Centerpoint Energy Resources 10-Q 8 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	9 Months Ended
	Sep. 30, 2018	Oct. 22, 2018	Jun. 30, 2017
Entity Information [Line Items]
Entity Registrant Name	CENTERPOINT ENERGY INC.
Entity Central Index Key	1,130,310
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		501,191,387
Entity Current Reporting Status	Yes
Entity Public Float			$ 11,722,467,012
Houston Electric [Member]
Entity Information [Line Items]
Entity Registrant Name	CENTERPOINT ENERGY HOUSTON ELECTRIC LLC
Entity Central Index Key	48,732
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Current Reporting Status	Yes
CERC Corp [Member]
Entity Information [Line Items]
Entity Registrant Name	CENTERPOINT ENERGY RESOURCES CORP
Entity Central Index Key	1,042,773
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Current Reporting Status	Yes

CONDENSED STATEMENTS OF CONSOLI

CONDENSED STATEMENTS OF CONSOLIDATED INCOME (Unaudited) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Revenues:
Utility revenues		$ 1,299	$ 1,233	$ 4,534		$ 4,001
Non-utility revenues		913	865	3,019		2,975
Total		2,212	2,098	7,553		6,976
Expenses:
Utility natural gas		134	106	959		706
Cost of Goods and Services Sold	[1]	864	832	2,927		2,843
Operation and maintenance		567	501	1,714		1,562
Depreciation and amortization		326	269	982		749
Taxes other than income taxes		95	93	307		288
Total		1,986	1,801	6,889		6,148
Operating Income (Loss)		226	297	664		828
Other Income (Expense):
Gain on marketable securities		43	37	66		104
Loss on indexed debt securities		(44)	(36)	(316)		(59)
Interest and other finance charges		(90)	(80)	(259)		(235)
Interest on Securitization Bonds		(16)	(18)	(46)		(58)
Equity in earnings of unconsolidated affiliate, net		81	68	208		199
Other, net		9	(1)	16		(2)
Total		(17)	(30)	(331)		(51)
Income (Loss) Before Income Taxes		209	267	333		777
Income tax expense (benefit)		51	98	85		281
Net Income		158	169	248		496
Series A Preferred Stock dividend requirement		5	0	5		0
Income Available to Common Shareholders		$ 153	$ 169	$ 243		$ 496
Basic Earnings Per Common Share		$ 0.35	$ 0.39	$ 0.56		$ 1.15
Diluted Earnings Per Common Share		0.35	0.39	0.56		1.14
Dividends Declared Per Share		$ 0.2775	$ 0.2675	$ 0.5550	[2]	$ 0.8025
Weighted Average Common Shares Outstanding, Basic		431,554,000	431,026,000	431,437,000		430,939,000
Weighted Average Common Shares Outstanding, Diluted		434,891,000	434,086,000	434,774,000		433,999,000
Houston Electric [Member]
Revenues:
Total		$ 897	$ 843	$ 2,506		$ 2,233
Expenses:
Operation and maintenance		369	337	1,062		1,021
Depreciation and amortization		242	193	737		525
Taxes other than income taxes		59	59	180		177
Total		670	589	1,979		1,723
Operating Income (Loss)		227	254	527		510
Other Income (Expense):
Interest and other finance charges		(32)	(32)	(101)		(97)
Interest on Securitization Bonds		(16)	(18)	(46)		(58)
Other, net		0	(3)	(6)		(9)
Total		(48)	(53)	(153)		(164)
Income (Loss) Before Income Taxes		179	201	374		346
Income tax expense (benefit)		36	71	78		123
Net Income		143	130	296		223
CERC Corp [Member]
Revenues:
Utility revenues		402	390	2,032		1,767
Non-utility revenues		910	861	3,008		2,964
Total		1,312	1,251	5,040		4,731
Expenses:
Utility natural gas		134	106	959		706
Cost of Goods and Services Sold		864	832	2,927		2,843
Operation and maintenance		211	182	666		587
Depreciation and amortization		77	68	222		202
Taxes other than income taxes		33	32	120		104
Total		1,319	1,220	4,894		4,442
Operating Income (Loss)		(7)	31	146		289
Other Income (Expense):
Interest and other finance charges		(30)	(32)	(92)		(92)
Other, net		0	(4)	(5)		(13)
Total		(30)	(36)	(97)		(105)
Income (Loss) Before Income Taxes		(37)	(5)	49		184
Income tax expense (benefit)		(2)	(1)	14		69
Income (Loss) From Continuing Operations		(35)	(4)	35		115
Income from discontinued operations (net of tax of $13, $26, $44 and $75, respectively)		44	42	140		124
Net Income		$ 9	$ 38	$ 175		$ 239
[1]	Income statement impact associated with cash flow hedge activity is related to gains and losses reclassified from accumulated other comprehensive income into income. Amounts are immaterial for the Registrants for both the three and nine months ended September 30, 2018 and 2017, respectively.
[2]	On December 13, 2017, CenterPoint Energy’s Board of Directors declared a regular quarterly cash dividend of $0.2775 per share of Common Stock, payable on March 8, 2018 to shareholders of record as of the close of business on February 15, 2018.

CONDENSED STATEMENTS OF CONSO_2

CONDENSED STATEMENTS OF CONSOLIDATED INCOME (Parentheticals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
CERC Corp [Member]
Income tax expense associated with discontinued operations	$ 13	$ 26	$ 44	$ 75

CONDENSED STATEMENTS OF CONSO_3

CONDENSED STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income	$ 158	$ 169	$ 248	$ 496
Other comprehensive income (loss):
Adjustment to pension and other postretirement plans (net of tax of $1, $2, $2 and $4)	1	0	4	2
Net deferred gain (loss) from cash flow hedges (net of tax)	3	(2)	6	(3)
Total	4	(2)	10	(1)
Comprehensive income	162	167	258	495
Houston Electric [Member]
Net income	143	130	296	223
Other comprehensive income (loss):
Net deferred gain (loss) from cash flow hedges (net of tax)	3	0	7	(1)
Total	3	0	7	(1)
Comprehensive income	146	130	303	222
CERC Corp [Member]
Net income	9	38	175	239
Other comprehensive income (loss):
Net deferred gain (loss) from cash flow hedges (net of tax)	0	(1)	0	(1)
Comprehensive income	$ 9	$ 38	$ 175	$ 239

CONDENSED STATEMENTS OF CONSO_4

CONDENSED STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Parentheticals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Tax benefit (expense) on adjustment related to pension and postretirement plans	$ (1)	$ (2)	$ (2)	$ (4)
Tax expense (benefit) on net deferred gain (loss) from cash flow hedges	1	(2)	2	(2)
Houston Electric [Member]
Tax expense (benefit) on net deferred gain (loss) from cash flow hedges	$ 1	$ 0	$ 2	$ 0

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 293	$ 260
Investment in marketable securities	627	960
Accounts receivable, less bad debt reserve	918	1,000
Accrued unbilled revenues	212	427
Natural gas inventory	207	222
Materials and supplies	198	175
Non-trading derivative assets	76	110
Taxes receivable	38	0
Prepaid expenses and other current assets	157	241
Total current assets	2,726	3,395
Property, Plant and Equipment:
Property, plant and equipment	19,861	19,031
Less: accumulated depreciation and amortization	6,208	5,974
Property, plant and equipment, net	13,653	13,057
Other Assets:
Goodwill	867	867
Regulatory assets	1,934	2,347
Non-trading derivative assets	38	44
Investment in unconsolidated affiliate	2,457	2,472
Preferred units – unconsolidated affiliate	363	363
Other	190	191
Total other assets	5,849	6,284
Total Assets	22,228	22,736
Current Liabilities:
Short-term borrowings	0	39
Current portion of VIE Securitization Bonds long-term debt	456	434
Indexed debt, net	25	122
Current portion of other long-term debt	50	50
Indexed debt securities derivative	685	668
Accounts payable	708	963
Taxes accrued	152	181
Interest accrued	80	104
Dividends accrued	0	120
Non-trading derivative liabilities	33	20
Other	392	368
Total current liabilities	2,581	3,069
Other Liabilities:
Deferred income taxes, net	3,220	3,174
Non-trading derivative liabilities	6	4
Benefit obligations	722	785
Regulatory liabilities	2,506	2,464
Other	433	357
Total other liabilities	6,887	6,784
Long-term Debt:
VIE Securitization Bonds, net	1,045	1,434
Other long-term debt, net	6,207	6,761
Total long-term debt, net	7,252	8,195
Commitments and Contingencies (Note 14)
Shareholders’ Equity:
Cumulative preferred stock, $0.01 par value, 20,000,000 shares authorized
Common stock	4	4
Additional paid-in capital	4,221	4,209
Retained earnings	551	543
Accumulated other comprehensive income (loss)	(58)	(68)
Total shareholders’ equity	5,508	4,688
Total Liabilities and Shareholders’ Equity	22,228	22,736
Houston Electric [Member]
Current Assets:
Cash and cash equivalents	279	238
Accounts and notes receivable, less bad debt reserve	389	284
Accounts and notes receivable–affiliated companies	13	7
Accrued unbilled revenues	122	120
Materials and supplies	129	119
Non-trading derivative assets	3	0
Taxes receivable	9	0
Prepaid expenses and other current assets	50	62
Total current assets	994	830
Property, Plant and Equipment:
Property, plant and equipment	11,962	11,496
Less: accumulated depreciation and amortization	3,742	3,633
Property, plant and equipment, net	8,220	7,863
Other Assets:
Regulatory assets	1,202	1,570
Other	20	29
Total other assets	1,222	1,599
Total Assets	10,436	10,292
Current Liabilities:
Current portion of VIE Securitization Bonds long-term debt	456	434
Accounts payable	220	243
Accounts and notes payable–affiliated companies	113	104
Taxes accrued	88	116
Interest accrued	43	65
Other	111	120
Total current liabilities	1,031	1,082
Other Liabilities:
Deferred income taxes, net	1,044	1,059
Benefit obligations	142	146
Regulatory liabilities	1,265	1,263
Other	79	54
Total other liabilities	2,530	2,522
Long-term Debt:
VIE Securitization Bonds, net	1,045	1,434
Other long-term debt, net	3,281	2,885
Total long-term debt, net	4,326	4,319
Commitments and Contingencies (Note 14)
Shareholders’ Equity:
Common stock	0	0
Additional paid-in capital	1,696	1,696
Retained earnings	846	673
Accumulated other comprehensive income (loss)	7	0
Total shareholders’ equity	2,549	2,369
Total Liabilities and Shareholders’ Equity	10,436	10,292
CERC Corp [Member]
Current Assets:
Cash and cash equivalents	1	12
Accounts receivable, less bad debt reserve	527	713
Accounts and notes receivable–affiliated companies	9	6
Accrued unbilled revenues	90	307
Natural gas inventory	206	222
Materials and supplies	69	56
Non-trading derivative assets	73	110
Prepaid expenses and other current assets	85	166
Total current assets	1,060	1,592
Property, Plant and Equipment:
Property, plant and equipment	7,260	6,888
Less: accumulated depreciation and amortization	2,185	2,036
Property, plant and equipment, net	5,075	4,852
Other Assets:
Goodwill	867	867
Regulatory assets	170	181
Non-trading derivative assets	38	44
Investment in unconsolidated affiliate - discontinued operations	0	2,472
Other	95	104
Total other assets	1,170	3,668
Total Assets	7,305	10,112
Current Liabilities:
Short-term borrowings	0	39
Accounts payable	429	669
Accounts and notes payable–affiliated companies	44	611
Taxes accrued	64	75
Interest accrued	31	32
Customer deposits	74	76
Non-trading derivative liabilities	33	20
Other	171	137
Total current liabilities	846	1,659
Other Liabilities:
Deferred income taxes, net	370	362
Deferred income taxes, net - discontinued operations	0	927
Non-trading derivative liabilities	6	4
Benefit obligations	98	97
Regulatory liabilities	1,241	1,201
Other	350	297
Total other liabilities	2,065	2,888
Long-term Debt:
Total long-term debt, net	2,257	2,457
Commitments and Contingencies (Note 14)
Shareholders’ Equity:
Common stock	0	0
Additional paid-in capital	1,668	2,528
Retained earnings	463	574
Accumulated other comprehensive income (loss)	6	6
Total shareholders’ equity	2,137	3,108
Total Liabilities and Shareholders’ Equity	7,305	10,112
Series A Preferred Stock [Member]
Shareholders’ Equity:
Series A Preferred Stock, $0.01 par value, $800,000 aggregate liquidation preference, 800,000 shares outstanding	$ 790	$ 0

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Cash and cash equivalents	$ 293,000,000	$ 260,000,000
Accounts receivable, less bad debt reserve	918,000,000	1,000,000,000
Bad debt reserve	15,000,000	19,000,000
Prepaid expenses and other current assets	157,000,000	241,000,000
Regulatory assets	$ 1,934,000,000	$ 2,347,000,000
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	1,000,000,000	1,000,000,000
Common stock outstanding (in shares)	431,555,853	431,044,845
Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents	$ 278,000,000	$ 230,000,000
Accounts receivable, less bad debt reserve	92,000,000	73,000,000
Prepaid expenses and other current assets	37,000,000	35,000,000
Regulatory assets	1,146,000,000	1,590,000,000
Houston Electric [Member]
Cash and cash equivalents	279,000,000	238,000,000
Bad debt reserve	1,000,000	1,000,000
Prepaid expenses and other current assets	50,000,000	62,000,000
Regulatory assets	1,202,000,000	1,570,000,000
Houston Electric [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents	278,000,000	230,000,000
Accounts receivable, less bad debt reserve	92,000,000	73,000,000
Prepaid expenses and other current assets	37,000,000	35,000,000
Regulatory assets	1,146,000,000	1,590,000,000
CERC Corp [Member]
Cash and cash equivalents	1,000,000	12,000,000
Accounts receivable, less bad debt reserve	527,000,000	713,000,000
Bad debt reserve	14,000,000	18,000,000
Prepaid expenses and other current assets	85,000,000	166,000,000
Regulatory assets	$ 170,000,000	$ 181,000,000
Cumulative Preferred Stock [Member]
Preferred stock par value (in dollars per share)	$ 0.01	$ 0.01
Cumulative preferred stock authorized (in shares)	20,000,000	20,000,000
Series A Preferred Stock [Member]
Preferred stock par value (in dollars per share)	$ 0.01	$ 0
Series A aggregate liquidation preference	$ 800,000	$ 0
Series A preferred stock outstanding (in shares)	800,000	0

CONDENSED STATEMENTS OF CONSO_5

CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows from Operating Activities:
Net income	$ 248	$ 496
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	982	749
Amortization of deferred financing costs	34	18
Deferred income taxes	33	185
Unrealized gain on marketable securities	(66)	(104)
Loss on indexed debt securities	316	59
Write-down of natural gas inventory	2	0
Equity in earnings of unconsolidated affiliate, net of distributions	(15)	(199)
Pension contributions	(67)	(46)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	355	216
Inventory	(10)	(52)
Taxes receivable	(38)	30
Accounts payable	(262)	(137)
Fuel cost recovery	53	(30)
Non-trading derivatives, net	63	(53)
Margin deposits, net	2	(49)
Interest and taxes accrued	(53)	2
Net regulatory assets and liabilities	44	(135)
Other current assets	11	18
Other current liabilities	16	19
Other assets	(3)	(3)
Other liabilities	24	28
Other, net	10	16
Net cash provided by operating activities	1,679	1,028
Cash Flows from Investing Activities:
Capital expenditures	(1,121)	(994)
Acquisitions, net of cash acquired	0	(132)
Distributions from unconsolidated affiliate in excess of cumulative earnings	30	223
Proceeds from sale of marketable securities	398	0
Other, net	19	6
Net cash used in investing activities	(674)	(897)
Cash Flows from Financing Activities:
Increase (decrease) in short-term borrowings, net	(39)	13
Payments of commercial paper, net	(1,551)	(428)
Proceeds from long-term debt, net	997	1,096
Payments of long-term debt	(368)	(597)
Debt issuance costs	(36)	(13)
Payment of dividends on Common Stock	(360)	(346)
Proceeds from issuance of Series A Preferred Stock, net	790	0
Distribution to ZENS note holders	(398)	0
Other, net	(5)	(4)
Net cash used in financing activities	(970)	(279)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	35	(148)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	296	381
Cash, Cash Equivalents and Restricted Cash at End of Period	331	233
Cash and Cash Equivalents at Beginning of Period	260
Cash and Cash Equivalents at End of Period	293
Houston Electric [Member]
Cash Flows from Operating Activities:
Net income	296	223
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	737	525
Amortization of deferred financing costs	8	10
Deferred income taxes	(24)	29
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	(95)	(131)
Accounts receivable/payable–affiliated companies	(12)	(49)
Inventory	(10)	(3)
Taxes receivable	(9)	6
Accounts payable	(6)	105
Interest and taxes accrued	(50)	(28)
Net regulatory assets and liabilities	(66)	(149)
Other current assets	13	8
Other current liabilities	(9)	25
Other assets	4	1
Other liabilities	16	(1)
Other, net	(5)	(4)
Net cash provided by operating activities	788	567
Cash Flows from Investing Activities:
Capital expenditures	(678)	(603)
Decrease in notes receivable–affiliated companies	0	29
Other, net	15	5
Net cash used in investing activities	(663)	(569)
Cash Flows from Financing Activities:
Proceeds from long-term debt, net	398	298
Payments of long-term debt	(368)	(347)
Decrease in notes payable–affiliated companies	15	0
Dividend to parent	(123)	(87)
Debt issuance costs	(4)	(3)
Contribution from parent	0	0
Other, net	0	0
Net cash used in financing activities	(82)	(139)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	43	(141)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	274	381
Cash, Cash Equivalents and Restricted Cash at End of Period	317	240
Cash and Cash Equivalents at Beginning of Period	238
Cash and Cash Equivalents at End of Period	279
CERC Corp [Member]
Cash Flows from Operating Activities:
Net income	175	239
Less: Income from discontinued operations, net of tax	140	124
Income from continuing operations	35	115
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	222	202
Amortization of deferred financing costs	7	7
Deferred income taxes	6	69
Write-down of natural gas inventory	2	0
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	449	346
Accounts receivable/payable–affiliated companies	0	(1)
Inventory	1	(49)
Accounts payable	(261)	(227)
Fuel cost recovery	53	(30)
Non-trading derivatives, net	60	(51)
Margin deposits, net	2	(49)
Interest and taxes accrued	(9)	(13)
Net regulatory assets and liabilities	73	(28)
Other current assets	7	16
Other current liabilities	24	(5)
Other assets	5	5
Other liabilities	(2)	4
Other, net	0	1
Net cash provided by operating activities from continuing operations	674	312
Net cash provided by operating activities from discontinued operations	176	0
Net cash provided by operating activities	850	312
Cash Flows from Investing Activities:
Capital expenditures	(411)	(373)
Acquisitions, net of cash acquired	0	(132)
Other, net	5	2
Net cash used in investing activities from continuing operations	(406)	(503)
Net cash provided by investing activities from discontinued operations	47	223
Net cash used in investing activities	(359)	(280)
Cash Flows from Financing Activities:
Increase (decrease) in short-term borrowings, net	(39)	13
Payments of commercial paper, net	(800)	(40)
Proceeds from long-term debt, net	599	298
Decrease in notes payable–affiliated companies	(570)	0
Dividend to parent	(286)	(337)
Debt issuance costs	(5)	(4)
Contribution from parent	600	38
Other, net	(1)	0
Net cash used in financing activities from continuing operations	(502)	(32)
Net cash provided by financing activities from discontinued operations	0	0
Net cash used in financing activities	(502)	(32)
Net Decrease in Cash and Cash Equivalents	(11)	0
Cash and Cash Equivalents at Beginning of Period	12	1
Cash and Cash Equivalents at End of Period	$ 1	$ 1

Background and Basis of Present

Background and Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation [Text Block]	Background and Basis of Presentation No Registrant makes any representations as to the information related solely to CenterPoint Energy or the subsidiaries of CenterPoint Energy other than itself. General. Included in this combined Form 10-Q are the Interim Condensed Financial Statements of CenterPoint Energy, Houston Electric and CERC, which are referred to collectively as the Registrants. The Combined Notes to the Unaudited Condensed Consolidated Financial Statements apply to all Registrants unless otherwise indicated. The Interim Condensed Financial Statements are unaudited, omit certain financial statement disclosures and should be read with each of the Registrants’ 2017 Form 10-K. Background. CenterPoint Energy, Inc. is a public utility holding company and owns interests in Enable as described below. CenterPoint Energy’s operating subsidiaries, Houston Electric and CERC, own and operate electric transmission and distribution and natural gas distribution facilities and supply natural gas to commercial and industrial customers and electric and natural gas utilities. • Houston Electric engages in the electric transmission and distribution business in the Texas Gulf Coast area that includes the city of Houston; and • CERC Corp. (i) owns and operates natural gas distribution systems in six states and (ii) obtains and offers competitive variable and fixed-price physical natural gas supplies and services primarily to commercial and industrial customers and electric and natural gas utilities in 33 states through its wholly-owned subsidiary, CES. As of September 30, 2018 , CenterPoint Energy, indirectly through CNP Midstream, owned approximately 54.0% of the common units representing limited partner interests in Enable, 50% of the management rights and 40% of the incentive distribution rights in Enable GP and also directly owned an aggregate of 14,520,000 Enable Series A Preferred Units. Enable owns, operates and develops natural gas and crude oil infrastructure assets. On September 4, 2018, CERC entered into a Contribution Agreement, by and between CERC and CNP Midstream, a new subsidiary formed by CERC in June 2018, pursuant to which CERC contributed its equity investment in Enable consisting of Enable common units and its interests in Enable GP, to CNP Midstream (collectively, the Enable Contribution). Immediately following the Enable Contribution, CERC distributed all of its interest in CNP Midstream to Utility Holding, CERC’s sole stockholder and a wholly-owned subsidiary of CenterPoint Energy. Utility Holding then distributed all of its interest in CNP Midstream to CenterPoint Energy, its sole member (collectively with the Enable Contribution, the Internal Spin). CERC executed the Internal Spin to, among other things, enhance the access of CERC and CenterPoint Energy to low cost debt and equity through increased transparency and understandability of the financial statements, improve CERC’s credit quality by eliminating the exposure to Enable’s midstream business and provide clarity of internal reporting and performance metrics to enhance management’s decision making for CERC and CNP Midstream. As a result of the Internal Spin, CERC’s equity in earnings in Enable and related income taxes have been classified as discontinued operations in CERC’s Interim Condensed Financial Statements. For further information regarding the Internal Spin and CERC’s presentation of discontinued operations, see Note 9. As of September 30, 2018 , CenterPoint Energy and Houston Electric had VIEs consisting of the Bond Companies, which are consolidated. The consolidated VIEs are wholly-owned, bankruptcy-remote, special purpose entities that were formed specifically for the purpose of securitizing transition and system restoration-related property. Creditors of CenterPoint Energy and Houston Electric have no recourse to any assets or revenues of the Bond Companies. The bonds issued by these VIEs are only payable from and secured by transition and system restoration property, and the bondholders have no recourse to the general credit of CenterPoint Energy or Houston Electric. 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. The 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 the 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. Certain prior year amounts have been reclassified to conform to the current year presentation. See Notes 2 and 9 for further discussion. For a description of the Registrants’ reportable business segments, see Note 16 .

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements [Text Block]	New Accounting Pronouncements The following table provides an overview of recently adopted or issued accounting pronouncements applicable to all the Registrants, unless otherwise noted. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2014-09- Revenue from Contracts with Customers (Topic 606) and related amendments This standard provides a comprehensive new revenue recognition model that requires revenue to be recognized in a manner that depicts the transfer of goods or services to a customer at an amount that reflects the consideration expected to be received in exchange for those goods or services. Transition method: modified retrospective January 1, 2018 Note 4 addresses the disclosure requirements. Adoption of the standard did not result in significant changes to revenue recognition. A substantial amount of the Registrants’ revenues are tariff and/or derivative based, which were not significantly impacted by these ASUs. ASU 2017-05- Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets This standard clarifies when and how to apply ASC 610-20, which was issued as part of ASU 2014-09. It amends or supersedes the guidance in ASC 350 and ASC 360 on determining a gain or loss recognized upon the derecognition of nonfinancial assets. Transition method: modified retrospective January 1, 2018 ASU 2017-05 eliminates industry specific guidance, including ASC 360-20 Property, Plant, and Equipment - Real Estate Sales, for the recognition of gains or losses upon the sale of in-substance real estate. CenterPoint Energy and CERC elected to apply the practical expedient upon adoption to only evaluate transactions that were not determined to be complete as of the date of adoption. Subsequent to adoption, gains or losses on sales or dilution events in CenterPoint Energy’s investment in Enable may result in gains or losses recognized in earnings. See Note 9 for further discussion. ASU 2016-01-Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ASU 2018-03-Technical Corrections and Improvements to Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This standard requires equity investments that do not result in consolidation and are not accounted for under the equity method to be measured at fair value and to recognize any changes in fair value in net income unless the investments qualify for the new practicability exception. It does not change the guidance for classifying and measuring investments in debt securities and loans. It also changes certain disclosure requirements and other aspects related to recognition and measurement of financial assets and financial liabilities. Transition method: cumulative-effect adjustment to beginning retained earnings, and two features prospective January 1, 2018 The adoption of this standard did not have an impact on the Registrants’ financial position, results of operations or cash flows. The Registrants elected the practicability exception for investments without a readily determinable fair value to be measured at cost. This includes the Enable Series A Preferred Units owned by CenterPoint Energy, which were previously accounted for under the cost method. See Note 9 for further discussion. ASU 2016-15- Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments This standard provides clarifying guidance on the classification of certain cash receipts and payments in the statement of cash flows and eliminates the variation in practice related to such classifications. Transition method: retrospective January 1, 2018 The adoption did not have a material impact on the Registrants’ financial position, results of operations or disclosures. However, CenterPoint Energy’s and Houston Electric’s Condensed Statements of Consolidated Cash Flows reflect an increase in investing activities and a corresponding decrease in operating activities of $1 million and $3 million for the nine months ended September 30, 2018 and 2017, respectively, due to the requirement that cash proceeds from COLI policies be classified as cash inflows from investing activity. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2016-18- Statement of Cash Flows (Topic 230): Restricted Cash This standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. Transition method: retrospective January 1, 2018 The adoption of this standard did not have an impact on the Registrants’ financial position, results of operations or disclosures. However, CenterPoint Energy’s and Houston Electric’s Condensed Statements of Consolidated Cash Flows are reconciled to cash, cash equivalents and restricted cash, resulting in a decrease in investing activities of $2 million and an increase in investing activities of $8 million for the nine months ended September 30, 2018 and 2017, respectively. See Note 17 for further discussion. ASU 2017-01- Business Combinations (Topic 805): Clarifying the Definition of a Business This standard revises the definition of a business. If substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, then under ASU 2017-01, the asset or group of assets is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs to be more closely aligned with how outputs are described in ASC 606. Transition method: prospective January 1, 2018 The adoption of this revised definition will reduce the number of transactions that are accounted for as a business combination, and therefore may have a potential impact on the Registrants’ accounting for future acquisitions. ASU 2017-04- Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This standard eliminates Step 2 of the goodwill impairment test, which required a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s and CERC’s future calculation of goodwill impairments if an impairment is identified. ASU 2017-07- Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This standard requires an employer to report the service cost component of the net periodic pension cost and postretirement benefit cost in the same line item(s) as other employee compensation costs arising from services rendered during the period; all other components will be presented separately from the line item(s) that includes the service cost and outside of any subtotal of operating income. In addition, only the service cost component will be eligible for capitalization in assets. Transition method: retrospective for the presentation of the service cost component and other components; prospective for the capitalization of the service cost component January 1, 2018 The adoption of this standard did not have a material impact on the Registrants’ financial position, results of operations, cash flows or disclosures; however, it resulted in the increases to operating income and corresponding decreases to other income reported in the table below. Other components previously capitalized in assets will be recorded as regulatory assets in the Registrants’ rate-regulated businesses, prospectively. ASU 2017-09- Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting This standard clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. Entities will apply the modification accounting guidance if the value, vesting conditions or classification of the award changes. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s accounting for future changes to share-based payment awards. ASU 2017-12- Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities This standard expands an entity’s ability to hedge and account for risk components, reduces the complexity of applying certain aspects of hedge accounting and updates the presentation and disclosure requirements. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness. Transition method : cumulative-effect adjustment for elimination of the separate measurement of ineffectiveness; prospective for presentation and disclosure July 1, 2018 Applicable January 1, 2018 The adoption of this standard did not have a material impact on the Registrants’ financial position, results of operations or cash flows. As a result of the adoption, the Registrants will no longer recognize ineffectiveness for derivatives designated as cash flow hedges; all changes in fair value will flow through other comprehensive income. As the Registrants did not have existing cash flow hedges as of the initial application date and the adoption date, no cumulative effective adjustment was recorded. Note 7 reflects disclosures modified upon adoption. ASU 2018-13- Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement This standard eliminates, modifies and adds certain disclosure requirements for fair value measurements. Transition method : prospective for additions and one modification and retrospective for all other amendments Adoption of eliminations and modifications as of September 30, 2018; Additions will be adopted January 1, 2020 The adoption of this standard did not impact the Registrants’ financial position, results of operations or cash flows. Note 8 reflects the disclosures modified upon adoption. The table below reflects the impact of adoption of ASU 2017-07: Three Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 9 $ 3 $ — $ 18 $ 7 $ 5 Decrease to other income 9 3 — 18 7 5 Nine Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 38 $ 18 $ 8 $ 52 $ 22 $ 16 Decrease to other income 38 18 8 52 22 16 Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2016-02- Leases (Topic 842) and related amendments ASU 2018-01- Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842 ASU 2018-10 - Codification Improvements to Topic 842, Leases ASU 2018-11- Leases (Topic 842)-Targeted Improvements ASU 2016-02 provides a comprehensive new lease model that requires lessees to recognize assets and liabilities for most leases and would change certain aspects of lessor accounting. Transition method : modified retrospective ASU 2018-01 allows entities to elect not to assess whether existing land easements that were not previously accounted for in accordance with ASC 840 Leases under ASC 842 Leases when transitioning to the new leasing standard. ASU 2018-10 makes sixteen narrow-scope amendments to ASC 842 Leases. ASU 2018-11 allows entities the transition option to not apply the new lease standards in the comparative financial statements presented in the year of adoption. It also gives lessors the practical expedient to not separate non-lease and lease components when certain criteria are met. January 1, 2019 Early adoption is permitted The Registrants will elect the practical expedient on existing easements provided by ASU 2018-01, and the transition option to not apply the new lease standards in the comparative financial statements presented in the year of adoption provided by ASU 2018-11. The Registrants are evaluating other available transitional practical expedients. The Registrants are in the process of reviewing contracts to identify leases as defined in ASU 2016-02 and expect to recognize on the statements of financial position right-of-use assets and lease liabilities for the majority of their respective leases that are currently classified as operating leases. The Registrants are continuing to assess the impact that adoption of these standards will have on their financial position, results of operations, cash flows and disclosures. ASU 2016-13- Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This standard requires a new model called CECL to estimate credit losses for (1) financial assets subject to credit losses and measured at amortized cost and (2) certain off-balance sheet credit exposures. 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. Transition method : modified retrospective January 1, 2020 The Registrants are currently assessing the impact that this standard will have on their financial position, results of operations, cash flows and disclosures. ASU 2018-02-Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA and requires entities to provide certain disclosures regarding stranded tax effects. Transition method: either in the period of adoption or retrospective January 1, 2019 Early adoption is permitted The adoption of this standard will allow the Registrants to reclass stranded deferred tax adjustments primarily related to benefit plans from other comprehensive income to retained earnings. The Registrants are currently assessing the impact that adoption of this standard will have on their financial position and disclosures. Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2018-14-Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans This standard eliminates, modifies and adds certain disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. Transition method : retrospective January 1, 2021 The adoption of this standard will impact the Registrants’ annual disclosures and is not expected to have an impact on their financial position, results of operations, and cash flows. The Registrants are currently assessing the standard’s impact on the Stock-Based Incentive Compensation Plans and Employee Benefit Plans footnote. ASU 2018-15- Intangibles-Goodwill and Other- Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract This standard aligns accounting for implementation costs incurred in a cloud computing arrangement that is accounted for as a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The update also prescribes the balance sheet, income statement, and cash flow classification of the capitalized implementation costs and related amortization expense, and requires additional quantitative and qualitative disclosures. Transition method : retrospective or prospective January 1, 2020 Early adoption is permitted The adoption of this standard will allow the Registrants to capitalize certain implementation costs incurred in cloud computing arrangements that are accounted for as service contracts. The Registrants are currently assessing the impact that adoption of this standard will have on their financial position, results of operations, cash flows and disclosures. Management believes that other recently adopted standards and recently issued standards that are not yet effective will not have a material impact on the Registrants’ financial position, results of operations or cash flows upon adoption.

Pending Merger with Vectren (Ce

Pending Merger with Vectren (CenterPoint Energy)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Pending Merger with Vectren (CenterPoint Energy) [Text Block]	Pending Merger with Vectren (CenterPoint Energy) On April 21, 2018, CenterPoint Energy entered into the Merger Agreement. Under the terms of the Merger Agreement, CenterPoint Energy will acquire Vectren for approximately $6 billion in cash. Upon closing, Vectren will become a wholly-owned subsidiary of CenterPoint Energy. Pursuant to the Merger Agreement, upon the closing of the Merger, each share of Vectren common stock issued and outstanding immediately prior to the closing will be converted automatically into the right to receive $72.00 in cash per share. During August and October 2018, CenterPoint Energy completed its permanent financing for the Merger through offerings of the Series A Preferred Stock, depositary shares, each representing a 1/20th interest in a share of Series B Preferred Stock, Common Stock and unsecured senior notes. See Notes 12 and 19 for further details regarding the Merger financings. As of September 30, 2018, Vectren and its subsidiaries had outstanding $325 million of short-term debt and $2.0 billion of long-term debt, including current maturities. It is anticipated that Vectren and its subsidiaries will have approximately $2.5 billion of outstanding short-term and long-term debt as of December 31, 2018. Consummation of the Merger is conditioned upon approval by federal regulatory commissions, orders from state regulatory commissions, expiration or termination of the applicable HSR waiting period and approval of the Merger by Vectren shareholders. In June 2018, CenterPoint Energy and Vectren (i) submitted their filings with the FERC and the FCC, (ii) submitted their filings with the FTC pursuant to the HSR Act and (iii) initiated informational proceedings with regulators in Indiana and Ohio. On June 26, 2018, CenterPoint Energy and Vectren received notice from the FTC granting early termination of the waiting period under the HSR Act in connection with the Merger. On August 28, 2018, shareholders of Vectren, during a special shareholders’ meeting, approved the Merger. The FCC granted approvals on July 20 and 24, 2018, and on October 5, 2018, the FERC authorized the Merger. A hearing before the Indiana Utility Regulatory Commission was held on October 17, 2018 with respect to the Merger. CenterPoint Energy has requested a final order for this proceeding by the end of January or early February 2019. The Merger Agreement contains termination rights for both CenterPoint Energy and Vectren, and provides that, upon termination of the Merger Agreement under specified circumstances, CenterPoint Energy would be required to pay a termination fee of $210 million to Vectren or Vectren would be required to pay CenterPoint Energy a termination fee of $150 million . Subject to receipt of required regulatory and statutory approvals and satisfaction and/or waiver of the closing conditions, CenterPoint Energy continues to anticipate closing the Merger in the first quarter of 2019.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition [Text Block]	Revenue Recognition The Registrants adopted ASC 606 and all related amendments on January 1, 2018 using the modified retrospective method for those contracts that were not completed as of the date of adoption. Application of the new revenue standard did not result in a cumulative effect adjustment to the opening balance of retained earnings. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. The adoption of the new standard did not have a material impact on the Registrants’ financial position, results of operations or cash flows. In accordance with ASC 606, revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which the Registrants expect to be entitled to receive in exchange for these goods or services. Contract assets and liabilities are not material. The following tables disaggregate revenues by reportable business segment and major source: CenterPoint Energy Three Months Ended September 30, 2018 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 904 $ 398 $ 82 $ 1 $ 1,385 $ 852 $ 396 $ 97 $ 2 $ 1,347 Derivatives income — — 838 — 838 — — 774 — 774 Other (3) (7 ) 12 — 2 7 (9 ) 2 — 2 (5 ) Eliminations — (8 ) (10 ) — (18 ) — (8 ) (10 ) — (18 ) Total revenues $ 897 $ 402 $ 910 $ 3 $ 2,212 $ 843 $ 390 $ 861 $ 4 $ 2,098 Nine Months Ended September 30, 2018 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 2,525 $ 2,093 $ 338 $ 4 $ 4,960 $ 2,254 $ 1,784 $ 355 $ 4 $ 4,397 Derivatives income (4 ) — 2,727 — 2,723 1 — 2,643 — 2,644 Other (3) (19 ) (35 ) — 7 (47 ) (21 ) 7 — 7 (7 ) Eliminations — (26 ) (57 ) — (83 ) — (24 ) (34 ) — (58 ) Total revenues $ 2,502 $ 2,032 $ 3,008 $ 11 $ 7,553 $ 2,234 $ 1,767 $ 2,964 $ 11 $ 6,976 Houston Electric Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Revenue from contracts $ 904 $ 852 $ 2,525 $ 2,254 Other (3) (7 ) (9 ) (19 ) (21 ) $ 897 $ 843 $ 2,506 $ 2,233 CERC Three Months Ended September 30, 2018 2017 Natural Gas Distribution (1) Energy Services (2) Total Natural Gas Distribution (1) Energy Services (2) Total (in millions) Revenue from contracts $ 398 $ 82 $ 480 $ 396 $ 97 $ 493 Derivatives income — 838 838 — 774 774 Other (3) 12 — 12 2 — 2 Eliminations (8 ) (10 ) (18 ) (8 ) (10 ) (18 ) Total revenues $ 402 $ 910 $ 1,312 $ 390 $ 861 $ 1,251 Nine Months Ended September 30, 2018 2017 Natural Gas Distribution (1) Energy Services (2) Total Natural Gas Distribution (1) Energy Services (2) Total (in millions) Revenue from contracts $ 2,093 $ 338 $ 2,431 $ 1,784 $ 355 $ 2,139 Derivatives income — 2,727 2,727 — 2,643 2,643 Other (3) (35 ) — (35 ) 7 — 7 Eliminations (26 ) (57 ) (83 ) (24 ) (34 ) (58 ) Total revenues $ 2,032 $ 3,008 $ 5,040 $ 1,767 $ 2,964 $ 4,731 (1) Reflected in Utility revenues in the Condensed Statements of Consolidated Income. (2) Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income. (3) Primarily consists of income from ARPs and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. The Registrants recognize ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period. Revenues from Contracts with Customers Electric Transmission & Distribution. Houston Electric distributes electricity to customers over time and customers consume the electricity when delivered. Revenue, consisting of both volumetric and fixed tariff rates set by the PUCT, is recognized as electricity is delivered and represents amounts both billed and unbilled. Discretionary services requested by customers are provided at a point in time with control transferring upon the completion of the service. Revenue for discretionary services is recognized upon completion of service based on the tariff rates set by the PUCT. Payments for electricity distribution and discretionary services are aggregated and received on a monthly basis. Houston Electric performs transmission services over time as a stand-ready obligation to provide a reliable network of transmission systems. Revenue is recognized upon time elapsed, and the monthly tariff rate set by the PUCT. Payments are received on a monthly basis. Natural Gas Distribution. CERC distributes and transports natural gas to customers over time, and customers consume the natural gas when delivered. Revenue, consisting of both volumetric and fixed tariff rates set by the state governing agency for that service area, is recognized as natural gas is delivered and represents amounts both billed and unbilled. Discretionary services requested by the customer are satisfied at a point in time and revenue is recognized upon completion of service and the tariff rates set by the applicable state regulator. Payments of natural gas distribution, transportation and discretionary services are aggregated and received on a monthly basis. Energy Services. The majority of CES natural gas sales contracts are considered a derivative, as the contracts typically have a stated minimum or contractual volume of delivery. For contracts in which CES delivers the full requirement of the natural gas needed by the customer and a volume is not stated, a contract as defined under ASC 606 is created upon the customer’s exercise of its option to take natural gas. CES supplies natural gas to retail customers over time as customers consume the natural gas when delivered. For wholesale customers, CES supplies natural gas at a point in time because the wholesale customer is presumed to have storage capabilities. Control is transferred to both types of customers upon delivery of natural gas. Revenue is recognized on a monthly basis based on the estimated volume of natural gas delivered and the price agreed upon with the customer. Payments are received on a monthly basis. AMAs are natural gas sales contracts under which CES also assumes management of a customer’s physical storage and/or transportation capacity. AMAs have two distinct performance obligations, which consist of natural gas sales and natural gas delivery because delivery could occur separate from the sale of natural gas (e.g., from storage to customer premises). Most AMAs’ natural gas sales performance obligations are accounted for as embedded derivatives. The transaction price is allocated between the sale of natural gas and the delivery based on the stand-alone selling price as stated in the contract. CES performs natural gas delivery over time as customers take delivery of the natural gas and recognizes revenue on an aggregated monthly basis based on the volume of natural gas delivered and the fees stated within the contract. Payments are received on a monthly basis. Practical Expedients and Exemption. Sales taxes and other similar taxes collected from customers are excluded from the transaction price.

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans [Text Block]	Employee Benefit Plans The Registrants’ net periodic cost, before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes, includes the following components relating to pension and postretirement benefits: Pension Benefits (CenterPoint Energy) Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Service cost (1) $ 10 $ 9 $ 28 $ 27 Interest cost (2) 20 22 59 66 Expected return on plan assets (2) (27 ) (24 ) (80 ) (72 ) Amortization of prior service cost (2) 3 2 7 7 Amortization of net loss (2) 10 14 32 43 Net periodic cost $ 16 $ 23 $ 46 $ 71 Postretirement Benefits Three Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ — $ — $ 1 $ — $ — $ 1 Interest cost (2) 3 2 1 4 3 1 Expected return on plan assets (2) (1 ) (1 ) — (1 ) (1 ) (1 ) Amortization of prior service credit (2) (1 ) (1 ) — (1 ) (2 ) — Net periodic cost $ 1 $ — $ 2 $ 2 $ — $ 1 Nine Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ 1 $ — $ 1 $ 1 $ — $ 1 Interest cost (2) 10 6 3 12 7 3 Expected return on plan assets (2) (4 ) (3 ) (1 ) (4 ) (3 ) (1 ) Amortization of prior service cost (credit) (2) (3 ) (4 ) 1 (3 ) (4 ) 1 Net periodic cost (credit) $ 4 $ (1 ) $ 4 $ 6 $ — $ 4 (1) Amounts presented in the table above are included in Operation and maintenance expense in each of the Registrants’ respective Condensed Statements of Consolidated Income, net of amounts capitalized and regulatory deferrals. (2) Amounts presented in the table above are included in Other, net in each of the Registrants’ respective Condensed Statements of Consolidated Income, net of regulatory deferrals. Changes in accumulated other comprehensive loss related to defined benefit and postretirement plans are as follows: CenterPoint Energy Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Beginning Balance $ (63 ) $ (70 ) $ (66 ) $ (72 ) Amounts reclassified from accumulated other comprehensive loss: Prior service cost (1) — — 1 1 Actuarial losses (1) 2 2 5 5 Tax expense (1 ) (2 ) (2 ) (4 ) Net current period other comprehensive income 1 — 4 2 Ending Balance $ (62 ) $ (70 ) $ (62 ) $ (70 ) (1) These accumulated other comprehensive components are included in the computation of net periodic cost. The table below reflects the expected contributions to be made to the pension plans and postretirement benefit plan during 2018: CenterPoint Energy Houston Electric CERC (in millions) Expected minimum contribution to pension plans during 2018 $ 67 $ — $ — Expected contribution to postretirement benefit plan in 2018 16 10 5 The table below reflects the contributions made to the pension plans and postretirement benefit plan during 2018: Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Pension plans $ 3 $ — $ — $ 67 $ — $ — Postretirement benefit plan 4 3 1 11 7 3

Regulatory Accounting

Regulatory Accounting	9 Months Ended
	Sep. 30, 2018
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Regulatory Accounting [Text Block]	Regulatory Accounting The following is a list of regulatory assets and liabilities reflected on the Registrants’ Condensed Consolidated Balance Sheets: September 30, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC Regulatory Assets: (in millions) Current regulatory assets (1) $ 60 $ — $ 60 $ 130 $ — $ 130 Non-current regulatory assets: Securitized regulatory assets 1,146 1,146 — 1,590 1,590 — Unrecognized equity return (2) (225 ) (225 ) — (287 ) (287 ) — Unamortized loss on reacquired debt 70 70 — 75 75 — Pension and postretirement-related regulatory asset (3) 609 32 15 646 31 20 Hurricane Harvey restoration costs (4) 67 61 6 64 58 6 Regulatory assets related to TCJA (5) 48 34 14 48 33 15 Other long-term regulatory assets (6) 219 84 135 211 70 140 Total non-current regulatory assets 1,934 1,202 170 2,347 1,570 181 Total regulatory assets 1,994 1,202 230 2,477 1,570 311 Regulatory Liabilities: Current regulatory liabilities (7) 47 22 25 24 22 2 Non-current regulatory liabilities: Regulatory liabilities related to TCJA (5) 1,362 858 504 1,354 862 492 Estimated removal costs 887 275 612 878 285 593 Other long-term regulatory liabilities 257 132 125 232 116 116 Total non-current regulatory liabilities 2,506 1,265 1,241 2,464 1,263 1,201 Total regulatory liabilities 2,553 1,287 1,266 2,488 1,285 1,203 Total regulatory assets and liabilities, net $ (559 ) $ (85 ) $ (1,036 ) $ (11 ) $ 285 $ (892 ) (1) Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ Condensed Consolidated Balance Sheets. (2) The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended September 30, 2018 and 2017 , CenterPoint Energy and Houston Electric recognized approximately $17 million and $13 million , respectively, of the allowed equity return. During the nine months ended September 30, 2018 and 2017 , CenterPoint Energy and Houston Electric recognized approximately $62 million and $30 million , respectively, of the allowed equity return. The timing of CenterPoint Energy’s and Houston Electric’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months. (3) Includes a portion of NGD’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates that is being deferred for rate making purposes, of which $4 million and $7 million as of September 30, 2018 and December 31, 2017 , respectively, were not earning a return. (4) The Registrants are not earning a return on Hurricane Harvey restoration costs. (5) The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities. (6) Other long-term regulatory assets that are not earning a return were not material as of September 30, 2018 and December 31, 2017 . (7) Current regulatory liabilities are included in Other current liabilities in each of the Registrants’ respective Condensed Consolidated Balance Sheets.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments [Text Block]	Derivative Instruments The Registrants are exposed to various market risks. These risks arise from transactions entered into in the normal course of business. The Registrants utilize derivative instruments such as physical forward contracts, swaps and options to mitigate the impact of changes in commodity prices, weather and interest rates on its operating results and cash flows. Such derivatives are recognized in the Registrants’ Condensed Consolidated Balance Sheets at their fair value unless the Registrants elect the normal purchase and sales exemption for qualified physical transactions. A derivative may be designated as a normal purchase or normal sale if the intent is to physically receive or deliver the product for use or sale in the normal course of business. CenterPoint Energy has a Risk Oversight Committee composed of corporate and business segment officers that oversees commodity price, weather and credit risk activities, including the Registrants’ marketing, risk management services and hedging activities. The committee’s duties are to establish the Registrants’ commodity risk policies, allocate board-approved commercial risk limits, approve the use of new products and commodities, monitor positions and ensure compliance with the Registrants’ commercial risk management policy and procedures and limits established by CenterPoint Energy’s Board of Directors. The Registrants’ 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 Commodity Derivative Instruments. CenterPoint Energy and CERC, through CES, enter into certain derivative instruments to mitigate the effects of commodity price movements. Certain financial instruments used to hedge portions of the natural gas inventory of the Energy Services business segment are designated as fair value hedges for accounting purposes. All other financial instruments do not qualify or are not designated as cash flow or fair value hedges. Weather Hedges. CenterPoint Energy and CERC have weather normalization or other rate mechanisms that mitigate the impact of weather on NGD in Arkansas, Louisiana, Mississippi, Minnesota and Oklahoma. NGD and electric operations in Texas do not have such mechanisms, although fixed customer charges are historically higher in Texas for NGD compared to its other jurisdictions. As a result, fluctuations from normal weather may have a positive or negative effect on NGD’s results in Texas and on electric operations’ results in its service territory. CenterPoint Energy and CERC, as applicable, enter into winter season weather hedges from time to time for certain NGD jurisdictions and electric operations’ service territory to mitigate the effect of fluctuations from normal weather on results of operations and cash flows. These weather hedges are based on heating degree days at 10 -year normal weather. Houston Electric does not enter into weather hedges. The table below summarizes CenterPoint Energy’s and CERC’s current weather hedge gain (loss) activity: Three Months Ended September 30, Nine Months Ended September 30, Jurisdiction Winter Season Bilateral Cap 2018 2017 2018 2017 (in millions) Certain NGD jurisdictions 2018 – 2019 $ 9 $ — $ — $ — $ — Certain NGD jurisdictions 2017 – 2018 8 — — — — Total CERC (1) — — — — Electric operations’ service territory 2018 – 2019 8 — — — — Electric operations’ service territory 2017 – 2018 9 — — (4 ) — Electric operations’ service territory 2016 – 2017 9 — — — 1 Total CenterPoint Energy (1) $ — $ — $ (4 ) $ 1 (1) Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income. Cash Flow Hedging of Interest Expense. From time to time, the Registrants enter into forward interest rate agreements with certain counterparties designated as cash flow hedges. The objective of these cash flow hedges is to reduce exposure to variability in cash flows related to interest payments on anticipated future fixed rate debt offerings or other exposure to variable rate debt. In October 2018, Houston Electric entered into an additional $100 million of notional amount on forward interest rate agreements classified as cash flow hedges. As of September 30, 2018 and December 31, 2017 , the total outstanding notional amount of Houston Electric’s forward interest rate agreements related to cash flow hedges was $100 million and $-0- , respectively. The maximum length of time over which Houston Electric is exposed to the variability in future cash flows of the forecasted debt offerings is less than 12 months. Economic Hedging of Interest Rate Risk . From time to time, the Registrants may enter into forward interest rate agreements with certain counterparties designated as economic hedges. The objective of these economic hedges is to offset any interest rate risk borne by one or more of the Registrants in connection with an anticipated future fixed rate debt offering or other exposure to variable rate debt. As of September 30, 2018 and December 31, 2017 , the total outstanding notional amount of CenterPoint Energy’s forward interest rate agreements related to economic hedges in connection with the permanent financing for the Merger was $200 million and $-0- , respectively. As of September 30, 2018 and December 31, 2017 , the fair value of interest rate derivatives was less than $1 million and therefore was not included in the tabular presentation below. (b) Derivative Fair Values and Income Statement Impacts The following tables present information about derivative instruments and hedging activities. The first two tables provide a balance sheet overview of Derivative Assets and Liabilities, while the last table provides a breakdown of the related income statement impacts. Fair Value of Derivative Instruments and Hedged Items September 30, 2018 December 31, 2017 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivative Assets Fair Value Derivative Liabilities Fair Value Derivatives designated as cash flow hedges: (in millions) Interest rate derivatives Current Assets: Non-trading derivative assets $ 3 $ — $ — $ — Total Houston Electric 3 — — — Derivatives designated as fair value hedges: Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities — 2 13 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 76 3 114 4 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 38 — 44 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 31 72 38 78 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 16 33 9 24 Total CERC 161 110 218 107 Indexed debt securities derivative Current Liabilities — 685 — 668 Total CenterPoint Energy $ 164 $ 795 $ 218 $ 775 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,865 Bcf or a net 310 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of September 30, 2018 and December 31, 2017 , respectively. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure. (2) Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $72 million asset and a $130 million asset as of September 30, 2018 and December 31, 2017 , respectively, as shown on CenterPoint Energy’s and CERC’s Condensed Consolidated Balance Sheets (and as detailed in the Offsetting of Natural Gas Derivative Assets and Liabilities table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, impacted by collateral netting of $21 million and $19 million , respectively. (3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable. Cumulative Basis Adjustment for Fair Value Hedges (CenterPoint Energy and CERC) September 30, 2018 December 31, 2017 Balance Sheet Location Carrying Amount of Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item Carrying Amount of Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item Hedged items in fair value hedge relationship: (in millions) Natural gas inventory Current Assets: Natural gas inventory $ 39 $ 1 $ 80 $ 14 Total CenterPoint Energy and CERC $ 39 $ 1 $ 80 $ 14 Offsetting of Natural Gas Derivative Assets and Liabilities (CenterPoint Energy and CERC) September 30, 2018 December 31, 2017 Gross Amounts Recognized (1) Gross Amounts Offset in the Consolidated Balance Sheets Net Amount Presented in the Consolidated Balance Sheets (2) 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 $ 107 $ (34 ) $ 73 $ 165 $ (55 ) $ 110 Other Assets: Non-trading derivative assets 54 (16 ) 38 53 (9 ) 44 Current Liabilities: Non-trading derivative liabilities (77 ) 44 (33 ) (83 ) 63 (20 ) Other Liabilities: Non-trading derivative liabilities (33 ) 27 (6 ) (24 ) 20 (4 ) Total $ 51 $ 21 $ 72 $ 111 $ 19 $ 130 (1) Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements. (2) The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default. Income Statement Impact of Hedge Accounting Activity (CenterPoint Energy and CERC) Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Location and Amount of Gain (Loss) recognized in Income on Hedging Relationship (2) Non-utility natural gas expense Non-utility natural gas expense (in millions) Total amounts presented in the statements of income in which the effects of hedges are recorded $ 864 $ 832 $ 2,927 $ 2,843 Gain (loss) on fair value hedging relationships: Commodity contracts: Hedged items - Natural gas inventory 1 4 (13 ) (10 ) Derivatives designated as hedging instruments (1 ) (4 ) 13 10 Amounts excluded from effectiveness testing recognized in earnings immediately (1) 6 (9 ) (73 ) (93 ) (1) As a result of the adoption of ASU 2017-12 effective January 1, 2018 (see Note 2 for additional information), CenterPoint Energy and CERC exclude from their assessment of hedge effectiveness the natural gas market price difference between locations of the hedged inventory and the delivery location specified in the hedge instruments. Prior to the adoption of this accounting guidance, the timing difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity, was excluded from the assessment of effectiveness for CenterPoint Energy’s and CERC’s existing fair value hedges and will continue to be excluded from the assessment of hedge effectiveness. CenterPoint Energy and CERC elected to continue to immediately recognize amounts excluded from hedge effectiveness in their respective Condensed Statements of Consolidated Income. (2) Income statement impact associated with cash flow hedge activity is related to gains and losses reclassified from accumulated other comprehensive income into income. Amounts are immaterial for the Registrants for both the three and nine months ended September 30, 2018 and 2017, respectively. Three Months Ended September 30, Nine Months Ended September 30, Income Statement Location 2018 2017 2018 2017 Effects of derivatives not designated as hedging instruments on the income statement: (in millions) Commodity contracts Gains (Losses) in Non-utility revenues $ 2 $ 30 $ 70 $ 162 Total CERC 2 30 70 162 Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (44 ) (36 ) (316 ) (59 ) Interest rate derivatives Gains (Losses) in Interest and other finance charges — — — — Total CenterPoint Energy $ (42 ) $ (6 ) $ (246 ) $ 103 Effect of Cash Flow Hedge Accounting on Accumulated Other Comprehensive Income Amount of Gain (Loss) Recognized in Other Comprehensive Income, Net of Tax on Derivative Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Effects of cash flow hedging Interest rate derivatives (1) $ 3 $ — $ 7 $ (1 ) Total Houston Electric 3 — 7 (1 ) Interest rate derivatives (1) — (1 ) — (1 ) Total CERC — (1 ) — (1 ) Interest rate derivatives (1) — (1 ) (1 ) (1 ) Total CenterPoint Energy $ 3 $ (2 ) $ 6 $ (3 ) (1) Gains and losses are reclassified from accumulated other comprehensive income into income when the hedged transactions affect earnings. The reclassification amounts are included in Interest and other finance charges in the Condensed Statements of Consolidated Income. Amounts are less than $1 million for each of the three and nine months ended September 30, 2018 and 2017. Over the next twelve months, estimated amortization of accumulated other comprehensive income into related income is expected to be immaterial. (c) Credit Risk Contingent Features CenterPoint Energy and CERC enter into financial derivative contracts containing material adverse change provisions. These provisions could require CenterPoint Energy or CERC to post additional collateral if the S&P or Moody’s credit ratings of CenterPoint Energy, Inc. or its subsidiaries, including CERC Corp., are downgraded. CenterPoint Energy and CERC September 30, December 31, 2017 (in millions) Aggregate fair value of derivatives containing material adverse change provisions in a net liability position $ 2 $ 2 Fair value of collateral already posted — — Additional collateral required to be posted if credit risk contingent features triggered 1 2

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements [Text Block]	Fair Value Measurements Assets and liabilities that are recorded at fair value in the Registrants’ Condensed Consolidated Balance Sheets are categorized based upon the level of judgment associated with the inputs used to measure their value. Hierarchical levels, as defined below and directly related to the amount of subjectivity associated with the inputs to fair valuations of these assets and liabilities, are as follows: Level 1: Inputs are unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date. The types of assets carried at Level 1 fair value generally are exchange-traded derivatives and equity securities, as well as natural gas inventory that has been designated as the hedged item in a fair value hedge. Level 2: Inputs, other than quoted prices included in Level 1, are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar instruments in active markets, and inputs other than quoted prices that are observable for the asset or liability. Fair value assets and liabilities that are generally included in this category are derivatives with fair values based on inputs from actively quoted markets. A market approach is utilized to value the Registrants’ Level 2 natural gas derivative assets or liabilities. CenterPoint Energy’s Level 2 indexed debt securities derivative is valued using an option model and a discounted cash flow model, which uses projected dividends on the ZENS-Related Securities and a discount rate as observable inputs. 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 the Registrants’ judgments about the assumptions market participants would use in pricing the asset or liability since limited market data exists. The Registrants develop these inputs based on the best information available, including the Registrants’ own data. A market approach is utilized to value the Registrants’ Level 3 assets or liabilities. As of September 30, 2018 , CenterPoint Energy’s and CERC’s Level 3 assets and liabilities are comprised of physical natural gas forward contracts and options. Level 3 physical natural gas forward contracts and options include illiquid forward price curve locations (ranging from $1.28 to $6.88 per MMBtu) as an unobservable input. CenterPoint Energy’s and CERC’s Level 3 physical natural gas forward contracts and options derivative assets and liabilities consist of both long and short positions (forwards and options). Forward price decreases (increases) as of September 30, 2018 would have resulted in lower (higher) values, respectively, for long forwards and options and higher (lower) values, respectively, for short forwards and options. The Registrants determine the appropriate level for each financial asset and liability on a quarterly basis. The Registrants also recognize 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 the Registrants’ assets and liabilities (including derivatives that are presented net) measured at fair value on a recurring basis and indicate the fair value hierarchy of the valuation techniques utilized by the Registrants to determine such fair value. CenterPoint Energy September 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting (1) Total Level 1 Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 630 $ — $ — $ — $ 630 $ 963 $ — $ — $ — $ 963 Investments, including money market funds (2) 70 — — — 70 68 — — — 68 Interest rate derivatives 3 — — — 3 — — — — — Natural gas derivatives (3) — 134 27 (50 ) 111 — 161 57 (64 ) 154 Hedged portion of natural gas inventory 1 — — — 1 14 — — — 14 Total assets $ 704 $ 134 $ 27 $ (50 ) $ 815 $ 1,045 $ 161 $ 57 $ (64 ) $ 1,199 Liabilities Indexed debt securities derivative $ — $ 685 $ — $ — $ 685 $ — $ — $ 668 $ — $ 668 Natural gas derivatives (3) — 105 5 (71 ) 39 — 96 11 (83 ) 24 Total liabilities $ — $ 790 $ 5 $ (71 ) $ 724 $ — $ 96 $ 679 $ (83 ) $ 692 Houston Electric September 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting Total Level 1 Level 2 Level 3 Netting Total Assets (in millions) Investments, including money market funds (2) $ 52 $ — $ — $ — $ 52 $ 51 $ — $ — $ — $ 51 Interest rate derivatives 3 — — — 3 — — — — — Total assets $ 55 $ — $ — $ — $ 55 $ 51 $ — $ — $ — $ 51 CERC September 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting (1) Total Level 1 Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 3 $ — $ — $ — $ 3 $ 3 $ — $ — $ — $ 3 Investments, including money market funds (2) 10 — — — 10 11 — — — 11 Natural gas derivatives (3) — 134 27 (50 ) 111 — 161 57 (64 ) 154 Hedged portion of natural gas inventory 1 — — — 1 14 — — — 14 Total assets $ 14 $ 134 $ 27 $ (50 ) $ 125 $ 28 $ 161 $ 57 $ (64 ) $ 182 Liabilities Natural gas derivatives (3) $ — $ 105 $ 5 $ (71 ) $ 39 $ — $ 96 $ 11 $ (83 ) $ 24 Total liabilities $ — $ 105 $ 5 $ (71 ) $ 39 $ — $ 96 $ 11 $ (83 ) $ 24 (1) Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy and CERC to settle positive and negative positions and also include cash collateral of $21 million and $19 million as of September 30, 2018 and December 31, 2017 , respectively, posted with the same counterparties. (2) Amounts are included in Prepaid expenses and other current assets in the Condensed Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable. The following table presents additional information about assets or liabilities, including derivatives that are measured at fair value on a recurring basis for which CenterPoint Energy and CERC have utilized Level 3 inputs to determine fair value: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC (in millions) Beginning balance $ (628 ) $ 13 $ (712 ) $ 28 $ (622 ) $ 46 $ (704 ) $ 13 Total gains (losses) 1 1 (38 ) (2 ) 4 4 (38 ) 21 Total settlements (1 ) (1 ) (1 ) (1 ) (36 ) (36 ) (5 ) (5 ) Transfers into Level 3 — — 7 7 (2 ) (2 ) 9 9 Transfers out of Level 3 (1) 650 9 (6 ) (6 ) 678 10 (12 ) (12 ) Ending balance (2) $ 22 $ 22 $ (750 ) $ 26 $ 22 $ 22 $ (750 ) $ 26 The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date: $ 11 $ 11 $ (36 ) $ — $ 9 $ 9 $ (42 ) $ 17 (1) As of September 30, 2018 , CenterPoint Energy transferred its indexed debt securities derivative from Level 3 to Level 2 to reflect changes in the significance of the unobservable inputs used in the valuation. (2) CenterPoint Energy and CERC did not have significant Level 3 sales or purchases during either of the three or nine months ended September 30, 2018 or 2017 . Estimated Fair Value of Financial Instruments The fair values of cash and cash equivalents, investments in debt and equity securities classified as “trading” and short-term borrowings are estimated to be approximately equivalent to carrying amounts and have been excluded from the table below. The carrying amounts of non-trading derivative assets and liabilities and CenterPoint Energy’s ZENS indexed debt securities derivative are stated at fair value and are excluded from the table below. The fair value of each debt instrument is determined by multiplying the principal amount of each debt instrument by a combination of historical trading prices and comparable issue data. These liabilities, which are not measured at fair value in the Registrants’ Condensed Consolidated Balance Sheets, but for which the fair value is disclosed, would be classified as Level 2 in the fair value hierarchy. September 30, 2018 December 31, 2017 CenterPoint Energy (1) Houston Electric (1) CERC CenterPoint Energy (1) Houston Electric (1) CERC Long-term debt, including current maturities (in millions) Carrying amount $ 7,758 $ 4,782 $ 2,257 $ 8,679 $ 4,753 $ 2,457 Fair value 7,888 4,813 2,367 9,220 5,034 2,708 (1) Includes Securitization Bond debt.

Unconsolidated Affiliate (Cente

Unconsolidated Affiliate (CenterPoint Energy and CERC)	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Unconsolidated Affiliate (CenterPoint Energy and CERC) [Text Block]	Unconsolidated Affiliate (CenterPoint Energy and CERC) CenterPoint Energy has the ability to significantly influence the operating and financial policies of Enable, a publicly traded MLP, and, accordingly, account for the investment in Enable’s common units using the equity method of accounting. Upon the adoption of ASU 2014-09 and ASU 2017-05 on January 1, 2018, CenterPoint Energy evaluated transactions in the investment in Enable that occurred prior to January 1, 2018 (the effective date) and concluded a cumulative effect adjustment to the opening balance of retained earnings was not required. See Note 2 for further discussion. CenterPoint Energy’s maximum exposure to loss related to Enable, a VIE in which CenterPoint Energy is not the primary beneficiary, is limited to the equity investment, the Series A Preferred Unit investment and outstanding current accounts receivable from Enable. On September 4, 2018, CERC completed the Internal Spin of its equity investment in Enable and Enable GP. The Internal Spin has been accounted for under the guidance for transactions between entities under common control. As of September 4, 2018, CERC derecognized its investment in Enable at carrying value on the date of distribution of $2.4 billion , net of deferred income taxes of $974 million , and CNP Midstream recorded the net asset contribution from CERC at CERC’s carrying value. Neither CERC nor CNP Midstream recognized a gain or loss upon the distribution or contribution, respectively, of net assets involved in the Internal Spin. In connection with the Internal Spin, CenterPoint Energy, through Utility Holding, made a $600 million capital contribution to CERC, which was used by CERC to repay outstanding indebtedness that historically supported CERC’s legacy midstream assets. See Note 18 for further discussion. Limited Partner Interest and Units Held in Enable (CenterPoint Energy): September 30, 2018 Limited Partner Interest (1) Common Units Enable Series A Preferred Units (2) CenterPoint Energy (3) 54.0 % 233,856,623 14,520,000 OGE 25.6 % 110,982,805 — Public unitholders 20.4 % 88,376,728 — Total units outstanding 100.0 % 433,216,156 14,520,000 (1) Excludes the Enable Series A Preferred Units owned by CenterPoint Energy. (2) The carrying amount of the Enable Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both September 30, 2018 and December 31, 2017 . No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion. (3) Includes Enable Series A Preferred Units held directly by CenterPoint Energy and common units held indirectly through CNP Midstream. Generally, sales to any person or entity (including a series of sales to the same person or entity) of more than 5% of the aggregate of the common units CNP Midstream owns in Enable or sales to any person or entity (including a series of sales to the same person or entity) by OGE of more than 5% of the aggregate of the common units it owns in Enable are subject to mutual rights of first offer and first refusal set forth in Enable’s Agreement of Limited Partnership. Interests Held in Enable GP (CenterPoint Energy): September 30, 2018 Management Rights (1) Incentive Distribution Rights (2) CenterPoint Energy (3) 50 % 40 % OGE 50 % 60 % (1) Enable is controlled jointly by CenterPoint Energy and OGE. Sale of CenterPoint Energy’s or OGE’s ownership interests in Enable GP to a third party is subject to mutual rights of first offer and first refusal, and CenterPoint Energy is not permitted to dispose of less than all of its interest in Enable GP. (2) Enable is expected to pay a minimum quarterly distribution of $0.2875 per common unit on its outstanding common units to the extent it has sufficient cash from operations after establishment of cash reserves and payment of fees and expenses, including payments to Enable GP and its affiliates, within 60 days after the end of each quarter. If cash distributions to Enable’s unitholders exceed $0.330625 per common unit in any quarter, Enable GP will receive increasing percentages or incentive distributions rights, up to 50% , of the cash Enable distributes in excess of that amount. In certain circumstances Enable GP will have the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election. To date, no incentive distributions have been made. (3) Includes interests held through CNP Midstream. Distributions Received from Enable (CenterPoint Energy and CERC): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Investment in Enable common units (1) $ 74 $ 74 $ 223 $ 223 Total CERC (2) 74 74 223 223 Investment in Enable Series A Preferred Units (3) 9 9 27 27 Total CenterPoint Energy $ 83 $ 83 $ 250 $ 250 (1) Reflects cash distributions of $0.318 and $0.954 per common unit for the three and nine months ended September 30, 2018 and 2017, respectively. (2) On September 4, 2018, CERC completed the Internal Spin. After such date, CNP Midstream owned the Enable common units previously owned by CERC. (3) Reflects cash distributions of $0.625 and $1.875 per Enable Series A Preferred Unit for the three and nine months ended September 30, 2018 and 2017, respectively. Transactions with Enable (CenterPoint Energy and CERC): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Reimbursement of transition services (1) (CenterPoint Energy) $ 1 $ — $ 4 $ 3 Natural gas expenses, including transportation and storage costs (CenterPoint Energy and CERC) 23 23 89 80 (1) Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement. September 30, 2018 December 31, 2017 (in millions) Accounts receivable for amounts billed for transition services (CenterPoint Energy) $ 3 $ 1 Accounts payable for natural gas purchases from Enable (CenterPoint Energy and CERC) 8 13 Summarized unaudited consolidated income information for Enable is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Operating revenues $ 928 $ 705 $ 2,481 $ 1,997 Cost of sales, excluding depreciation and amortization 516 349 1,335 936 Depreciation and amortization 100 90 292 267 Operating income 171 137 436 399 Net income attributable to Enable common units 129 104 320 301 Reconciliation of Equity in Earnings, net: CenterPoint Energy’s interest $ 70 $ 56 $ 173 $ 163 Basis difference amortization (1) 11 12 35 36 CenterPoint Energy’s equity in earnings, net $ 81 $ 68 $ 208 $ 199 (1) Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s share of Enable’s earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s original investment in Enable and their underlying equity in Enable’s net assets. The basis difference is amortized over approximately 31 years, the average life of the assets to which the basis difference is attributed. Summarized unaudited consolidated balance sheet information for Enable is as follows: September 30, December 31, 2017 (in millions) Current assets $ 481 $ 416 Non-current assets 11,454 11,177 Current liabilities 1,403 1,279 Non-current liabilities 2,964 2,660 Non-controlling interest 11 12 Preferred equity 362 362 Enable partners’ equity 7,195 7,280 Reconciliation of Investment in Enable: CenterPoint Energy’s ownership interest in Enable partners’ equity $ 3,883 $ 3,935 CenterPoint Energy’s basis difference (1,426 ) (1,463 ) CenterPoint Energy’s equity method investment in Enable $ 2,457 $ 2,472 Discontinued Operations (CERC): The Internal Spin represents a significant strategic shift that has a material effect on CERC’s operations and financial results and, as a result, CERC’s distribution of its equity investment in Enable met the criteria for discontinued operations classification. CERC has no continuing involvement in the equity investment of Enable. Therefore, CERC’s equity in earnings and related income taxes have been classified as Income from discontinued operations, net of tax, in CERC’s Condensed Statements of Consolidated Income for the periods presented. CERC’s equity method investment and related deferred income tax liabilities have been classified as Investment in unconsolidated affiliate - discontinued operations and Deferred income taxes, net - discontinued operations, respectively, in CERC’s Condensed Consolidated Balance Sheets for the periods presented. The following table presents amounts included in Income from discontinued operations, net of tax in CERC’s Condensed Statements of Consolidated Income. Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Equity in earnings of unconsolidated affiliate, net $ 57 $ 68 $ 184 $ 199 Income tax expense 13 26 44 75 Income from discontinued operations, net of tax $ 44 $ 42 $ 140 $ 124

Goodwill and Other Intangibles

Goodwill and Other Intangibles (CenterPoint Energy and CERC)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles (CenterPoint Energy and CERC) [Text Block]	Goodwill and Other Intangibles (CenterPoint Energy and CERC) CenterPoint Energy’s and CERC’s goodwill by reportable business segment as of both September 30, 2018 and December 31, 2017 is as follows: (in millions) Natural Gas Distribution $ 746 Energy Services (1) 110 Other Operations 11 Total $ 867 (1) Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012. CenterPoint Energy and CERC perform goodwill impairment tests at least annually and evaluate goodwill when events or changes in circumstances indicate that its carrying value may not be recoverable. The impairment evaluation for goodwill is performed by comparing the fair value of each reporting unit with the carrying amount of the reporting unit, including goodwill. The estimated fair value of the reporting unit is primarily determined on the basis of discounted cash flows. If the carrying amount is in excess of the estimated fair value of the reporting unit, then the excess amount is the impairment charge that should be recorded, not to exceed the carrying amount of goodwill. See Note 2 for further discussion. CenterPoint Energy and CERC performed the annual goodwill impairment test in the third quarter of 2018 and determined that no goodwill impairment charge was required for any reporting unit, which approximate the reportable segments. The tables below present information on CenterPoint Energy’s and CERC’s other intangible assets recorded in Other non-current assets on the Condensed Consolidated Balance Sheets. September 30, 2018 December 31, 2017 Useful Lives Gross Carrying Amount Accumulated Amortization Net Balance Gross Carrying Amount Accumulated Amortization Net Balance (in years) (in millions) Customer relationships 15 $ 86 $ (26 ) $ 60 $ 86 $ (21 ) $ 65 Covenants not to compete 4 4 (2 ) 2 4 (2 ) 2 Other Various 15 (10 ) 5 15 (8 ) 7 Total $ 105 $ (38 ) $ 67 $ 105 $ (31 ) $ 74 Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Amortization expense of intangible assets $ 2 $ 2 $ 7 $ 5

Indexed Debt Securities (ZENS)

Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) [Text Block]	Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) (a) Investment in Securities Related to ZENS In 1995, CenterPoint Energy sold a cable television subsidiary to TW and received certain TW securities as partial consideration. A subsidiary of CenterPoint Energy holds shares of certain securities detailed in the table below, which are classified as trading securities and are expected to be held to facilitate CenterPoint Energy’s ability to meet its obligation under the ZENS. Unrealized gains and losses resulting from changes in the market value of the ZENS-Related Securities are recorded in CenterPoint Energy’s Condensed Statements of Consolidated Income. Shares Held September 30, 2018 December 31, 2017 AT&T Common 10,212,945 — Charter Common 872,503 872,503 Time Common — 888,392 TW Common — 7,107,130 (b) ZENS In September 1999, CenterPoint Energy issued ZENS having an original principal amount of $1 billion of which $828 million remain outstanding as of September 30, 2018 . Each ZENS was originally exchangeable at the holder’s option at any time for an amount of cash equal to 95% of the market value of the reference shares of TW Common attributable to such note. The number and identity of the reference shares attributable to each ZENS are adjusted for certain corporate events. On October 22, 2016, AT&T announced that it had entered into a definitive agreement to acquire TW in a stock and cash transaction. On February 15, 2017, TW shareholders approved the announced transaction with AT&T. The merger closed on June 14, 2018. CenterPoint Energy received $53.75 and 1.437 shares of AT&T Common for each share of TW Common held, resulting in cash proceeds of $382 million and 10,212,945 shares of AT&T Common. In accordance with the terms of the ZENS, CenterPoint Energy remitted $382 million to ZENS note holders in July 2018, which reduced the contingent principal amount. On November 26, 2017, Meredith announced that it had entered into a definitive merger agreement with Time. Pursuant to the merger agreement, upon closing of the merger, a subsidiary of Meredith would purchase for cash all outstanding Time Common shares for $18.50 per share. The transaction was consummated on January 31, 2018. CenterPoint Energy elected to make a reference share offer adjustment and distribute additional interest, if any, in accordance with the terms of its ZENS rather than electing to increase the early exchange ratio to 100% . CenterPoint Energy’s distribution of additional interest in connection with the reference share offer was proportionate to the percentage of eligible shares that were validly tendered by Time stockholders in Meredith’s tender offer. CenterPoint Energy received $18.50 for each share of Time Common held, resulting in cash proceeds of approximately $16 million . In accordance with the terms of the ZENS, CenterPoint Energy distributed additional interest of approximately $16 million to ZENS holders on March 6, 2018, which reduced the contingent principal amount. As a result, CenterPoint Energy recorded the following during the nine months ended September 30, 2018 : Meredith/Time AT&T/TW (in millions) Cash payment to ZENS note holders $ 16 $ 382 Indexed debt – reduction (4 ) (95 ) Indexed debt securities derivative – reduction (1 ) (45 ) Loss on indexed debt securities $ 11 $ 242 CenterPoint Energy’s reference shares for each ZENS consisted of the following: September 30, 2018 December 31, 2017 (in shares) AT&T Common 0.7185 — Charter Common 0.061382 0.061382 Time Common — 0.0625 TW Common — 0.5 As of September 30, 2018 , the contingent principal amount of the ZENS was $98 million .

Short-Term Borrowings and Long-

Short-Term Borrowings and Long-term Debt	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Short-term Borrowings and Long-term Debt [Text Block]	Short-term Borrowings and Long-term Debt (a) Short-term Borrowings (CenterPoint Energy and CERC) Inventory Financing . NGD has AMAs associated with its utility distribution service in Arkansas, Louisiana, Mississippi, Oklahoma and Texas. In March 2018, NGD’s third party AMAs in Arkansas, Louisiana and Oklahoma expired, and NGD entered into new AMAs with CES effective April 1, 2018 in these states. The AMAs have varying terms, the longest of which expires in 2021. Pursuant to the provisions of the agreements, NGD sells natural gas and agrees to repurchase an equivalent amount of natural gas during the winter heating seasons at the same cost. These transactions are accounted for as an inventory financing and had an associated principal obligation of $ -0- and $39 million as of September 30, 2018 and December 31, 2017 , respectively. (b) Long-term Debt Debt Issuances. During the nine months ended September 30, 2018 , the following debt instruments were issued: Issuance Date Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) Houston Electric February 2018 General mortgage bonds $ 400 3.95% 2048 CERC Corp. March 2018 Unsecured senior notes 300 3.55% 2023 CERC Corp. March 2018 Unsecured senior notes 300 4.00% 2028 The proceeds from these issuances were used for general limited liability company and corporate purposes, as applicable, including to repay portions of outstanding commercial paper and borrowings under CenterPoint Energy’s money pool. Merger Financings. On October 5, 2018, the following debt instruments were issued: Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) CenterPoint Energy Unsecured senior notes $ 500 3.60% 2021 CenterPoint Energy Unsecured senior notes 500 3.85% 2024 CenterPoint Energy Unsecured senior notes 500 4.25% 2028 CenterPoint Energy intends to use the net proceeds from these debt issuances to fund a portion of the pending Merger and to pay related fees and expenses. If CenterPoint Energy does not consummate the Merger on or prior to October 31, 2019, or if, on or prior to such date, the Merger Agreement is terminated, CenterPoint Energy will be required to redeem all of the outstanding notes at a redemption price equal to 101% of the principal amount of the notes plus accrued and unpaid interest, if any, to, but excluding, the date of such special mandatory redemption. The notes may also be redeemed at CenterPoint Energy’s option, in whole but not in part, at any time before October 31, 2019, at a redemption price equal to 101% of the aggregate principal amount thereof plus accrued and unpaid interest thereon to, but excluding, the date of such redemption, if CenterPoint Energy determines, in its reasonable judgment, that the Merger will not be consummated on or before close of business on October 31, 2019. Credit Facility . In May 2018, CenterPoint Energy entered into an amendment to its revolving credit facility to increase the aggregate commitments from $1.7 billion to $3.3 billion effective the earlier of (i) the termination of all commitments by certain lenders to provide the Bridge Facility and (ii) the payment in full of all obligations (other than contingent obligations) under the Bridge Facility and termination of all commitments to advance additional credit thereunder, and in each case, so long as the Merger Agreement has not been terminated pursuant to the terms thereof without consummation of the Merger. This increase to CenterPoint Energy’s revolving credit facility will automatically expire on the earlier of the (a) termination date of the revolving credit facility and (b) if the Merger Agreement is terminated without consummation of the Merger, the date that is 90 days after such termination. In addition, the amendment provides for a temporary increase on the maximum ratio of debt for borrowed money to capital from 65% to 75% until the earlier of (i) June 30, 2019 and (ii) the termination of all commitments in respect of the Bridge Facility without any borrowing thereunder. On October 5, 2018, CenterPoint Energy terminated all remaining commitments by lenders to provide the Bridge Facility. As a result, the aggregate commitments under the revolving credit facility automatically increased from $1.7 billion to $3.3 billion and the maximum ratio of debt for borrowed money to capital reverted to 65% . The Registrants had the following revolving credit facilities and utilization of such facilities: September 30, 2018 December 31, 2017 Size of Loans Letters Commercial Weighted Average Interest Rate Loans Letters Commercial Weighted Average Interest Rate (in millions, except weighted average interest rate) CenterPoint Energy $ 1,700 (1) $ — $ 6 $ 104 2.42 % $ — $ 6 $ 855 1.88 % Houston Electric 300 — 4 — — — 4 — — CERC Corp. 900 — 1 98 2.43 % — 1 898 1.72 % Total $ 2,900 $ — $ 11 $ 202 $ — $ 11 $ 1,753 (1) Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility increased to $3.3 billion on October 5, 2018 as a result of the satisfaction of certain conditions described above. Execution Date Company Size of Facility Draw Rate of LIBOR plus (1) Financial Covenant Limit on Debt for Borrowed Money to Capital Ratio Debt for Borrowed Money to Capital Ratio as of September 30, 2018 (2) Termination Date (in millions) March 3, 2016 CenterPoint Energy $ 1,700 (3) 1.250% 75% (4) (5) 47.5% March 3, 2022 March 3, 2016 Houston Electric 300 1.125% 65% (5) 50.7% March 3, 2022 March 3, 2016 CERC Corp. 900 1.125% 65% 48.6% March 3, 2022 (1) Based on current credit ratings. (2) As defined in the revolving credit facility agreement, excluding Securitization Bonds. (3) Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility increased to $3.3 billion on October 5, 2018 as a result of the satisfaction of certain conditions described above. (4) On October 5, 2018, CenterPoint Energy’s financial covenant limit returned to 65% due to the termination of all commitments in respect of the Bridge Facility without any borrowing thereunder. (5) For CenterPoint Energy (whenever its financial covenant limit is 65% ) and Houston Electric, the financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive 12 -month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date CenterPoint Energy delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of CenterPoint Energy’s certification or (iii) the revocation of such certification. The Registrants were in compliance with all financial debt covenants as of September 30, 2018 . Other. As of both September 30, 2018 and December 31, 2017 , Houston Electric had issued $118 million of general mortgage bonds as collateral for long-term debt of CenterPoint Energy. These bonds are not reflected in Houston Electric’s consolidated financial statements because of the contingent nature of the obligations.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes [Text Block]	Income Taxes The Registrants reported the following effective tax rates: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 CenterPoint Energy (1) 24 % 37 % 26 % 36 % Houston Electric (2) 20 % 35 % 21 % 36 % CERC - Continuing operations (3) (4) 5 % 20 % 29 % 38 % CERC - Discontinued operations (5) 23 % 38 % 24 % 38 % (1) CenterPoint Energy’s lower effective tax rate for the three and nine months ended September 30, 2018 compared to the same periods for 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate decreased by 5% and 4% , respectively, for the three and nine months ended September 30, 2018 due to the amortization of EDIT. These decreases were partially offset by an increase to the effective tax rate of 5% for the three-month period ended September 30, 2018 as a result of the establishment of a state valuation allowance on certain net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. The effective tax rate increased by 7% for the nine-month period ended September 30, 2018 due to state law changes and the state valuation allowance. See Note 9 for further discussion on the Internal Spin. (2) Houston Electric’s lower effective tax rate for the three and nine months ended September 30, 2018 compared to the same periods for 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate was further reduced by 2% for both periods due to the amortization of EDIT. (3) CERC’s lower effective tax rate on the loss from continuing operations for the three months ended September 30, 2018 compared to the same period in 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate decreased by 18% due to state taxes as a result of the establishment of a state valuation allowance on certain net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These decreases were partially offset by an increase to the effective tax rate of 15% due to the amortization of EDIT. See Note 9 for further discussion on the Internal Spin. (4) CERC’s lower effective tax rate on income from continuing operations for the nine months ended September 30, 2018 compared to the same period in 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate decreased by 20% due to the amortization of EDIT. These decreases were partially offset by an increase to the effective tax rate of 22% as a result of an increase in state tax rates and the establishment of a state valuation allowance on certain net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. See Note 9 for further discussion on the Internal Spin. (5) CERC’s lower effective tax rate on income from discontinued operations for the three and nine months ended September 30, 2018 compared to the same periods in 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. See Note 9 for further discussion on the Internal Spin and the associated discontinued operations presentation. The Registrants reported no uncertain tax liability as of September 30, 2018 and expect no significant changes to the uncertain tax liability over the next twelve months. Tax years through 2016 have been audited and settled with the IRS, however, during the three months ended September 30, 2018, CenterPoint Energy filed an amended 2014 tax return to claim additional tax credits that is currently under review by the IRS. For the 2017 and 2018 tax years, CenterPoint Energy is a participant in the IRS’s Compliance Assurance Process.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies [Text Block]	Commitments and Contingencies (a) Natural Gas Supply Commitments (CenterPoint Energy and CERC) Natural gas supply commitments include natural gas contracts related to CenterPoint Energy’s and 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 CenterPoint Energy’s and CERC’s Condensed Consolidated Balance Sheets as of September 30, 2018 and December 31, 2017 as these contracts meet an exception as “normal purchases contracts” or do not meet the definition of a derivative. Natural gas supply commitments also include natural gas transportation contracts that do not meet the definition of a derivative. As of September 30, 2018 , minimum payment obligations for natural gas supply commitments are approximately: (in millions) Remaining three months of 2018 $ 88 2019 325 2020 303 2021 219 2022 183 2023 and beyond 1,644 (b) Legal, Environmental and Other Matters Legal Matters Gas Market Manipulation Cases (CenterPoint Energy and CERC) . CenterPoint Energy, its predecessor, Reliant Energy, and certain of their former subsidiaries were named as defendants in a large number of lawsuits 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 were released or dismissed from all such cases, except for one case pending in federal court in Nevada in which CES, a subsidiary of CERC Corp., is a defendant. Plaintiffs in that case allege a conspiracy to inflate Wisconsin natural gas prices in 2000-2002. In May 2016, the district court granted CES’s motion for summary judgment, dismissing CES from the case. In August 2018, the Ninth Circuit Court of Appeals reversed that ruling, and CES requested further appellate review of that decision. 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. Through a series of transactions, RRI became known as GenOn and a wholly-owned subsidiary of NRG. None of those transactions alters GenOn’s contractual obligations to indemnify CenterPoint Energy and its subsidiaries for certain liabilities, including their indemnification obligations regarding the gas market manipulation litigation. In June 2017, however, GenOn and various affiliates filed for protection under Chapter 11 of the U.S. Bankruptcy Code and are expected to emerge from Chapter 11 in 2018. CenterPoint Energy, CERC, and CES submitted proofs of claim in the bankruptcy proceedings to protect their indemnity rights. In October 2018, CES, GenOn, and the plaintiffs reached an agreement to settle all claims against CES and CES’s indemnity claims against GenOn, subject to approvals by the bankruptcy court and the federal district court. If the settlement agreement is not approved and if GenOn’s bankruptcy proceedings result in it not being required to fulfill its indemnity obligations, CES could incur liability and be responsible for satisfying it. CenterPoint Energy does not expect the ultimate outcome of this matter to have a material adverse effect on its financial condition, results of operations or cash flows. Minnehaha Academy (CenterPoint Energy and CERC). On August 2, 2017, a natural gas explosion occurred at the Minnehaha Academy in Minneapolis, Minnesota, resulting in the deaths of two school employees, serious injuries to others and significant property damage to the school. CenterPoint Energy, certain of its subsidiaries, including CERC, and the contractor company working in the school have been named in litigation arising out of this incident. CenterPoint Energy has reached confidential settlement agreements with some claimants. Additionally, CenterPoint Energy is cooperating with the ongoing investigation conducted by the National Transportation Safety Board. Further, CenterPoint Energy is contesting approximately $200,000 in fines imposed by the Minnesota Office of Pipeline Safety. In early 2018, the Minnesota Occupational Safety and Health Administration concluded its investigation without any adverse findings against CenterPoint Energy. CenterPoint Energy’s general and excess liability insurance policies provide coverage for third party bodily injury and property damage claims. Environmental Matters MGP Sites (CenterPoint Energy and CERC). 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, 2018 , CERC had a recorded liability of $7 million for continued monitoring and any future remediation required by regulators in Minnesota. The estimated range of possible remediation costs for the sites for which CERC believes it may have responsibility was $4 million to $30 million based on remediation continuing for 30 to 50 years. The cost estimates are based on studies of a site or industry average costs for remediation of sites of similar size. The actual remediation costs will depend on the number of sites to be remediated, the participation of other PRPs, if any, and the remediation methods used. In addition to the Minnesota sites, the EPA and other regulators have investigated MGP sites that were owned or operated by CERC or may have been owned by one of its former affiliates. CenterPoint Energy and CERC do not expect the ultimate outcome of these matters to have a material adverse effect on the financial condition, results of operations or cash flows of either CenterPoint Energy or CERC. Asbestos. Some facilities owned by the Registrants or their predecessors in interest contain or have contained asbestos insulation and other asbestos-containing materials. The Registrants 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 the Registrants anticipate that additional claims may be asserted in the future. Although their ultimate outcome cannot be predicted at this time, the Registrants do not expect these matters, either individually or in the aggregate, to have a material adverse effect on their financial condition, results of operations or cash flows. Other Environmental. From time to time, the Registrants identify the presence of environmental contaminants during operations or on property where predecessor companies have conducted operations. Other such sites involving contaminants may be identified in the future. The Registrants have and expect to continue to remediate any identified sites consistent with state and federal legal obligations. From time to time, the Registrants have received notices, and may receive notices in the future, from regulatory authorities or others regarding status as a PRP in connection with sites found to require remediation due to the presence of environmental contaminants. In addition, the Registrants have been, or may be, named from time to time as defendants in litigation related to such sites. Although the ultimate outcome of such matters cannot be predicted at this time, the Registrants do not expect these matters, either individually or in the aggregate, to have a material adverse effect on their financial condition, results of operations or cash flows. Other Proceedings The Registrants are 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, the Registrants are also defendants 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. The Registrants regularly analyze current information and, as necessary, provide accruals for probable and reasonably estimable liabilities on the eventual disposition of these matters. The Registrants do not expect the disposition of these matters to have a material adverse effect on the Registrants’ financial condition, results of operations or cash flows.

Earnings Per Share (CenterPoint

Earnings Per Share (CenterPoint Energy)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share (CenterPoint Energy) [Text Block]	Earnings Per Share (CenterPoint Energy) The following table reconciles numerators and denominators of CenterPoint Energy’s basic and diluted earnings per share calculations: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions, except share and per share amounts) Income available to common shareholders $ 153 $ 169 $ 243 $ 496 Basic weighted average common shares outstanding 431,554,000 431,026,000 431,437,000 430,939,000 Plus: Incremental shares from assumed conversions: Restricted stock 3,337,000 3,060,000 3,337,000 3,060,000 Diluted weighted average common shares 434,891,000 434,086,000 434,774,000 433,999,000 Basic earnings per common share $ 0.35 $ 0.39 $ 0.56 $ 1.15 Diluted earnings per common share $ 0.35 $ 0.39 $ 0.56 $ 1.14

Reportable Business Segments

Reportable Business Segments	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Reportable Business Segments [Text Block]	Reportable Business Segments The Registrants’ determination of reportable business segments considers the strategic operating units under which the Registrants manage sales, allocate resources and assess performance of various products and services to wholesale or retail customers in differing regulatory environments. The Registrants use operating income as the measure of profit or loss for the business segments other than Midstream Investments, where equity in earnings is used. As of September 30, 2018, reportable business segments by Registrant are as follows: Electric Transmission & Distribution Natural Gas Distribution Energy Services Midstream Investments Other Operations CenterPoint Energy X X X X X Houston Electric X CERC X X (1) X (1) In the three months ended September 30, 2018, CERC completed the Internal Spin. Previously, CERC’s equity method investment in Enable was included in the Midstream Investments segment. CERC’s equity in earnings in Enable, net of basis difference amortization and income tax, has been classified as discontinued operations for all periods presented. See Note 9 for further discussion on the Internal Spin and the associated discontinued operations presentation. Electric Transmission & Distribution consists of the electric transmission and distribution function. 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 consists of non-rate regulated natural gas sales and services operations. Midstream Investments consists of the equity investment in Enable (excluding the Enable Series A Preferred Units). Other Operations consists primarily of other corporate operations which support all of the business operations. Houston Electric consists of a single reportable business segment and therefore is not included in the tabular business segment presentation below. Operating income (loss) amounts for 2017 have been recast to reflect the adoption of ASU 2017-07 (see Note 2 for further information). Financial data for business segments is as follows: CenterPoint Energy Three Months Ended September 30, 2018 2017 Revenues from Net Operating (Loss) Revenues from Net Operating (in millions) Electric Transmission & Distribution $ 897 (1) $ — $ 227 $ 843 (1) $ — $ 254 Natural Gas Distribution 402 8 3 390 8 25 Energy Services 910 10 (9 ) 861 10 7 Midstream Investments (2) — — — — — — Other Operations 3 — 5 4 — 11 Eliminations — (18 ) — — (18 ) — Consolidated $ 2,212 $ — $ 226 $ 2,098 $ — $ 297 Nine Months Ended September 30, 2018 2017 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Revenues from External Customers Net Intersegment Revenues Operating (in millions) Electric Transmission & Distribution $ 2,502 (1) $ — $ 523 $ 2,234 (1) $ — $ 511 Natural Gas Distribution 2,032 26 166 1,767 24 235 Energy Services 3,008 57 (20 ) 2,964 34 58 Midstream Investments (2) — — — — — — Other Operations 11 — (5 ) 11 — 24 Eliminations — (83 ) — — (58 ) — Consolidated $ 7,553 $ — $ 664 $ 6,976 $ — $ 828 (1) CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Affiliates of NRG $ 213 $ 221 $ 543 $ 540 Affiliates of Vistra Energy Corp. 79 72 192 172 (2) CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Enable $ 81 $ 68 $ 208 $ 199 CERC Three Months Ended September 30, 2018 2017 Revenues from Net Operating Revenues from Net Operating (in millions) Natural Gas Distribution $ 402 $ 8 $ 3 $ 390 $ 8 $ 25 Energy Services 910 10 (9 ) 861 10 7 Other Operations — — (1 ) — — (1 ) Eliminations — (18 ) — — (18 ) — Consolidated $ 1,312 $ — $ (7 ) $ 1,251 $ — $ 31 Nine Months Ended September 30, 2018 2017 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) (in millions) Natural Gas Distribution $ 2,032 $ 26 $ 166 $ 1,767 $ 24 $ 235 Energy Services 3,008 57 (20 ) 2,964 34 58 Other Operations — — — — — (4 ) Eliminations — (83 ) — — (58 ) — Consolidated $ 5,040 $ — $ 146 $ 4,731 $ — $ 289 CenterPoint Energy and CERC Total Assets September 30, 2018 December 31, 2017 CenterPoint Energy CERC CenterPoint CERC (in millions) Electric Transmission & Distribution $ 10,436 $ — $ 10,292 $ — Natural Gas Distribution 6,557 6,557 6,608 6,608 Energy Services 1,253 1,253 1,521 1,521 Midstream Investments 2,457 — 2,472 — Assets of discontinued operations — — (1) — 2,472 (1) Other Operations 2,206 (2) 110 2,497 (2) 70 Eliminations (681 ) (615 ) (654 ) (559 ) Consolidated $ 22,228 $ 7,305 $ 22,736 $ 10,112 (1) On September 4, 2018, CERC completed the Internal Spin. For further information regarding the Internal Spin, see Note 9. (2) Includes pension and other postemployment-related regulatory assets of $566 million and $600 million , respectively, as of September 30, 2018 and December 31, 2017 .

Supplemental Disclosure of Cash

Supplemental Disclosure of Cash Flow Information	9 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosure of Cash Flow Information [Text Block]	Supplemental Disclosure of Cash Flow Information The table below provides supplemental disclosure of cash flow information: Nine Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Cash Payments/Receipts: Interest, net of capitalized interest $ 301 $ 173 $ 85 $ 306 $ 176 $ 86 Income taxes, net 89 122 3 14 76 4 Non-cash transactions: Accounts payable related to capital expenditures 140 87 66 111 70 53 Capital distribution associated with the Internal Spin — — 1,460 — — — The table below provides a reconciliation of cash, cash equivalents and restricted cash reported in the Condensed Consolidated Balance Sheets to the amount reported in the Condensed Statements of Consolidated Cash Flows: September 30, 2018 December 31, 2017 CenterPoint Energy Houston Electric CenterPoint Energy Houston Electric (in millions) Cash and cash equivalents $ 293 $ 279 $ 260 $ 238 Restricted cash included in Prepaid expenses and other current assets 37 37 35 35 Restricted cash included in Other 1 1 1 1 Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows $ 331 $ 317 $ 296 $ 274 CERC does not have restricted cash and therefore was not included in the table above.

Related Party Transactions (Hou

Related Party Transactions (Houston Electric and CERC)	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions (Houston Electric and CERC) [Text Block]	Related Party Transactions (Houston Electric and CERC) Houston Electric and CERC participate in a money pool through which they 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. The table below summarizes money pool activity: September 30, 2018 December 31, 2017 Houston Electric CERC Houston Electric CERC (in millions) Money pool investments (borrowings) (1) $ (75 ) $ — $ (60 ) $ (570 ) Weighted average interest rate 2.45 % 2.45 % 1.90 % 1.90 % (1) Included in Accounts and notes receivable (payable)–affiliated companies in the Condensed Consolidated Balance Sheets. Houston Electric and CERC affiliate related net interest income (expense) were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Interest income (expense) (1) $ 1 $ (2 ) $ 1 $ — $ 1 $ (4 ) $ 3 $ — (1) Interest income is included in Other, net and interest expense is included in Interest and other finance charges on the Condensed Statements of Consolidated Income. CenterPoint Energy provides some corporate services to Houston Electric and CERC. The costs of services have been charged directly to Houston Electric and 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 certain 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 Houston Electric and CERC not been affiliates. Amounts charged 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, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Corporate service charges $ 47 $ 36 $ 41 $ 30 $ 138 $ 105 $ 127 $ 93 Net affiliate service charges (billings) (3 ) 3 (1 ) 1 (8 ) 8 (6 ) 6 The table below presents transactions among Houston Electric, CERC and their parent, Utility Holding. Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Cash dividends paid to parent $ 60 $ 75 $ 45 $ 89 $ 123 $ 286 $ 87 $ 337 Cash contribution from parent — 600 — — — 600 — 38 Capital distribution to parent associated with the Internal Spin — 1,460 — — — 1,460 — —

Equity (CenterPoint Energy)

Equity (CenterPoint Energy)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Equity (CenterPoint Energy) [Text Block]	Equity (CenterPoint Energy) Dividends Declared CenterPoint Energy declared dividends for the periods presented in the table below: Three Months Ended September 30, Nine Months Ended September 30, Equity Instrument 2018 2017 2018 (1) 2017 (per share) Common Stock $ 0.2775 $ 0.2675 $ 0.5550 $ 0.8025 (1) On December 13, 2017, CenterPoint Energy’s Board of Directors declared a regular quarterly cash dividend of $0.2775 per share of Common Stock, payable on March 8, 2018 to shareholders of record as of the close of business on February 15, 2018. Series A Preferred Stock On August 22, 2018, CenterPoint Energy completed the issuance of 800,000 shares of its Series A Preferred Stock, at a price of $1,000 per share, resulting in net proceeds of $790 million after issuance costs. The aggregate liquidation value of the Series A Preferred Stock is $800 million with a per share liquidation value of $1,000 . CenterPoint Energy intends to use the net proceeds from the Series A Preferred Stock offering to fund a portion of the pending Merger and to pay related fees and expenses. Dividends. The Series A Preferred Stock accrue cumulative dividends, calculated as a percentage of the stated amount per share, at a fixed annual rate of 6.125% per annum to, but excluding, September 1, 2023, and at an annual rate of three-month LIBOR plus a spread of 3.270% thereafter to be paid in cash if, when and as declared. If declared, prior to September 1, 2023, dividends are payable semi-annually in arrears on each March 1 and September 1, beginning on March 1, 2019, and, for the period commencing on September 1, 2023, dividends are payable quarterly in arrears each March 1, June 1, September 1 and December 1, beginning on December 1, 2023. Cumulative dividends accrued during the applicable periods are presented on CenterPoint Energy’s Condensed Statements of Consolidated Income as Series A Preferred Stock dividend requirement. Optional Redemption. On or after September 1, 2023, CenterPoint Energy may, at its option, redeem the Series A Preferred Stock, in whole or in part, at any time or from time to time, for cash at a redemption price of $1,000 per share, plus any accumulated and unpaid dividends thereon to, but excluding, the redemption date. At any time within 120 days after the conclusion of any review or appeal process instituted by CenterPoint Energy, if any, following the occurrence of a ratings event, CenterPoint Energy may, at its option, redeem the Series A Preferred Stock in whole, but not in part, at a redemption price in cash per share equal to $1,020 ( 102% of the liquidation value of $1,000 ) plus an amount equal to all accumulated and unpaid dividends thereon to, but excluding, the redemption date, whether or not declared. Ranking. The Series A Preferred Stock, with respect to anticipated dividends and distributions upon CenterPoint Energy’s liquidation or dissolution, or winding-up of CenterPoint Energy’s affairs, ranks or will rank: • senior to Common Stock and to each other class or series of capital stock established after the initial issue date of the Series A Preferred Stock that is expressly made subordinated to the Series A Preferred Stock; • on a parity with any class or series of capital stock established after the initial issue date of the Series A Preferred Stock that is not expressly made senior or subordinated to the Series A Preferred Stock, including the Series B Preferred Stock; • junior to any class or series of capital stock established after the initial issue date of the Series A Preferred Stock that is expressly made senior to the Series A Preferred Stock; • junior to all existing and future indebtedness (including indebtedness outstanding under CenterPoint Energy’s credit facilities, senior notes and commercial paper) and other liabilities with respect to assets available to satisfy claims against CenterPoint Energy; and • structurally subordinated to any existing and future indebtedness and other liabilities of CenterPoint Energy’s subsidiaries and capital stock of CenterPoint Energy’s subsidiaries held by third parties. Voting Rights. Holders of the Series A Preferred Stock generally will not have voting rights. Whenever dividends on shares of Series A Preferred Stock have not been declared and paid for the equivalent of three or more semi-annual or six or more quarterly dividend periods (including, for the avoidance of doubt, the dividend period beginning on, and including, the original issue date and ending on, but excluding, March 1, 2019), whether or not consecutive, the holders of such shares of Series A Preferred Stock, voting together as a single class with holders of any and all other series of voting preferred stock (as defined in the Statement of Resolution for the Series A Preferred Stock) then outstanding, will be entitled at CenterPoint Energy’s next annual or special meeting of shareholders to vote for the election of a total of two additional members of CenterPoint Energy’s Board of Directors, subject to certain limitations. This right will terminate if and when all accumulated dividends have been paid in full and, upon such termination, the term of office of each director so elected will terminate at such time and the number of directors on CenterPoint Energy’s Board of Directors will automatically decrease by two, subject to the revesting of such rights in the event of each subsequent nonpayment. Series B Preferred Stock On October 1, 2018, CenterPoint Energy completed the issuance of 19,550,000 depositary shares, each representing a 1/20th interest in a share of its Series B Preferred Stock, at a price of $50 per depositary share, resulting in net proceeds of $950 million after issuance costs. The aggregate liquidation value of Series B Preferred Stock is $978 million with a per share liquidation value of $1,000 . The amount issued included 2,550,000 depositary shares issued pursuant to the exercise in full of the option granted to the underwriters to purchase additional depositary shares. CenterPoint Energy intends to use the net proceeds from the offering of depositary shares, each representing a 1/20th interest in a share of Series B Preferred Stock, to fund a portion of the pending Merger and to pay related fees and expenses. Dividends. Dividends on the Series B Preferred Stock will be payable on a cumulative basis when, as and if declared at an annual rate of 7.00% on the liquidation value of $1,000 per share. CenterPoint Energy may pay declared dividends in cash or, subject to certain limitations, in shares of Common Stock, or in any combination of cash and shares of Common Stock on March 1, June 1, September 1 and December 1 of each year, commencing on December 1, 2018 and ending on, and including, September 1, 2021. Acquisition Termination Redemption. If the pending Merger has not closed at or prior to close of business on April 21, 2019 or if an acquisition termination event occurs, CenterPoint Energy may, at its option, give notice of an acquisition termination redemption to the holders of the Series B Preferred Stock. If CenterPoint Energy provides such notice, then, on the acquisition termination redemption date, CenterPoint Energy will be required to redeem the Series B Preferred Stock, in whole but not in part, at a redemption amount per share of the Series B Preferred Stock equal to the acquisition termination redemption amount. CenterPoint Energy will pay the acquisition termination redemption amount in cash unless the acquisition termination share price is greater than the initial price, in which case CenterPoint Energy will instead pay the acquisition termination redemption amount by delivering shares of Common Stock and cash; provided, that CenterPoint Energy may elect, subject to certain limitations, to pay cash or deliver shares of Common Stock in lieu of these amounts. If CenterPoint Energy redeems shares of the Series B Preferred Stock held by the depositary, the depositary will redeem, on the same acquisition termination redemption date, the number of the depositary shares representing the shares of the Series B Preferred Stock so redeemed. Mandatory Conversion. Unless earlier converted or redeemed, each share of the Series B Preferred Stock will automatically convert on the mandatory conversion date, which is expected to be September 1, 2021, into not less than 30.5820 and not more than 36.6980 shares of Common Stock, subject to certain anti-dilution adjustments. Correspondingly, the conversion rate per depositary share will be not less than 1.5291 and not more than 1.8349 shares of Common Stock, subject to certain anti-dilution adjustments. The conversion rate will be determined based on a preceding 20-day volume-weighted-average-price of Common Stock. The following table illustrates the conversion rate per share of the Series B Preferred Stock, subject to certain anti-dilution adjustments: Applicable Market Value of the Common Stock Conversion Rate per Share of Series B Preferred Stock Greater than $32.6990 (threshold appreciation price) 30.5820 shares of Common Stock Equal to or less than $32.6990 but greater than or equal to $27.2494 Between 30.5820 and 36.6980 shares of Common Stock, determined by dividing $1,000 by the applicable market value Less than $27.2494 (initial price) 36.6980 shares of Common Stock The following table illustrates the conversion rate per depositary share, subject to certain anti-dilution adjustments: Applicable Market Value of the Common Stock Conversion Rate per Depository Share Greater than $32.6990 (threshold appreciation price) 1.5291 shares of Common Stock Equal to or less than $32.6990 but greater than or equal to $27.2494 Between 1.5291 and 1.8349 shares of Common Stock, determined by dividing $50 by the applicable market value Less than $27.2494 (initial price) 1.8349 shares of Common Stock Optional Conversion of the Holder. Other than during a fundamental change conversion period, and unless CenterPoint Energy has redeemed the Series B Preferred Stock, a holder of the Series B Preferred Stock may, at any time prior to September 1, 2021, elect to convert such holder’s shares of the Series B Preferred Stock, in whole or in part, at the minimum conversion rate of 30.5820 shares of Common Stock per share of the Series B Preferred Stock (equivalent to 1.5291 shares of Common Stock per depositary share), subject to certain anti-dilution and other adjustments. Because each depositary share represents a 1/20th fractional interest in a share of the Series B Preferred Stock, a holder of depositary shares may convert its depositary shares only in lots of 20 depositary shares. Fundamental Change Conversion. If a fundamental change occurs on or prior to September 1, 2021, holders of the Series B Preferred Stock will have the right to convert their shares of the Series B Preferred Stock, in whole or in part, into shares of Common Stock at the fundamental change conversion rate during the period beginning on, and including, the effective date of such fundamental change and ending on, and including, the date that is 20 calendar days after such effective date (or, if later, the date that is 20 calendar days after holders receive notice of such fundamental change, but in no event later than September 1, 2021). Holders who convert shares of the Series B Preferred Stock during that period will also receive a make-whole dividend amount comprised of a fundamental change dividend make-whole amount, and to the extent there is any, the accumulated dividend amount. Because each depositary share represents a 1/20th fractional interest in a share of the Series B Preferred Stock, a holder of depositary shares may convert its depositary shares upon a fundamental change only in lots of 20 depositary shares. Ranking. The Series B Preferred Stock, with respect to anticipated dividends and distributions upon CenterPoint Energy’s liquidation or dissolution, or winding-up of CenterPoint Energy’s affairs, ranks or will rank: • senior to Common Stock and to each other class or series of capital stock established after the initial issue date of the Series B Preferred Stock that is expressly made subordinated to the Series B Preferred Stock; • on a parity with the Series A Preferred Stock and any class or series of capital stock established after the initial issue date that is not expressly made senior or subordinated to the Series B Preferred Stock; • junior to any class or series of capital stock established after the initial issue date that is expressly made senior to the Series B Preferred Stock; • junior to all existing and future indebtedness (including indebtedness outstanding under CenterPoint Energy’s credit facilities, senior notes and commercial paper) and other liabilities with respect to assets available to satisfy claims against CenterPoint Energy; and • structurally subordinated to any existing and future indebtedness and other liabilities of CenterPoint Energy’s subsidiaries and capital stock of CenterPoint Energy’s subsidiaries held by third parties. Voting Rights. Holders of the Series B Preferred Stock generally will not have voting rights. Whenever dividends on shares of the Series B Preferred Stock have not been declared and paid for six or more dividend periods (including, for the avoidance of doubt, the dividend period beginning on, and including, the initial issue date and ending on, but excluding, December 1, 2018), whether or not consecutive, the holders of such shares of Series B Preferred Stock, voting together as a single class with holders of any and all other series of voting preferred stock then outstanding (as defined in the Statement of Resolution for the Series B Preferred Stock), will be entitled at CenterPoint Energy’s next annual or special meeting of shareholders to vote for the election of a total of two additional members of CenterPoint Energy’s Board of Directors, subject to certain limitations. This right will terminate if and when all accumulated and unpaid dividends have been paid in full and, upon such termination, the term of office of each director so elected will terminate at such time and the number of directors on CenterPoint Energy’s Board of Directors will automatically decrease by two, subject to the revesting of such rights in the event of each subsequent nonpayment. Common Stock On October 1, 2018, CenterPoint Energy completed the issuance of approximately 69,633,027 shares of Common Stock at a price of $27.25 per share, for net proceeds of $1,844 million after issuance costs. The amount issued included 9,082,568 shares of Common Stock issued pursuant to the exercise in full of the option granted to the underwriters to purchase additional shares of Common Stock. CenterPoint Energy intends to use the net proceeds from the Common Stock offering to fund a portion of the pending Merger and to pay related fees and expenses.

Subsequent Events (CenterPoint

Subsequent Events (CenterPoint Energy and CERC)	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events (CenterPoint Energy and CERC) [Text Block]	Subsequent Events (CenterPoint Energy) CenterPoint Energy Dividend Declarations On October 23, 2018 , CenterPoint Energy’s Board of Directors declared a regular quarterly cash dividend of $0.2775 per share of Common Stock payable on December 13, 2018 to shareholders of record as of the close of business on November 15, 2018 . On October 23, 2018 , CenterPoint Energy’s Board of Directors declared a regular quarterly cash dividend of $11.6667 per share of the newly issued Series B Preferred Stock ( $0.5833 per depository share) payable on December 1, 2018 to shareholders of record as of the close of business on November 15, 2018 . For more information about the Series B Preferred Stock, see Note 19. Enable Distributions Declarations On November 6, 2018 , Enable declared a quarterly cash distribution of $0.318 per unit on all of its outstanding common units for the quarter ended September 30, 2018. Accordingly, CNP Midstream expects to receive a cash distribution of approximately $74 million from Enable in the fourth quarter of 2018 to be made with respect to CNP Midstream’s investment in common units of Enable. On November 6, 2018 , Enable declared a quarterly cash distribution of $0.625 per Series A Preferred Unit for the quarter ended September 30, 2018 . Accordingly, CenterPoint Energy expects to receive a cash distribution of approximately $9 million from Enable in the fourth quarter of 2018 to be made with respect to CenterPoint Energy’s investment in Enable Series A Preferred Units. Merger Financing Transactions On October 1, 2018, CenterPoint Energy completed concurrent equity offerings of depositary shares, each representing a 1/20th interest in a share of Series B Preferred Stock, and Common Stock. For more information about the concurrent equity offerings, see Note 19. On October 5, 2018, CenterPoint Energy issued $1.5 billion aggregate principal amount of senior notes. For more information about the senior notes offering, see Note 12.

New Accounting Pronouncements (

New Accounting Pronouncements (Tables)	9 Months Ended
	Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	The following table provides an overview of recently adopted or issued accounting pronouncements applicable to all the Registrants, unless otherwise noted. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2014-09- Revenue from Contracts with Customers (Topic 606) and related amendments This standard provides a comprehensive new revenue recognition model that requires revenue to be recognized in a manner that depicts the transfer of goods or services to a customer at an amount that reflects the consideration expected to be received in exchange for those goods or services. Transition method: modified retrospective January 1, 2018 Note 4 addresses the disclosure requirements. Adoption of the standard did not result in significant changes to revenue recognition. A substantial amount of the Registrants’ revenues are tariff and/or derivative based, which were not significantly impacted by these ASUs. ASU 2017-05- Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets This standard clarifies when and how to apply ASC 610-20, which was issued as part of ASU 2014-09. It amends or supersedes the guidance in ASC 350 and ASC 360 on determining a gain or loss recognized upon the derecognition of nonfinancial assets. Transition method: modified retrospective January 1, 2018 ASU 2017-05 eliminates industry specific guidance, including ASC 360-20 Property, Plant, and Equipment - Real Estate Sales, for the recognition of gains or losses upon the sale of in-substance real estate. CenterPoint Energy and CERC elected to apply the practical expedient upon adoption to only evaluate transactions that were not determined to be complete as of the date of adoption. Subsequent to adoption, gains or losses on sales or dilution events in CenterPoint Energy’s investment in Enable may result in gains or losses recognized in earnings. See Note 9 for further discussion. ASU 2016-01-Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ASU 2018-03-Technical Corrections and Improvements to Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This standard requires equity investments that do not result in consolidation and are not accounted for under the equity method to be measured at fair value and to recognize any changes in fair value in net income unless the investments qualify for the new practicability exception. It does not change the guidance for classifying and measuring investments in debt securities and loans. It also changes certain disclosure requirements and other aspects related to recognition and measurement of financial assets and financial liabilities. Transition method: cumulative-effect adjustment to beginning retained earnings, and two features prospective January 1, 2018 The adoption of this standard did not have an impact on the Registrants’ financial position, results of operations or cash flows. The Registrants elected the practicability exception for investments without a readily determinable fair value to be measured at cost. This includes the Enable Series A Preferred Units owned by CenterPoint Energy, which were previously accounted for under the cost method. See Note 9 for further discussion. ASU 2016-15- Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments This standard provides clarifying guidance on the classification of certain cash receipts and payments in the statement of cash flows and eliminates the variation in practice related to such classifications. Transition method: retrospective January 1, 2018 The adoption did not have a material impact on the Registrants’ financial position, results of operations or disclosures. However, CenterPoint Energy’s and Houston Electric’s Condensed Statements of Consolidated Cash Flows reflect an increase in investing activities and a corresponding decrease in operating activities of $1 million and $3 million for the nine months ended September 30, 2018 and 2017, respectively, due to the requirement that cash proceeds from COLI policies be classified as cash inflows from investing activity. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2016-18- Statement of Cash Flows (Topic 230): Restricted Cash This standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. Transition method: retrospective January 1, 2018 The adoption of this standard did not have an impact on the Registrants’ financial position, results of operations or disclosures. However, CenterPoint Energy’s and Houston Electric’s Condensed Statements of Consolidated Cash Flows are reconciled to cash, cash equivalents and restricted cash, resulting in a decrease in investing activities of $2 million and an increase in investing activities of $8 million for the nine months ended September 30, 2018 and 2017, respectively. See Note 17 for further discussion. ASU 2017-01- Business Combinations (Topic 805): Clarifying the Definition of a Business This standard revises the definition of a business. If substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, then under ASU 2017-01, the asset or group of assets is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs to be more closely aligned with how outputs are described in ASC 606. Transition method: prospective January 1, 2018 The adoption of this revised definition will reduce the number of transactions that are accounted for as a business combination, and therefore may have a potential impact on the Registrants’ accounting for future acquisitions. ASU 2017-04- Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This standard eliminates Step 2 of the goodwill impairment test, which required a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s and CERC’s future calculation of goodwill impairments if an impairment is identified. ASU 2017-07- Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This standard requires an employer to report the service cost component of the net periodic pension cost and postretirement benefit cost in the same line item(s) as other employee compensation costs arising from services rendered during the period; all other components will be presented separately from the line item(s) that includes the service cost and outside of any subtotal of operating income. In addition, only the service cost component will be eligible for capitalization in assets. Transition method: retrospective for the presentation of the service cost component and other components; prospective for the capitalization of the service cost component January 1, 2018 The adoption of this standard did not have a material impact on the Registrants’ financial position, results of operations, cash flows or disclosures; however, it resulted in the increases to operating income and corresponding decreases to other income reported in the table below. Other components previously capitalized in assets will be recorded as regulatory assets in the Registrants’ rate-regulated businesses, prospectively. ASU 2017-09- Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting This standard clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. Entities will apply the modification accounting guidance if the value, vesting conditions or classification of the award changes. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s accounting for future changes to share-based payment awards. ASU 2017-12- Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities This standard expands an entity’s ability to hedge and account for risk components, reduces the complexity of applying certain aspects of hedge accounting and updates the presentation and disclosure requirements. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness. Transition method : cumulative-effect adjustment for elimination of the separate measurement of ineffectiveness; prospective for presentation and disclosure July 1, 2018 Applicable January 1, 2018 The adoption of this standard did not have a material impact on the Registrants’ financial position, results of operations or cash flows. As a result of the adoption, the Registrants will no longer recognize ineffectiveness for derivatives designated as cash flow hedges; all changes in fair value will flow through other comprehensive income. As the Registrants did not have existing cash flow hedges as of the initial application date and the adoption date, no cumulative effective adjustment was recorded. Note 7 reflects disclosures modified upon adoption. ASU 2018-13- Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement This standard eliminates, modifies and adds certain disclosure requirements for fair value measurements. Transition method : prospective for additions and one modification and retrospective for all other amendments Adoption of eliminations and modifications as of September 30, 2018; Additions will be adopted January 1, 2020 The adoption of this standard did not impact the Registrants’ financial position, results of operations or cash flows. Note 8 reflects the disclosures modified upon adoption. The table below reflects the impact of adoption of ASU 2017-07: Three Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 9 $ 3 $ — $ 18 $ 7 $ 5 Decrease to other income 9 3 — 18 7 5 Nine Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 38 $ 18 $ 8 $ 52 $ 22 $ 16 Decrease to other income 38 18 8 52 22 16 Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2016-02- Leases (Topic 842) and related amendments ASU 2018-01- Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842 ASU 2018-10 - Codification Improvements to Topic 842, Leases ASU 2018-11- Leases (Topic 842)-Targeted Improvements ASU 2016-02 provides a comprehensive new lease model that requires lessees to recognize assets and liabilities for most leases and would change certain aspects of lessor accounting. Transition method : modified retrospective ASU 2018-01 allows entities to elect not to assess whether existing land easements that were not previously accounted for in accordance with ASC 840 Leases under ASC 842 Leases when transitioning to the new leasing standard. ASU 2018-10 makes sixteen narrow-scope amendments to ASC 842 Leases. ASU 2018-11 allows entities the transition option to not apply the new lease standards in the comparative financial statements presented in the year of adoption. It also gives lessors the practical expedient to not separate non-lease and lease components when certain criteria are met. January 1, 2019 Early adoption is permitted The Registrants will elect the practical expedient on existing easements provided by ASU 2018-01, and the transition option to not apply the new lease standards in the comparative financial statements presented in the year of adoption provided by ASU 2018-11. The Registrants are evaluating other available transitional practical expedients. The Registrants are in the process of reviewing contracts to identify leases as defined in ASU 2016-02 and expect to recognize on the statements of financial position right-of-use assets and lease liabilities for the majority of their respective leases that are currently classified as operating leases. The Registrants are continuing to assess the impact that adoption of these standards will have on their financial position, results of operations, cash flows and disclosures. ASU 2016-13- Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This standard requires a new model called CECL to estimate credit losses for (1) financial assets subject to credit losses and measured at amortized cost and (2) certain off-balance sheet credit exposures. 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. Transition method : modified retrospective January 1, 2020 The Registrants are currently assessing the impact that this standard will have on their financial position, results of operations, cash flows and disclosures. ASU 2018-02-Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA and requires entities to provide certain disclosures regarding stranded tax effects. Transition method: either in the period of adoption or retrospective January 1, 2019 Early adoption is permitted The adoption of this standard will allow the Registrants to reclass stranded deferred tax adjustments primarily related to benefit plans from other comprehensive income to retained earnings. The Registrants are currently assessing the impact that adoption of this standard will have on their financial position and disclosures. Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2018-14-Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans This standard eliminates, modifies and adds certain disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. Transition method : retrospective January 1, 2021 The adoption of this standard will impact the Registrants’ annual disclosures and is not expected to have an impact on their financial position, results of operations, and cash flows. The Registrants are currently assessing the standard’s impact on the Stock-Based Incentive Compensation Plans and Employee Benefit Plans footnote. ASU 2018-15- Intangibles-Goodwill and Other- Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract This standard aligns accounting for implementation costs incurred in a cloud computing arrangement that is accounted for as a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The update also prescribes the balance sheet, income statement, and cash flow classification of the capitalized implementation costs and related amortization expense, and requires additional quantitative and qualitative disclosures. Transition method : retrospective or prospective January 1, 2020 Early adoption is permitted The adoption of this standard will allow the Registrants to capitalize certain implementation costs incurred in cloud computing arrangements that are accounted for as service contracts. The Registrants are currently assessing the impact that adoption of this standard will have on their financial position, results of operations, cash flows and disclosures.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	The following tables disaggregate revenues by reportable business segment and major source: CenterPoint Energy Three Months Ended September 30, 2018 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 904 $ 398 $ 82 $ 1 $ 1,385 $ 852 $ 396 $ 97 $ 2 $ 1,347 Derivatives income — — 838 — 838 — — 774 — 774 Other (3) (7 ) 12 — 2 7 (9 ) 2 — 2 (5 ) Eliminations — (8 ) (10 ) — (18 ) — (8 ) (10 ) — (18 ) Total revenues $ 897 $ 402 $ 910 $ 3 $ 2,212 $ 843 $ 390 $ 861 $ 4 $ 2,098 Nine Months Ended September 30, 2018 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 2,525 $ 2,093 $ 338 $ 4 $ 4,960 $ 2,254 $ 1,784 $ 355 $ 4 $ 4,397 Derivatives income (4 ) — 2,727 — 2,723 1 — 2,643 — 2,644 Other (3) (19 ) (35 ) — 7 (47 ) (21 ) 7 — 7 (7 ) Eliminations — (26 ) (57 ) — (83 ) — (24 ) (34 ) — (58 ) Total revenues $ 2,502 $ 2,032 $ 3,008 $ 11 $ 7,553 $ 2,234 $ 1,767 $ 2,964 $ 11 $ 6,976 Houston Electric Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Revenue from contracts $ 904 $ 852 $ 2,525 $ 2,254 Other (3) (7 ) (9 ) (19 ) (21 ) $ 897 $ 843 $ 2,506 $ 2,233 CERC Three Months Ended September 30, 2018 2017 Natural Gas Distribution (1) Energy Services (2) Total Natural Gas Distribution (1) Energy Services (2) Total (in millions) Revenue from contracts $ 398 $ 82 $ 480 $ 396 $ 97 $ 493 Derivatives income — 838 838 — 774 774 Other (3) 12 — 12 2 — 2 Eliminations (8 ) (10 ) (18 ) (8 ) (10 ) (18 ) Total revenues $ 402 $ 910 $ 1,312 $ 390 $ 861 $ 1,251 Nine Months Ended September 30, 2018 2017 Natural Gas Distribution (1) Energy Services (2) Total Natural Gas Distribution (1) Energy Services (2) Total (in millions) Revenue from contracts $ 2,093 $ 338 $ 2,431 $ 1,784 $ 355 $ 2,139 Derivatives income — 2,727 2,727 — 2,643 2,643 Other (3) (35 ) — (35 ) 7 — 7 Eliminations (26 ) (57 ) (83 ) (24 ) (34 ) (58 ) Total revenues $ 2,032 $ 3,008 $ 5,040 $ 1,767 $ 2,964 $ 4,731 (1) Reflected in Utility revenues in the Condensed Statements of Consolidated Income. (2) Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income. (3) Primarily consists of income from ARPs and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. The Registrants recognize ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Schedule of Defined Benefit Plans Disclosures [Table Text Block]	The table below reflects the expected contributions to be made to the pension plans and postretirement benefit plan during 2018: CenterPoint Energy Houston Electric CERC (in millions) Expected minimum contribution to pension plans during 2018 $ 67 $ — $ — Expected contribution to postretirement benefit plan in 2018 16 10 5 The table below reflects the contributions made to the pension plans and postretirement benefit plan during 2018: Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Pension plans $ 3 $ — $ — $ 67 $ — $ — Postretirement benefit plan 4 3 1 11 7 3 The Registrants’ net periodic cost, before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes, includes the following components relating to pension and postretirement benefits: Pension Benefits (CenterPoint Energy) Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Service cost (1) $ 10 $ 9 $ 28 $ 27 Interest cost (2) 20 22 59 66 Expected return on plan assets (2) (27 ) (24 ) (80 ) (72 ) Amortization of prior service cost (2) 3 2 7 7 Amortization of net loss (2) 10 14 32 43 Net periodic cost $ 16 $ 23 $ 46 $ 71 Postretirement Benefits Three Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ — $ — $ 1 $ — $ — $ 1 Interest cost (2) 3 2 1 4 3 1 Expected return on plan assets (2) (1 ) (1 ) — (1 ) (1 ) (1 ) Amortization of prior service credit (2) (1 ) (1 ) — (1 ) (2 ) — Net periodic cost $ 1 $ — $ 2 $ 2 $ — $ 1 Nine Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ 1 $ — $ 1 $ 1 $ — $ 1 Interest cost (2) 10 6 3 12 7 3 Expected return on plan assets (2) (4 ) (3 ) (1 ) (4 ) (3 ) (1 ) Amortization of prior service cost (credit) (2) (3 ) (4 ) 1 (3 ) (4 ) 1 Net periodic cost (credit) $ 4 $ (1 ) $ 4 $ 6 $ — $ 4 (1) Amounts presented in the table above are included in Operation and maintenance expense in each of the Registrants’ respective Condensed Statements of Consolidated Income, net of amounts capitalized and regulatory deferrals. (2) Amounts presented in the table above are included in Other, net in each of the Registrants’ respective Condensed Statements of Consolidated Income, net of regulatory deferrals.
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	Changes in accumulated other comprehensive loss related to defined benefit and postretirement plans are as follows: CenterPoint Energy Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Beginning Balance $ (63 ) $ (70 ) $ (66 ) $ (72 ) Amounts reclassified from accumulated other comprehensive loss: Prior service cost (1) — — 1 1 Actuarial losses (1) 2 2 5 5 Tax expense (1 ) (2 ) (2 ) (4 ) Net current period other comprehensive income 1 — 4 2 Ending Balance $ (62 ) $ (70 ) $ (62 ) $ (70 ) (1) These accumulated other comprehensive components are included in the computation of net periodic cost.

Regulatory Accounting (Tables)

Regulatory Accounting (Tables)	9 Months Ended
	Sep. 30, 2018
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Schedule of Regulatory Assets and Liabilities [Table Text Block]	The following is a list of regulatory assets and liabilities reflected on the Registrants’ Condensed Consolidated Balance Sheets: September 30, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC Regulatory Assets: (in millions) Current regulatory assets (1) $ 60 $ — $ 60 $ 130 $ — $ 130 Non-current regulatory assets: Securitized regulatory assets 1,146 1,146 — 1,590 1,590 — Unrecognized equity return (2) (225 ) (225 ) — (287 ) (287 ) — Unamortized loss on reacquired debt 70 70 — 75 75 — Pension and postretirement-related regulatory asset (3) 609 32 15 646 31 20 Hurricane Harvey restoration costs (4) 67 61 6 64 58 6 Regulatory assets related to TCJA (5) 48 34 14 48 33 15 Other long-term regulatory assets (6) 219 84 135 211 70 140 Total non-current regulatory assets 1,934 1,202 170 2,347 1,570 181 Total regulatory assets 1,994 1,202 230 2,477 1,570 311 Regulatory Liabilities: Current regulatory liabilities (7) 47 22 25 24 22 2 Non-current regulatory liabilities: Regulatory liabilities related to TCJA (5) 1,362 858 504 1,354 862 492 Estimated removal costs 887 275 612 878 285 593 Other long-term regulatory liabilities 257 132 125 232 116 116 Total non-current regulatory liabilities 2,506 1,265 1,241 2,464 1,263 1,201 Total regulatory liabilities 2,553 1,287 1,266 2,488 1,285 1,203 Total regulatory assets and liabilities, net $ (559 ) $ (85 ) $ (1,036 ) $ (11 ) $ 285 $ (892 ) (1) Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ Condensed Consolidated Balance Sheets. (2) The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended September 30, 2018 and 2017 , CenterPoint Energy and Houston Electric recognized approximately $17 million and $13 million , respectively, of the allowed equity return. During the nine months ended September 30, 2018 and 2017 , CenterPoint Energy and Houston Electric recognized approximately $62 million and $30 million , respectively, of the allowed equity return. The timing of CenterPoint Energy’s and Houston Electric’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months. (3) Includes a portion of NGD’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates that is being deferred for rate making purposes, of which $4 million and $7 million as of September 30, 2018 and December 31, 2017 , respectively, were not earning a return. (4) The Registrants are not earning a return on Hurricane Harvey restoration costs. (5) The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities. (6) Other long-term regulatory assets that are not earning a return were not material as of September 30, 2018 and December 31, 2017 . (7) Current regulatory liabilities are included in Other current liabilities in each of the Registrants’ respective Condensed Consolidated Balance Sheets.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The table below summarizes CenterPoint Energy’s and CERC’s current weather hedge gain (loss) activity: Three Months Ended September 30, Nine Months Ended September 30, Jurisdiction Winter Season Bilateral Cap 2018 2017 2018 2017 (in millions) Certain NGD jurisdictions 2018 – 2019 $ 9 $ — $ — $ — $ — Certain NGD jurisdictions 2017 – 2018 8 — — — — Total CERC (1) — — — — Electric operations’ service territory 2018 – 2019 8 — — — — Electric operations’ service territory 2017 – 2018 9 — — (4 ) — Electric operations’ service territory 2016 – 2017 9 — — — 1 Total CenterPoint Energy (1) $ — $ — $ (4 ) $ 1 (1) Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income.
Fair Value of Derivative Instruments [Table Text Block]	The following tables present information about derivative instruments and hedging activities. The first two tables provide a balance sheet overview of Derivative Assets and Liabilities, while the last table provides a breakdown of the related income statement impacts. Fair Value of Derivative Instruments and Hedged Items September 30, 2018 December 31, 2017 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivative Assets Fair Value Derivative Liabilities Fair Value Derivatives designated as cash flow hedges: (in millions) Interest rate derivatives Current Assets: Non-trading derivative assets $ 3 $ — $ — $ — Total Houston Electric 3 — — — Derivatives designated as fair value hedges: Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities — 2 13 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 76 3 114 4 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 38 — 44 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 31 72 38 78 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 16 33 9 24 Total CERC 161 110 218 107 Indexed debt securities derivative Current Liabilities — 685 — 668 Total CenterPoint Energy $ 164 $ 795 $ 218 $ 775 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,865 Bcf or a net 310 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of September 30, 2018 and December 31, 2017 , respectively. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure. (2) Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $72 million asset and a $130 million asset as of September 30, 2018 and December 31, 2017 , respectively, as shown on CenterPoint Energy’s and CERC’s Condensed Consolidated Balance Sheets (and as detailed in the Offsetting of Natural Gas Derivative Assets and Liabilities table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, impacted by collateral netting of $21 million and $19 million , respectively. (3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable. Cumulative Basis Adjustment for Fair Value Hedges (CenterPoint Energy and CERC) September 30, 2018 December 31, 2017 Balance Sheet Location Carrying Amount of Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item Carrying Amount of Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item Hedged items in fair value hedge relationship: (in millions) Natural gas inventory Current Assets: Natural gas inventory $ 39 $ 1 $ 80 $ 14 Total CenterPoint Energy and CERC $ 39 $ 1 $ 80 $ 14
Offsetting of Natural Gas Derivative Assets and Liabilities [Table Text Block]	Offsetting of Natural Gas Derivative Assets and Liabilities (CenterPoint Energy and CERC) September 30, 2018 December 31, 2017 Gross Amounts Recognized (1) Gross Amounts Offset in the Consolidated Balance Sheets Net Amount Presented in the Consolidated Balance Sheets (2) 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 $ 107 $ (34 ) $ 73 $ 165 $ (55 ) $ 110 Other Assets: Non-trading derivative assets 54 (16 ) 38 53 (9 ) 44 Current Liabilities: Non-trading derivative liabilities (77 ) 44 (33 ) (83 ) 63 (20 ) Other Liabilities: Non-trading derivative liabilities (33 ) 27 (6 ) (24 ) 20 (4 ) Total $ 51 $ 21 $ 72 $ 111 $ 19 $ 130 (1) Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements. (2) The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
Income Statement Impact of Derivative Activity [Table Text Block]	Income Statement Impact of Hedge Accounting Activity (CenterPoint Energy and CERC) Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Location and Amount of Gain (Loss) recognized in Income on Hedging Relationship (2) Non-utility natural gas expense Non-utility natural gas expense (in millions) Total amounts presented in the statements of income in which the effects of hedges are recorded $ 864 $ 832 $ 2,927 $ 2,843 Gain (loss) on fair value hedging relationships: Commodity contracts: Hedged items - Natural gas inventory 1 4 (13 ) (10 ) Derivatives designated as hedging instruments (1 ) (4 ) 13 10 Amounts excluded from effectiveness testing recognized in earnings immediately (1) 6 (9 ) (73 ) (93 ) (1) As a result of the adoption of ASU 2017-12 effective January 1, 2018 (see Note 2 for additional information), CenterPoint Energy and CERC exclude from their assessment of hedge effectiveness the natural gas market price difference between locations of the hedged inventory and the delivery location specified in the hedge instruments. Prior to the adoption of this accounting guidance, the timing difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity, was excluded from the assessment of effectiveness for CenterPoint Energy’s and CERC’s existing fair value hedges and will continue to be excluded from the assessment of hedge effectiveness. CenterPoint Energy and CERC elected to continue to immediately recognize amounts excluded from hedge effectiveness in their respective Condensed Statements of Consolidated Income. (2) Income statement impact associated with cash flow hedge activity is related to gains and losses reclassified from accumulated other comprehensive income into income. Amounts are immaterial for the Registrants for both the three and nine months ended September 30, 2018 and 2017, respectively. Three Months Ended September 30, Nine Months Ended September 30, Income Statement Location 2018 2017 2018 2017 Effects of derivatives not designated as hedging instruments on the income statement: (in millions) Commodity contracts Gains (Losses) in Non-utility revenues $ 2 $ 30 $ 70 $ 162 Total CERC 2 30 70 162 Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (44 ) (36 ) (316 ) (59 ) Interest rate derivatives Gains (Losses) in Interest and other finance charges — — — — Total CenterPoint Energy $ (42 ) $ (6 ) $ (246 ) $ 103
Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) [Table Text Block]	Effect of Cash Flow Hedge Accounting on Accumulated Other Comprehensive Income Amount of Gain (Loss) Recognized in Other Comprehensive Income, Net of Tax on Derivative Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Effects of cash flow hedging Interest rate derivatives (1) $ 3 $ — $ 7 $ (1 ) Total Houston Electric 3 — 7 (1 ) Interest rate derivatives (1) — (1 ) — (1 ) Total CERC — (1 ) — (1 ) Interest rate derivatives (1) — (1 ) (1 ) (1 ) Total CenterPoint Energy $ 3 $ (2 ) $ 6 $ (3 ) (1) Gains and losses are reclassified from accumulated other comprehensive income into income when the hedged transactions affect earnings. The reclassification amounts are included in Interest and other finance charges in the Condensed Statements of Consolidated Income. Amounts are less than $1 million for each of the three and nine months ended September 30, 2018 and 2017. Over the next twelve months, estimated amortization of accumulated other comprehensive income into related income is expected to be immaterial.
Disclosure of Credit Derivatives [Table Text Block]	CenterPoint Energy and CERC enter into financial derivative contracts containing material adverse change provisions. These provisions could require CenterPoint Energy or CERC to post additional collateral if the S&P or Moody’s credit ratings of CenterPoint Energy, Inc. or its subsidiaries, including CERC Corp., are downgraded. CenterPoint Energy and CERC September 30, December 31, 2017 (in millions) Aggregate fair value of derivatives containing material adverse change provisions in a net liability position $ 2 $ 2 Fair value of collateral already posted — — Additional collateral required to be posted if credit risk contingent features triggered 1 2

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair value, assets and liabilities measured on a recurring basis [Table Text Block]	The following tables present information about the Registrants’ assets and liabilities (including derivatives that are presented net) measured at fair value on a recurring basis and indicate the fair value hierarchy of the valuation techniques utilized by the Registrants to determine such fair value. CenterPoint Energy September 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting (1) Total Level 1 Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 630 $ — $ — $ — $ 630 $ 963 $ — $ — $ — $ 963 Investments, including money market funds (2) 70 — — — 70 68 — — — 68 Interest rate derivatives 3 — — — 3 — — — — — Natural gas derivatives (3) — 134 27 (50 ) 111 — 161 57 (64 ) 154 Hedged portion of natural gas inventory 1 — — — 1 14 — — — 14 Total assets $ 704 $ 134 $ 27 $ (50 ) $ 815 $ 1,045 $ 161 $ 57 $ (64 ) $ 1,199 Liabilities Indexed debt securities derivative $ — $ 685 $ — $ — $ 685 $ — $ — $ 668 $ — $ 668 Natural gas derivatives (3) — 105 5 (71 ) 39 — 96 11 (83 ) 24 Total liabilities $ — $ 790 $ 5 $ (71 ) $ 724 $ — $ 96 $ 679 $ (83 ) $ 692 Houston Electric September 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting Total Level 1 Level 2 Level 3 Netting Total Assets (in millions) Investments, including money market funds (2) $ 52 $ — $ — $ — $ 52 $ 51 $ — $ — $ — $ 51 Interest rate derivatives 3 — — — 3 — — — — — Total assets $ 55 $ — $ — $ — $ 55 $ 51 $ — $ — $ — $ 51 CERC September 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting (1) Total Level 1 Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 3 $ — $ — $ — $ 3 $ 3 $ — $ — $ — $ 3 Investments, including money market funds (2) 10 — — — 10 11 — — — 11 Natural gas derivatives (3) — 134 27 (50 ) 111 — 161 57 (64 ) 154 Hedged portion of natural gas inventory 1 — — — 1 14 — — — 14 Total assets $ 14 $ 134 $ 27 $ (50 ) $ 125 $ 28 $ 161 $ 57 $ (64 ) $ 182 Liabilities Natural gas derivatives (3) $ — $ 105 $ 5 $ (71 ) $ 39 $ — $ 96 $ 11 $ (83 ) $ 24 Total liabilities $ — $ 105 $ 5 $ (71 ) $ 39 $ — $ 96 $ 11 $ (83 ) $ 24 (1) Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy and CERC to settle positive and negative positions and also include cash collateral of $21 million and $19 million as of September 30, 2018 and December 31, 2017 , respectively, posted with the same counterparties. (2) Amounts are included in Prepaid expenses and other current assets in the Condensed Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable.
Assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs [Table Text Block]	The following table presents additional information about assets or liabilities, including derivatives that are measured at fair value on a recurring basis for which CenterPoint Energy and CERC have utilized Level 3 inputs to determine fair value: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC (in millions) Beginning balance $ (628 ) $ 13 $ (712 ) $ 28 $ (622 ) $ 46 $ (704 ) $ 13 Total gains (losses) 1 1 (38 ) (2 ) 4 4 (38 ) 21 Total settlements (1 ) (1 ) (1 ) (1 ) (36 ) (36 ) (5 ) (5 ) Transfers into Level 3 — — 7 7 (2 ) (2 ) 9 9 Transfers out of Level 3 (1) 650 9 (6 ) (6 ) 678 10 (12 ) (12 ) Ending balance (2) $ 22 $ 22 $ (750 ) $ 26 $ 22 $ 22 $ (750 ) $ 26 The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date: $ 11 $ 11 $ (36 ) $ — $ 9 $ 9 $ (42 ) $ 17 (1) As of September 30, 2018 , CenterPoint Energy transferred its indexed debt securities derivative from Level 3 to Level 2 to reflect changes in the significance of the unobservable inputs used in the valuation. (2) CenterPoint Energy and CERC did not have significant Level 3 sales or purchases during either of the three or nine months ended September 30, 2018 or 2017 .
Estimated fair value of financial instruments, debt instruments [Table Text Block]	The fair values of cash and cash equivalents, investments in debt and equity securities classified as “trading” and short-term borrowings are estimated to be approximately equivalent to carrying amounts and have been excluded from the table below. The carrying amounts of non-trading derivative assets and liabilities and CenterPoint Energy’s ZENS indexed debt securities derivative are stated at fair value and are excluded from the table below. The fair value of each debt instrument is determined by multiplying the principal amount of each debt instrument by a combination of historical trading prices and comparable issue data. These liabilities, which are not measured at fair value in the Registrants’ Condensed Consolidated Balance Sheets, but for which the fair value is disclosed, would be classified as Level 2 in the fair value hierarchy. September 30, 2018 December 31, 2017 CenterPoint Energy (1) Houston Electric (1) CERC CenterPoint Energy (1) Houston Electric (1) CERC Long-term debt, including current maturities (in millions) Carrying amount $ 7,758 $ 4,782 $ 2,257 $ 8,679 $ 4,753 $ 2,457 Fair value 7,888 4,813 2,367 9,220 5,034 2,708 (1) Includes Securitization Bond debt.

Unconsolidated Affiliate (Cen_2

Unconsolidated Affiliate (CenterPoint Energy and CERC) (Tables)	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments [Table Text Block]	Interests Held in Enable GP (CenterPoint Energy): September 30, 2018 Management Rights (1) Incentive Distribution Rights (2) CenterPoint Energy (3) 50 % 40 % OGE 50 % 60 % (1) Enable is controlled jointly by CenterPoint Energy and OGE. Sale of CenterPoint Energy’s or OGE’s ownership interests in Enable GP to a third party is subject to mutual rights of first offer and first refusal, and CenterPoint Energy is not permitted to dispose of less than all of its interest in Enable GP. (2) Enable is expected to pay a minimum quarterly distribution of $0.2875 per common unit on its outstanding common units to the extent it has sufficient cash from operations after establishment of cash reserves and payment of fees and expenses, including payments to Enable GP and its affiliates, within 60 days after the end of each quarter. If cash distributions to Enable’s unitholders exceed $0.330625 per common unit in any quarter, Enable GP will receive increasing percentages or incentive distributions rights, up to 50% , of the cash Enable distributes in excess of that amount. In certain circumstances Enable GP will have the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election. To date, no incentive distributions have been made. (3) Includes interests held through CNP Midstream. Distributions Received from Enable (CenterPoint Energy and CERC): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Investment in Enable common units (1) $ 74 $ 74 $ 223 $ 223 Total CERC (2) 74 74 223 223 Investment in Enable Series A Preferred Units (3) 9 9 27 27 Total CenterPoint Energy $ 83 $ 83 $ 250 $ 250 (1) Reflects cash distributions of $0.318 and $0.954 per common unit for the three and nine months ended September 30, 2018 and 2017, respectively. (2) On September 4, 2018, CERC completed the Internal Spin. After such date, CNP Midstream owned the Enable common units previously owned by CERC. (3) Reflects cash distributions of $0.625 and $1.875 per Enable Series A Preferred Unit for the three and nine months ended September 30, 2018 and 2017, respectively. Transactions with Enable (CenterPoint Energy and CERC): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Reimbursement of transition services (1) (CenterPoint Energy) $ 1 $ — $ 4 $ 3 Natural gas expenses, including transportation and storage costs (CenterPoint Energy and CERC) 23 23 89 80 (1) Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement. September 30, 2018 December 31, 2017 (in millions) Accounts receivable for amounts billed for transition services (CenterPoint Energy) $ 3 $ 1 Accounts payable for natural gas purchases from Enable (CenterPoint Energy and CERC) 8 13 Summarized unaudited consolidated income information for Enable is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Operating revenues $ 928 $ 705 $ 2,481 $ 1,997 Cost of sales, excluding depreciation and amortization 516 349 1,335 936 Depreciation and amortization 100 90 292 267 Operating income 171 137 436 399 Net income attributable to Enable common units 129 104 320 301 Reconciliation of Equity in Earnings, net: CenterPoint Energy’s interest $ 70 $ 56 $ 173 $ 163 Basis difference amortization (1) 11 12 35 36 CenterPoint Energy’s equity in earnings, net $ 81 $ 68 $ 208 $ 199 (1) Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s share of Enable’s earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s original investment in Enable and their underlying equity in Enable’s net assets. The basis difference is amortized over approximately 31 years, the average life of the assets to which the basis difference is attributed. Summarized unaudited consolidated balance sheet information for Enable is as follows: September 30, December 31, 2017 (in millions) Current assets $ 481 $ 416 Non-current assets 11,454 11,177 Current liabilities 1,403 1,279 Non-current liabilities 2,964 2,660 Non-controlling interest 11 12 Preferred equity 362 362 Enable partners’ equity 7,195 7,280 Reconciliation of Investment in Enable: CenterPoint Energy’s ownership interest in Enable partners’ equity $ 3,883 $ 3,935 CenterPoint Energy’s basis difference (1,426 ) (1,463 ) CenterPoint Energy’s equity method investment in Enable $ 2,457 $ 2,472 Limited Partner Interest and Units Held in Enable (CenterPoint Energy): September 30, 2018 Limited Partner Interest (1) Common Units Enable Series A Preferred Units (2) CenterPoint Energy (3) 54.0 % 233,856,623 14,520,000 OGE 25.6 % 110,982,805 — Public unitholders 20.4 % 88,376,728 — Total units outstanding 100.0 % 433,216,156 14,520,000 (1) Excludes the Enable Series A Preferred Units owned by CenterPoint Energy. (2) The carrying amount of the Enable Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both September 30, 2018 and December 31, 2017 . No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion. (3) Includes Enable Series A Preferred Units held directly by CenterPoint Energy and common units held indirectly through CNP Midstream.
Discontinued Operations (CERC) [Table Text Block]	The Internal Spin represents a significant strategic shift that has a material effect on CERC’s operations and financial results and, as a result, CERC’s distribution of its equity investment in Enable met the criteria for discontinued operations classification. CERC has no continuing involvement in the equity investment of Enable. Therefore, CERC’s equity in earnings and related income taxes have been classified as Income from discontinued operations, net of tax, in CERC’s Condensed Statements of Consolidated Income for the periods presented. CERC’s equity method investment and related deferred income tax liabilities have been classified as Investment in unconsolidated affiliate - discontinued operations and Deferred income taxes, net - discontinued operations, respectively, in CERC’s Condensed Consolidated Balance Sheets for the periods presented. The following table presents amounts included in Income from discontinued operations, net of tax in CERC’s Condensed Statements of Consolidated Income. Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Equity in earnings of unconsolidated affiliate, net $ 57 $ 68 $ 184 $ 199 Income tax expense 13 26 44 75 Income from discontinued operations, net of tax $ 44 $ 42 $ 140 $ 124

Goodwill and Other Intangible_2

Goodwill and Other Intangibles (CenterPoint Energy and CERC) (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	CenterPoint Energy’s and CERC’s goodwill by reportable business segment as of both September 30, 2018 and December 31, 2017 is as follows: (in millions) Natural Gas Distribution $ 746 Energy Services (1) 110 Other Operations 11 Total $ 867 (1) Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012.
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The tables below present information on CenterPoint Energy’s and CERC’s other intangible assets recorded in Other non-current assets on the Condensed Consolidated Balance Sheets. September 30, 2018 December 31, 2017 Useful Lives Gross Carrying Amount Accumulated Amortization Net Balance Gross Carrying Amount Accumulated Amortization Net Balance (in years) (in millions) Customer relationships 15 $ 86 $ (26 ) $ 60 $ 86 $ (21 ) $ 65 Covenants not to compete 4 4 (2 ) 2 4 (2 ) 2 Other Various 15 (10 ) 5 15 (8 ) 7 Total $ 105 $ (38 ) $ 67 $ 105 $ (31 ) $ 74
Finite-lived Intangible Assets Amortization Expense [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Amortization expense of intangible assets $ 2 $ 2 $ 7 $ 5

Indexed Debt Securities (ZENS_2

Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) (Tables)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Indexed Debt Securities and Marketable Securities [Table Text Block]	As a result, CenterPoint Energy recorded the following during the nine months ended September 30, 2018 : Meredith/Time AT&T/TW (in millions) Cash payment to ZENS note holders $ 16 $ 382 Indexed debt – reduction (4 ) (95 ) Indexed debt securities derivative – reduction (1 ) (45 ) Loss on indexed debt securities $ 11 $ 242 CenterPoint Energy’s reference shares for each ZENS consisted of the following: September 30, 2018 December 31, 2017 (in shares) AT&T Common 0.7185 — Charter Common 0.061382 0.061382 Time Common — 0.0625 TW Common — 0.5 In 1995, CenterPoint Energy sold a cable television subsidiary to TW and received certain TW securities as partial consideration. A subsidiary of CenterPoint Energy holds shares of certain securities detailed in the table below, which are classified as trading securities and are expected to be held to facilitate CenterPoint Energy’s ability to meet its obligation under the ZENS. Unrealized gains and losses resulting from changes in the market value of the ZENS-Related Securities are recorded in CenterPoint Energy’s Condensed Statements of Consolidated Income. Shares Held September 30, 2018 December 31, 2017 AT&T Common 10,212,945 — Charter Common 872,503 872,503 Time Common — 888,392 TW Common — 7,107,130

Short-Term Borrowings and Lon_2

Short-Term Borrowings and Long-term Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Debt [Table Text Block]	Debt Issuances. During the nine months ended September 30, 2018 , the following debt instruments were issued: Issuance Date Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) Houston Electric February 2018 General mortgage bonds $ 400 3.95% 2048 CERC Corp. March 2018 Unsecured senior notes 300 3.55% 2023 CERC Corp. March 2018 Unsecured senior notes 300 4.00% 2028 The proceeds from these issuances were used for general limited liability company and corporate purposes, as applicable, including to repay portions of outstanding commercial paper and borrowings under CenterPoint Energy’s money pool. Merger Financings. On October 5, 2018, the following debt instruments were issued: Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) CenterPoint Energy Unsecured senior notes $ 500 3.60% 2021 CenterPoint Energy Unsecured senior notes 500 3.85% 2024 CenterPoint Energy Unsecured senior notes 500 4.25% 2028 CenterPoint Energy intends to use the net proceeds from these debt issuances to fund a portion of the pending Merger and to pay related fees and expenses.
Schedule of Line of Credit Facilities [Table Text Block]	The Registrants had the following revolving credit facilities and utilization of such facilities: September 30, 2018 December 31, 2017 Size of Loans Letters Commercial Weighted Average Interest Rate Loans Letters Commercial Weighted Average Interest Rate (in millions, except weighted average interest rate) CenterPoint Energy $ 1,700 (1) $ — $ 6 $ 104 2.42 % $ — $ 6 $ 855 1.88 % Houston Electric 300 — 4 — — — 4 — — CERC Corp. 900 — 1 98 2.43 % — 1 898 1.72 % Total $ 2,900 $ — $ 11 $ 202 $ — $ 11 $ 1,753 (1) Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility increased to $3.3 billion on October 5, 2018 as a result of the satisfaction of certain conditions described above. Execution Date Company Size of Facility Draw Rate of LIBOR plus (1) Financial Covenant Limit on Debt for Borrowed Money to Capital Ratio Debt for Borrowed Money to Capital Ratio as of September 30, 2018 (2) Termination Date (in millions) March 3, 2016 CenterPoint Energy $ 1,700 (3) 1.250% 75% (4) (5) 47.5% March 3, 2022 March 3, 2016 Houston Electric 300 1.125% 65% (5) 50.7% March 3, 2022 March 3, 2016 CERC Corp. 900 1.125% 65% 48.6% March 3, 2022 (1) Based on current credit ratings. (2) As defined in the revolving credit facility agreement, excluding Securitization Bonds. (3) Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility increased to $3.3 billion on October 5, 2018 as a result of the satisfaction of certain conditions described above. (4) On October 5, 2018, CenterPoint Energy’s financial covenant limit returned to 65% due to the termination of all commitments in respect of the Bridge Facility without any borrowing thereunder. (5) For CenterPoint Energy (whenever its financial covenant limit is 65% ) and Houston Electric, the financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive 12 -month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date CenterPoint Energy delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of CenterPoint Energy’s certification or (iii) the revocation of such certification.

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The Registrants reported the following effective tax rates: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 CenterPoint Energy (1) 24 % 37 % 26 % 36 % Houston Electric (2) 20 % 35 % 21 % 36 % CERC - Continuing operations (3) (4) 5 % 20 % 29 % 38 % CERC - Discontinued operations (5) 23 % 38 % 24 % 38 % (1) CenterPoint Energy’s lower effective tax rate for the three and nine months ended September 30, 2018 compared to the same periods for 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate decreased by 5% and 4% , respectively, for the three and nine months ended September 30, 2018 due to the amortization of EDIT. These decreases were partially offset by an increase to the effective tax rate of 5% for the three-month period ended September 30, 2018 as a result of the establishment of a state valuation allowance on certain net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. The effective tax rate increased by 7% for the nine-month period ended September 30, 2018 due to state law changes and the state valuation allowance. See Note 9 for further discussion on the Internal Spin. (2) Houston Electric’s lower effective tax rate for the three and nine months ended September 30, 2018 compared to the same periods for 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate was further reduced by 2% for both periods due to the amortization of EDIT. (3) CERC’s lower effective tax rate on the loss from continuing operations for the three months ended September 30, 2018 compared to the same period in 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate decreased by 18% due to state taxes as a result of the establishment of a state valuation allowance on certain net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These decreases were partially offset by an increase to the effective tax rate of 15% due to the amortization of EDIT. See Note 9 for further discussion on the Internal Spin. (4) CERC’s lower effective tax rate on income from continuing operations for the nine months ended September 30, 2018 compared to the same period in 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate decreased by 20% due to the amortization of EDIT. These decreases were partially offset by an increase to the effective tax rate of 22% as a result of an increase in state tax rates and the establishment of a state valuation allowance on certain net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. See Note 9 for further discussion on the Internal Spin. (5) CERC’s lower effective tax rate on income from discontinued operations for the three and nine months ended September 30, 2018 compared to the same periods in 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. See Note 9 for further discussion on the Internal Spin and the associated discontinued operations presentation.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Long-term Purchase Commitment [Table Text Block]	As of September 30, 2018 , minimum payment obligations for natural gas supply commitments are approximately: (in millions) Remaining three months of 2018 $ 88 2019 325 2020 303 2021 219 2022 183 2023 and beyond 1,644

Earnings Per Share (CenterPoi_2

Earnings Per Share (CenterPoint Energy) (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table reconciles numerators and denominators of CenterPoint Energy’s basic and diluted earnings per share calculations: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions, except share and per share amounts) Income available to common shareholders $ 153 $ 169 $ 243 $ 496 Basic weighted average common shares outstanding 431,554,000 431,026,000 431,437,000 430,939,000 Plus: Incremental shares from assumed conversions: Restricted stock 3,337,000 3,060,000 3,337,000 3,060,000 Diluted weighted average common shares 434,891,000 434,086,000 434,774,000 433,999,000 Basic earnings per common share $ 0.35 $ 0.39 $ 0.56 $ 1.15 Diluted earnings per common share $ 0.35 $ 0.39 $ 0.56 $ 1.14

Reportable Business Segments (T

Reportable Business Segments (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Financial data for business segments is as follows: CenterPoint Energy Three Months Ended September 30, 2018 2017 Revenues from Net Operating (Loss) Revenues from Net Operating (in millions) Electric Transmission & Distribution $ 897 (1) $ — $ 227 $ 843 (1) $ — $ 254 Natural Gas Distribution 402 8 3 390 8 25 Energy Services 910 10 (9 ) 861 10 7 Midstream Investments (2) — — — — — — Other Operations 3 — 5 4 — 11 Eliminations — (18 ) — — (18 ) — Consolidated $ 2,212 $ — $ 226 $ 2,098 $ — $ 297 Nine Months Ended September 30, 2018 2017 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Revenues from External Customers Net Intersegment Revenues Operating (in millions) Electric Transmission & Distribution $ 2,502 (1) $ — $ 523 $ 2,234 (1) $ — $ 511 Natural Gas Distribution 2,032 26 166 1,767 24 235 Energy Services 3,008 57 (20 ) 2,964 34 58 Midstream Investments (2) — — — — — — Other Operations 11 — (5 ) 11 — 24 Eliminations — (83 ) — — (58 ) — Consolidated $ 7,553 $ — $ 664 $ 6,976 $ — $ 828 (1) CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Affiliates of NRG $ 213 $ 221 $ 543 $ 540 Affiliates of Vistra Energy Corp. 79 72 192 172 (2) CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Enable $ 81 $ 68 $ 208 $ 199 CERC Three Months Ended September 30, 2018 2017 Revenues from Net Operating Revenues from Net Operating (in millions) Natural Gas Distribution $ 402 $ 8 $ 3 $ 390 $ 8 $ 25 Energy Services 910 10 (9 ) 861 10 7 Other Operations — — (1 ) — — (1 ) Eliminations — (18 ) — — (18 ) — Consolidated $ 1,312 $ — $ (7 ) $ 1,251 $ — $ 31 Nine Months Ended September 30, 2018 2017 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) (in millions) Natural Gas Distribution $ 2,032 $ 26 $ 166 $ 1,767 $ 24 $ 235 Energy Services 3,008 57 (20 ) 2,964 34 58 Other Operations — — — — — (4 ) Eliminations — (83 ) — — (58 ) — Consolidated $ 5,040 $ — $ 146 $ 4,731 $ — $ 289 CenterPoint Energy and CERC Total Assets September 30, 2018 December 31, 2017 CenterPoint Energy CERC CenterPoint CERC (in millions) Electric Transmission & Distribution $ 10,436 $ — $ 10,292 $ — Natural Gas Distribution 6,557 6,557 6,608 6,608 Energy Services 1,253 1,253 1,521 1,521 Midstream Investments 2,457 — 2,472 — Assets of discontinued operations — — (1) — 2,472 (1) Other Operations 2,206 (2) 110 2,497 (2) 70 Eliminations (681 ) (615 ) (654 ) (559 ) Consolidated $ 22,228 $ 7,305 $ 22,736 $ 10,112 (1) On September 4, 2018, CERC completed the Internal Spin. For further information regarding the Internal Spin, see Note 9. (2) Includes pension and other postemployment-related regulatory assets of $566 million and $600 million , respectively, as of September 30, 2018 and December 31, 2017 . As of September 30, 2018, reportable business segments by Registrant are as follows: Electric Transmission & Distribution Natural Gas Distribution Energy Services Midstream Investments Other Operations CenterPoint Energy X X X X X Houston Electric X CERC X X (1) X (1) In the three months ended September 30, 2018, CERC completed the Internal Spin. Previously, CERC’s equity method investment in Enable was included in the Midstream Investments segment. CERC’s equity in earnings in Enable, net of basis difference amortization and income tax, has been classified as discontinued operations for all periods presented. See Note 9 for further discussion on the Internal Spin and the associated discontinued operations presentation.
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Affiliates of NRG $ 213 $ 221 $ 543 $ 540 Affiliates of Vistra Energy Corp. 79 72 192 172
Midstream Investments [Table Text Block]	CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Enable $ 81 $ 68 $ 208 $ 199

Supplemental Disclosure of Ca_2

Supplemental Disclosure of Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]	The table below provides supplemental disclosure of cash flow information: Nine Months Ended September 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Cash Payments/Receipts: Interest, net of capitalized interest $ 301 $ 173 $ 85 $ 306 $ 176 $ 86 Income taxes, net 89 122 3 14 76 4 Non-cash transactions: Accounts payable related to capital expenditures 140 87 66 111 70 53 Capital distribution associated with the Internal Spin — — 1,460 — — — The table below provides a reconciliation of cash, cash equivalents and restricted cash reported in the Condensed Consolidated Balance Sheets to the amount reported in the Condensed Statements of Consolidated Cash Flows: September 30, 2018 December 31, 2017 CenterPoint Energy Houston Electric CenterPoint Energy Houston Electric (in millions) Cash and cash equivalents $ 293 $ 279 $ 260 $ 238 Restricted cash included in Prepaid expenses and other current assets 37 37 35 35 Restricted cash included in Other 1 1 1 1 Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows $ 331 $ 317 $ 296 $ 274 CERC does not have restricted cash and therefore was not included in the table above.

Related Party Transactions (H_2

Related Party Transactions (Houston Electric and CERC) (Tables)	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Schedule of Money Pool Investment and Borrowing [Table Text Block]	The table below summarizes money pool activity: September 30, 2018 December 31, 2017 Houston Electric CERC Houston Electric CERC (in millions) Money pool investments (borrowings) (1) $ (75 ) $ — $ (60 ) $ (570 ) Weighted average interest rate 2.45 % 2.45 % 1.90 % 1.90 % (1) Included in Accounts and notes receivable (payable)–affiliated companies in the Condensed Consolidated Balance Sheets.
Schedule of Related Party Transactions [Table Text Block]	Houston Electric and CERC affiliate related net interest income (expense) were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Interest income (expense) (1) $ 1 $ (2 ) $ 1 $ — $ 1 $ (4 ) $ 3 $ — (1) Interest income is included in Other, net and interest expense is included in Interest and other finance charges on the Condensed Statements of Consolidated Income. Amounts charged 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, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Corporate service charges $ 47 $ 36 $ 41 $ 30 $ 138 $ 105 $ 127 $ 93 Net affiliate service charges (billings) (3 ) 3 (1 ) 1 (8 ) 8 (6 ) 6 The table below presents transactions among Houston Electric, CERC and their parent, Utility Holding. Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Cash dividends paid to parent $ 60 $ 75 $ 45 $ 89 $ 123 $ 286 $ 87 $ 337 Cash contribution from parent — 600 — — — 600 — 38 Capital distribution to parent associated with the Internal Spin — 1,460 — — — 1,460 — —

Equity (CenterPoint Energy) (Ta

Equity (CenterPoint Energy) (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Dividends Declared [Table Text Block]	CenterPoint Energy declared dividends for the periods presented in the table below: Three Months Ended September 30, Nine Months Ended September 30, Equity Instrument 2018 2017 2018 (1) 2017 (per share) Common Stock $ 0.2775 $ 0.2675 $ 0.5550 $ 0.8025 (1) On December 13, 2017, CenterPoint Energy’s Board of Directors declared a regular quarterly cash dividend of $0.2775 per share of Common Stock, payable on March 8, 2018 to shareholders of record as of the close of business on February 15, 2018.
Convertible Debt [Table Text Block]	The following table illustrates the conversion rate per share of the Series B Preferred Stock, subject to certain anti-dilution adjustments: Applicable Market Value of the Common Stock Conversion Rate per Share of Series B Preferred Stock Greater than $32.6990 (threshold appreciation price) 30.5820 shares of Common Stock Equal to or less than $32.6990 but greater than or equal to $27.2494 Between 30.5820 and 36.6980 shares of Common Stock, determined by dividing $1,000 by the applicable market value Less than $27.2494 (initial price) 36.6980 shares of Common Stock The following table illustrates the conversion rate per depositary share, subject to certain anti-dilution adjustments: Applicable Market Value of the Common Stock Conversion Rate per Depository Share Greater than $32.6990 (threshold appreciation price) 1.5291 shares of Common Stock Equal to or less than $32.6990 but greater than or equal to $27.2494 Between 1.5291 and 1.8349 shares of Common Stock, determined by dividing $50 by the applicable market value Less than $27.2494 (initial price) 1.8349 shares of Common Stock

Background and Basis of Prese_2

Background and Basis of Presentation (Details)	9 Months Ended
	Sep. 30, 2018stateshares
Enable Midstream Partners [Member]
Ownership percentage of equity method investment	54.00%	[1],[2]
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Preferred units held | shares	14,520,000	[2],[3]
Natural Gas Distribution [Member]
Number of states in which entity operates	6
Energy Services [Member]
Number of states in which entity operates	33
Enable GP, LLC [Member] | CenterPoint Energy [Member]
Management rights ownership percentage	50.00%	[4],[5]
Incentive distribution right	40.00%	[5],[6]
[1]	Excludes the Enable Series A Preferred Units owned by CenterPoint Energy.
[2]	Includes Enable Series A Preferred Units held directly by CenterPoint Energy and common units held indirectly through CNP Midstream.
[3]	The carrying amount of the Enable Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both September 30, 2018 and December 31, 2017. No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion.
[4]	Enable is controlled jointly by CenterPoint Energy and OGE. Sale of CenterPoint Energy’s or OGE’s ownership interests in Enable GP to a third party is subject to mutual rights of first offer and first refusal, and CenterPoint Energy is not permitted to dispose of less than all of its interest in Enable GP.
[5]	Includes interests held through CNP Midstream.
[6]	Enable is expected to pay a minimum quarterly distribution of $0.2875 per common unit on its outstanding common units to the extent it has sufficient cash from operations after establishment of cash reserves and payment of fees and expenses, including payments to Enable GP and its affiliates, within 60 days after the end of each quarter. If cash distributions to Enable’s unitholders exceed $0.330625 per common unit in any quarter, Enable GP will receive increasing percentages or incentive distributions rights, up to 50%, of the cash Enable distributes in excess of that amount. In certain circumstances Enable GP will have the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election. To date, no incentive distributions have been made.

New Accounting Pronouncements_2

New Accounting Pronouncements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounting Standards Update 2016-15 [Member]
Effect of change on cash flow activities due to adoption of new ASU			$ 1	$ 3
Accounting Standards Update 2016-15 [Member] | Houston Electric [Member]
Effect of change on cash flow activities due to adoption of new ASU			1	3
Accounting Standards Update 2016-18 [Member]
Effect of change on cash flow activities due to adoption of new ASU			(2)	8
Accounting Standards Update 2016-18 [Member] | Houston Electric [Member]
Effect of change on cash flow activities due to adoption of new ASU			(2)	8
Accounting Standards Update 2017-07 [Member] | Operating Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	$ 9	$ 18	38	52
Accounting Standards Update 2017-07 [Member] | Other Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	(9)	(18)	(38)	(52)
Accounting Standards Update 2017-07 [Member] | Houston Electric [Member] | Operating Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	3	7	18	22
Accounting Standards Update 2017-07 [Member] | Houston Electric [Member] | Other Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	(3)	(7)	(18)	(22)
Accounting Standards Update 2017-07 [Member] | CERC Corp [Member] | Operating Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	0	5	8	16
Accounting Standards Update 2017-07 [Member] | CERC Corp [Member] | Other Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	$ 0	$ (5)	$ (8)	$ (16)

Pending Merger with Vectren (_2

Pending Merger with Vectren (CenterPoint Energy) (Details) $ / shares in Units, $ in Millions	Oct. 01, 2018	Sep. 30, 2018USD ($)$ / shares	Dec. 31, 2017USD ($)
Amount of cash to be paid to acquire Vectren		$ 6,000
Cash to be paid per share of Vectren common stock prior to closing of the Merger | $ / shares		$ 72
Short-term debt		$ 0	$ 39
Anticipated amount of short and long-term debt at the closing of the Merger		2,500
Vectren [Member]
Short-term debt		325
Long-term debt, including current maturities		2,000
Termination fee		150
CenterPoint Energy [Member]
Termination fee		$ 210
Series B Preferred Stock [Member] | Subsequent Event [Member]
Depositary share interest in a share of Series B Preferred Stock	0.05

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from contracts		$ 1,385	$ 1,347	$ 4,960	$ 4,397
Derivatives income		838	774	2,723	2,644
Other (3)	[1]	7	(5)	(47)	(7)
Total revenues		2,212	2,098	7,553	6,976
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(18)	(18)	(83)	(58)
Electric Transmission and Distribution [Member]
Disaggregation of Revenue [Line Items]
Total revenues	[2]	897	843	2,502	2,234
Electric Transmission and Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		0	0	0	0
Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Total revenues		402	390	2,032	1,767
Natural Gas Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(8)	(8)	(26)	(24)
Energy Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues		910	861	3,008	2,964
Energy Services [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(10)	(10)	(57)	(34)
Other Operations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		3	4	11	11
Other Operations [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		0	0	0	0
Reportable Subsegments [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	(8)	(8)	(26)	(24)
Derivatives income	[4]	(10)	(10)	(57)	(34)
Total revenues		(18)	(18)	(83)	(58)
Reportable Subsegments [Member] | Electric Transmission and Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	904	852	2,525	2,254
Derivatives income	[3]	0	0	(4)	1
Other (3)	[1],[3]	(7)	(9)	(19)	(21)
Total revenues	[3]	897	843	2,502	2,234
Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	398	396	2,093	1,784
Derivatives income	[3]	0	0	0	0
Other (3)	[1],[3]	12	2	(35)	7
Total revenues	[3]	402	390	2,032	1,767
Reportable Subsegments [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]	82	97	338	355
Derivatives income	[4]	838	774	2,727	2,643
Other (3)	[1],[4]	0	0	0	0
Total revenues	[4]	910	861	3,008	2,964
Reportable Subsegments [Member] | Other Operations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]	1	2	4	4
Derivatives income	[4]	0	0	0	0
Other (3)	[1],[4]	2	2	7	7
Total revenues	[4]	3	4	11	11
Houston Electric [Member]
Disaggregation of Revenue [Line Items]
Total revenues		897	843	2,506	2,233
Houston Electric [Member] | Reportable Subsegments [Member] | Electric Transmission and Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		904	852	2,525	2,254
Other (3)	[1]	(7)	(9)	(19)	(21)
Total revenues		897	843	2,506	2,233
CERC Corp [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		480	493	2,431	2,139
Derivatives income		838	774	2,727	2,643
Other (3)	[1]	12	2	(35)	7
Total revenues		1,312	1,251	5,040	4,731
CERC Corp [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(18)	(18)	(83)	(58)
CERC Corp [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Total revenues		402	390	2,032	1,767
CERC Corp [Member] | Natural Gas Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(8)	(8)	(26)	(24)
CERC Corp [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues		910	861	3,008	2,964
CERC Corp [Member] | Energy Services [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(10)	(10)	(57)	(34)
CERC Corp [Member] | Other Operations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		0	0	0	0
CERC Corp [Member] | Other Operations [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		0	0	0	0
CERC Corp [Member] | Reportable Subsegments [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	(8)	(8)	(26)	(24)
Derivatives income	[4]	(10)	(10)	(57)	(34)
Total revenues		(18)	(18)	(83)	(58)
CERC Corp [Member] | Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	398	396	2,093	1,784
Derivatives income	[3]	0	0	0	0
Other (3)	[1],[3]	12	2	(35)	7
Total revenues	[3]	402	390	2,032	1,767
CERC Corp [Member] | Reportable Subsegments [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]	82	97	338	355
Derivatives income	[4]	838	774	2,727	2,643
Other (3)	[1],[4]	0	0	0	0
Total revenues	[4]	$ 910	$ 861	$ 3,008	$ 2,964
[1]	Primarily consists of income from ARPs and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. The Registrants recognize ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period.
[2]	CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions)Affiliates of NRG $213 $221 $543 $540Affiliates of Vistra Energy Corp. 79 72 192 172
[3]	Reflected in Utility revenues in the Condensed Statements of Consolidated Income.
[4]	Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income.

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan, Change in Accumulated Comprehensive Loss [Roll Forward]
Beginning Balance		$ (63)	$ (70)	$ (66)	$ (72)
Amounts reclassified from accumulated other comprehensive loss:
Prior service cost (1)	[1]	0	0	1	1
Actuarial losses (1)	[1]	2	2	5	5
Tax expense		(1)	(2)	(2)	(4)
Net current period other comprehensive income		1	0	4	2
Ending Balance		(62)	(70)	(62)	(70)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost (credit)		16	23	46	71
Total contributions expected in current year		67		67
Total contributions to the plans during the period		3		67
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost (credit)		1	2	4	6
Total contributions expected in current year		16		16
Total contributions to the plans during the period		4		11
Operation and maintenance expense [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	10	9	28	27
Operation and maintenance expense [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	0	0	1	1
Other, net [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	20	22	59	66
Expected return on plan assets (2)	[3]	(27)	(24)	(80)	(72)
Amortization of prior service cost (credit) (2)	[3]	3	2	7	7
Amortization of net loss (2)	[3]	10	14	32	43
Other, net [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	3	4	10	12
Expected return on plan assets (2)	[3]	(1)	(1)	(4)	(4)
Amortization of prior service cost (credit) (2)	[3]	(1)	(1)	(3)	(3)
Houston Electric [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost (credit)		0	0	(1)	0
Total contributions expected in current year		10		10
Total contributions to the plans during the period		3		7
Houston Electric [Member] | Operation and maintenance expense [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	0	0	0	0
Houston Electric [Member] | Other, net [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	2	3	6	7
Expected return on plan assets (2)	[3]	(1)	(1)	(3)	(3)
Amortization of prior service cost (credit) (2)	[3]	(1)	(2)	(4)	(4)
CERC Corp [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost (credit)		2	1	4	4
Total contributions expected in current year		5		5
Total contributions to the plans during the period		1		3
CERC Corp [Member] | Operation and maintenance expense [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	1	1	1	1
CERC Corp [Member] | Other, net [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	1	1	3	3
Expected return on plan assets (2)	[3]	0	(1)	(1)	(1)
Amortization of prior service cost (credit) (2)	[3]	$ 0	$ 0	$ 1	$ 1
[1]	These accumulated other comprehensive components are included in the computation of net periodic cost.
[2]	Amounts presented in the table above are included in Operation and maintenance expense in each of the Registrants’ respective Condensed Statements of Consolidated Income, net of amounts capitalized and regulatory deferrals.
[3]	Amounts presented in the table above are included in Other, net in each of the Registrants’ respective Condensed Statements of Consolidated Income, net of regulatory deferrals.

Regulatory Accounting (Details)

Regulatory Accounting (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Securitized regulatory assets		$ 1,146		$ 1,146		$ 1,590
Unrecognized equity return (2)	[1]	(225)		(225)		(287)
Unamortized loss on reacquired debt		70		70		75
Regulatory assets		1,934		1,934		2,347
Total regulatory assets		1,994		1,994		2,477
Regulatory liabilities		2,506		2,506		2,464
Total regulatory liabilities		2,553		2,553		2,488
Total regulatory assets and liabilities, net		(559)		(559)		(11)
Houston Electric [Member]
Securitized regulatory assets		1,146		1,146		1,590
Unrecognized equity return (2)	[1]	(225)		(225)		(287)
Unamortized loss on reacquired debt		70		70		75
Regulatory assets		1,202		1,202		1,570
Total regulatory assets		1,202		1,202		1,570
Regulatory liabilities		1,265		1,265		1,263
Total regulatory liabilities		1,287		1,287		1,285
Total regulatory assets and liabilities, net		(85)		(85)		285
Amount of allowed equity return on the true-up balance that was recognized in the period		17	$ 13	62	$ 30
CERC Corp [Member]
Securitized regulatory assets		0		0		0
Unrecognized equity return (2)	[1]	0		0		0
Unamortized loss on reacquired debt		0		0		0
Regulatory assets		170		170		181
Total regulatory assets		230		230		311
Regulatory liabilities		1,241		1,241		1,201
Total regulatory liabilities		1,266		1,266		1,203
Total regulatory assets and liabilities, net		(1,036)		(1,036)		(892)
Hurricane Harvey [Member]
Regulatory assets	[2]	67		67		64
Hurricane Harvey [Member] | Houston Electric [Member]
Regulatory assets	[2]	61		61		58
Hurricane Harvey [Member] | CERC Corp [Member]
Regulatory assets	[2]	6		6		6
Prepaid expenses and other current assets [Member]
Current regulatory assets (1)	[3]	60		60		130
Prepaid expenses and other current assets [Member] | Houston Electric [Member]
Current regulatory assets (1)	[3]	0		0		0
Prepaid expenses and other current assets [Member] | CERC Corp [Member]
Current regulatory assets (1)	[3]	60		60		130
Other current liabilities [Member]
Current regulatory liabilities (7)	[4]	47		47		24
Other current liabilities [Member] | Houston Electric [Member]
Current regulatory liabilities (7)	[4]	22		22		22
Other current liabilities [Member] | CERC Corp [Member]
Current regulatory liabilities (7)	[4]	25		25		2
Pension and Other Postretirement Plans Costs [Member]
Regulatory assets	[5]	609		609		646
Pension and Other Postretirement Plans Costs [Member] | Houston Electric [Member]
Regulatory assets	[5]	32		32		31
Pension and Other Postretirement Plans Costs [Member] | CERC Corp [Member]
Regulatory assets	[5]	15		15		20
Amounts related to TCJA [Member]
Regulatory assets	[6]	48		48		48
Amounts related to TCJA [Member] | Houston Electric [Member]
Regulatory assets	[6]	34		34		33
Amounts related to TCJA [Member] | CERC Corp [Member]
Regulatory assets	[6]	14		14		15
Other Regulatory Assets (Liabilities) [Member]
Regulatory assets	[7]	219		219		211
Other Regulatory Assets (Liabilities) [Member] | Houston Electric [Member]
Regulatory assets	[7]	84		84		70
Other Regulatory Assets (Liabilities) [Member] | CERC Corp [Member]
Regulatory assets	[7]	135		135		140
Amounts related to TCJA [Member]
Regulatory liabilities	[6]	1,362		1,362		1,354
Amounts related to TCJA [Member] | Houston Electric [Member]
Regulatory liabilities	[6]	858		858		862
Amounts related to TCJA [Member] | CERC Corp [Member]
Regulatory liabilities	[6]	504		504		492
Removal Costs [Member]
Regulatory liabilities		887		887		878
Removal Costs [Member] | Houston Electric [Member]
Regulatory liabilities		275		275		285
Removal Costs [Member] | CERC Corp [Member]
Regulatory liabilities		612		612		593
Other Regulatory Assets (Liabilities) [Member]
Regulatory liabilities		257		257		232
Other Regulatory Assets (Liabilities) [Member] | Houston Electric [Member]
Regulatory liabilities		132		132		116
Other Regulatory Assets (Liabilities) [Member] | CERC Corp [Member]
Regulatory liabilities		125		125		116
Natural Gas Distribution [Member] | Pension and Other Postretirement Plans Costs [Member]
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		$ 4		$ 4		$ 7
[1]	The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended September 30, 2018 and 2017, CenterPoint Energy and Houston Electric recognized approximately $17 million and $13 million, respectively, of the allowed equity return. During the nine months ended September 30, 2018 and 2017, CenterPoint Energy and Houston Electric recognized approximately $62 million and $30 million, respectively, of the allowed equity return. The timing of CenterPoint Energy’s and Houston Electric’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months.
[2]	The Registrants are not earning a return on Hurricane Harvey restoration costs.
[3]	Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ Condensed Consolidated Balance Sheets.
[4]	Current regulatory liabilities are included in Other current liabilities in each of the Registrants’ respective Condensed Consolidated Balance Sheets.
[5]	Includes a portion of NGD’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates that is being deferred for rate making purposes, of which $4 million and $7 million as of September 30, 2018 and December 31, 2017, respectively, were not earning a return.
[6]	The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities.
[7]	Other long-term regulatory assets that are not earning a return were not material as of September 30, 2018 and December 31, 2017.

Derivative Instruments Derivati

Derivative Instruments Derivatives and Hedging (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Oct. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Weather hedges term				10 years
Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges	[1]	$ 0	$ 0	$ (4)	$ 1
2018 to 2019 [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				9
2018 to 2019 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				8
2018 to 2019 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	0	0	0
2017 to 2018 [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				8
2017 to 2018 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				9
2017 to 2018 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	0	(4)	0
2016 to 2017 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				9
2016 to 2017 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	0	0	1
Houston Electric [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Aggregate notional amount		100		100
CERC Corp [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges	[1]	0	0	0	0
CERC Corp [Member] | 2018 to 2019 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	0	0	0
CERC Corp [Member] | 2017 to 2018 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	$ 0	0	$ 0
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Aggregate notional amount		$ 200		$ 200			$ 0
Cash Flow Hedging [Member] | Houston Electric [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Aggregate notional amount							$ 0
Cash Flow Hedging [Member] | Subsequent Event [Member] | Houston Electric [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Aggregate notional amount						$ 100
[1]	Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income.

Derivative Instruments Summary

Derivative Instruments Summary of Derivative Activity (Details) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)Bcf	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)Bcf
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		$ 164		$ 164		$ 218
Derivative Liabilities Fair Value		795		795		775
Derivative Asset		39		39		80
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item		1		1		14
Total amounts presented in the statements of income in which the effects of hedges are recorded	[1]	864	$ 832	2,927	$ 2,843
Gain (loss) on derivative instruments not designated as hedging instruments		(42)	(6)	(246)	103
Net deferred gain (loss) from cash flow hedges (net of tax)		3	(2)	6	(3)
Aggregate fair value of derivatives containing material adverse change provisions in a net liability position		2		2		2
Fair value of collateral already posted		0		0		0
Additional collateral required to be posted if credit risk contingent features triggered		1		1		2
Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Net deferred gain (loss) from cash flow hedges (net of tax)	[2]	0	(1)	(1)	(1)
Interest Rate Contract [Member] | Not Designated as Hedging Instrument, Economic Hedge [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		1		$ 1		$ 1
Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative gross volume notional amount (in Bcf) | Bcf				1,865		1,795
Net amount presented in the consolidated balance sheets	[3]	72		$ 72		$ 130
Gross Amounts Recognized	[4]	51		51		111
Gross Amounts Offset in the Consolidated Balance Sheets		21		21		19
Energy Related Derivative [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	[3]	73		73		110
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item		1		1		14
Gross Amounts Recognized	[4]	107		107		165
Gross Amounts Offset		(34)		(34)		(55)
Energy Related Derivative [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	[3]	38		38		44
Gross Amounts Recognized	[4]	54		54		53
Gross Amounts Offset		(16)		(16)		(9)
Energy Related Derivative [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[4]	(77)		(77)		(83)
Gross Amounts Offset		44		44		63
Derivative Liability	[3]	(33)		(33)		(20)
Energy Related Derivative [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[4]	(33)		(33)		(24)
Gross Amounts Offset		27		27		20
Derivative Liability	[3]	(6)		$ (6)		$ (4)
Energy Related Derivative [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
Derivative gross volume notional amount (in Bcf) | Bcf				310		224
IDS Derivative [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		0		$ 0		$ 0
Derivative Liabilities Fair Value		685		685		668
Houston Electric [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		3		3		0
Derivative Liabilities Fair Value		0		0		0
Net deferred gain (loss) from cash flow hedges (net of tax)		3	0	7	(1)
Houston Electric [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Net deferred gain (loss) from cash flow hedges (net of tax)	[2]	3	0	7	(1)
CERC Corp [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		161		161		218
Derivative Liabilities Fair Value		110		110		107
Total amounts presented in the statements of income in which the effects of hedges are recorded		864	832	2,927	2,843
Gain (loss) on derivative instruments not designated as hedging instruments		2	30	70	162
Net deferred gain (loss) from cash flow hedges (net of tax)		0	(1)	0	(1)
CERC Corp [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Net deferred gain (loss) from cash flow hedges (net of tax)	[2]	0	(1)	0	(1)
CERC Corp [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[5],[6],[7]	76		76		114
Derivative Liabilities Fair Value	[5],[6],[7]	3		3		4
CERC Corp [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[5],[6],[7]	38		38		44
Derivative Liabilities Fair Value	[5],[6],[7]	0		0		0
CERC Corp [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[5],[6],[7]	31		31		38
Derivative Liabilities Fair Value	[5],[6],[7]	72		72		78
CERC Corp [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[5],[6],[7]	16		16		9
Derivative Liabilities Fair Value	[5],[6],[7]	33		33		24
Cash Flow Hedging [Member] | Houston Electric [Member] | Interest Rate Contract [Member] | Designated as Fair Value Hedge [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		3		3		0
Derivative Liabilities Fair Value		0		0		0
Fair Value Hedging [Member] | Energy Related Derivative [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		39		39		80
Fair Value Hedging [Member] | CERC Corp [Member] | Energy Related Derivative [Member] | Designated as Fair Value Hedge [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[5],[6],[7]	0		0		13
Derivative Liabilities Fair Value	[5],[6],[7]	2		2		$ 1
Gains (Losses) in Revenue [Member] | CERC Corp [Member] | Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments not designated as hedging instruments		2	30	70	162
Non-utility Natural Gas Expense [Member] | Fair Value Hedging [Member] | Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Change in unrealized gain (loss) on fair value hedging instruments	[1]	1	4	(13)	(10)
Amounts excluded from effectiveness testing recognized in earnings immediately (1)	[1],[8]	6	(9)	(73)	(93)
Non-utility Natural Gas Expense [Member] | Fair Value Hedging [Member] | Energy Related Derivative [Member] | Designated as Fair Value Hedge [Member]
Derivatives, Fair Value [Line Items]
Change in unrealized gain (loss) on fair value hedging instruments	[1]	(1)	(4)	13	10
Gains (Losses) in Other Income (Expense) [Member] | IDS Derivative [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments not designated as hedging instruments		(44)	(36)	(316)	(59)
Gains (Losses) in Interest and other finance charges [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments not designated as hedging instruments		0	0	0	0
Gains (Losses) in Interest and other finance charges [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) reclassified from accumulated OCI into income		$ 1	$ (1)	$ 1	$ (1)
[1]	Income statement impact associated with cash flow hedge activity is related to gains and losses reclassified from accumulated other comprehensive income into income. Amounts are immaterial for the Registrants for both the three and nine months ended September 30, 2018 and 2017, respectively.
[2]	Gains and losses are reclassified from accumulated other comprehensive income into income when the hedged transactions affect earnings. The reclassification amounts are included in Interest and other finance charges in the Condensed Statements of Consolidated Income. Amounts are less than $1 million for each of the three and nine months ended September 30, 2018 and 2017. Over the next twelve months, estimated amortization of accumulated other comprehensive income into related income is expected to be immaterial.
[3]	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.
[4]	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.
[5]	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
[6]	Natural gas contracts are presented on a net basis in the 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 $72 million asset and a $130 million asset as of September 30, 2018 and December 31, 2017, respectively, as shown on CenterPoint Energy’s and CERC’s Condensed Consolidated Balance Sheets (and as detailed in the Offsetting of Natural Gas Derivative Assets and Liabilities table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, impacted by collateral netting of $21 million and $19 million, respectively.
[7]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,865 Bcf or a net 310 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of September 30, 2018 and December 31, 2017, respectively. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure.
[8]	As a result of the adoption of ASU 2017-12 effective January 1, 2018 (see Note 2 for additional information), CenterPoint Energy and CERC exclude from their assessment of hedge effectiveness the natural gas market price difference between locations of the hedged inventory and the delivery location specified in the hedge instruments. Prior to the adoption of this accounting guidance, the timing difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity, was excluded from the assessment of effectiveness for CenterPoint Energy’s and CERC’s existing fair value hedges and will continue to be excluded from the assessment of hedge effectiveness. CenterPoint Energy and CERC elected to continue to immediately recognize amounts excluded from hedge effectiveness in their respective Condensed Statements of Consolidated Income.

Fair Value Measurements (Detail

Fair Value Measurements (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Financial Liabilities Fair Value Disclosure		$ 724		$ 724		$ 692
Assets
Derivative assets		39		39		80
Assets, Fair Value Disclosure		815		815		1,199
Total derivative assets, netting adjustment	[1]	(50)		(50)		(64)
Liabilities
Total derivative liabilities, netting adjustment	[1]	(71)		(71)		(83)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		(628)	$ (712)	(622)	$ (704)
Total gains (losses)		1	(38)	4	(38)
Total settlements		(1)	(1)	(36)	(5)
Transfers into Level 3		0	7	(2)	9
Transfers out of Level 3 (1)	[2]	650	(6)	678	(12)
Ending balance (2)	[3]	22	(750)	22	(750)
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date:		11	(36)	9	(42)
Carrying Amount [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[4]	7,758		7,758		8,679
Fair Value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[4]	7,888		7,888		9,220
Energy Related Derivative [Member]
Assets
Derivative fair value offsets, net		21		21		19
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Financial Liabilities Fair Value Disclosure		0		0		0
Assets
Assets, Fair Value Disclosure		704		704		1,045
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Financial Liabilities Fair Value Disclosure		790		790		96
Assets
Assets, Fair Value Disclosure		134		134		161
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Financial Liabilities Fair Value Disclosure		5		5		679
Assets
Assets, Fair Value Disclosure		27		$ 27		57
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair value inputs (price per MMBtu)				1.28
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair value inputs (price per MMBtu)				6.88
Fair Value, Measurements, Recurring [Member]
Assets
Corporate equities		630		$ 630		963
Investments, including money market funds (2)	[5]	70		70		68
Hedged portion of natural gas inventory		1		1		14
Fair Value, Measurements, Recurring [Member] | Interest Rate Contract [Member]
Assets
Derivative assets		3		3		0
Fair Value, Measurements, Recurring [Member] | Energy Related Derivative [Member]
Assets
Derivative asset, netting adjustment	[1],[6]	(50)		(50)		(64)
Derivative assets	[6]	111		111		154
Liabilities
Derivative liabilities, netting adjustment	[1],[6]	(71)		(71)		(83)
Derivative liabilities	[6]	39		39		24
Fair Value, Measurements, Recurring [Member] | IDS Derivative [Member]
Liabilities
Derivative liabilities, netting adjustment	[1]	0		0		0
Derivative liabilities		685		685		668
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Corporate equities		630		630		963
Investments, including money market funds (2)	[5]	70		70		68
Hedged portion of natural gas inventory		1		1		14
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Contract [Member]
Assets
Derivative asset		3		3		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Energy Related Derivative [Member]
Assets
Derivative asset	[6]	0		0		0
Liabilities
Derivative liability	[6]	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | IDS Derivative [Member]
Liabilities
Derivative liability		0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Corporate equities		0		0		0
Investments, including money market funds (2)	[5]	0		0		0
Hedged portion of natural gas inventory		0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Contract [Member]
Assets
Derivative asset		0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Energy Related Derivative [Member]
Assets
Derivative asset	[6]	134		134		161
Liabilities
Derivative liability	[6]	105		105		96
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | IDS Derivative [Member]
Liabilities
Derivative liability		685		685		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Corporate equities		0		0		0
Investments, including money market funds (2)	[5]	0		0		0
Hedged portion of natural gas inventory		0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Contract [Member]
Assets
Derivative asset		0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Energy Related Derivative [Member]
Assets
Derivative asset	[6]	27		27		57
Liabilities
Derivative liability	[6]	5		5		11
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | IDS Derivative [Member]
Liabilities
Derivative liability		0		0		668
CERC Corp [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Financial Liabilities Fair Value Disclosure		39		39		24
Assets
Assets, Fair Value Disclosure		125		125		182
Total derivative assets, netting adjustment	[1]	(50)		(50)		(64)
Liabilities
Total derivative liabilities, netting adjustment	[1]	(71)		(71)		(83)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		13	28	46	13
Total gains (losses)		1	(2)	4	21
Total settlements		(1)	(1)	(36)	(5)
Transfers into Level 3		0	7	(2)	9
Transfers out of Level 3 (1)	[2]	9	(6)	10	(12)
Ending balance (2)	[3]	22	26	22	26
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date:		11	$ 0	9	$ 17
CERC Corp [Member] | Carrying Amount [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities		2,257		2,257		2,457
CERC Corp [Member] | Fair Value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities		2,367		2,367		2,708
CERC Corp [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Financial Liabilities Fair Value Disclosure		0		0		0
Assets
Assets, Fair Value Disclosure		14		14		28
CERC Corp [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Financial Liabilities Fair Value Disclosure		105		105		96
Assets
Assets, Fair Value Disclosure		134		134		161
CERC Corp [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Financial Liabilities Fair Value Disclosure		5		5		11
Assets
Assets, Fair Value Disclosure		27		27		57
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Corporate equities		3		3		3
Investments, including money market funds (2)	[5]	10		10		11
Hedged portion of natural gas inventory		1		1		14
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Energy Related Derivative [Member]
Assets
Derivative asset, netting adjustment	[1],[6]	(50)		(50)		(64)
Derivative assets	[6]	111		111		154
Liabilities
Derivative liabilities, netting adjustment	[1],[6]	(71)		(71)		(83)
Derivative liabilities	[6]	39		39		24
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Corporate equities		3		3		3
Investments, including money market funds (2)	[5]	10		10		11
Hedged portion of natural gas inventory		1		1		14
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Energy Related Derivative [Member]
Assets
Derivative asset	[6]	0		0		0
Liabilities
Derivative liability	[6]	0		0		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Corporate equities		0		0		0
Investments, including money market funds (2)	[5]	0		0		0
Hedged portion of natural gas inventory		0		0		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Energy Related Derivative [Member]
Assets
Derivative asset	[6]	134		134		161
Liabilities
Derivative liability	[6]	105		105		96
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Corporate equities		0		0		0
Investments, including money market funds (2)	[5]	0		0		0
Hedged portion of natural gas inventory		0		0		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Energy Related Derivative [Member]
Assets
Derivative asset	[6]	27		27		57
Liabilities
Derivative liability	[6]	5		5		11
Houston Electric [Member]
Assets
Assets, Fair Value Disclosure		55		55		51
Total derivative assets, netting adjustment		0		0		0
Houston Electric [Member] | Carrying Amount [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[4]	4,782		4,782		4,753
Houston Electric [Member] | Fair Value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[4]	4,813		4,813		5,034
Houston Electric [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Assets, Fair Value Disclosure		55		55		51
Houston Electric [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Assets, Fair Value Disclosure		0		0		0
Houston Electric [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Assets, Fair Value Disclosure		0		0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Investments, including money market funds (2)	[5]	52		52		51
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Contract [Member]
Assets
Derivative assets		3		3		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Investments, including money market funds (2)	[5]	52		52		51
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Contract [Member]
Assets
Derivative asset		3		3		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Investments, including money market funds (2)	[5]	0		0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Contract [Member]
Assets
Derivative asset		0		0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Investments, including money market funds (2)	[5]	0		0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Contract [Member]
Assets
Derivative asset		$ 0		$ 0		$ 0
[1]	Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy and CERC to settle positive and negative positions and also include cash collateral of $21 million and $19 million as of September 30, 2018 and December 31, 2017, respectively, posted with the same counterparties.
[2]	As of September 30, 2018, CenterPoint Energy transferred its indexed debt securities derivative from Level 3 to Level 2 to reflect changes in the significance of the unobservable inputs used in the valuation.
[3]	CenterPoint Energy and CERC did not have significant Level 3 sales or purchases during either of the three or nine months ended September 30, 2018 or 2017.
[4]	Includes Securitization Bond debt.
[5]	Amounts are included in Prepaid expenses and other current assets in the Condensed Consolidated Balance Sheets.
[6]	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.

Unconsolidated Affiliate (Cen_3

Unconsolidated Affiliate (CenterPoint Energy and CERC) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017	Sep. 04, 2018	Dec. 31, 2017
Enable Units [Abstract]
Preferred units – unconsolidated affiliate		$ 363			$ 363				$ 363
Percentage of sales that trigger right of first refusal					5.00%
Enable Distributions [Abstract]
Total distributions received from Enable		83		$ 83	$ 250		$ 250
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
Equity in earnings of unconsolidated affiliate, net		81		68	208		199
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s equity method investment in Enable		2,457			2,457				2,472
CERC Corp [Member]
Investment in unconsolidated affiliate - discontinued operations		0			0				2,472
Deferred income taxes, net - discontinued operations		0			0				927
Contribution from parent		600		0	600		38
Enable Distributions [Abstract]
Total distributions received from Enable	[1]	74		74	223		223
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Income tax expense		13		26	44		75
Income from discontinued operations (net of tax of $13, $26, $44 and $75, respectively)		$ 44		42	$ 140		124
OGE [Member]
Enable Units [Abstract]
Percentage of sales that trigger right of first refusal					5.00%
Enable Midstream Partners [Member]
Enable Partnership Interest [Abstract]
Ownership percentage of equity method investment	[2],[3]	54.00%			54.00%
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
Operating revenues		$ 928		705	$ 2,481		1,997
Cost of sales, excluding depreciation and amortization		516		349	1,335		936
Depreciation and amortization		100		90	292		267
Operating income		171		137	436		399
Net income attributable to Enable common units		129		104	320		301
CenterPoint Energy’s interest		70		56	173		163
Basis difference amortization (1)	[4]	11		12	35		36
Equity in earnings of unconsolidated affiliate, net		81		68	$ 208		199
Basis difference amortization period					31 years
Equity Method Investment, Summarized Financial Information, Assets and Liabilities [Abstract]
Current assets		481			$ 481				416
Non-current assets		11,454			11,454				11,177
Current liabilities		1,403			1,403				1,279
Non-current liabilities		2,964			2,964				2,660
Non-controlling interest		11			11				12
Preferred equity		362			362				362
Enable partners’ equity		7,195			7,195				7,280
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s ownership interest in Enable partners’ equity		3,883			3,883				3,935
CenterPoint Energy’s basis difference		(1,426)			(1,426)				(1,463)
CenterPoint Energy’s equity method investment in Enable		2,457			2,457				2,472
Enable Midstream Partners [Member] | Common Units [Member]
Enable Distributions [Abstract]
Distributions received from Enable equity method investment	[5]	74		74	223		223
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Enable Distributions [Abstract]
Distributions received from Enable cost method investment	[6]	$ 9		9	$ 27		27
Common Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Limited partner interest units held	[3]	233,856,623			233,856,623
Series A Preferred Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Preferred Units Held	[3],[7]	14,520,000			14,520,000
Transitional Service [Member] | Enable Midstream Partners [Member]
Related Party Transaction, Other Revenues from Transactions with Related Party	[8]	$ 1		0	$ 4		3
Transactions with Enable [Abstract]
Accounts receivable for amounts billed for transition services (CenterPoint Energy)		3			3				1
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Natural gas expenses, including transportation and storage costs (CenterPoint Energy and CERC)		23		23	89		80
Accounts payable for natural gas purchases from Enable (CenterPoint Energy and CERC)		$ 8			$ 8				13
Enable Midstream Partners [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[2]				100.00%
Enable Units [Abstract]
Maximum incentive distribution right					50.00%
Enable Midstream Partners [Member] | OGE [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[2]				25.60%
Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[2]				20.40%
Enable Midstream Partners [Member] | Minimum [Member]
Enable Units [Abstract]
Incentive distribution per unit					$ 0.2875
Enable Midstream Partners [Member] | Maximum [Member]
Enable Units [Abstract]
Incentive distribution per unit					$ 0.330625
Enable Midstream Partners [Member] | Common Units [Member]
Enable Units [Abstract]
Limited partner interest units held		433,216,156			433,216,156
Enable Midstream Partners [Member] | Common Units [Member] | OGE [Member]
Enable Units [Abstract]
Limited partner interest units held		110,982,805			110,982,805
Enable Midstream Partners [Member] | Common Units [Member] | Public unitholders [Member]
Enable Units [Abstract]
Limited partner interest units held		88,376,728			88,376,728
Enable GP, LLC [Member] | CenterPoint Energy [Member]
Enable Units [Abstract]
Management rights ownership percentage	[9],[10]				50.00%
Incentive distribution right	[10],[11]				40.00%
Enable GP, LLC [Member] | OGE [Member]
Enable Units [Abstract]
Management rights ownership percentage	[9]				50.00%
Incentive distribution right	[11]				60.00%
Enable Midstream Partners [Member] | Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] | CERC Corp [Member]
Investment in unconsolidated affiliate - discontinued operations		$ 0	[12]		$ 0	[12]		$ 2,400	$ 2,472	[12]
Deferred income taxes, net - discontinued operations								$ 974
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Equity in earnings of unconsolidated affiliate, net		57		68	184		199
Income tax expense		13		26	44		75
Income from discontinued operations (net of tax of $13, $26, $44 and $75, respectively)		$ 44		$ 42	$ 140		$ 124
Common Units [Member] | Enable Midstream Partners [Member]
Enable Distributions [Abstract]
Enable common units distributions paid (per unit)		$ 0.318			$ 0.954
Series A Preferred Units [Member] | Enable Midstream Partners [Member]
Enable Distributions [Abstract]
Enable common units distributions paid (per unit)		$ 0.625			$ 1.875
[1]	On September 4, 2018, CERC completed the Internal Spin. After such date, CNP Midstream owned the Enable common units previously owned by CERC.
[2]	Excludes the Enable Series A Preferred Units owned by CenterPoint Energy.
[3]	Includes Enable Series A Preferred Units held directly by CenterPoint Energy and common units held indirectly through CNP Midstream.
[4]	Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s share of Enable’s earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s original investment in Enable and their underlying equity in Enable’s net assets. The basis difference is amortized over approximately 31 years, the average life of the assets to which the basis difference is attributed.
[5]	Reflects cash distributions of $0.318 and $0.954 per common unit for the three and nine months ended September 30, 2018 and 2017, respectively.
[6]	Reflects cash distributions of $0.625 and $1.875 per Enable Series A Preferred Unit for the three and nine months ended September 30, 2018 and 2017, respectively.
[7]	The carrying amount of the Enable Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both September 30, 2018 and December 31, 2017. No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion.
[8]	Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement.
[9]	Enable is controlled jointly by CenterPoint Energy and OGE. Sale of CenterPoint Energy’s or OGE’s ownership interests in Enable GP to a third party is subject to mutual rights of first offer and first refusal, and CenterPoint Energy is not permitted to dispose of less than all of its interest in Enable GP.
[10]	Includes interests held through CNP Midstream.
[11]	Enable is expected to pay a minimum quarterly distribution of $0.2875 per common unit on its outstanding common units to the extent it has sufficient cash from operations after establishment of cash reserves and payment of fees and expenses, including payments to Enable GP and its affiliates, within 60 days after the end of each quarter. If cash distributions to Enable’s unitholders exceed $0.330625 per common unit in any quarter, Enable GP will receive increasing percentages or incentive distributions rights, up to 50%, of the cash Enable distributes in excess of that amount. In certain circumstances Enable GP will have the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election. To date, no incentive distributions have been made.
[12]	On September 4, 2018, CERC completed the Internal Spin. For further information regarding the Internal Spin, see Note 9.

Goodwill and Other Intangible_3

Goodwill and Other Intangibles (CenterPoint Energy and CERC) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Goodwill [Line Items]
Goodwill		$ 867		$ 867		$ 867
Intangible assets gross carrying amount		105		105		105
Intangible assets accumulated amortization		(38)		(38)		(31)
Net intangible assets		67		67		74
Amortization expense of intangible assets		2	$ 2	7	$ 5
Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill		746		746		746
Energy Services [Member]
Goodwill [Line Items]
Goodwill	[1]	110		110		110
Accumulated goodwill impairment charge recorded in 2012		252		252		252
Other Operations [Member]
Goodwill [Line Items]
Goodwill		11		$ 11		$ 11
Customer Relationships [Member]
Goodwill [Line Items]
Intangible asset useful lives				15 years		15 years
Intangible assets gross carrying amount		86		$ 86		$ 86
Intangible assets accumulated amortization		(26)		(26)		(21)
Net intangible assets		60		$ 60		$ 65
Noncompete Agreements [Member]
Goodwill [Line Items]
Intangible asset useful lives				4 years		4 years
Intangible assets gross carrying amount		4		$ 4		$ 4
Intangible assets accumulated amortization		(2)		(2)		(2)
Net intangible assets		2		2		2
Other Intangible Assets [Member]
Goodwill [Line Items]
Intangible assets gross carrying amount		15		15		15
Intangible assets accumulated amortization		(10)		(10)		(8)
Net intangible assets		$ 5		$ 5		$ 7
[1]	Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012.

Indexed Debt Securities (ZENS_3

Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)shares$ / shares	Sep. 30, 2017USD ($)	Jun. 14, 2018$ / sharesshares	Jan. 31, 2018$ / shares	Dec. 31, 2017shares	Nov. 26, 2017$ / shares
Cash paid per share exchanged | $ / shares	$ 72
Distribution To ZENS holders	$ 398	$ 0
Subordinated Debt ZENS [Member]
Principal amount of debt issued	1,000
Outstanding debt balance	$ 828
Subordinated note cash exchangeable percentage of fair value	95.00%
Contingent principal amount outstanding	$ 98
AT&T To Acquire Time Warner [Member]
Distribution To ZENS holders	382
Indexed debt – reduction	(95)
Indexed debt securities derivative – reduction	(45)
Loss on indexed debt securities	242
Meredith to acquire Time [Member]
Distribution To ZENS holders	16
Indexed debt – reduction	(4)
Indexed debt securities derivative – reduction	(1)
Loss on indexed debt securities	$ 11
AT&T Common [Member]
Balance of investment owned (in shares) | shares	10,212,945
AT&T Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares	0.7185
AT&T Common [Member] | AT&T To Acquire Time Warner [Member]
Cash paid per share exchanged | $ / shares			$ 53.75
Fractional shares exchanged for each TW Common share held | shares			1.437
Cash proceeds received for shares exchanged	$ 382
Total AT&T shares received in exchange for TW Common shares held | shares			10,212,945
Charter Common [Member]
Balance of investment owned (in shares) | shares	872,503				872,503
Charter Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares	0.061382				0.061382
Time Common [Member]
Balance of investment owned (in shares) | shares					888,392
ZENS early exchange ratio				100.00%
Time Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares					0.0625
Time Common [Member] | Meredith to acquire Time [Member]
Cash paid per share exchanged | $ / shares				$ 18.50		$ 18.50
Cash proceeds received for shares exchanged	$ 16
TW Common [Member]
Balance of investment owned (in shares) | shares					7,107,130
TW Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares					0.5

Short-Term Borrowings and Lon_3

Short-Term Borrowings and Long-term Debt (Details)		Oct. 05, 2018USD ($)	Mar. 26, 2018USD ($)	Feb. 28, 2018USD ($)	Sep. 30, 2018USD ($)		Dec. 31, 2017USD ($)
Short-term Debt [Line Items]
Short-term borrowings					$ 0		$ 39,000,000
Line of Credit Facility [Abstract]
Size of credit facility					2,900,000,000		2,900,000,000
Parent Company [Member]
Line of Credit Facility [Abstract]
Size of credit facility					1,700,000,000	[1]	1,700,000,000
Temporary increased line of credit facility, maximum borrowing capacity					3,300,000,000
Houston Electric [Member]
Line of Credit Facility [Abstract]
Size of credit facility					300,000,000		300,000,000
General mortgage bonds used as collateral					118,000,000		118,000,000
CERC Corp [Member]
Short-term Debt [Line Items]
Short-term borrowings					0		39,000,000
Line of Credit Facility [Abstract]
Size of credit facility					900,000,000		900,000,000
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					0		0
Revolving Credit Facility [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					0		0
Revolving Credit Facility [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					0		0
Revolving Credit Facility [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					$ 0		0
Line of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant					65.00%
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)					70.00%
Ratio of indebtedness to net capital	[2]				0.475
System restoration costs threshold for increase in permitted debt to EBITDA covenant ratio					$ 100,000,000
Consecutive period for system restoration costs to exceed $100 million (in months)					12
Line of Credit [Member] | Parent Company [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[3]				1.25%
Line of Credit [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant	[4]				65.00%
Ratio of indebtedness to net capital	[2]				0.507
Line of Credit [Member] | Houston Electric [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[3]				1.125%
Line of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant					65.00%
Ratio of indebtedness to net capital	[2]				0.486
Line of Credit [Member] | CERC Corp [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[3]				1.125%
Letter of Credit [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					$ 11,000,000		11,000,000
Letter of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					6,000,000		6,000,000
Letter of Credit [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					4,000,000		4,000,000
Letter of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					1,000,000		1,000,000
Commercial Paper [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					202,000,000		1,753,000,000
Commercial Paper [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					$ 104,000,000		$ 855,000,000
Weighted average interest rate of debt					2.42%		1.88%
Commercial Paper [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					$ 0		$ 0
Commercial Paper [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit					$ 98,000,000		$ 898,000,000
Weighted average interest rate of debt					2.43%		1.72%
General Mortgage Bonds Due 2048 [Member] | Houston Electric [Member]
Debt Instruments [Abstract]
Principal amount of debt issued				$ 400,000,000
Interest rate of debt issued				3.95%
Maturity date of debt issued				Mar. 1, 2048
Senior Notes Due 2023 [Member] | CERC Corp [Member]
Debt Instruments [Abstract]
Principal amount of debt issued			$ 300,000,000
Interest rate of debt issued			3.55%
Maturity date of debt issued			Apr. 1, 2023
Senior Notes Due 2028 [Member] | CERC Corp [Member]
Debt Instruments [Abstract]
Principal amount of debt issued			$ 300,000,000
Interest rate of debt issued			4.00%
Maturity date of debt issued			Apr. 1, 2028
Merger Agreement with Vectren [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Temporary increased line of credit facility, maximum borrowing capacity					$ 3,300,000,000
Merger Agreement with Vectren [Member] | Line of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)	[4],[5]				75.00%
Subsequent Event [Member]
Debt Instruments [Abstract]
Principal amount of debt issued		$ 1,500,000,000
Subsequent Event [Member] | Senior Notes Due 2021 [Member]
Debt Instruments [Abstract]
Principal amount of debt issued		$ 500,000,000
Interest rate of debt issued		3.60%
Maturity date of debt issued		Nov. 1, 2021
Subsequent Event [Member] | Senior Notes Due 2024 [Member]
Debt Instruments [Abstract]
Principal amount of debt issued		$ 500,000,000
Interest rate of debt issued		3.85%
Maturity date of debt issued		Feb. 1, 2024
Subsequent Event [Member] | CNP Senior Notes Due 2028 [Member]
Debt Instruments [Abstract]
Principal amount of debt issued		$ 500,000,000
Interest rate of debt issued		4.25%
Maturity date of debt issued		Nov. 1, 2028
Product Financing Arrangement [Member]
Short-term Debt [Line Items]
Short-term borrowings					$ 0		$ 39,000,000
Senior Notes Redemption Period One [Member] | Subsequent Event [Member] | CNP Senior Notes [Member]
Debt Instruments [Abstract]
Debt instrument redemption price (percentage)		101.00%
Senior Notes Redemption Period Two [Member] | Subsequent Event [Member] | CNP Senior Notes [Member]
Debt Instruments [Abstract]
Debt instrument redemption price (percentage)		101.00%
[1]	Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility increased to $3.3 billion on October 5, 2018 as a result of the satisfaction of certain conditions described above.
[2]	As defined in the revolving credit facility agreement, excluding Securitization Bonds.
[3]	Based on current credit ratings.
[4]	For CenterPoint Energy (whenever its financial covenant limit is 65%) and Houston Electric, the financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive 12-month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date CenterPoint Energy delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of CenterPoint Energy’s certification or (iii) the revocation of such certification.
[5]	On October 5, 2018, CenterPoint Energy’s financial covenant limit returned to 65% due to the termination of all commitments in respect of the Bridge Facility without any borrowing thereunder.

Income Taxes (Details)

Income Taxes (Details)		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017
Effective income tax rate	[1]	24.00%		37.00%		26.00%		36.00%
Federal statutory income tax rate						21.00%		35.00%
Houston Electric [Member]
Effective income tax rate	[2]	20.00%		35.00%		21.00%		36.00%
CERC Corp [Member]
Effective income tax rate		5.00%	[3]	20.00%	[3]	29.00%	[4]	38.00%	[4]
Effective income tax rate - discontinued operations	[5]	23.00%		38.00%		24.00%		38.00%
State and Local Jurisdiction [Member]
Percentage impact to effective income tax rate		5.00%				7.00%
State and Local Jurisdiction [Member] | CERC Corp [Member]
Percentage impact to effective income tax rate		18.00%				22.00%
EDIT [Member]
Percentage impact to effective income tax rate		5.00%				4.00%
EDIT [Member] | Houston Electric [Member]
Percentage impact to effective income tax rate		2.00%				2.00%
EDIT [Member] | CERC Corp [Member]
Percentage impact to effective income tax rate		15.00%				20.00%
[1]	CenterPoint Energy’s lower effective tax rate for the three and nine months ended September 30, 2018 compared to the same periods for 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate decreased by 5% and 4%, respectively, for the three and nine months ended September 30, 2018 due to the amortization of EDIT. These decreases were partially offset by an increase to the effective tax rate of 5% for the three-month period ended September 30, 2018 as a result of the establishment of a state valuation allowance on certain net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. The effective tax rate increased by 7% for the nine-month period ended September 30, 2018 due to state law changes and the state valuation allowance. See Note 9 for further discussion on the Internal Spin.
[2]	Houston Electric’s lower effective tax rate for the three and nine months ended September 30, 2018 compared to the same periods for 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate was further reduced by 2% for both periods due to the amortization of EDIT.
[3]	CERC’s lower effective tax rate on the loss from continuing operations for the three months ended September 30, 2018 compared to the same period in 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate decreased by 18% due to state taxes as a result of the establishment of a state valuation allowance on certain net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These decreases were partially offset by an increase to the effective tax rate of 15% due to the amortization of EDIT. See Note 9 for further discussion on the Internal Spin.
[4]	CERC’s lower effective tax rate on income from continuing operations for the nine months ended September 30, 2018 compared to the same period in 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The effective tax rate decreased by 20% due to the amortization of EDIT. These decreases were partially offset by an increase to the effective tax rate of 22% as a result of an increase in state tax rates and the establishment of a state valuation allowance on certain net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. See Note 9 for further discussion on the Internal Spin.
[5]	CERC’s lower effective tax rate on income from discontinued operations for the three and nine months ended September 30, 2018 compared to the same periods in 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. See Note 9 for further discussion on the Internal Spin and the associated discontinued operations presentation.

Commitments and Contingencies_2

Commitments and Contingencies (Details)	9 Months Ended
	Sep. 30, 2018USD ($)
CERC Corp [Member] | Minnesota Service Territory [Member]
Legal, Environmental and Other Matters
Liability recorded for remediation of Minnesota sites	$ 7,000,000
CERC Corp [Member] | Minnesota Service Territory [Member] | Minimum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 4,000,000
Years to resolve contingency	30 years
CERC Corp [Member] | Minnesota Service Territory [Member] | Maximum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 30,000,000
Years to resolve contingency	50 years
Natural Gas Supply Commitments [Member]
Natural Gas Supply Commitments
Remaining three months of 2018	$ 88,000,000
2,019	325,000,000
2,020	303,000,000
2,021	219,000,000
2,022	183,000,000
2023 and beyond	1,644,000,000
Minnehaha Academy Gas Explosion [Member]
Legal, Environmental and Other Matters
Contested amount of fines imposed	$ 200,000

Earnings Per Share (CenterPoi_3

Earnings Per Share (CenterPoint Energy) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income available to common shareholders	$ 153	$ 169	$ 243	$ 496
Basic weighted average common shares outstanding	431,554,000	431,026,000	431,437,000	430,939,000
Plus: Incremental shares from assumed conversions:
Diluted weighted average common shares	434,891,000	434,086,000	434,774,000	433,999,000
Basic earnings per common share
Basic earnings per common share	$ 0.35	$ 0.39	$ 0.56	$ 1.15
Diluted earnings per common share
Diluted earnings per common share	$ 0.35	$ 0.39	$ 0.56	$ 1.14
Restricted Stock [Member]
Plus: Incremental shares from assumed conversions:
Restricted stock	3,337,000	3,060,000	3,337,000	3,060,000

Reportable Business Segments (D

Reportable Business Segments (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017	Sep. 04, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues		$ 2,212		$ 2,098	$ 7,553		$ 6,976
Operating Income (Loss)		226		297	664		828
Equity in earnings from investment in Enable		81		68	208		199
Assets		22,228			22,228				$ 22,736
Total regulatory assets		1,994			1,994				2,477
Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	897		843	2,502		2,234
Operating Income (Loss)		227		254	523		511
Electric Transmission and Distribution [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues		213		221	543		540
Electric Transmission and Distribution [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues		79		72	192		172
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		402		390	2,032		1,767
Operating Income (Loss)		3		25	166		235
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		910		861	3,008		2,964
Operating Income (Loss)		(9)		7	(20)		58
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0		0	0		0
Operating Income (Loss)	[2]	0		0	0		0
Equity in earnings from investment in Enable		81		68	208		199
Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		3		4	11		11
Operating Income (Loss)		5		11	(5)		24
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(18)		(18)	(83)		(58)
Assets		(681)			(681)				(654)
Intersegment Eliminations [Member] | Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		0		0	0		0
Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		(8)		(8)	(26)		(24)
Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(10)		(10)	(57)		(34)
Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0		0	0		0
Intersegment Eliminations [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		0		0	0		0
Operating Segments [Member] | Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Assets		10,436			10,436				10,292
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		6,557			6,557				6,608
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		1,253			1,253				1,521
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets		2,457			2,457				2,472
Operating Segments [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Assets	[3]	2,206			2,206				2,497
Pension and Other Postretirement Plans Costs [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Total regulatory assets		566			566				600
CERC Corp [Member]
Segment Reporting Information [Line Items]
Revenues		1,312		1,251	5,040		4,731
Operating Income (Loss)		(7)		31	146		289
Assets		7,305			7,305				10,112
Assets of discontinued operations		0			0				2,472
Total regulatory assets		230			230				311
CERC Corp [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		402		390	2,032		1,767
Operating Income (Loss)		3		25	166		235
CERC Corp [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		910		861	3,008		2,964
Operating Income (Loss)		(9)		7	(20)		58
CERC Corp [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		0		0	0		0
Operating Income (Loss)		(1)		(1)	0		(4)
CERC Corp [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(18)		(18)	(83)		(58)
Assets		(615)			(615)				(559)
CERC Corp [Member] | Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		(8)		(8)	(26)		(24)
CERC Corp [Member] | Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(10)		(10)	(57)		(34)
CERC Corp [Member] | Intersegment Eliminations [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		0		$ 0	0		$ 0
CERC Corp [Member] | Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		6,557			6,557				6,608
CERC Corp [Member] | Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		1,253			1,253				1,521
CERC Corp [Member] | Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets		0			0				0
CERC Corp [Member] | Operating Segments [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Assets		110			110				70
Enable Midstream Partners [Member] | Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] | CERC Corp [Member]
Segment Reporting Information [Line Items]
Assets of discontinued operations		$ 0	[4]		$ 0	[4]		$ 2,400	$ 2,472	[4]
[1]	CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions)Affiliates of NRG $213 $221 $543 $540Affiliates of Vistra Energy Corp. 79 72 192 172
[2]	CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions)Enable $81 $68 $208 $199
[3]	Includes pension and other postemployment-related regulatory assets of $566 million and $600 million, respectively, as of September 30, 2018 and December 31, 2017.
[4]	On September 4, 2018, CERC completed the Internal Spin. For further information regarding the Internal Spin, see Note 9.

Supplemental Disclosure of Ca_3

Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Interest, net of capitalized interest			$ 301	$ 306
Income taxes, net			89	14
Accounts payable related to capital expenditures			140	111
Capital distribution associated with the Internal Spin			0	0
Cash and cash equivalents	$ 293		293		$ 260
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	331	$ 233	331	233	296	$ 381
Prepaid expenses and other current assets [Member]
Restricted cash	37		37		35
Other [Member]
Restricted cash	1		1		1
Houston Electric [Member]
Interest, net of capitalized interest			173	176
Income taxes, net			122	76
Accounts payable related to capital expenditures			87	70
Capital distribution associated with the Internal Spin	0	0	0	0
Cash and cash equivalents	279		279		238
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	317	240	317	240	274	381
Houston Electric [Member] | Prepaid expenses and other current assets [Member]
Restricted cash	37		37		35
Houston Electric [Member] | Other [Member]
Restricted cash	1		1		1
CERC Corp [Member]
Interest, net of capitalized interest			85	86
Income taxes, net			3	4
Accounts payable related to capital expenditures			66	53
Capital distribution associated with the Internal Spin	1,460	0	1,460	0
Cash and cash equivalents	$ 1	$ 1	$ 1	$ 1	$ 12	$ 1

Related Party Transactions (H_3

Related Party Transactions (Houston Electric and CERC) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Capital distribution to parent associated with the Internal Spin				$ 0	$ 0
Houston Electric [Member]
Related Party Transaction [Line Items]
Interest income (expense) (1)	[1]	$ 1	$ 1	1	3
Cash dividends paid to parent		60	45	123	87
Cash contribution from parent		0	0	0	0
Capital distribution to parent associated with the Internal Spin		0	0	0	0
Houston Electric [Member] | Operation and maintenance expense [Member]
Related Party Transaction [Line Items]
Net affiliate service charges (billings)		(3)	(1)	(8)	(6)
Houston Electric [Member] | CenterPoint Energy [Member] | Operation and maintenance expense [Member]
Related Party Transaction [Line Items]
Corporate service charges		47	41	138	127
CERC Corp [Member]
Related Party Transaction [Line Items]
Interest income (expense) (1)	[1]	(2)	0	(4)	0
Cash dividends paid to parent		75	89	286	337
Cash contribution from parent		600	0	600	38
Capital distribution to parent associated with the Internal Spin		1,460	0	1,460	0
CERC Corp [Member] | Operation and maintenance expense [Member]
Related Party Transaction [Line Items]
Net affiliate service charges (billings)		3	1	8	6
CERC Corp [Member] | CenterPoint Energy [Member] | Operation and maintenance expense [Member]
Related Party Transaction [Line Items]
Corporate service charges		$ 36	$ 30	$ 105	$ 93
Investments [Member] | Houston Electric [Member]
Related Party Transaction [Line Items]
Weighted average interest rate		2.45%		2.45%		1.90%
Investments [Member] | CERC Corp [Member]
Related Party Transaction [Line Items]
Weighted average interest rate		2.45%		2.45%		1.90%
Accounts and notes receivable (payable) - affiliate companies [Member] | Houston Electric [Member]
Related Party Transaction [Line Items]
Money pool investments (borrowings) (1)	[2]	$ (75)		$ (75)		$ (60)
Accounts and notes receivable (payable) - affiliate companies [Member] | CERC Corp [Member]
Related Party Transaction [Line Items]
Money pool investments (borrowings) (1)	[2]	$ 0		$ 0		$ (570)
[1]	Interest income is included in Other, net and interest expense is included in Interest and other finance charges on the Condensed Statements of Consolidated Income.
[2]	Included in Accounts and notes receivable (payable)–affiliated companies in the Condensed Consolidated Balance Sheets.

Equity (CenterPoint Energy) (De

Equity (CenterPoint Energy) (Details)	Oct. 23, 2018$ / shares	Oct. 01, 2018USD ($)day$ / sharesshares	Aug. 22, 2018USD ($)day$ / sharesshares	Dec. 13, 2017$ / shares	Sep. 30, 2018USD ($)$ / shares	Sep. 30, 2017$ / shares	Sep. 30, 2018USD ($)$ / shares		Sep. 30, 2017USD ($)$ / shares	Dec. 31, 2017USD ($)$ / shares
Class of Stock [Line Items]
Dividends Declared Per Share				$ 0.2775	$ 0.2775	$ 0.2675	$ 0.5550	[1]	$ 0.8025
Proceeds from issuance of Series A Preferred Stock, net | $							$ 790,000,000		$ 0
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Stock issued (in shares) | shares			800,000
Preferred stock par value (in dollars per share)			$ 1,000		$ 0.01		$ 0.01			$ 0
Preferred stock liquidation preference | $			$ 800,000,000		$ 800,000		$ 800,000			$ 0
Preferred stock liquidation preference (per share)			$ 1,000
Preferred stock dividend rate			6.125%
Preferred stock redemption price (per share)			$ 1,000
Preferred stock convertible threshold (in days) | day			120
Subsequent Event [Member] | Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock liquidation preference | $		$ 978,000,000
Preferred stock liquidation preference (per share)		$ 1,000
Preferred Stock, Convertible, Conversion Price		$ 1,000
Preferred stock dividend rate		7.00%
Proceeds from issuance of Series B Preferred Stock | $		$ 950,000,000
Conversion rate per share		0.05
Preferred Stock, Convertible, Threshold Consecutive Calendar Days | day		20
Subsequent Event [Member] | Depositary Share [Member]
Class of Stock [Line Items]
Stock issued (in shares) | shares		19,550,000
Number of depositary shares eligible for conversion (in shares) | shares		20
Preferred Stock, Convertible, Conversion Price		$ 50
Subsequent Event [Member] | Common Stock [Member]
Class of Stock [Line Items]
Dividends Declared Per Share	$ 0.2775
Stock issued (in shares) | shares		69,633,027
Common stock issued per share price		$ 27.25
Proceeds from issuance of common stock | $		$ 1,844,000,000
Plus LIBOR Spread [Member] | Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividend rate			3.27%
Minimum [Member] | Subsequent Event [Member] | Series B Preferred Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion | shares		30.5820
Preferred Stock, Convertible, Stock Price Trigger		$ 27.2494
Minimum [Member] | Subsequent Event [Member] | Series B Depositary Shares [Member]
Class of Stock [Line Items]
Preferred Stock, Convertible, Stock Price Trigger		$ 27.2494
Minimum [Member] | Subsequent Event [Member] | Depositary Share [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion | shares		1.5291
Maximum [Member] | Subsequent Event [Member] | Series B Preferred Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion | shares		36.6980
Preferred Stock, Convertible, Stock Price Trigger		$ 32.6990
Maximum [Member] | Subsequent Event [Member] | Series B Depositary Shares [Member]
Class of Stock [Line Items]
Preferred Stock, Convertible, Stock Price Trigger		$ 32.6990
Maximum [Member] | Subsequent Event [Member] | Depositary Share [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion | shares		1.8349
Over-Allotment Option [Member] | Subsequent Event [Member] | Series B Depositary Shares [Member]
Class of Stock [Line Items]
Stock issued (in shares) | shares		2,550,000
Over-Allotment Option [Member] | Subsequent Event [Member] | Common Stock [Member]
Class of Stock [Line Items]
Stock issued (in shares) | shares		9,082,568
120 Days After Conclusion of Review or Appeal [Member] | Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock redemption price (per share)			$ 1,020
Preferred stock redemption percentage of liquidation value			102.00%
[1]	On December 13, 2017, CenterPoint Energy’s Board of Directors declared a regular quarterly cash dividend of $0.2775 per share of Common Stock, payable on March 8, 2018 to shareholders of record as of the close of business on February 15, 2018.

Subsequent Events (CenterPoin_2

Subsequent Events (CenterPoint Energy and CERC) (Details) $ / shares in Units, $ in Millions	Nov. 06, 2018USD ($)$ / shares	Oct. 23, 2018$ / shares	Oct. 01, 2018	Dec. 13, 2017$ / shares	Sep. 30, 2018$ / shares	Sep. 30, 2017$ / shares	Sep. 30, 2018$ / shares	[1]	Sep. 30, 2017$ / shares	Oct. 05, 2018USD ($)
Subsequent Event [Line Items]
Quarterly cash dividend/distribution declared per share				$ 0.2775	$ 0.2775	$ 0.2675	$ 0.5550		$ 0.8025
Subsequent Event [Member]
Subsequent Event [Line Items]
Aggregate principal amount of debt issued | $										$ 1,500
Subsequent Event [Member] | Common Units [Member]
Subsequent Event [Line Items]
Dividends payable, date declared		Oct. 23, 2018
Quarterly cash dividend/distribution declared per share		$ 0.2775
Dividends payable, date to be paid		Dec. 13, 2018
Dividends payable, date of record		Nov. 15, 2018
Subsequent Event [Member] | Series B Preferred Stock [Member]
Subsequent Event [Line Items]
Dividends payable, date declared		Oct. 23, 2018
Dividends payable, date to be paid		Dec. 1, 2018
Dividends payable, date of record		Nov. 15, 2018
Preferred stock dividends declared per share		$ 11.6667
Depositary share interest in a share of Series B Preferred Stock			0.05
Subsequent Event [Member] | Series B Depositary Shares [Member]
Subsequent Event [Line Items]
Preferred stock dividends declared per share		$ 0.5833
Subsequent Event [Member] | Enable Midstream Partners [Member] | Common Units [Member]
Subsequent Event [Line Items]
Expected cash distribution from equity method investment | $	$ 74
Subsequent Event [Member] | Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Subsequent Event [Line Items]
Expected cash distribution from cost method investment | $	$ 9
Common Units [Member] | Subsequent Event [Member] | Enable Midstream Partners [Member]
Subsequent Event [Line Items]
Quarterly Cash Distribution, Declaration Date	Nov. 6, 2018
Quarterly Cash Distribution, Distributions Declared, Per Unit	$ 0.318
Series A Preferred Units [Member] | Subsequent Event [Member] | Enable Midstream Partners [Member]
Subsequent Event [Line Items]
Quarterly Cash Distribution, Declaration Date	Nov. 6, 2018
Quarterly Cash Distribution, Distributions Declared, Per Unit	$ 0.625
[1]	On December 13, 2017, CenterPoint Energy’s Board of Directors declared a regular quarterly cash dividend of $0.2775 per share of Common Stock, payable on March 8, 2018 to shareholders of record as of the close of business on February 15, 2018.