceable master netting arrangements that allow CERC to settle positive and negative positions and also include cash collateral of $6 million posted with the same counterparties.


(2)	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.


(3)	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.



	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Netting Adjustments (1)			Balance as of December 31, 2015
	(in millions)
Assets
Corporate equities	$	2	$	—	$	—	$	—		$	2
Investments, including money market funds (2)	11		—		—		—			11
Natural gas derivatives (3)	4		115		21		(15		)	125
Total assets	$	17	$	115	$	21	$	(15	)	$	138
Liabilities
Natural gas derivatives (3)	$	13	$	65	$	9	$	(71	)	$	16
Total liabilities	$	13	$	65	$	9	$	(71	)	$	16


(1)	Amounts represent the impact of legally enforceable master netting arrangements that allow CERC to settle positive and negative positions and also include cash collateral of $56 million posted with the same counterparties.


(2)	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.


(3)	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.

The following table presents additional information about assets or liabilities, including derivatives that are measured at fair value on a recurring basis for which CERC 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 September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
	(in millions)
Beginning balance	$	16		$	10		$	12		$	17
Purchases	—			—			12			—
Total gains	9			5			13			5
Total settlements	(8		)	(2		)	(24		)	(8		)
Transfers into Level 3	—			1			5			1
Transfers out of Level 3	—			—			(1		)	(1		)
Ending balance (1)	$	17		$	14		$	17		$	14
The amount of total gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	$	6		$	6		$	14		$	7


(1)	CERC did not have significant Level 3 sales during either of the three or nine months ended September 30, 2016 or 2015.

Estimated Fair Value of Financial Instruments

The fair values of cash and cash equivalents 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 are stated at fair value and are excluded from the table below. The fair value of each debt instrument is determined by multiplying the principal amount of each debt instrument by the market price. These assets and liabilities, which are not measured at fair value in the Condensed Consolidated Balance Sheets but for which the fair value is disclosed, would be classified as Level 1 or Level 2 in the fair value hierarchy.



	September 30, 2016				December 31, 2015
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(in millions)
Financial assets:
Notes receivable–unconsolidated affiliate	$	—	$	—	$	363	$	356
Financial liabilities:
Long-term debt	$	2,263	$	2,500	$	2,341	$	2,539

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Unconsolidated Affiliates

9 Months Ended

Sep. 30, 2016

Equity Method Investments and Joint Ventures [Abstract]

Unconsolidated Affiliates [Text Block]

Unconsolidated Affiliate

On May 1, 2013 (the Formation Date) CERC Corp., OGE and ArcLight closed on the formation of Enable. CERC has the ability to significantly influence the operating and financial policies of Enable and, accordingly, accounts for its investment in Enable’s common and subordinated units using the equity method of accounting.

CERC’s maximum exposure to loss related to Enable, a VIE in which CERC is not the primary beneficiary, is limited to its equity investment as presented in the Condensed Consolidated Balance Sheets as of September 30, 2016, the guarantees discussed in Note 11, and outstanding current accounts receivable from Enable. In connection with the Private Placement, Enable redeemed $363 million of notes owed to a wholly-owned subsidiary of CERC Corp., which bore interest at an annual rate of 2.10% to 2.45%. CERC recorded interest income of $-0- and $2 million during the three months ended September 30, 2016 and 2015, respectively, and $1 million and $6 million during the nine months ended September 30, 2016 and 2015, respectively, and had interest receivable from Enable of $-0- and $4 million as of September 30, 2016 and December 31, 2015, respectively, on its notes receivable.

Effective on the Formation Date, CenterPoint Energy and Enable entered into the Transition Agreements. Under the Services Agreement, CERC agreed to provide certain support services to Enable such as accounting, legal, risk management and treasury functions for an initial term, which ended on April 30, 2016. CERC is providing certain services to Enable on a year-to-year basis. Enable may terminate (i) the entire Services Agreement with at least 90 days’ notice prior to the end of any extension term, or (ii) either any service provided under the Services Agreement, or the entire Services Agreement, at any time upon approval by its board of directors and with at least 180 days’ notice.

CERC billed Enable for reimbursement of transition services of $1 million and $3 million during the three months ended September 30, 2016 and 2015, respectively, and $6 million and $10 million during the nine months ended September 30, 2016 and 2015, respectively, under the Transition Agreements. Actual transition services costs are recorded net of reimbursements received from Enable. CERC had accounts receivable from Enable of $2 million and $3 million as of September 30, 2016 and December 31, 2015, respectively, for amounts billed for transition services.

CERC incurred natural gas expenses, including transportation and storage costs, of $22 million and $23 million during the three months ended September 30, 2016 and 2015, respectively, and $79 million and $87 million during the nine months ended September 30, 2016 and 2015, respectively, for transactions with Enable. CERC had accounts payable to Enable of $8 million and $11 million as of September 30, 2016 and December 31, 2015, respectively, from such transactions.

As of September 30, 2016, CERC held an approximate 55.4% limited partner interest in Enable consisting of 94,151,707 common units and 139,704,916 subordinated units. As of September 30, 2016, CERC and OGE each owned a 50% management interest in the general partner of Enable and a 40% and 60% interest, respectively, in the incentive distribution rights held by the general partner.

CERC evaluates its equity method investments for impairment when factors indicate that a decrease in value of its investment has occurred and the carrying amount of its investment may not be recoverable. An impairment loss, based on the excess of the carrying value over the best estimate of fair value of the investment, is recognized in earnings when an impairment is deemed to be other than temporary. Considerable judgment is used in determining if an impairment loss is other than temporary and the amount of any impairment. As of September 30, 2016, the carrying value of CERC’s equity method investment in Enable was $10.84 per unit, which includes limited partner common and subordinated units, a general partner interest and incentive distribution rights. On September 30, 2016, Enable’s common unit price closed at $15.25.

Summarized unaudited consolidated income information for Enable is as follows:



	Three Months Ended September 30,					Nine Months Ended September 30,
	2016		2015			2016		2015
	(in millions)
Operating revenues	$	620	$	646		$	1,658	$	1,852
Cost of sales, excluding depreciation and amortization	268		287			717		856
Impairment of goodwill and other long-lived assets	8		1,105			8		1,105
Operating income (loss)	139		(975		)	299		(778		)
Net income (loss) attributable to Enable	110		(985		)	231		(817		)

Reconciliation of Equity in Earnings (Losses), net:
CERC’s interest	$	61	$	(546	)	$	128	$	(453	)
Basis difference amortization (1)	12		2			36		4
Impairment of CERC’s equity method investment in Enable	—		(250		)	—		(250		)
CERC’s equity in earnings (losses), net (2)	$	73	$	(794	)	$	164	$	(699	)


(1)	Equity in earnings (losses) of unconsolidated affiliates includes CERC’s share of Enable’s earnings adjusted for the amortization of the basis difference of CERC’s original investment in Enable and its underlying equity in Enable’s net assets. The basis difference is amortized over approximately 33 years, the average life of the assets to which the basis difference is attributed.


(2)	These amounts include CERC’s share of Enable’s impairment of goodwill and long-lived assets and the impairment of CERC’s equity method investment in Enable totaling $862 million during the three and nine months ended September 30, 2015. This impairment is partially offset by $68 million and $163 million of earnings for the three and nine months ended September 30, 2015, respectively.

Summarized unaudited consolidated balance sheet information for Enable is as follows:



	September 30, 2016			December 31, 2015
	(in millions)
Current assets	$	408		$	381
Non-current assets	10,833			10,845
Current liabilities	338			615
Non-current liabilities	3,174			3,080
Non-controlling interest	11			12
Preferred equity	362			—
Enable partners’ equity	7,356			7,519

Reconciliation of Equity Method Investment in Enable:
CERC’s ownership interest in Enable partners’ capital	$	4,073		$	4,163
CERC’s basis difference	(1,538		)	(1,569		)
CERC’s equity method investment in Enable	$	2,535		$	2,594

Distributions Received from Unconsolidated Affiliate:



	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
	(in millions)
Enable	$	74	$	74	$	223	$	219

Goodwill

9 Months Ended

Sep. 30, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill [Text Block]

Goodwill

Goodwill by reportable business segment as of December 31, 2015 and changes in the carrying amount of goodwill as of September 30, 2016 are as follows:



	December 31, 2015			Continuum Acquisition (1)		September 30, 2016
	(in millions)
Natural Gas Distribution	$	746		$	—	$	746
Energy Services	83		(2)	22		105
Other Operations	11			—		11
Total	$	840		$	22	$	862


(1)	See Note 3.


(2)	Amount presented is net of the accumulated goodwill impairment charge of $252 million.

CERC performs its goodwill impairment tests at least annually and evaluates goodwill when events or changes in circumstances indicate that its carrying value may not be recoverable. The impairment evaluation for goodwill is performed by using a two-step process. In the first step, the fair value of each reporting unit is compared with the carrying amount of the reporting unit, including goodwill. The estimated fair value of the reporting unit is generally determined on the basis of discounted cash flows. If the estimated fair value of the reporting unit is less than the carrying amount of the reporting unit, then a second step must be completed in order to determine the amount of the goodwill impairment that should be recorded. In the second step, the implied fair value of the reporting unit’s goodwill is determined by allocating the reporting unit’s fair value to all of its assets and liabilities other than goodwill (including any unrecognized intangible assets) in a manner similar to a purchase price allocation. The resulting implied fair value of the goodwill that results from the application of this second step is then compared to the carrying amount of the goodwill and an impairment charge is recorded for the difference.

CERC performed its annual impairment test in the third quarter of 2016 and determined, based on the results of the first step, that no impairment charge was required for any reportable segment.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Related Party Transactions

9 Months Ended

Sep. 30, 2016

Related Party Transactions [Text Block]

Related Party Transactions

CERC participates in a money pool through which it can borrow or invest on a short-term basis. Funding needs are aggregated and external borrowing or investing is based on the net cash position. The net funding requirements of the money pool are expected to be met with borrowings under CenterPoint Energy’s revolving credit facility or the sale of CenterPoint Energy’s commercial paper. CERC had no investments in the money pool as of both September 30, 2016 and December 31, 2015, which are included in accounts and notes receivable–affiliated companies in the Condensed Consolidated Balance Sheets. Affiliate related net interest income (expense) was not material for either the three or nine months ended September 30, 2016 and 2015.

CenterPoint Energy provides some corporate services to CERC. The costs of services have been charged directly to CERC using methods that management believes are reasonable. These methods include negotiated usage rates, dedicated asset assignment and proportionate corporate formulas based on operating expenses, assets, gross margin, employees and a composite of assets, gross margin and employees. Houston Electric provides a number of services to CERC. These services are billed at actual cost, either directly or as an allocation, and include fleet services, shop services, geographic services, surveying and right-of-way services, radio communications, data circuit management and field operations. Additionally, CERC provides certain services to Houston Electric. These services are billed at actual cost, either directly or as an allocation and include line locating and other miscellaneous services. These charges are not necessarily indicative of what would have been incurred had CERC not been an affiliate of CenterPoint Energy. Amounts charged to and from CERC for these services were as follows and are included primarily in operation and maintenance expenses:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
	(in millions)
Corporate service charges	$	31		$	25		$	90		$	80
Charges from Houston Electric for services provided	4			5			11			12
Billings to Houston Electric for services provided	(2		)	(1		)	(5		)	(4		)
	$	33		$	29		$	96		$	88

See Note 7 for related party transactions with Enable.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

Short-term Borrowings and Long-term Debt

9 Months Ended

Sep. 30, 2016

Debt Disclosure [Abstract]

Short-term Borrowings and Long-term Debt [Text Block]

Short-term Borrowings and Long-term Debt

(a)Short-term Borrowings

Inventory Financing. NGD has asset management agreements associated with its utility distribution service in Arkansas, north Louisiana and Oklahoma that extend through 2019. Pursuant to the provisions of the agreements, NGD sells natural gas and agrees to repurchase an equivalent amount of natural gas during the winter heating seasons at the same cost, plus a financing charge. These transactions are accounted for as a financing and had an associated principal obligation of $43 million and $40 million as of September 30, 2016 and December 31, 2015, respectively.


(b)	Long-term Debt

Debt Repayments. In May 2016, CERC retired approximately $325 million aggregate principal amount of its 6.15% senior notes at their maturity. The retirement of senior notes was financed by the issuance of commercial paper.

Revolving Credit Facility. On March 4, 2016, CERC Corp. announced that it had refinanced its existing $600 million revolving credit facility, which would have expired in 2019, with a new $600 million five-year senior unsecured revolving credit facility. As of September 30, 2016 and December 31, 2015, CERC Corp. had the following revolving credit facility and utilization of such facility:



		September 30, 2016							December 31, 2015
Size of Facility		Loans		Letters of Credit		Commercial Paper			Loans		Letters of Credit		Commercial Paper
(in millions)
$	600	$	—	$	3	$	459	(1)	$	—	$	2	$	219	(1)


(1)	Weighted average interest rate was 0.76% and 0.81% as of September 30, 2016 and December 31, 2015, respectively.

CERC Corp.’s $600 million revolving credit facility, which is scheduled to terminate on March 3, 2021, can be drawn at LIBOR plus 1.25% based on CERC Corp.’s current credit ratings. The revolving credit facility contains a financial covenant which limits CERC’s consolidated debt to an amount not to exceed 65% of CERC’s consolidated capitalization. As of September 30, 2016, CERC’s debt to capital ratio, as defined in its credit facility agreement, was 34.7%.

CERC Corp. was in compliance with all financial covenants as of September 30, 2016.

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2016
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 CERC’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 CERC’s Condensed Consolidated Balance Sheets as of September 30, 2016 and December 31, 2015 as these contracts meet an exception as “normal purchases contracts” or do not meet the definition of a derivative. Natural gas supply commitments also include natural gas transportation contracts that do not meet the definition of a derivative. As of September 30, 2016, minimum payment obligations for natural gas supply commitments are approximately $132 million for the remaining three months in 2016, $454 million in 2017, $455 million in 2018, $267 million in 2019, $124 million in 2020 and $133 million after 2020. (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, nor does it affect the terms of existing guarantee arrangements for certain GenOn gas transportation contracts discussed below. A large number of lawsuits were filed against numerous gas market participants in a number of federal and western state courts in connection with the operation of the natural gas markets in 2000–2002. CenterPoint Energy and its affiliates have since been released or dismissed from all 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. That ruling is subject to appeal. CenterPoint Energy and CES intend to continue vigorously defending against the plaintiffs’ claims. CERC does not expect the ultimate outcome of this matter to have a material adverse effect on its financial condition, results of operations or cash flows. Environmental Matters Manufactured Gas Plant Sites. CERC and its predecessors operated MGPs in the past. With respect to certain Minnesota MGP sites, CERC has completed state-ordered remediation and continues state-ordered monitoring and water treatment. As of September 30, 2016, CERC had a recorded liability of $7 million for continued monitoring and any future remediation required by regulators in Minnesota. The estimated range of possible remediation costs for the sites for which CERC believes it may have responsibility was $4 million to $29 million based on remediation continuing for 30 to 50 years. The cost estimates are based on studies of a site or industry average costs for remediation of sites of similar size. The actual remediation costs will depend on the number of sites to be remediated, the participation of other PRPs, if any, and the remediation methods used. In addition to the Minnesota sites, the Environmental Protection Agency and other regulators have investigated MGP sites that were owned or operated by CERC or may have been owned by one of its former affiliates. CERC does not expect the ultimate outcome of these matters to have a material adverse effect on its financial condition, results of operations or cash flows. Asbestos. Some facilities owned by CERC or its predecessors contain or have contained asbestos insulation and other asbestos-containing materials. CERC and its predecessor companies 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 CERC anticipates that additional claims may be asserted in the future. Although their ultimate outcome cannot be predicted at this time, CERC does not expect these matters, either individually or in the aggregate, to have a material adverse effect on its financial condition, results of operations or cash flows. Other Environmental. From time to time, CERC 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. CERC has and expects to continue to remediate identified sites consistent with its legal obligations. From time to time, CERC has received notices from regulatory authorities or others regarding its status as a PRP in connection with sites found to require remediation due to the presence of environmental contaminants. In addition, CERC has been named from time to time as a defendant in litigation related to such sites. Although the ultimate outcome of such matters cannot be predicted at this time, CERC does not expect these matters, either individually or in the aggregate, to have a material adverse effect on its financial condition, results of operations or cash flows. Other Proceedings CERC 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, CERC 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. CERC regularly analyzes current information and, as necessary, provides accruals for probable and reasonably estimable liabilities on the eventual disposition of these matters. CERC does not expect the disposition of these matters to have a material adverse effect on its financial condition, results of operations or cash flows. (c) Guarantees Prior to the distribution of CenterPoint Energy’s ownership in RRI to its shareholders, CERC had guaranteed certain contractual obligations of what became RRI’s trading subsidiary. When the companies separated, RRI agreed to secure CERC against obligations under the guarantees RRI had been unable to extinguish by the time of separation. Pursuant to such agreement, as amended in December 2007, RRI (now GenOn) agreed to provide to CERC cash or letters of credit as security against CERC’s obligations under its remaining guarantees for demand charges under certain gas transportation agreements if and to the extent changes in market conditions expose CERC to a risk of loss on those guarantees based on an annual calculation, with any required collateral to be posted each December. The undiscounted maximum potential payout of the demand charges under these transportation contracts, which will be in effect until 2018, was approximately $15 million as of September 30, 2016. Based on market conditions in the fourth quarter of 2016 at the time the most recent annual calculation was made under the agreement, GenOn was not obligated to post any security. If GenOn should fail to perform the contractual obligations, CERC could have to honor its guarantee and, in such event, any collateral then provided as security may be insufficient to satisfy CERC’s obligations. CERC Corp. had also provided a guarantee of collection of $1.1 billion of Enable’s senior notes due 2019 and 2024. This guarantee was subordinated to all senior debt of CERC Corp. and was automatically released on May 1, 2016. The fair value of these guarantees is not material.

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes [Text Block]	Income Taxes The effective tax rate reported for the three months ended September 30, 2016 was 38% compared to 37% for the same period in 2015. The effective tax rate reported for the nine months ended September 30, 2016 was 40% compared to 37% for the same period in 2015. The higher effective tax rate for the nine months ended September 30, 2016 is due to a Louisiana state tax law change in the second quarter of 2016 resulting in an increase to CERC’s deferred tax liability. CERC reported no uncertain tax liability as of September 30, 2016 and expects no significant change to the uncertain tax liability over the next twelve months. CenterPoint Energy’s consolidated federal income tax returns have been audited and settled through 2014. CenterPoint Energy is under examination by the IRS for 2015 and 2016.

Reportable Business Segments

9 Months Ended

Sep. 30, 2016

Segment Reporting [Abstract]

Reportable Business Segments [Text Block]

Reportable Business Segments

Because CERC is an indirect, wholly-owned subsidiary of CenterPoint Energy, CERC’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. CERC uses operating income as the measure of profit or loss for its business segments.

CERC’s reportable business segments include the following: Natural Gas Distribution, Energy Services, Midstream Investments and Other Operations. 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 CERC’s non-rate regulated gas sales and services operations. Midstream Investments consists of CERC’s investment in Enable. The Other Operations business segment includes unallocated corporate costs and inter-segment eliminations.

Financial data for business segments is as follows:



	For the Three Months Ended September 30, 2016
	Revenues from External Customers		Inter-segment Revenues			Operating Income (Loss)
	(in millions)
Natural Gas Distribution	$	370	$	7		$	22
Energy Services	608		6			5
Midstream Investments (1)	—		—			—
Other Operations	—		—			(1		)
Reconciling Eliminations	—		(13		)	—
Consolidated	$	978	$	—		$	26



	For the Three Months Ended September 30, 2015
	Revenues from External Customers		Inter-segment Revenues			Operating Income
	(in millions)
Natural Gas Distribution	$	353	$	6		$	11
Energy Services	446		6			7
Midstream Investments (1)	—		—			—
Other Operations	—		—			—
Reconciling Eliminations	—		(12		)	—
Consolidated	$	799	$	—		$	18



	For the Nine Months Ended September 30, 2016
	Revenues from External Customers		Inter-segment Revenues			Operating Income (Loss)			Total Assets as of September 30, 2016
	(in millions)
Natural Gas Distribution	$	1,672	$	21		$	202		$	5,732
Energy Services	1,433		17			11			990
Midstream Investments (1)	—		—			—			2,535
Other Operations	—		—			(3		)	410
Reconciling Eliminations	—		(38		)	—			(841		)
Consolidated	$	3,105	$	—		$	210		$	8,826



	For the Nine Months Ended September 30, 2015
	Revenues from External Customers		Inter-segment Revenues			Operating Income		Total Assets as of December 31, 2015
	(in millions)
Natural Gas Distribution	$	1,958	$	21		$	176	$	5,657
Energy Services	1,482		28			29		857
Midstream Investments (1)	—		—			—		2,594
Other Operations	—		—			—		777
Reconciling Eliminations	—		(49		)	—		(744		)
Consolidated	$	3,440	$	—		$	205	$	9,141


(1)	Midstream Investments’ equity earnings are as follows:



	Three Months Ended September 30,					Nine Months Ended September 30,
	2016		2015			2016		2015
	(in millions)
Enable (a)	$	73	$	(794	)	$	164	$	(699	)


(a)	These amounts include CERC’s share of Enable’s impairment of goodwill and long-lived assets and the impairment of CERC’s equity method investment in Enable totaling $862 million during the three and nine months ended September 30, 2015. This impairment is partially offset by $68 million and $163 million of earnings for the three and nine months ended September 30, 2015, respectively.

Midstream Investments’ total assets are as follows:



	September 30, 2016		December 31, 2015
	(in millions)
Enable	$	2,535	$	2,594

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

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+ Details

Other Current Assets and Liabilities	9 Months Ended
Other Current Assets and Liabilities	Sep. 30, 2016
Other Current Assets and Liabilities [Abstract]
Other Current Assets and Liabilities [Text Block]	Other Current Assets and Liabilities Included in other current assets on the Condensed Consolidated Balance Sheets at September 30, 2016 and December 31, 2015 were $16 million and $31 million, respectively, of margin deposits and $29 million and $12 million, respectively, of under-recovered gas cost. Included in other current liabilities on the Condensed Consolidated Balance Sheets at September 30, 2016 and December 31, 2015 were $28 million and $55 million, respectively, of over-recovered gas cost.

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2016
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events On October 31, 2016, CES, a wholly-owned subsidiary of CERC Corp., announced an agreement to acquire Atmos Energy Marketing for approximately $120 million, including estimated working capital of $80 million. The transaction is conditioned upon the receipt of certain third party consents and approvals, including expiration of any Hart-Scott-Rodino waiting period. CERC expects the transaction to close in early 2017. On November 1, 2016, Enable declared a quarterly cash distribution of $0.318 per unit on all of its outstanding common and subordinated units for the quarter ended September 30, 2016. Accordingly, CERC Corp. expects to receive a cash distribution of approximately $74 million from Enable in the fourth quarter of 2016 to be made with respect to CERC Corp.’s investment in common and subordinated units in Enable for the third quarter of 2016.

Acquisition (Tables)

9 Months Ended

Sep. 30, 2016

Business Combinations [Abstract]

Schedule of Business Acquisitions, by Acquisition [Table Text Block]

The following table summarizes the final purchase price allocation and the fair value amounts recognized for the assets acquired and liabilities assumed related to the acquisition:



	(in millions)
Total purchase price consideration	$	102
Receivables	$	76
Derivative assets	38
Property and equipment	1
Identifiable intangibles	38
Total assets acquired	153
Accounts payable	49
Derivative liabilities	24
Total liabilities assumed	73
Identifiable net assets acquired	80
Goodwill	22
Net assets acquired	$	102

Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]

The estimated fair value of the identifiable intangible assets and related useful lives as included in the final purchase price allocation include:



	Estimate Fair Value		Estimate Useful Life
	(in millions)		(in years)
Customer relationships	$	34	15
Covenants not to compete	4		4
Total identifiable intangibles	$	38

Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2016

Compensation and Retirement Disclosure [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

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



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2016			2015			2016			2015
	(in millions)
Service cost	$	1		$	1		$	1		$	1
Interest cost on accumulated benefit obligation	1			2			3			4
Expected return on plan assets	(1		)	(1		)	(1		)	(1		)
Amortization of net loss	—			—			—			1
Net periodic cost	$	1		$	2		$	3		$	5

Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2016

Derivatives, Fair Value [Line Items]

Fair Value of Derivative Instruments [Table Text Block]



Fair Value of Derivative Instruments
		September 30, 2016
Total derivatives not designated as hedging instruments	Balance Sheet Location	Derivative Assets Fair Value		Derivative Liabilities Fair Value
		(in millions)
Natural gas derivatives (1) (2) (3)	Current Assets: Non-trading derivative assets	$	51	$	2
Natural gas derivatives (1) (2) (3)	Other Assets: Non-trading derivative assets	24		—
Natural gas derivatives (1) (2) (3)	Current Liabilities: Non-trading derivative liabilities	19		41
Natural gas derivatives (1) (2) (3)	Other Liabilities: Non-trading derivative liabilities	4		11
Total		$	98	$	54


(1)	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,080 Bcf or a net 16 Bcf short position. Of the net short position, basis swaps constitute a net 128 Bcf long position.

(2)


(3)	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.



Fair Value of Derivative Instruments
		December 31, 2015
Total derivatives not designated as hedging instruments	Balance Sheet Location	Derivative Assets Fair Value		Derivative Liabilities Fair Value
		(in millions)
Natural gas derivatives (1) (2) (3)	Current Assets: Non-trading derivative assets	$	90	$	2
Natural gas derivatives (1) (2) (3)	Other Assets: Non-trading derivative assets	36		—
Natural gas derivatives (1) (2) (3)	Current Liabilities: Non-trading derivative liabilities	10		60
Natural gas derivatives (1) (2) (3)	Other Liabilities: Non-trading derivative liabilities	4		25
Total		$	140	$	87


(1)	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 767 Bcf or a net 112 Bcf long position. Of the net long position, basis swaps constitute 133 Bcf.

(2)

Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $109 million asset as shown on CERC’s Condensed Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, offset by collateral netting of $56 million.


(3)	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.

Derivative Instruments, Offsetting Assets and Liabilities [Table Text Block]



Offsetting of Natural Gas Derivative Assets and Liabilities
	September 30, 2016
	Gross Amounts Recognized (1)			Gross Amounts Offset in the Consolidated Balance Sheets			Net Amount Presented in the Consolidated Balance Sheets (2)
	(in millions)
Current Assets: Non-trading derivative assets	$	70		$	(21	)	$	49
Other Assets: Non-trading derivative assets	28			(4		)	24
Current Liabilities: Non-trading derivative liabilities	(43		)	24			(19		)
Other Liabilities: Non-trading derivative liabilities	(11		)	7			(4		)
Total	$	44		$	6		$	50


(1)	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.


(2)	The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.



Offsetting of Natural Gas Derivative Assets and Liabilities
	December 31, 2015
	Gross Amounts Recognized (1)			Gross Amounts Offset in the Consolidated Balance Sheets			Net Amount Presented in the Consolidated Balance Sheets (2)
	(in millions)
Current Assets: Non-trading derivative assets	$	100		$	(11	)	$	89
Other Assets: Non-trading derivative assets	40			(4		)	36
Current Liabilities: Non-trading derivative liabilities	(62		)	51			(11		)
Other Liabilities: Non-trading derivative liabilities	(25		)	20			(5		)
Total	$	53		$	56		$	109


(1)	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.


(2)	The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.

Income Statement Impact of Derivative Activity [Table Text Block]



Income Statement Impact of Derivative Activity
		Three Months Ended September 30,
Total derivatives not designated as hedging instruments	Income Statement Location	2016			2015
		(in millions)
Natural gas derivatives	Gains (Losses) in Revenues	$	31		$	39
Natural gas derivatives	Gains (Losses) in Expenses: Natural Gas	(13		)	(30		)
Total		$	18		$	9



Income Statement Impact of Derivative Activity
		Nine Months Ended September 30,
Total derivatives not designated as hedging instruments	Income Statement Location	2016		2015
		(in millions)
Natural gas derivatives	Gains (Losses) in Revenues	$	1	$	88
Natural gas derivatives	Gains (Losses) in Expenses: Natural Gas	35		(72		)
Total		$	36	$	16

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2016

Fair Value Disclosures [Abstract]

Fair Value, Assets Measured on Recurring Basis [Table Text Block]



	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Netting Adjustments (1)			Balance as of September 30, 2016
	(in millions)
Assets
Corporate equities	$	2	$	—	$	—	$	—		$	2
Investments, including money market funds (2)	10		—		—		—			10
Natural gas derivatives (3)	4		72		22		(25		)	73
Total assets	$	16	$	72	$	22	$	(25	)	$	85
Liabilities
Natural gas derivatives (3)	$	5	$	44	$	5	$	(31	)	$	23
Total liabilities	$	5	$	44	$	5	$	(31	)	$	23


(1)	Amounts represent the impact of legally enforceable master netting arrangements that allow CERC to settle positive and negative positions and also include cash collateral of $6 million posted with the same counterparties.


(2)	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.


(3)	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.



	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Netting Adjustments (1)			Balance as of December 31, 2015
	(in millions)
Assets
Corporate equities	$	2	$	—	$	—	$	—		$	2
Investments, including money market funds (2)	11		—		—		—			11
Natural gas derivatives (3)	4		115		21		(15		)	125
Total assets	$	17	$	115	$	21	$	(15	)	$	138
Liabilities
Natural gas derivatives (3)	$	13	$	65	$	9	$	(71	)	$	16
Total liabilities	$	13	$	65	$	9	$	(71	)	$	16


(1)	Amounts represent the impact of legally enforceable master netting arrangements that allow CERC to settle positive and negative positions and also include cash collateral of $56 million posted with the same counterparties.


(2)	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.


(3)	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]



	Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Derivative Assets and Liabilities, Net
	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
	(in millions)
Beginning balance	$	16		$	10		$	12		$	17
Purchases	—			—			12			—
Total gains	9			5			13			5
Total settlements	(8		)	(2		)	(24		)	(8		)
Transfers into Level 3	—			1			5			1
Transfers out of Level 3	—			—			(1		)	(1		)
Ending balance (1)	$	17		$	14		$	17		$	14
The amount of total gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	$	6		$	6		$	14		$	7


(1)	CERC did not have significant Level 3 sales during either of the three or nine months ended September 30, 2016 or 2015.

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

Estimated Fair Value of Financial Instruments



	September 30, 2016				December 31, 2015
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(in millions)
Financial assets:
Notes receivable–unconsolidated affiliate	$	—	$	—	$	363	$	356
Financial liabilities:
Long-term debt	$	2,263	$	2,500	$	2,341	$	2,539

Unconsolidated Affiliates (Tables)

9 Months Ended

Sep. 30, 2016

Equity Method Investments and Joint Ventures [Abstract]

Equity Method Investments [Table Text Block]

Summarized unaudited consolidated income information for Enable is as follows:



	Three Months Ended September 30,					Nine Months Ended September 30,
	2016		2015			2016		2015
	(in millions)
Operating revenues	$	620	$	646		$	1,658	$	1,852
Cost of sales, excluding depreciation and amortization	268		287			717		856
Impairment of goodwill and other long-lived assets	8		1,105			8		1,105
Operating income (loss)	139		(975		)	299		(778		)
Net income (loss) attributable to Enable	110		(985		)	231		(817		)

Reconciliation of Equity in Earnings (Losses), net:
CERC’s interest	$	61	$	(546	)	$	128	$	(453	)
Basis difference amortization (1)	12		2			36		4
Impairment of CERC’s equity method investment in Enable	—		(250		)	—		(250		)
CERC’s equity in earnings (losses), net (2)	$	73	$	(794	)	$	164	$	(699	)


(1)	Equity in earnings (losses) of unconsolidated affiliates includes CERC’s share of Enable’s earnings adjusted for the amortization of the basis difference of CERC’s original investment in Enable and its underlying equity in Enable’s net assets. The basis difference is amortized over approximately 33 years, the average life of the assets to which the basis difference is attributed.


(2)	These amounts include CERC’s share of Enable’s impairment of goodwill and long-lived assets and the impairment of CERC’s equity method investment in Enable totaling $862 million during the three and nine months ended September 30, 2015. This impairment is partially offset by $68 million and $163 million of earnings for the three and nine months ended September 30, 2015, respectively.

Summarized unaudited consolidated balance sheet information for Enable is as follows:



	September 30, 2016			December 31, 2015
	(in millions)
Current assets	$	408		$	381
Non-current assets	10,833			10,845
Current liabilities	338			615
Non-current liabilities	3,174			3,080
Non-controlling interest	11			12
Preferred equity	362			—
Enable partners’ equity	7,356			7,519

Reconciliation of Equity Method Investment in Enable:
CERC’s ownership interest in Enable partners’ capital	$	4,073		$	4,163
CERC’s basis difference	(1,538		)	(1,569		)
CERC’s equity method investment in Enable	$	2,535		$	2,594

Distributions Received from Unconsolidated Affiliate:



	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
	(in millions)
Enable	$	74	$	74	$	223	$	219

Goodwill (Tables)

9 Months Ended

Sep. 30, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill [Table Text Block]

Goodwill by reportable business segment as of December 31, 2015 and changes in the carrying amount of goodwill as of September 30, 2016 are as follows:



	December 31, 2015			Continuum Acquisition (1)		September 30, 2016
	(in millions)
Natural Gas Distribution	$	746		$	—	$	746
Energy Services	83		(2)	22		105
Other Operations	11			—		11
Total	$	840		$	22	$	862


(1)	See Note 3.


(2)	Amount presented is net of the accumulated goodwill impairment charge of $252 million.

Related Party Transactions (Tables)

9 Months Ended

Sep. 30, 2016



	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
	(in millions)
Corporate service charges	$	31		$	25		$	90		$	80
Charges from Houston Electric for services provided	4			5			11			12
Billings to Houston Electric for services provided	(2		)	(1		)	(5		)	(4		)
	$	33		$	29		$	96		$	88

Short-term Borrowings and Long-term Debt (Tables)

9 Months Ended

Sep. 30, 2016

Debt Disclosure [Abstract]

Schedule of Line of Credit Facilities [Table Text Block]



		September 30, 2016							December 31, 2015
Size of Facility		Loans		Letters of Credit		Commercial Paper			Loans		Letters of Credit		Commercial Paper
(in millions)
$	600	$	—	$	3	$	459	(1)	$	—	$	2	$	219	(1)


(1)	Weighted average interest rate was 0.76% and 0.81% as of September 30, 2016 and December 31, 2015, respectively.

Reportable Business Segments (Tables)

9 Months Ended

Sep. 30, 2016

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

Financial data for business segments is as follows:



	For the Three Months Ended September 30, 2016
	Revenues from External Customers		Inter-segment Revenues			Operating Income (Loss)
	(in millions)
Natural Gas Distribution	$	370	$	7		$	22
Energy Services	608		6			5
Midstream Investments (1)	—		—			—
Other Operations	—		—			(1		)
Reconciling Eliminations	—		(13		)	—
Consolidated	$	978	$	—		$	26



	For the Three Months Ended September 30, 2015
	Revenues from External Customers		Inter-segment Revenues			Operating Income
	(in millions)
Natural Gas Distribution	$	353	$	6		$	11
Energy Services	446		6			7
Midstream Investments (1)	—		—			—
Other Operations	—		—			—
Reconciling Eliminations	—		(12		)	—
Consolidated	$	799	$	—		$	18



	For the Nine Months Ended September 30, 2016
	Revenues from External Customers		Inter-segment Revenues			Operating Income (Loss)			Total Assets as of September 30, 2016
	(in millions)
Natural Gas Distribution	$	1,672	$	21		$	202		$	5,732
Energy Services	1,433		17			11			990
Midstream Investments (1)	—		—			—			2,535
Other Operations	—		—			(3		)	410
Reconciling Eliminations	—		(38		)	—			(841		)
Consolidated	$	3,105	$	—		$	210		$	8,826



	For the Nine Months Ended September 30, 2015
	Revenues from External Customers		Inter-segment Revenues			Operating Income		Total Assets as of December 31, 2015
	(in millions)
Natural Gas Distribution	$	1,958	$	21		$	176	$	5,657
Energy Services	1,482		28			29		857
Midstream Investments (1)	—		—			—		2,594
Other Operations	—		—			—		777
Reconciling Eliminations	—		(49		)	—		(744		)
Consolidated	$	3,440	$	—		$	205	$	9,141


(1)	Midstream Investments’ equity earnings are as follows:



	Three Months Ended September 30,					Nine Months Ended September 30,
	2016		2015			2016		2015
	(in millions)
Enable (a)	$	73	$	(794	)	$	164	$	(699	)


(a)	These amounts include CERC’s share of Enable’s impairment of goodwill and long-lived assets and the impairment of CERC’s equity method investment in Enable totaling $862 million during the three and nine months ended September 30, 2015. This impairment is partially offset by $68 million and $163 million of earnings for the three and nine months ended September 30, 2015, respectively.

Midstream Investments’ total assets are as follows:



	September 30, 2016		December 31, 2015
	(in millions)
Enable	$	2,535	$	2,594

Midstream Investments [Table Text Block]

Midstream Investments’ equity earnings are as follows:



	Three Months Ended September 30,					Nine Months Ended September 30,
	2016		2015			2016		2015
	(in millions)
Enable (a)	$	73	$	(794	)	$	164	$	(699	)


(a)	These amounts include CERC’s share of Enable’s impairment of goodwill and long-lived assets and the impairment of CERC’s equity method investment in Enable totaling $862 million during the three and nine months ended September 30, 2015. This impairment is partially offset by $68 million and $163 million of earnings for the three and nine months ended September 30, 2015, respectively.

Midstream Investments’ total assets are as follows:



	September 30, 2016		December 31, 2015
	(in millions)
Enable	$	2,535	$	2,594

Background and Basis of Presentation (Details)	Sep. 30, 2016
Enable Midstream Partners [Member]
Equity Method Investment, Ownership Percentage	55.40%

New Accounting Pronouncements (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Unamortized Debt Issuance Expense	$ 11	$ 12

Acquisition (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
Acquisition (Details) - USD ($) $ in Millions	Apr. 01, 2016	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Goodwill		$ 862.0	$ 862.0	$ 840.0
Revenue of Acquiree since Acquisition Date		$ 170.0	$ 270.0
Operating Income Of Acquiree Since Acquisition Date		2	2
Continuum Energy Services [Member]
Business Acquisition [Line Items]
Preliminary Purchase Price	$ 98.0
Total purchase price consideration	102.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Total purchase price consideration	102.0
Receivables	76.0
Derivative assets	38.0
Property and equipment	1.0
Identifiable intangibles	38.0
Total assets acquired	153.0
Accounts payable	49.0
Derivative liabilities	24.0
Total liabilities assumed	73.0
Identifiable net assets acquired	80.0
Goodwill	22.0
Net assets acquired	102.0
Total identifiable intangibles	38.0
Amortization of Intangible Assets		$ 1.0	$ 2.0
Customer Relationships [Member] \| Continuum Energy Services [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Finite-lived Intangible Assets Acquired	$ 34.0
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	15 years
Noncompete Agreements [Member] \| Continuum Energy Services [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Finite-lived Intangible Assets Acquired	$ 4.0
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	4 years

Employee Benefit Plans (Details) - Other Postretirement Benefit Plans, Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 1	$ 1	$ 1
Interest cost on accumulated benefit obligation	1	2	3	4
Expected return on plan assets	(1)	(1)	(1)	(1)
Amortization of net loss	0	0	0	1
Net periodic cost	1	$ 2	3	$ 5
Contribution expected in 2016			6
Contribution made in period	$ 1		$ 4

Derivative Instruments Derivatives and Hedging (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Term of normal weather used as the basis for weather hedges (in years)			10 years
Weather Hedge Swaps [Member] \| Sales [Member]
Gains (Losses) Recognized Related to Weather Hedges	$ 0	$ 0	$ 0	$ (4)
Natural Gas Distribution \| 2014To2015 [Member]
Weather Hedge, Bilateral Cap Amount			$ 16

Derivative Instruments Derivative Instruments (Details)
$ in Millions

3 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2016

USD ($)

Sep. 30, 2015

USD ($)

Sep. 30, 2016

USD ($)

Bcf

Sep. 30, 2015

USD ($)

Dec. 31, 2015

USD ($)

Bcf

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Instruments, Assets, Physical Forwards Purchased

$ 98

$ 140

Derivative Liability, Fair Value, Gross Liability

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net

$ 9

$ 16

Derivative, Fair Value, Net [Abstract]

Total fair value of the derivative instruments that contain credit risk contingency features that are in a net liability position

Collateral Already Posted, Aggregate Fair Value

Credit Risk Contingent Feature assets

$ 2

Weather Hedge Swaps [Member] | Gains (Losses) in Revenue

Derivatives, Fair Value [Line Items]

Derivative, Gain (Loss) on Derivative, Net

$ 0

(4)

Energy Related Derivative [Member]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative, Nonmonetary Notional Amount, Volume | Bcf

1,080

767

Gross Amounts Recognized (1)

^[1]

$ 44

$ 53

Derivative, Fair Value, Offsets, Net

Derivative Assets (Liabilities), at Fair Value, Net

^[2]

109

collateral Netting

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement

^[1]

100

Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset

(21)

(11)

Derivative Asset

^[2]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement

^[1]

Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset

(4)

Derivative Asset

^[2]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement

^[1]

(43)

(62)

Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset

Derivative Liability

^[2]

(19)

(11)

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement

^[1]

(11)

(25)

Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset

Derivative Liability

^[2]

(4)

(5)

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net

(13)

$ (30)

$ (72)

Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Current Assets [Member]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Instruments, Assets, Physical Forwards Purchased

^[3]

^[4],[5]

^[6],[7]

Derivative Liability, Fair Value, Gross Liability

^[3]

^[4],[5]

^[6],[7]

Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other Noncurrent Assets [Member]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Instruments, Assets, Physical Forwards Purchased

^[3]

^[4],[5]

^[6],[7]

Derivative Liability, Fair Value, Gross Liability

^[3]

^[4],[5]

^[6],[7]

Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Current Liabilities [Member]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Instruments, Assets, Physical Forwards Purchased

^[3]

^[4],[5]

^[6],[7]

Derivative Liability, Fair Value, Gross Liability

^[3]

^[4],[5]

^[6],[7]

Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other Noncurrent Liabilities [Member]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative Instruments, Assets, Physical Forwards Purchased

^[3]

^[4],[5]

^[6],[7]

Derivative Liability, Fair Value, Gross Liability

^[3]

$ 11

^[4],[5]

$ 11

^[4],[5]

$ 25

^[6],[7]

Short [Member] | Energy Related Derivative [Member]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative, Nonmonetary Notional Amount, Volume | Bcf

Long [Member] | Energy Related Derivative [Member]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative, Nonmonetary Notional Amount, Volume | Bcf

112

Swap [Member] | Long [Member] | Energy Related Derivative [Member]

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]

Derivative, Nonmonetary Notional Amount, Volume | Bcf

128

133

[1]	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.
[2]	The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
[3]	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
[4]	Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $50 million asset as shown on CERC’s Condensed Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, offset by collateral netting of $6 million.
[5]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,080 Bcf or a net 16 Bcf short position. Of the net short position, basis swaps constitute a net 128 Bcf long position.
[6]	Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $109 million asset as shown on CERC’s Condensed Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, offset by collateral netting of $56 million.
[7]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 767 Bcf or a net 112 Bcf long position. Of the net long position, basis swaps constitute 133 Bcf.

Fair Value Measurements (Details)

3 Months Ended

9 Months Ended

Sep. 30, 2016

USD ($)

Sep. 30, 2015

USD ($)

Sep. 30, 2016

USD ($)

Sep. 30, 2015

USD ($)

Dec. 31, 2015

USD ($)

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

Fair Value, Assets, Level 1 to Level 2 Transfers, Amount

$ 0

Fair Value, Assets, Level 2 to Level 1 Transfers, Amount

Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount

Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount

ASSETS

Natural gas derivatives, netting adjustment

(25,000,000)

^[1]

(25,000,000)

^[1]

$ (15,000,000)

^[2]

Total assets

85,000,000

138,000,000

Liabilities [Abstract]

Natural gas derivatives, netting adjustment

(31,000,000)

^[1]

(31,000,000)

^[1]

(71,000,000)

^[2]

Liabilities, Fair Value Disclosure, Recurring

23,000,000

16,000,000

Cash collateral posted with counterparties

6,000,000

56,000,000

Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]

Beginning balance

16,000,000

$ 10,000,000

12,000,000

$ 17,000,000

Purchases

12,000,000

Total gains

9,000,000

5,000,000

13,000,000

5,000,000

Total settlements

(8,000,000)

(2,000,000)

(24,000,000)

(8,000,000)

Transfers into Level 3

1,000,000

5,000,000

1,000,000

Transfers out of Level 3

(1,000,000)

Ending balance (1)

^[3]

17,000,000

14,000,000

17,000,000

14,000,000

The amount of total gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date

6,000,000

$ 6,000,000

14,000,000

$ 7,000,000

Carrying Amount [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation Roll Forward

Notes receivable–unconsolidated affiliate

363,000,000

Long-term debt

2,263,000,000

2,341,000,000

Fair Value [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation Roll Forward

Notes receivable–unconsolidated affiliate

356,000,000

Long-term debt

2,500,000,000

2,539,000,000

Fair Value, Inputs, Level 1 [Member]

ASSETS

Total assets

16,000,000

17,000,000

Liabilities [Abstract]

Liabilities, Fair Value Disclosure, Recurring

5,000,000

13,000,000

Fair Value, Inputs, Level 2 [Member]

ASSETS

Total assets

72,000,000

115,000,000

Liabilities [Abstract]

Liabilities, Fair Value Disclosure, Recurring

44,000,000

65,000,000

Fair Value, Inputs, Level 3 [Member]

ASSETS

Total assets

22,000,000

21,000,000

Liabilities [Abstract]

Liabilities, Fair Value Disclosure, Recurring

5,000,000

$ 5,000,000

9,000,000

Forward Contracts [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]

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

Fair Value Inputs, Price Per MMBtu

0.77

Forward Contracts [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]

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

Fair Value Inputs, Price Per MMBtu

7.90

Options Held [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]

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

Fair Value Assumptions, Expected Volatility Rate

0.00%

Options Held [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]

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

Fair Value Assumptions, Expected Volatility Rate

73.00%

Fair Value, Measurements, Recurring [Member]

ASSETS

Corporate equities

2,000,000

$ 2,000,000

2,000,000

Investments, including money market funds

^[4]

10,000,000

11,000,000

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]

ASSETS

Corporate equities

2,000,000

Investments, including money market funds

^[4]

10,000,000

11,000,000

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]

ASSETS

Corporate equities

Investments, including money market funds

^[4]

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

ASSETS

Corporate equities

Investments, including money market funds

^[4]

Fair Value, Measurements, Recurring [Member] | Energy Related Derivative [Member]

ASSETS

Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset

^[5]

(25,000,000)

^[1]

(25,000,000)

^[1]

(15,000,000)

^[2]

Derivative Asset

^[5]

73,000,000

125,000,000

Liabilities [Abstract]

Derivative Liability

^[5]

23,000,000

16,000,000

Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset

^[5]

(31,000,000)

^[1]

(31,000,000)

^[1]

(71,000,000)

^[2]

Fair Value, Measurements, Recurring [Member] | Energy Related Derivative [Member] | Fair Value, Inputs, Level 1 [Member]

ASSETS

Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement

^[5]

4,000,000

Liabilities [Abstract]

Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement

^[5]

5,000,000

13,000,000

Fair Value, Measurements, Recurring [Member] | Energy Related Derivative [Member] | Fair Value, Inputs, Level 2 [Member]

ASSETS

Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement

^[5]

72,000,000

115,000,000

Liabilities [Abstract]

Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement

^[5]

44,000,000

65,000,000

Fair Value, Measurements, Recurring [Member] | Energy Related Derivative [Member] | Fair Value, Inputs, Level 3 [Member]

ASSETS

Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement

^[5]

22,000,000

21,000,000

Liabilities [Abstract]

Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement

^[5]

$ 5,000,000

$ 9,000,000

[1]	Amounts represent the impact of legally enforceable master netting arrangements that allow CERC to settle positive and negative positions and also include cash collateral of $6 million posted with the same counterparties.
[2]	Amounts represent the impact of legally enforceable master netting arrangements that allow CERC to settle positive and negative positions and also include cash collateral of $56 million posted with the same counterparties.
[3]	CERC did not have significant Level 3 sales during either of the three or nine months ended September 30, 2016 or 2015.
[4]	Amounts are included in Prepaid Expenses and Other Current Assets in the Condensed Consolidated Balance Sheets.
[5]	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.

Unconsolidated Affiliates Description (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Feb. 18, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Interest receivable		$ 5		$ 5		$ 8
Service Agreement Notice For Termination At Term End, Number Of Days				90 days
Service Agreement Notice For Termination At Will Number Of Days				180 days
Enable Midstream Partners [Member]
Share Price		$ 15.25		$ 15.25
Enable Midstream Partners [Member]
Equity Method Investment, Ownership Percentage		55.40%		55.40%
Equity Method Investment, Carrying Value Per Unit		$ 10.84		$ 10.84
Impairment Charges			$ 862		$ 862
Subordinated Units [Member] \| Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares		139,704,916		139,704,916
Common Stock [Member] \| Enable Midstream Partners [Member]
Equity Method Investment, Ownership, Shares		94,151,707		94,151,707
Enable Midstream Partners [Member]
Extinguishment of Debt, Amount	$ 363
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum				2.10%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum				2.45%
Interest Income, Related Party		$ 0	2	$ 1	6
Interest receivable		0		0		4
Transitional Service [Member] \| Enable Midstream Partners [Member]
Reimbursement Revenue		1	3	6	10
Accounts Receivable, Related Parties		2		2		3
Natural Gas Expenses [Member] \| Enable Midstream Partners [Member]
Affiliate Costs		22	$ 23	79	$ 87
Accounts Payable, Related Parties, Current		$ 8		$ 8		$ 11
Enable Midstream Partners [Member] \| CERC Corp [Member]
Management Rights Ownership Percentage				50.00%
Incentive Distribution Right				40.00%
Enable Midstream Partners [Member] \| OGE [Member]
Management Rights Ownership Percentage				50.00%
Incentive Distribution Right				60.00%

Unconsolidated Affiliates Financial Data (Details) - USD ($)

3 Months Ended

9 Months Ended

Sep. 30, 2016

Sep. 30, 2015

Sep. 30, 2016

Sep. 30, 2015

Dec. 31, 2015

Equity Method Investment, Summarized Financial Information, Assets [Abstract]

CERC’s equity method investment in Enable

$ 2,535,000,000

$ 2,594,000,000

Enable Midstream Partners [Member]

Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]

Operating revenues

620,000,000

$ 646,000,000

1,658,000,000

$ 1,852,000,000

Cost of sales, excluding depreciation and amortization

268,000,000

287,000,000

717,000,000

856,000,000

Impairment of goodwill and other long-lived assets

8,000,000

1,105,000,000

8,000,000

1,105,000,000

Operating income (loss)

139,000,000

(975,000,000)

299,000,000

(778,000,000)

Net income (loss) attributable to Enable

110,000,000

(985,000,000)

231,000,000

(817,000,000)

CERC’s interest

61,000,000

(546,000,000)

128,000,000

(453,000,000)

Basis difference amortization (1)

^[1]

12,000,000

2,000,000

36,000,000

4,000,000

Impairment of CERC’s equity method investment in Enable

(250,000,000)

CERC’s equity in earnings (losses), net (2)

^[2]

73,000,000

(794,000,000)

$ 164,000,000

(699,000,000)

Basis Difference, Amortization Period

33 years

Impairment Charges

862,000,000

Income (Loss) From Equity Method Investment, Excluding Impairment Charge

68,000,000

163,000,000

Equity Method Investment, Summarized Financial Information, Assets [Abstract]

Current assets

408,000,000

$ 408,000,000

381,000,000

Non-current assets

10,833,000,000

10,845,000,000

Current liabilities

338,000,000

615,000,000

Non-current liabilities

3,174,000,000

3,080,000,000

Non-controlling interest

11,000,000

12,000,000

Preferred equity

362,000,000

Enable partners’ capital

7,356,000,000

7,519,000,000

CERC’s ownership interest in Enable partners’ capital

4,073,000,000

4,163,000,000

CERC’s basis difference

(1,538,000,000)

(1,569,000,000)

CERC’s equity method investment in Enable

2,535,000,000

$ 2,594,000,000

Proceeds from Equity Method Investment, Dividends or Distributions

$ 74,000,000

$ 223,000,000

$ 219,000,000

[1]	Equity in earnings (losses) of unconsolidated affiliates includes CERC’s share of Enable’s earnings adjusted for the amortization of the basis difference of CERC’s original investment in Enable and its underlying equity in Enable’s net assets. The basis difference is amortized over approximately 33 years, the average life of the assets to which the basis difference is attributed.
[2]	These amounts include CERC’s share of Enable’s impairment of goodwill and long-lived assets and the impairment of CERC’s equity method investment in Enable totaling $862 million during the three and nine months ended September 30, 2015. This impairment is partially offset by $68 million and $163 million of earnings for the three and nine months ended September 30, 2015, respectively.

Goodwill (Details) - USD ($)
$ in Millions

9 Months Ended

Sep. 30, 2016

Dec. 31, 2015

Goodwill [Line Items]

Goodwill, Beginning Balance

$ 840

Goodwill, Acquired During Period

^[1]

Goodwill, Ending Balance

862

Natural Gas Distribution

Goodwill [Line Items]

Goodwill, Beginning Balance

746

Goodwill, Acquired During Period

^[1]

Goodwill, Ending Balance

746

Energy Services

Goodwill [Line Items]

Goodwill, Beginning Balance

^[2]

Goodwill, Acquired During Period

^[1]

Goodwill, Ending Balance

105

Goodwill, Impaired, Accumulated Impairment Loss

$ 252

Other Operations

Goodwill [Line Items]

Goodwill, Beginning Balance

Goodwill, Acquired During Period

^[1]

Goodwill, Ending Balance

$ 11

[1]	See Note 3.
[2]	Amount presented is net of the accumulated goodwill impairment charge of $252 million

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Investments in Money Pool	$ 0		$ 0		$ 0
Net Related Party Charges	33	$ 29	96	$ 88
CenterPoint Energy [Member] \| Operation And Maintenance Expense [Member]
Corporate service charges	31	25	90	80
CenterPoint Houston [Member] \| Operation And Maintenance Expense [Member]
Corporate service charges	4	5	11	12
Billings to Houston Electric for services provided	$ (2)	$ (1)	$ (5)	$ (4)

Short-term Borrowings and Long-term Debt (Details) - USD ($)
$ in Millions

9 Months Ended

Sep. 30, 2016

May 01, 2016

Dec. 31, 2015

Short-term Debt

$ 43

$ 40

Line of Credit Facility, Maximum Borrowing Capacity

$ 600

600

Debt Instrument, Term

5 years

Senior Notes [Member]

Debt Instrument, Face Amount

$ 325

Debt Instrument, Interest Rate, Stated Percentage

6.15%

Product Financing Arrangement [Member]

Short-term Debt

$ 43

Line of Credit [Member]

Percentage on limitation of debt to total capitalization under covenant

65.00%

Ratio of Indebtedness to Net Capital

0.347

Revolving Credit Facility [Member]

Loans Outstanding

$ 0

Letter of Credit [Member]

Loans Outstanding

Commercial Paper [Member]

Loans Outstanding

^[1]

$ 459

$ 219

Debt, Weighted Average Interest Rate

0.76%

0.81%

London Interbank Offered Rate (LIBOR) [Member] | Line of Credit [Member]

Debt Instrument, Basis Spread on Variable Rate

1.25%

[1]	Weighted average interest rate was 0.76% and 0.81% as of September 30, 2016 and December 31, 2015, respectively.

Commitments and Contingencies (Details) $ in Millions	9 Months Ended
Commitments and Contingencies (Details) $ in Millions	Sep. 30, 2016 USD ($)
Natural Gas Supply Commitments [Member]
Recorded Unconditional Purchase Obligation Payment Schedule [Abstract]
2016	$ 132
2017	454
2018	455
2019	267
2020	124
After 2020	133
Minnesota Service Territory [Member]
LegalEnvironmentalAndOtherRegulatoryMattersLegalMattersGasMarketManipulationCasesAbstract
Accrual for Environmental Loss Contingencies	7
Minnesota Service Territory [Member] \| Maximum [Member]
LegalEnvironmentalAndOtherRegulatoryMattersLegalMattersGasMarketManipulationCasesAbstract
Estimated remediation costs for the Minnesota sites	$ 29
Site Contingency, Years to Resolve Contingency	50 years
Minnesota Service Territory [Member] \| Minimum [Member]
LegalEnvironmentalAndOtherRegulatoryMattersLegalMattersGasMarketManipulationCasesAbstract
Estimated remediation costs for the Minnesota sites	$ 4
Site Contingency, Years to Resolve Contingency	30 years
GenOn Demand Charges Transportation Contracts [Member]
LegalEnvironmentalAndOtherRegulatoryMattersLegalMattersGasMarketManipulationCasesAbstract
Guarantee of Affiliate Senior Notes	$ 15
Enable Guaranteed Senior Notes [Member]
LegalEnvironmentalAndOtherRegulatoryMattersLegalMattersGasMarketManipulationCasesAbstract
Guarantee of Affiliate Senior Notes	$ 1,100

Income Taxes (Details)	3 Months Ended		9 Months Ended
Income Taxes (Details)	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Effective Income Tax Rate	38.00%	37.00%	40.00%	37.00%

Reportable Business Segments (Details) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2016

Sep. 30, 2015

Sep. 30, 2016

Sep. 30, 2015

Dec. 31, 2015

Segment Reporting Information [Line Items]

Revenues

$ 978

$ 799

$ 3,105

$ 3,440

Operating Income

210

205

Assets

8,826

$ 9,141

Equity in earnings (losses) of unconsolidated affiliate, net

(794)

164

(699)

Investment in unconsolidated affiliate

2,535

2,594

Natural Gas Distribution

Segment Reporting Information [Line Items]

Revenues

370

353

1,672

1,958

Operating Income

202

176

Energy Services

Segment Reporting Information [Line Items]

Revenues

608

446

1,433

1,482

Operating Income

Midstream Investments (1)

Segment Reporting Information [Line Items]

Revenues

^[1]

Operating Income

^[1]

Other Operations

Segment Reporting Information [Line Items]

Revenues

Operating Income

(1)

(3)

Intersegment Eliminations

Segment Reporting Information [Line Items]

Revenues

(13)

(12)

(38)

(49)

Assets

(841)

(744)

Intersegment Eliminations | Natural Gas Distribution

Segment Reporting Information [Line Items]

Revenues

(7)

(6)

(21)

Intersegment Eliminations | Energy Services

Segment Reporting Information [Line Items]

Revenues

(6)

(17)

(28)

Intersegment Eliminations | Midstream Investments (1)

Segment Reporting Information [Line Items]

Revenues

^[1]

Intersegment Eliminations | Other Operations

Segment Reporting Information [Line Items]

Revenues

Operating Segments [Member] | Natural Gas Distribution

Segment Reporting Information [Line Items]

Assets

5,732

5,657

Operating Segments [Member] | Energy Services

Segment Reporting Information [Line Items]

Assets

990

857

Operating Segments [Member] | Midstream Investments (1)

Segment Reporting Information [Line Items]

Assets

^[1]

2,535

2,594

Operating Segments [Member] | Other Operations

Segment Reporting Information [Line Items]

Assets

410

777

Enable Midstream Partners [Member]

Segment Reporting Information [Line Items]

Impairment Charges

862

Income (Loss) From Equity Method Investment, Excluding Impairment Charge

163

Investment in unconsolidated affiliate

2,535

2,594

Enable Midstream Partners [Member] | Midstream Investments (1)

Segment Reporting Information [Line Items]

Equity in earnings (losses) of unconsolidated affiliate, net

$ (794)

164

$ (699)

Investment in unconsolidated affiliate

$ 2,535

$ 2,594

[1]

Midstream Investments’ equity earnings are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 (in millions)Enable (a) $73 $(794) $164 $(699)(a)These amounts include CERC’s share of Enable’s impairment of goodwill and long-lived assets and the impairment of CERC’s equity method investment in Enable totaling $862 million during the three and nine months ended September 30, 2015. This impairment is partially offset by $68 million and $163 million of earnings for the three and nine months ended September 30, 2015, respectively.Midstream Investments’ total assets are as follows: September 30, 2016 December 31, 2015 (in millions)Enable $2,535 $2,594

Other Current Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Margin Deposits	$ 16	$ 31
Under Recovered Gas Costs	29	12
Over Recovered Gas Costs	$ 28	$ 55

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		9 Months Ended
	Nov. 01, 2016	Oct. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Enable Midstream Partners [Member]
Subsequent Event [Line Items]
Proceeds from Equity Method Investment, Dividends or Distributions			$ 74	$ 74	$ 223	$ 219
Enable Midstream Partners [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared	Nov. 01, 2016
Quarterly Cash Distribution Per Unit Declared	$ 0.318
Proceeds from Equity Method Investment, Dividends or Distributions	$ 74
Atmos Energy Marketing [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Business Acquisition, Effective Date of Acquisition		Oct. 31, 2016
Approximate Acquisition Cost, Including Working Capital		$ 120
Estimated Working Capital		$ 80