CenterPoint Energy (CNP) 10-K 28 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 12, 2019	Jun. 30, 2018
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-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		501,206,304
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 11,873,304,802
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
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-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			0
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
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-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false

STATEMENTS OF CONSOLIDATED INCO

STATEMENTS OF CONSOLIDATED INCOME - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Revenues:
Utility revenues		$ 6,163		$ 5,603		$ 5,440
Non-utility revenues		4,426		4,011		2,088
Total		10,589		9,614		7,528
Expenses:
Utility natural gas		1,410		1,109		983
Non-utility natural gas	[1]	4,364		3,785		1,983
Operation and maintenance		2,335		2,157		2,029
Depreciation and amortization		1,243		1,036		1,126
Taxes other than income taxes		406		391		384
Total		9,758		8,478		6,505
Operating Income		831		1,136		1,023
Other Income (Expense):
Gain (loss) on marketable securities		(22)		7		326
Gain (loss) on indexed debt securities		(232)		49		(413)
Interest and other finance charges		(361)		(313)		(338)
Interest on Securitization Bonds		(59)		(77)		(91)
Equity in earnings of unconsolidated affiliates, net		307		265		208
Other, net		50		(4)		(29)
Total		(317)		(73)		(337)
Income Before Income Taxes		514	[2]	1,063	[3]	686	[4]
Income tax expense (benefit)		146	[2]	(729)	[3]	254	[4]
Net Income		368		1,792		432
Preferred stock dividend requirement		35		0		0
Income Available to Common Shareholders	[5]	$ 333		$ 1,792		$ 432
Basic Earnings Per Common Share		$ 0.74		$ 4.16		$ 1
Diluted Earnings Per Common Share		$ 0.74		$ 4.13		$ 1
Weighted Average Common Shares Outstanding, Basic		448,829,000		430,964,000		430,606,000
Weighted Average Common Shares Outstanding, Diluted		452,465,000		434,308,000		433,603,000
Houston Electric [Member]
Revenues:
Total		$ 3,234		$ 2,998		$ 3,059
Expenses:
Operation and maintenance		1,452		1,402		1,338
Depreciation and amortization		917		724		838
Taxes other than income taxes		240		235		231
Total		2,609		2,361		2,407
Operating Income		625		637		652
Other Income (Expense):
Interest and other finance charges		(138)		(128)		(126)
Interest on Securitization Bonds		(59)		(77)		(91)
Other, net		(3)		(8)		(10)
Total		(200)		(213)		(227)
Income Before Income Taxes		425	[6]	424	[7]	425
Income tax expense (benefit)		89	[6]	(9)	[7]	149
Net Income		336		433		276
CERC Corp [Member]
Revenues:
Utility revenues		2,931		2,606		2,380
Non-utility revenues		4,412		3,997		2,074
Total		7,343		6,603		4,454
Expenses:
Utility natural gas		1,410		1,109		983
Non-utility natural gas		4,364		3,785		1,983
Operation and maintenance		898		816		754
Depreciation and amortization		293		279		249
Taxes other than income taxes		156		147		144
Total		7,121		6,136		4,113
Operating Income		222		467		341
Other Income (Expense):
Interest and other finance charges		(122)		(123)		(122)
Other, net		(8)		(25)		(20)
Total		(130)		(148)		(142)
Income Before Income Taxes		92		319		199
Income tax expense (benefit)		22		(265)		81
Income From Continuing Operations		70		584		118
Income from discontinued operations (net of tax expense of $46, $104, and $81, respectively)		138		161		127
Net Income		$ 208		$ 745		$ 245
[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 the years ended December 31, 2018, 2017 and 2016, respectively.
[2]	Recognized a $32 million deferred tax expense due to state law changes that resulted in remeasurement of state deferred taxes in those jurisdictions. Also recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These items are partially offset by $24 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018.
[3]	Recognized a $1.1 billion deferred tax benefit from the remeasurement of CenterPoint Energy’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21%. For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below.
[4]	Recognized a $6 million deferred tax expense in 2016 due to Louisiana state law change and recorded an additional $3 million valuation allowance on certain state carryforwards.
[5]	Income available to common shareholders for the year ended December 31, 2017 includes a reduction in income tax expense of $1,113 million due to tax reform. See Note 15 for further discussion of the impacts of the TCJA.
[6]	Recognized $9 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018.
[7]	Recognized a $158 million deferred tax benefit from the remeasurement of Houston Electric’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21%. For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below.

STATEMENTS OF CONSOLIDATED IN_2

STATEMENTS OF CONSOLIDATED INCOME (Parentheticals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CERC Corp [Member]
Income tax expense (benefit) associated with discontinued operations	$ 46	$ 104	$ 81

STATEMENTS OF CONSOLIDATED COMP

STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income	$ 368	$ 1,792	$ 432
Other comprehensive income (loss):
Adjustment to pension and other postretirement plans	(10)	6	(7)
Net deferred gain (loss) from cash flow hedges	(15)	(3)	1
Reclassification of deferred loss from cash flow hedges realized in net income (net of tax expense of $-0-, $-0-, and $1, respectively)	0	0	1
Other comprehensive income (loss)	(25)	3	(5)
Comprehensive income	343	1,795	427
Preferred stock dividend requirement	35	0	0
Comprehensive income	308	1,795	427
Houston Electric [Member]
Net income	336	433	276
Other comprehensive income (loss):
Net deferred gain (loss) from cash flow hedges	(14)	(1)	1
Other comprehensive income (loss)	(14)	(1)	1
Comprehensive income	322	432	277
CERC Corp [Member]
Net income	208	745	245
Other comprehensive income (loss):
Adjustment to pension and other postretirement plans	1	4	(6)
Net deferred gain (loss) from cash flow hedges	(1)	(1)	0
Other comprehensive income (loss)	0	3	(6)
Comprehensive income	$ 208	$ 748	$ 239

STATEMENTS OF CONSOLIDATED CO_2

STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax benefit (expense) on adjustment related to pension and postretirement plans	$ 2	$ (6)	$ 4
Tax expense (benefit) on net deferred gain (loss) from cash flow hedges	(4)	(2)	0
Tax expense (benefit) on deferred loss from cash flow hedges realized in net income	0	0	1
Houston Electric [Member]
Tax expense (benefit) on net deferred gain (loss) from cash flow hedges	(4)	0	0
CERC Corp [Member]
Tax benefit (expense) on adjustment related to pension and postretirement plans	(1)	(4)	4
Tax expense (benefit) on net deferred gain (loss) from cash flow hedges	$ 0	$ (1)	$ 0

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions		Dec. 31, 2018		Dec. 31, 2017
Current Assets:
Cash and cash equivalents	[1]	$ 4,231		$ 260
Investment in marketable securities		540		960
Accounts receivable		1,190		1,000
Accrued unbilled revenues		378		427
Natural gas inventory		194		222
Materials and supplies		200		175
Non-trading derivative assets		100		110
Prepaid expense and other current assets		192		241
Total current assets		7,025		3,395
Property, Plant and Equipment, net		14,044		13,057
Other Assets:
Goodwill		867		867
Regulatory assets		1,967		2,347
Non-trading derivative assets		38		44
Investment in unconsolidated affiliates		2,482		2,472
Preferred units - unconsolidated affiliate		363		363
Other		223		191
Total other assets		5,940		6,284
Total Assets		27,009		22,736
Current Liabilities:
Short-term borrowings		0		39
Current portion of VIE Securitization Bonds long-term debt		458		434
Indexed debt, net		24		122
Current portion of other long-term debt		0		50
Indexed debt securities derivative		601		668
Accounts payable		1,240		963
Taxes accrued		204		181
Interest accrued		121		104
Dividends accrued		187		120
Non-trading derivative liabilities		126		20
Other		341		368
Total current liabilities		3,302		3,069
Other Liabilities:
Deferred income taxes, net		3,239		3,174
Non-trading derivative liabilities		5		4
Benefit obligations		796		785
Regulatory liabilities		2,525		2,464
Other		402		357
Total other liabilities		6,967		6,784
Long-term Debt:
VIE Securitization Bonds, net		977		1,434
Other long-term debt, net		7,705		6,761
Total long-term debt, net		8,682		8,195
Commitments and Contingencies (Note 16)
Shareholders’ Equity:
Cumulative preferred stock, $0.01 par value, 20,000,000 shares authorized		0		0
Common stock		5		4
Additional paid-in capital		6,072		4,209
Retained earnings		349		543
Accumulated other comprehensive income (loss)		(108)		(68)
Total shareholders’ equity		8,058		4,688
Total Liabilities and Shareholders’ Equity		27,009		22,736
Houston Electric [Member]
Current Assets:
Cash and cash equivalents	[2]	335		238
Accounts and notes receivable, net		283		284
Accounts and notes receivable—affiliated companies		20		7
Accrued unbilled revenues		110		120
Materials and supplies		135		119
Taxes receivable		5		0
Prepaid expense and other current assets		61		62
Total current assets		949		830
Property, Plant and Equipment, net		8,402		7,863
Other Assets:
Regulatory assets		1,124		1,570
Other		32		29
Total other assets		1,156		1,599
Total Assets		10,507		10,292
Current Liabilities:
Current portion of VIE Securitization Bonds long-term debt		458		434
Accounts payable		262		243
Accounts and notes payable—affiliated companies		78		104
Taxes accrued		115		116
Interest accrued		64		65
Non-trading derivative liabilities		24		0
Other		89		120
Total current liabilities		1,090		1,082
Other Liabilities:
Deferred income taxes, net		1,023		1,059
Benefit obligations		91		146
Regulatory liabilities		1,298		1,263
Other		65		54
Total other liabilities		2,477		2,522
Long-term Debt:
VIE Securitization Bonds, net		977		1,434
Other long-term debt, net		3,281		2,885
Total long-term debt, net		4,258		4,319
Commitments and Contingencies (Note 16)
Shareholders’ Equity:
Common stock		0		0
Additional paid-in capital		1,896		1,696
Retained earnings		800		673
Accumulated other comprehensive income (loss)		(14)		0
Total shareholders’ equity		2,682		2,369
Total Liabilities and Shareholders’ Equity		10,507		10,292
CERC Corp [Member]
Current Assets:
Cash and cash equivalents		14		12
Accounts receivable		894		713
Accounts and notes receivable—affiliated companies		120		6
Accrued unbilled revenues		268		307
Natural gas inventory		194		222
Materials and supplies		65		56
Non-trading derivative assets		100		110
Prepaid expense and other current assets		115		166
Total current assets		1,770		1,592
Property, Plant and Equipment, net		5,226		4,852
Other Assets:
Goodwill		867		867
Regulatory assets		181		181
Non-trading derivative assets		38		44
Investment in unconsolidated affiliates - discontinued operations		0		2,472
Other		132		104
Total other assets		1,218		3,668
Total Assets		8,214	[3]	10,112
Current Liabilities:
Short-term borrowings	[4],[5]	0		39
Current portion of long-term debt	[4],[5]	0		0
Accounts payable		856		669
Accounts and notes payable—affiliated companies		50		611
Taxes accrued		82		75
Interest accrued		38		32
Customer deposits		75		76
Non-trading derivative liabilities		102		20
Other		137		137
Total current liabilities		1,340		1,659
Other Liabilities:
Deferred income taxes, net		406		362
Deferred income taxes, net - discontinued operations		0		927
Non-trading derivative liabilities		5		4
Benefit obligations		93		97
Regulatory liabilities		1,227		1,201
Other		329		297
Total other liabilities		2,060		2,888
Long-term Debt:
Total long-term debt, net	[5]	2,371		2,457
Commitments and Contingencies (Note 16)
Shareholders’ Equity:
Common stock		0		0
Additional paid-in capital		2,015		2,528
Retained earnings		423		574
Accumulated other comprehensive income (loss)		5		6
Total shareholders’ equity		2,443		3,108
Total Liabilities and Shareholders’ Equity		8,214		10,112
Series A Preferred Stock [Member]
Shareholders’ Equity:
Preferred Stock		790		0
Series B Preferred Stock [Member]
Shareholders’ Equity:
Preferred Stock		$ 950		$ 0
[1]	CenterPoint Energy’s Cash and cash equivalents as of December 31, 2018 included $3.9 billion of temporary investments resulting from the Merger financings. CenterPoint Energy recorded interest income of $28 million, $2 million and $1 million for the years ended December 31, 2018, 2017 and 2016, respectively, in Other, net on CenterPoint Energy’s Statements of Consolidated Income. See Notes 13 and 14 for further details related to the Merger financings.
[2]	Houston Electric’s Cash and cash equivalents as of December 31, 2018 and 2017 included $335 million and $230 million, respectively, of cash related to the Bond Companies. Houston Electric recorded interest income of $4 million, $2 million and $1 million for the years ended December 31, 2018, 2017 and 2016, respectively, in Other, net on Houston Electric’s Statement of Consolidated Income.
[3]	On September 4, 2018, CERC completed the Internal Spin. For further information regarding the Internal Spin, see Note 11.
[4]	Includes amounts due or exchangeable within one year of the date noted.
[5]	Issued by CERC Corp.

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)		Dec. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	[1]	$ 4,231,000,000	$ 260,000,000
Bad debt reserve		18,000,000	19,000,000
Accounts receivable		1,190,000,000	1,000,000,000
Prepaid expense and other current assets		192,000,000	241,000,000
Other Assets:
Regulatory assets		$ 1,967,000,000	$ 2,347,000,000
Shareholders’ Equity:
Cumulative preferred stock par value (in dollars per share)		$ 0.01	$ 0.01
Cumulative preferred stock authorized (in shares)		20,000,000	20,000,000
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)		501,197,784	431,044,845
Variable Interest Entity, Primary Beneficiary [Member]
Current Assets:
Cash and cash equivalents		$ 335,000,000	$ 230,000,000
Accounts receivable		56,000,000	73,000,000
Prepaid expense and other current assets		34,000,000	35,000,000
Other Assets:
Regulatory assets		1,059,000,000	1,590,000,000
Houston Electric [Member]
Current Assets:
Cash and cash equivalents	[2]	335,000,000	238,000,000
Prepaid expense and other current assets		61,000,000	62,000,000
Other Assets:
Regulatory assets		1,124,000,000	1,570,000,000
Houston Electric [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Current Assets:
Cash and cash equivalents		335,000,000	230,000,000
Bad debt reserve		1,000,000	1,000,000
Accounts receivable		56,000,000	73,000,000
Prepaid expense and other current assets		34,000,000	35,000,000
Other Assets:
Regulatory assets		1,059,000,000	1,590,000,000
CERC Corp [Member]
Current Assets:
Cash and cash equivalents		14,000,000	12,000,000
Bad debt reserve		17,000,000	18,000,000
Accounts receivable		894,000,000	713,000,000
Prepaid expense and other current assets		115,000,000	166,000,000
Other Assets:
Regulatory assets		$ 181,000,000	$ 181,000,000
Cumulative Preferred Stock [Member]
Shareholders’ Equity:
Cumulative preferred stock par value (in dollars per share)		$ 0.01	$ 0.01
Cumulative preferred stock authorized (in shares)		20,000,000	20,000,000
Series A Preferred Stock [Member]
Shareholders’ Equity:
Cumulative preferred stock par value (in dollars per share)		$ 0.01	$ 0
Preferred Stock, Liquidation Preference, Value		$ 800,000,000	$ 0
Cumulative preferred stock outstanding (in shares)		800,000	0
Series B Preferred Stock [Member]
Shareholders’ Equity:
Cumulative preferred stock par value (in dollars per share)		$ 0.01	$ 0
Preferred Stock, Liquidation Preference, Value		$ 977,500,000	$ 0
Cumulative preferred stock outstanding (in shares)		977,500	0
[1]	CenterPoint Energy’s Cash and cash equivalents as of December 31, 2018 included $3.9 billion of temporary investments resulting from the Merger financings. CenterPoint Energy recorded interest income of $28 million, $2 million and $1 million for the years ended December 31, 2018, 2017 and 2016, respectively, in Other, net on CenterPoint Energy’s Statements of Consolidated Income. See Notes 13 and 14 for further details related to the Merger financings.
[2]	Houston Electric’s Cash and cash equivalents as of December 31, 2018 and 2017 included $335 million and $230 million, respectively, of cash related to the Bond Companies. Houston Electric recorded interest income of $4 million, $2 million and $1 million for the years ended December 31, 2018, 2017 and 2016, respectively, in Other, net on Houston Electric’s Statement of Consolidated Income.

STATEMENTS OF CONSOLIDATED CASH

STATEMENTS OF CONSOLIDATED CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities:
Net income	$ 368	$ 1,792	$ 432
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,243	1,036	1,126
Amortization of deferred financing costs	48	24	26
Deferred income taxes	48	(770)	213
Unrealized loss (gain) on marketable securities	22	(7)	(326)
Loss (gain) on indexed debt securities	232	(49)	413
Write-down of natural gas inventory	2	0	1
Equity in earnings of unconsolidated affiliates, net of distributions	(40)	(265)	(208)
Pension contributions	(69)	(48)	(9)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	(154)	(216)	(117)
Inventory	1	(7)	34
Taxes receivable	0	30	142
Accounts payable	220	136	133
Fuel cost recovery	33	(85)	(72)
Non-trading derivatives, net	103	(84)	30
Margin deposits, net	5	(55)	101
Interest and taxes accrued	40	5	5
Net regulatory assets and liabilities	28	(107)	(60)
Other current assets	0	(3)	(25)
Other current liabilities	(24)	34	22
Other assets	6	(4)	(16)
Other liabilities	12	36	30
Other, net	12	24	48
Net cash provided by operating activities	2,136	1,417	1,923
Cash Flows from Investing Activities:
Capital expenditures	(1,651)	(1,426)	(1,414)
Acquisitions, net of cash acquired	0	(132)	(102)
Decrease in notes receivable - unconsolidated affiliate	0	0	363
Investment in preferred units - unconsolidated affiliate	0	0	(363)
Distributions from unconsolidated affiliates in excess of cumulative earnings	30	297	297
Proceeds from sale of marketable securities	398	0	178
Other, net	16	4	7
Net cash provided by (used in) investing activities	(1,207)	(1,257)	(1,034)
Cash Flows from Financing Activities:
Increase (decrease) in short-term borrowings, net	(39)	4	(5)
Proceeds from (payments of) commercial paper, net	(1,543)	349	469
Proceeds from long-term debt, net	2,495	1,096	600
Payments of long-term debt	(484)	(1,211)	(1,218)
Loss on reacquired debt	0	(5)	(22)
Debt and equity issuance costs	(47)	(13)	(9)
Payment of dividends on Common Stock	(499)	(461)	(443)
Payment of dividends on preferred stock	(11)	0	0
Proceeds from issuance of Common Stock, net	1,844	0	0
Proceeds from issuance of preferred stock, net	1,740	0	0
Distribution to ZENS holders	(398)	0	(178)
Other, net	(5)	(4)	(2)
Net cash provided by (used in) financing activities	3,053	(245)	(808)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	3,982	(85)	81
Cash, Cash Equivalents and Restricted Cash at Beginning of Year	296	381	300
Cash, Cash Equivalents and Restricted Cash at End of Year	4,278	296	381
Houston Electric [Member]
Cash Flows from Operating Activities:
Net income	336	433	276
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	917	724	838
Amortization of deferred financing costs	11	13	14
Deferred income taxes	(38)	(98)	(34)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	11	(73)	(1)
Accounts receivable/payable–affiliated companies	20	(46)	63
Inventory	(16)	15	(1)
Taxes receivable	(5)	6	53
Accounts payable	(1)	59	(4)
Non-trading derivatives, net	5	0	0
Interest and taxes accrued	(2)	7	4
Net regulatory assets and liabilities	(97)	(148)	(110)
Other current assets	(2)	(6)	(6)
Other current liabilities	(26)	16	21
Other assets	(3)	13	(8)
Other liabilities	17	(4)	(4)
Other, net	(12)	(6)	1
Net cash provided by operating activities	1,115	905	1,102
Cash Flows from Investing Activities:
Capital expenditures	(922)	(875)	(862)
Increase in notes receivable–affiliated companies	0	96	(96)
Other, net	11	3	7
Net cash provided by (used in) investing activities	(911)	(776)	(951)
Cash Flows from Financing Activities:
Proceeds from long-term debt, net	398	298	600
Payments of long-term debt	(434)	(411)	(590)
Dividend to parent	(209)	(180)	(135)
Increase (decrease) in notes payable–affiliated companies	(59)	60	(312)
Debt issuance costs	(4)	(3)	(6)
Contribution from parent	200	0	374
Net cash provided by (used in) financing activities	(108)	(236)	(69)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	96	(107)	82
Cash, Cash Equivalents and Restricted Cash at Beginning of Year	274	381	299
Cash, Cash Equivalents and Restricted Cash at End of Year	370	274	381
CERC Corp [Member]
Cash Flows from Operating Activities:
Net income	208	745	245
Income (loss) from discontinued operations, net of tax	138	161	127
Income (loss) from continuing operations	70	584	118
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	293	279	249
Amortization of deferred financing costs	9	9	9
Deferred income taxes	31	(224)	56
Write-down of natural gas inventory	2	0	1
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	(155)	(143)	(122)
Accounts receivable/payable–affiliated companies	9	0	4
Inventory	17	(22)	34
Accounts payable	163	64	117
Fuel cost recovery	33	(85)	(72)
Non-trading derivatives, net	98	(82)	29
Margin deposits, net	5	(55)	101
Interest and taxes accrued	0	(41)	26
Net regulatory assets and liabilities	50	(27)	0
Other current assets	4	2	(19)
Other current liabilities	(3)	15	2
Other assets	5	(8)	(21)
Other liabilities	6	6	(2)
Other, net	1	6	2
Net cash provided by operating activities from continuing operations	638	278	512
Net cash provided by operating activities from discontinued operations	176	0	0
Net cash provided by operating activities	814	278	512
Cash Flows from Investing Activities:
Capital expenditures	(633)	(513)	(517)
Acquisitions, net of cash acquired	0	(132)	(102)
Increase in notes receivable–affiliated companies	(114)	0	0
Other, net	3	2	1
Net cash used in investing activities from continuing operations	(744)	(643)	(618)
Net cash provided by investing activities from discontinued operations	47	297	660
Net cash provided by (used in) investing activities	(697)	(346)	42
Cash Flows from Financing Activities:
Increase (decrease) in short-term borrowings, net	(39)	4	(5)
Proceeds from (payments of) commercial paper, net	(688)	329	350
Proceeds from long-term debt, net	599	298	0
Payments of long-term debt	0	(550)	(325)
Dividend to parent	(360)	(601)	(643)
Increase (decrease) in notes payable–affiliated companies	(570)	570	0
Loss on reacquired debt	0	(5)	0
Debt issuance costs	(5)	(4)	0
Contribution from parent	960	38	72
Other, net	(1)	0	(2)
Net cash used in financing activities from continuing operations	(104)	79	(553)
Net cash provided by financing activities from discontinued operations	0	0	0
Net cash provided by (used in) financing activities	(104)	79	(553)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	13	11	1
Cash, Cash Equivalents and Restricted Cash at Beginning of Year	12	1	0
Cash, Cash Equivalents and Restricted Cash at End of Year	$ 25	$ 12	$ 1

STATEMENTS OF CONSOLIDATED SHAR

STATEMENTS OF CONSOLIDATED SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Series A Preferred Stock [Member]	Series B Preferred Stock [Member]	Preferred Stock [Member]	Preferred Stock [Member]Series A Preferred Stock [Member]	Preferred Stock [Member]Series B Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Common Stock [Member]	Retained Earnings [Member]	Retained Earnings [Member]Series A Preferred Stock [Member]	Retained Earnings [Member]Series B Preferred Stock [Member]	AOCI Attributable to Parent [Member]	Houston Electric [Member]	Houston Electric [Member]Common Stock [Member]	Houston Electric [Member]Additional Paid-in Capital [Member]	Houston Electric [Member]Retained Earnings [Member]	Houston Electric [Member]AOCI Attributable to Parent [Member]	CERC Corp [Member]	CERC Corp [Member]Common Stock [Member]	CERC Corp [Member]Additional Paid-in Capital [Member]	CERC Corp [Member]Retained Earnings [Member]	CERC Corp [Member]AOCI Attributable to Parent [Member]
Balance, beginning of year at Dec. 31, 2015				0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of stock					0	0	0
Balance, end of year at Dec. 31, 2016				0
Balance, beginning of year at Dec. 31, 2015							430,000,000								1,000					1,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances related to benefit and investment plans							1,000,000
Balance, end of year at Dec. 31, 2016							431,000,000								1,000					1,000
Balance, beginning of year at Dec. 31, 2015				$ 0			$ 4	$ 4,180		$ (657)			$ (66)		$ 0	$ 1,322	$ 279	$ 0		$ 0	$ 2,417	$ 828	$ 9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances related to benefit and investment plans							0	15
Issuances of stock					$ 0	$ 0	0		$ 0
Contribution From Parent																374					72
Capital distribution associated with the Internal Spin	$ 0													$ 0					$ 0		0
Other																					0
Net income	432									432				276			276		245			245
Common Stock dividends declared ($1.12, $1.3475 and $1.03 per share, respectively)										(443)
Preferred stock dividends declared											$ 0	$ 0
Dividend to parent																	(135)					(643)
Other comprehensive income (loss)													(5)					1					(6)
Balance, end of year at Dec. 31, 2016	$ 3,460			$ 0			$ 4	4,195		(668)			(71)	2,117	$ 0	1,696	420	1	2,922	$ 0	2,489	430	3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU 2018-02 | Adjustments for New Accounting Principle, Early Adoption [Member]										0			0									0	0
Issuances of stock					0	0	0
Balance, end of year at Dec. 31, 2017		0	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances related to benefit and investment plans							0
Balance, end of year at Dec. 31, 2017	431,044,845						431,000,000								1,000					1,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances related to benefit and investment plans							$ 0	14
Issuances of stock					$ 0	$ 0	0		0
Contribution From Parent																0					38
Capital distribution associated with the Internal Spin	$ 0													0					0		0
Other																					1
Net income	1,792									1,792				433			433		745			745
Common Stock dividends declared ($1.12, $1.3475 and $1.03 per share, respectively)										(581)
Preferred stock dividends declared											0	0
Dividend to parent																	(180)					(601)
Other comprehensive income (loss)													3					(1)					3
Balance, end of year at Dec. 31, 2017	$ 4,688			$ 0			$ 4	4,209		543			(68)	2,369	$ 0	1,696	673	0	3,108	$ 0	2,528	574	6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU 2018-02 | Adjustments for New Accounting Principle, Early Adoption [Member]										0			0									0	0
Issuances of stock					1,000,000	1,000,000	70,000,000
Balance, end of year at Dec. 31, 2018		800,000	977,500	2,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances related to benefit and investment plans							0
Balance, end of year at Dec. 31, 2018	501,197,784						501,000,000								1,000					1,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances related to benefit and investment plans							$ 0	19
Issuances of stock					$ 790	$ 950	1		$ 1,844
Contribution From Parent																200					960
Capital distribution associated with the Internal Spin	$ 0													0					(1,473)		(1,473)
Other																					0
Net income	368									368				336			336		208			208
Common Stock dividends declared ($1.12, $1.3475 and $1.03 per share, respectively)										(523)
Preferred stock dividends declared		$ (26)	$ (28)								$ (26)	$ (28)
Dividend to parent																	(209)					(360)
Other comprehensive income (loss)													(25)					(14)					0
Balance, end of year at Dec. 31, 2018	$ 8,058			$ 1,740			$ 5	$ 6,072		349			(108)	$ 2,682	$ 0	$ 1,896	$ 800	$ (14)	$ 2,443	$ 0	$ 2,015	423	5
Balance, end of year (Adjustments for New Accounting Principle, Early Adoption [Member]) at Dec. 31, 2018																							2,443
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU 2018-02 | Adjustments for New Accounting Principle, Early Adoption [Member]										$ 15			$ (15)									$ 1	$ (1)

STATEMENTS OF CONSOLIDATED SH_2

STATEMENTS OF CONSOLIDATED SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	Dec. 12, 2018	Oct. 23, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Aug. 22, 2018
Cumulative preferred stock par value (in dollars per share)			$ 0.01	$ 0.01	$ 0.01
Cumulative preferred stock shares authorized (in shares)			20,000,000	20,000,000	20,000,000
Common stock shares par value (in dollars per share)			$ 0.01	$ 0.01	$ 0.01
Common stock shares authorized (in shares)			1,000,000,000	1,000,000,000	1,000,000,000
Common stock dividends declared per share			$ 1.12	$ 1.3475	$ 1.03
Series A Preferred Stock [Member]
Cumulative preferred stock par value (in dollars per share)			0.01	0		$ 1,000
Preferred stock dividends declared per share	$ 32.1563		32.1563	0	0
Series B Preferred Stock [Member]
Cumulative preferred stock par value (in dollars per share)			0.01	0
Preferred stock dividends declared per share	$ 17.5000	$ 11.6667	$ 29.1667	$ 0	$ 0

Background

Background	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background [Text Block]	Background 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-K are the Financial Statements of CenterPoint Energy, Houston Electric and CERC, which are referred to collectively as the Registrants. The Combined Notes to the Consolidated Financial Statements apply to all Registrants and specific references to Houston Electric and CERC herein also pertain to CenterPoint Energy, unless otherwise indicated. Background. CenterPoint Energy, Inc. is a public utility holding company and owns interests in Enable as described below. As of December 31, 2018, CenterPoint Energy’s operating subsidiaries, Houston Electric and CERC, owned and operated electric transmission and distribution and natural gas distribution facilities and supplied 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 over 30 states through its wholly-owned subsidiary, CES. As of December 31, 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 April 21, 2018, CenterPoint Energy entered into the Merger Agreement to acquire Vectren for approximately $6 billion in cash. On February 1, 2019, pursuant to the Merger Agreement, CenterPoint Energy consummated the previously announced Merger and acquired Vectren. For further information about the closing of the Merger, see Note 4. For a description of CenterPoint Energy’s and CERC’s reportable segments, see Note 19 . Houston Electric consists of a single reportable segment, Electric Transmission & Distribution.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies [Text Block]	Summary of Significant Accounting Policies (a) Use of Estimates 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. (b) Principles of Consolidation The accounts of the Registrants and their wholly-owned and majority-owned subsidiaries are included in the consolidated financial statements. All intercompany transactions and balances are eliminated in consolidation. As of December 31, 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 solely 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 payable only 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. (c) Equity and Investments without a Readily Determinable Fair Value (CenterPoint Energy and CERC) CenterPoint Energy and CERC generally use the equity method of accounting for investments in entities in which they have an ownership interest between 20% and 50% and exercise significant influence. CenterPoint Energy and CERC also use the equity method for investments in which they have ownership percentages greater than 50%, when they exercise significant influence, do not have control and are not considered the primary beneficiary, if applicable. Under the equity method, CenterPoint Energy and CERC adjust their investments each period for contributions made, distributions received, respective shares of comprehensive income and amortization of basis differences, as appropriate. CenterPoint Energy and CERC evaluate their equity method investments for impairment when events or changes in circumstances indicate there is a loss in value of the investment that is other than a temporary decline. CenterPoint Energy and CERC consider distributions received from equity method investments which do not exceed cumulative equity in earnings subsequent to the date of investment to be a return on investment and classify these distributions as operating activities in their respective Statements of Consolidated Cash Flows. CenterPoint Energy and CERC consider distributions received from equity method investments in excess of cumulative equity in earnings subsequent to the date of investment to be a return of investment and classify these distributions as investing activities in their respective Statements of Consolidated Cash Flows. On September 4, 2018, CERC completed the Internal Spin of its equity investment in Enable and Enable GP. For further information regarding the Internal Spin, see Note 11. Investments without a readily determinable fair value will be measured at cost, less impairment, plus or minus observable prices changes of an identical or similar investment of the same issuer. (d) Revenues The Registrants record revenue for electricity delivery and natural gas sales and services under the accrual method and these revenues are recognized upon delivery to customers. Electricity deliveries not billed by month-end are accrued based on actual AMS data, daily supply volumes and applicable rates. Natural gas sales not billed by month-end are accrued based upon estimated purchased gas volumes, estimated lost and unaccounted for gas and currently effective tariff rates. For further discussion, see Note 5. (e) Long-lived Assets and Intangibles Subject to Amortization The Registrants record property, plant and equipment at historical cost and expense repair and maintenance costs as incurred. The Registrants periodically evaluate long-lived assets, including property, plant and equipment, and specifically identifiable intangibles subject to amortization, when events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. The determination of whether an impairment has occurred is based on an estimate of undiscounted cash flows attributable to the assets compared to the carrying value of the assets. (f) Regulatory Assets and Liabilities The Registrants apply the guidance for accounting for regulated operations to the Electric Transmission & Distribution reportable segment and the Natural Gas Distribution reportable segment. The Registrants’ rate-regulated subsidiaries may collect revenues subject to refund pending final determination in rate proceedings. In connection with such revenues, estimated rate refund liabilities are recorded which reflect management’s current judgment of the ultimate outcomes of the proceedings. The Registrants’ rate-regulated businesses recognize removal costs as a component of depreciation expense in accordance with regulatory treatment. In addition, a portion of the amount of removal costs collected from customers that relate to AROs has been reclassified from a regulatory liability to an asset retirement liability in accordance with accounting guidance for AROs. For further detail on the Registrants’ regulatory assets and liabilities, see Note 7. (g) Depreciation and Amortization Expense The Registrants compute depreciation and amortization using the straight-line method based on economic lives or regulatory-mandated recovery periods. Amortization expense includes amortization of certain regulatory assets and other intangibles. (h) Capitalization of Interest and AFUDC The Registrants capitalize interest and AFUDC as a component of projects under construction and amortize over the assets’ estimated useful lives once the assets are placed in service. AFUDC represents the composite interest cost of borrowed funds and a reasonable return on the equity funds used for construction for subsidiaries that apply the guidance for accounting for regulated operations. Although AFUDC increases both utility plant and earnings, it is realized in cash when the assets are included in rates. Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Interest and AFUDC debt (1) $ 8 $ 6 $ 2 $ 9 $ 6 $ 2 $ 8 $ 6 $ 2 AFUDC equity (2) 12 10 2 11 10 1 7 6 1 (1) Included in Interest and other finance charges on the Registrants’ respective Statements of Consolidated Income. (2) Included in Other Income (Expense) on the Registrants’ respective Statements of Consolidated Income. (i) Income Taxes Houston Electric and CERC are included in CenterPoint Energy’s U.S. federal consolidated income tax return. Houston Electric and CERC report their income tax provision on a separate entity basis pursuant to a tax sharing agreement with CenterPoint Energy. Current federal and certain state income taxes are payable to or receivable from CenterPoint Energy. The Registrants use the asset and liability method of accounting for deferred income taxes. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. A valuation allowance is established against deferred tax assets for which management believes realization is not considered to be more likely than not. The Registrants recognize interest and penalties as a component of income tax expense (benefit), as applicable, in their respective Statements of Consolidated Income. CenterPoint Energy reports the income tax provision associated with its interest in Enable in income tax expense (benefit) in its Statements of Consolidated Income. On December 22, 2017, President Trump signed into law comprehensive tax reform legislation informally called the Tax Cuts and Jobs Acts, or TCJA, which resulted in significant changes to federal tax laws effective January 1, 2018. See Note 15 for further discussion of the impacts of tax reform implementation. To the extent certain EDIT of the Registrants’ rate-regulated subsidiaries may be recoverable or payable through future rates, regulatory assets and liabilities have been recorded, respectively. The Registrants use the portfolio approach to recognize income tax effects on other comprehensive income from accumulated other comprehensive income. (j) Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are recorded at the invoiced amount and do not bear interest. Management reviews the outstanding accounts receivable, as well as the bad debt write-offs experienced in the past, and establishes an allowance for doubtful accounts. Account balances are charged off against the allowance when management determines it is probable the receivable will not be recovered. The table below summarizes the Registrants’ provision for doubtful accounts for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Provision for doubtful accounts $ 16 $ — $ 16 $ 14 $ 1 $ 13 $ 7 $ — $ 7 (k) Inventory The Registrants’ inventory consists principally of materials and supplies and, for CERC, natural gas. Materials and supplies are valued at the lower of average cost or market. Materials and supplies are recorded to inventory when purchased and subsequently charged to expense or capitalized to plant when installed. Natural gas inventories of CERC’s Energy Services business segment at locations qualifying for and utilizing the fair value hedge accounting election are valued at fair value; inventories at locations not qualifying for or not utilizing the fair value hedge accounting election are valued at the lower of average cost or market. During 2018 , 2017 and 2016 , CERC recorded write-downs of natural gas inventory to the lower of average cost or market which are disclosed on the respective Statements of Consolidated Cash Flows. (l) 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 operating results and cash flows. Such derivatives are recognized in the Registrants’ Consolidated Balance Sheets at their fair value unless the Registrant elects the normal purchase and sales exemption for qualified physical transactions. A derivative may be designated as a normal purchase or normal sale if the intent is to physically receive or deliver the product for use or sale in the normal course of business. CenterPoint Energy has a Risk Oversight Committee composed of corporate and reportable 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’ risk management policies 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. (m) Investments in Equity Securities (CenterPoint Energy and CERC) CenterPoint Energy and CERC report equity securities at estimated fair value in their respective Consolidated Balance Sheets, and any unrealized holding gains and losses are recorded as Other Income (Expense) in their respective Statements of Consolidated Income. (n) Environmental Costs The Registrants expense or capitalize environmental expenditures, as appropriate, depending on their future economic benefit. The Registrants expense amounts that relate to an existing condition caused by past operations that do not have future economic benefit. The Registrants record undiscounted liabilities related to these future costs when environmental assessments and/or remediation activities are probable and the costs can be reasonably estimated. (o) Cash and Cash Equivalents and Restricted Cash For purposes of reporting cash flows, the Registrants consider cash equivalents to be short-term, highly-liquid investments with maturities of three months or less from the date of purchase. Cash and cash equivalents held by the Bond Companies (VIEs) solely to support servicing the Securitization Bonds as of December 31, 2018 and 2017 are reflected on CenterPoint Energy’s and Houston Electric’s Consolidated Balance Sheets. In connection with the issuance of Securitization Bonds, CenterPoint Energy and Houston Electric were required to establish restricted cash accounts to collateralize the bonds that were issued in these financing transactions. These restricted cash accounts are not available for withdrawal until the maturity of the bonds and are not included in cash and cash equivalents. For more information on restricted cash see Note 20 . (p) Preferred Stock and Dividends Preferred stock is evaluated to determine balance sheet classification, and all conversion and redemption features are evaluated for bifurcation treatment. Proceeds received net of issuance costs are recognized on the settlement date. Cash dividends become a liability once declared. Income available to common stockholders is computed by deducting from net income the dividends accumulated and earned during the period on cumulative preferred stock. (q) Purchase Accounting The Registrants evaluate acquisitions to determine when a set of acquired activities and assets represent a business. When control of a business is obtained, the Registrants apply the acquisition method of accounting and record the assets acquired, liabilities assumed and any non-controlling interest obtained based on fair value at the acquisition date. The excess of the fair value of purchase consideration over the fair value of the net assets acquired is recorded as goodwill. The results of operations of the acquired business are included in the Registrants’ respective Statements of Consolidated Income beginning on the date of the acquisition. (r) 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 5 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. This standard also 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. Transition method: modified retrospective January 1, 2018 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. 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 11 for further discussion. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption 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 Statements of Consolidated Cash Flows reflect an increase in investing activities and a corresponding decrease in operating activities of $2 million, $4 million and $8 million for the years ended December 31, 2018, 2017 and 2016, respectively, due to the requirement that cash proceeds from COLI policies be classified as cash inflows from investing activity. ASU 2016-18- Statement of Cash Flows (Topic 230): Restricted Cash This standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. Transition method: retrospective January 1, 2018 The adoption of this standard did not have a material impact on the Registrants’ financial position, results of operations or disclosures. However, the Registrants’ respective Statements of Consolidated Cash Flows are reconciled to cash, cash equivalents and restricted cash, resulting in a decrease in investing activities of $11 million for each of CenterPoint Energy’s and CERC’s respective Statements of Consolidated Cash Flows for the year ended December 31, 2018. In addition, each of CenterPoint Energy and Houston Electric showed a decrease of $4 million and an increase of $5 million in investing activities for the years ended December 31, 2017 and 2016, respectively, in their respective Statements of Consolidated Cash Flows. See Note 20 for further discussion. 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 of net periodic costs previously capitalized in assets are recorded as regulatory assets by the Registrants’ rate-regulated businesses prospectively from date of adoption. ASU 2017-12- Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities This standard, including standards amending 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 9 reflects disclosures modified upon adoption. ASU 2018-02-Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA and requires entities to provide certain disclosures regarding stranded tax effects. Transition method : in the period of adoption October 1, 2018 The adoption of this standard did not impact the Registrants’ results of operations or cash flows. As a result of the adoption, CenterPoint Energy and CERC elected to reclassify a stranded tax benefit of $15 million and $1 million, respectively, primarily related to benefit plans, from accumulated other comprehensive loss and income to Retained earnings on their respective Consolidated Balance Sheets. The reclassification only encompasses the change in the federal corporate income tax rate due to the TCJA. 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 10 reflects the disclosures modified upon adoption. Recently Adopted 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 October 1, 2018 The adoption of this standard did not impact the Registrants’ financial position, results of operations, and cash flows. Note 8 reflects the disclosures modified upon adoption. The table below reflects the impact of adoption of ASU 2017-07 (Compensation—Retirement Benefits (Topic 715)) on each of the Registrants’ respective Statements of Consolidated Income: Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 47 $ 21 $ 11 $ 64 $ 26 $ 23 $ 64 $ 25 $ 23 Decrease to other income 47 21 11 64 26 23 64 25 23 Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Effective Date 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 2018-20- Leases (Topic 842)-Narrow-Scope Improvements for Lessors 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. ASU 2018-20 updates several narrow-scope changes for lessors, including sales taxes collected from lessees, lessor costs paid directly by lessees, and recognition of variable payments for contracts with lease and non-lease components. January 1, 2019 Early adoption is permitted The Registrants have completed the identification of leases under the revised definition. In addition to expanded disclosure for lessees and lessors, which will include qualitative disclosures of the nature of the lease population and additional quantitative information, the Registrants expect to recognize approximately $30 million, $1 million and $28 million of right-of-use assets and lease liabilities on the statements of financial position of CenterPoint Energy, Houston Electric and CERC, respectively, on the date of adoption but do not expect a material impact on their results of operations and cash flows. The Registrants elected the practical expedient for 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. ASU 2016-13- Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This standard, including standards amending 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 Early adoption is permitted starting January 1, 2019 The Registrants are currently assessing the impact that this standard will have on their financial position, results of operations, cash flows and disclosures. Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Effective Date Financial Statement Impact upon Adoption 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.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Text Block]	Property, Plant and Equipment (a) Property, Plant and Equipment Property, plant and equipment includes the following: December 31, 2018 December 31, 2017 Weighted Average Useful Lives Property, Plant and Equipment, Gross Accumulated Depreciation & Amortization Property, Plant and Equipment, Net Property, Plant and Equipment, Gross Accumulated Depreciation & Amortization Property, Plant and Equipment, Net CenterPoint Energy (in years) (in millions) Electric Transmission & Distribution 35 $ 12,148 $ 3,746 $ 8,402 $ 11,496 $ 3,633 $ 7,863 Natural Gas Distribution 28 7,257 2,128 5,129 6,735 1,968 4,767 Energy Services 27 121 43 78 102 35 67 Other property 26 741 306 435 698 338 360 Total $ 20,267 $ 6,223 $ 14,044 $ 19,031 $ 5,974 $ 13,057 Houston Electric Electric Transmission 45 $ 3,077 $ 650 $ 2,427 $ 2,767 $ 620 $ 2,147 Electric Distribution 33 7,524 2,553 4,971 7,178 2,522 4,656 Other transmission & distribution property 18 1,547 543 1,004 1,551 491 1,060 Total $ 12,148 $ 3,746 $ 8,402 $ 11,496 $ 3,633 $ 7,863 CERC Natural Gas Distribution 28 $ 7,257 $ 2,128 $ 5,129 $ 6,735 $ 1,968 $ 4,767 Energy Services 27 121 43 78 102 35 67 Other property 23 53 34 19 51 33 18 Total $ 7,431 $ 2,205 $ 5,226 $ 6,888 $ 2,036 $ 4,852 (b) Depreciation and Amortization The following table presents depreciation and amortization expense for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Depreciation $ 626 $ 342 $ 264 $ 619 $ 354 $ 243 $ 607 $ 349 $ 230 Amortization of securitized regulatory assets 531 531 — 329 329 — 455 455 — Other amortization 86 44 29 88 41 36 64 34 19 Total $ 1,243 $ 917 $ 293 $ 1,036 $ 724 $ 279 $ 1,126 $ 838 $ 249 (c) AROs The Registrants recorded AROs associated with the removal of asbestos and asbestos-containing material in its buildings, including substation building structures. CenterPoint Energy and Houston Electric also recorded AROs relating to treated wood poles for electric distribution, distribution transformers containing PCB (also known as Polychlorinated Biphenyl), and underground fuel storage tanks. CenterPoint Energy and CERC also recorded AROs relating to gas pipelines abandoned in place. The estimates of future liabilities were developed using historical information, and where available, quoted prices from outside contractors. A reconciliation of the changes in the ARO liability recorded in Other non-current liabilities on each of the Registrants’ respective Consolidated Balance Sheets is as follows: December 31, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Beginning balance $ 281 $ 35 $ 243 $ 205 $ 33 $ 169 Accretion expense (1) 10 1 9 8 1 7 Revisions in estimates (2) (33 ) (2 ) (31 ) 68 1 67 Ending balance $ 258 $ 34 $ 221 $ 281 $ 35 $ 243 (1) Reflected in Regulatory assets on each of the Registrants’ respective Consolidated Balance Sheets. (2) In 2018, CenterPoint Energy and CERC reflected a decrease in their respective ARO liability which is primarily attributable to increases in the long-term interest rates used for discounting in the ARO calculation. In 2017, CenterPoint Energy and CERC reflected an increase in their respective ARO liability which is primarily attributable to decreases in the long-term interest rates used for discounting in the ARO calculation.

Mergers and Acquisitions

Mergers and Acquisitions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Mergers and Acquisitions [Text Block]	Mergers and Acquisitions Merger with Vectren (CenterPoint Energy) On February 1, 2019 (the Merger Date), pursuant to the Merger Agreement, CenterPoint Energy consummated the previously announced Merger and acquired Vectren for approximately $6 billion in cash. Each share of Vectren common stock issued and outstanding immediately prior to the closing was canceled and converted into the right to receive $72.00 in cash per share, without interest. At the closing, each stock unit payable in Vectren common stock or whose value is determined with reference to the value of Vectren common stock, whether vested or unvested, was canceled with cash consideration paid therefor in accordance with the terms of the Merger Agreement. These amounts did not include a stub period cash dividend of $0.41145 per share, which was declared, with CenterPoint Energy’s consent, by Vectren’s board of directors on January 16, 2019 , and paid to Vectren stockholders as of the record date of February 1, 2019 . See Notes 13 and 14 for further details regarding the Merger financings. Following the closing, shares of Vectren common stock, which previously traded under the ticker symbol “VVC” on the NYSE, ceased trading on and were delisted from the NYSE. On the Merger Date, Vectren became a wholly-owned subsidiary of CenterPoint Energy. Vectren, through its wholly owned subsidiary, VUHI, holds three public utilities: • Indiana Gas provides energy delivery services to natural gas customers located in central and southern Indiana; • SIGECO provides energy delivery services to electric and natural gas customers located near Evansville in southwestern Indiana and owns and operates electric generation assets to serve its electric customers and optimizes those assets in the wholesale power market; and • VEDO provides energy delivery services to natural gas customers located near Dayton in west-central Ohio. Vectren is also involved in non-utility activities through two business units: • Infrastructure Services provides underground pipeline construction and repair services; and • ESG provides energy performance contracting and sustainable infrastructure, such as renewables, distributed generation and combined heat and power projects. As of December 31, 2018, Vectren and its subsidiaries had outstanding $167 million of short-term debt and $2.2 billion of long-term debt, including current maturities. Vectren’s outstanding short-term and long-term debt on the closing date of the Merger became debt of CenterPoint Energy. The Merger is anticipated to provide significant potential strategic benefits to CenterPoint Energy, including growth opportunities for more rate-regulated investment, more customers for existing products and services and additional products and services for existing customers. Additionally, CenterPoint Energy believes the Merger will increase geographic and business diversity as well as scale in attractive jurisdictions and economies. The Merger is being accounted for in accordance with ASC 805, Business Combinations, with identifiable assets acquired and liabilities assumed recorded at their estimated fair values on the Merger Date. Due to the limited time between the Merger Date and this filing, CenterPoint Energy’s purchase price allocation for the assets acquired and the liabilities assumed in the Merger has not been completed. CenterPoint Energy will provide the required disclosures in the first quarter of 2019. The results of operations of Vectren will be reported in CenterPoint Energy’s consolidated financial statements beginning on the Merger Date. CenterPoint Energy incurred transaction costs of $28 million and integration costs of $18 million in connection with the Merger for the year ended December 31, 2018, which were included in operation and maintenance expenses in CenterPoint Energy’s Statements of Consolidated Income. Acquisition of AEM (CenterPoint Energy and CERC) On January 3, 2017, CES completed the acquisition of AEM. After working capital adjustments, the final purchase price of $147 million was allocated to identifiable assets acquired and liabilities assumed based on their fair values on the acquisition date. The goodwill of $5 million recorded as part of the acquisition primarily reflects the value of the complementary operational and geographic footprints, scale and expanded capabilities provided by the acquisition. The fair value of the identifiable intangible assets and related useful lives included in the final purchase price allocation is as follows: Fair Value Useful Life (in millions) (in years) Customer relationships $ 25 15 The following unaudited pro forma financial information reflects the consolidated results of operations of CenterPoint Energy and CERC, assuming the AEM acquisition had taken place on January 1, 2016. The unaudited pro forma financial information has been presented for illustrative purposes only and is not necessarily indicative of the consolidated results of operations that would have been achieved had the acquisition taken place on the dates indicated or the future consolidated results of operations of the combined companies. Year Ended December 31, 2017 2016 CenterPoint Energy CERC CenterPoint Energy CERC (in millions) Revenues $ 9,614 $ 6,603 $ 8,541 $ 5,467 Net Income (1) 1,792 745 442 255 (1) Net income for the year ended December 31, 2017 includes a reduction in income tax expense of $1,113 million and $396 million due to the TCJA for CenterPoint Energy and CERC, respectively. See Note 15 for further discussion of the impacts of tax reform implementation.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 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 segment and major source: Year Ended December 31, 2018 CenterPoint Energy Houston Electric CERC Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 3,235 $ 3,011 $ 493 $ 6 $ 6,745 $ 3,235 $ 3,011 $ 493 $ 1 $ 3,505 Derivatives income (2 ) (2 ) 4,028 — 4,024 — (2 ) 4,028 — 4,026 Other (3) (1 ) (42 ) — 9 (34 ) (1 ) (42 ) — — (42 ) Eliminations — (36 ) (110 ) — (146 ) — (36 ) (110 ) — (146 ) Total revenues $ 3,232 $ 2,931 $ 4,411 $ 15 $ 10,589 $ 3,234 $ 2,931 $ 4,411 $ 1 $ 7,343 Year Ended December 31, 2017 CenterPoint Energy Houston Electric CERC Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 3,001 $ 2,638 $ 480 $ 5 $ 6,124 $ 3,001 $ 2,638 $ 480 $ — $ 3,118 Derivatives income (1 ) — 3,569 — 3,568 — — 3,569 — 3,569 Other (3) (3 ) 1 — 9 7 (3 ) 1 — — 1 Eliminations — (33 ) (52 ) — (85 ) — (33 ) (52 ) — (85 ) Total revenues $ 2,997 $ 2,606 $ 3,997 $ 14 $ 9,614 $ 2,998 $ 2,606 $ 3,997 $ — $ 6,603 Year Ended December 31, 2016 CenterPoint Energy Houston Electric CERC Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 3,050 $ 2,368 $ 288 $ 5 $ 5,711 $ 3,050 $ 2,368 $ 288 $ — $ 2,656 Derivatives income 1 — 1,811 — 1,812 — — 1,811 — 1,811 Other (3) 9 41 — 10 60 9 41 — 1 42 Eliminations — (29 ) (26 ) — (55 ) — (29 ) (26 ) — (55 ) Total revenues $ 3,060 $ 2,380 $ 2,073 $ 15 $ 7,528 $ 3,059 $ 2,380 $ 2,073 $ 1 $ 4,454 (1) Reflected in Utility revenues in the Statements of Consolidated Income. (2) Reflected in Non-utility revenues in the 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.

Goodwill and Other Intangibles

Goodwill and Other Intangibles (CenterPoint Energy and CERC)	12 Months Ended
	Dec. 31, 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 segment as of both December 31, 2018 and 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(e) for further discussion. CenterPoint Energy and CERC performed the annual goodwill impairment test in the third quarter of each of 2018 and 2017 and determined that no goodwill impairment charge was required for any reporting unit, which approximate the Registrants’ applicable reportable segments. The tables below present information on CenterPoint Energy’s and CERC’s finite lived intangible assets recorded in Other non-current assets on the Consolidated Balance Sheets. Finite lived intangible assets are amortized over their estimated useful lives. December 31, 2018 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Balance Gross Carrying Amount Accumulated Amortization Net Balance (in millions) Customer relationships $ 86 $ (27 ) $ 59 $ 86 $ (21 ) $ 65 Covenants not to compete 4 (3 ) 1 4 (2 ) 2 Other 16 (11 ) 5 15 (8 ) 7 Total $ 106 $ (41 ) $ 65 $ 105 $ (31 ) $ 74 Year Ended December 31, 2018 2017 2016 (in millions) Amortization expense of intangible assets (1) $ 10 $ 13 $ 4 (1) Recorded in Depreciation and amortization expenses on CenterPoint Energy’s and CERC’s respective Statements of Consolidated Income. CenterPoint Energy and CERC estimate that amortization expense of intangible assets with finite lives for the next five years will be as follows: Amortization Expense (in millions) 2019 $ 11 2020 6 2021 6 2022 6 2023 5

Regulatory Accounting

Regulatory Accounting	12 Months Ended
	Dec. 31, 2018
Regulated Operations [Abstract]
Regulatory Accounting [Text Block]	Regulatory Accounting The following is a list of regulatory assets and liabilities reflected on the Registrants’ respective Consolidated Balance Sheets as of December 31, 2018 and 2017 : December 31, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Regulatory Assets: Current regulatory assets (1) $ 77 $ — $ 77 $ 130 $ — $ 130 Non-current regulatory assets: Securitized regulatory assets 1,059 1,059 — 1,590 1,590 — Unrecognized equity return (2) (213 ) (213 ) — (287 ) (287 ) — Unamortized loss on reacquired debt 68 68 — 75 75 — Pension and postretirement-related regulatory asset (3) 725 33 30 646 31 20 Hurricane Harvey restoration costs (4) 68 64 4 64 58 6 Regulatory assets related to TCJA (5) 33 23 10 48 33 15 Other long-term regulatory assets (6) 227 90 137 211 70 140 Total non-current regulatory assets 1,967 1,124 181 2,347 1,570 181 Total regulatory assets 2,044 1,124 258 2,477 1,570 311 Regulatory Liabilities: Current regulatory liabilities (7) 38 17 21 24 22 2 Non-current regulatory liabilities: Regulatory liabilities related to TCJA (5) 1,323 847 476 1,354 862 492 Estimated removal costs 886 269 617 878 285 593 Other long-term regulatory liabilities 316 182 134 232 116 116 Total non-current regulatory liabilities 2,525 1,298 1,227 2,464 1,263 1,201 Total regulatory liabilities 2,563 1,315 1,248 2,488 1,285 1,203 Total regulatory assets and liabilities, net $ (519 ) $ (191 ) $ (990 ) $ (11 ) $ 285 $ (892 ) (1) Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ respective Consolidated Balance Sheets. (2) The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the years ended December 31, 2018 , 2017 and 2016 , Houston Electric recognized approximately $74 million , $42 million and $64 million , respectively, of the allowed equity return. The timing of 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 Houston Electric’s and CERC’s 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 $33 million and $4 million as of December 31, 2018 , respectively, and $31 million and $7 million as of December 31, 2017 , respectively, were not earning a return. (4) The Registrants suffered damage as a result of Hurricane Harvey, a major storm classified as a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale, that first struck the Texas coast on Friday, August 25, 2017 and remained over the Houston area for the next several days. The unprecedented flooding from torrential amounts of rainfall accompanying the storm caused significant damage to or destruction of residences and businesses served by the Registrants. The Registrants deferred the uninsured storm restoration costs as management believed it was probable that such costs will be recovered through traditional rate adjustment mechanisms for capital costs and through the next base rate proceeding for operation and maintenance expenses. As a result, storm restoration costs did not materially affect the Registrants’ reported net income for 2017. 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. See Note 15 for additional information. (6) Other long-term regulatory assets that are not earning a return were not material as of December 31, 2018 and 2017 . (7) Current regulatory liabilities are included in Other current liabilities in each of the Registrants’ respective Consolidated Balance Sheets.

Stock-Based Incentive Compensat

Stock-Based Incentive Compensation Plans and Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
Disclosure of Stock-Based Incentive Compensation Plans and Employee Benefit Plans [Abstract]
Stock-Based Incentive Compensation Plans and Employee Benefit Plans [Text Block]	Stock-Based Incentive Compensation Plans and Employee Benefit Plans (a) Stock-Based Incentive Compensation Plans (CenterPoint Energy) CenterPoint Energy has LTIPs that provide for the issuance of stock-based incentives, including stock options, performance awards, restricted stock unit awards and restricted and unrestricted stock awards to officers, employees and non-employee directors. Approximately 14 million shares of Common Stock are authorized under these plans for awards. CenterPoint Energy issues new shares of its Common Stock to satisfy stock-based payments related to LTIPs. Equity awards are granted to employees without cost to the participants. Compensation costs for the performance and stock awards granted under LTIPs are measured using fair value and expected achievement levels on the grant date. For performance awards with operational goals, the achievement levels are revised as goals are evaluated. The fair value of awards granted to employees is based on the closing stock price of CenterPoint Energy’s Common Stock on the grant date. The compensation expense is recorded on a straight-line basis over the vesting period. Forfeitures are estimated on the date of grant based on historical averages and estimates are updated periodically throughout the vesting period. The performance awards granted in 2018 , 2017 and 2016 are distributed based upon the achievement of certain objectives over a three-year performance cycle. The stock unit awards granted in 2018 , 2017 and 2016 are service based. The stock unit awards generally vest at the end of a three-year period, provided, however, that stock unit awards granted to non-employee directors vested at the end of a one-year period (for awards granted in 2017 and 2016) or vested immediately upon grant (for awards granted in 2018). Upon vesting, both the performance and stock awards are issued to the participants along with the value of dividend equivalents earned over the performance cycle or vesting period. The following table summarizes CenterPoint Energy’s expenses related to LTIPs for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 (in millions) LTIP Compensation expense (1) $ 26 $ 21 $ 19 Income tax benefit recognized 6 8 7 Actual tax benefit realized for tax deductions 5 6 5 (1) Included in Operation and maintenance expense in CenterPoint Energy’s Statements of Consolidated Income and not capitalized as a part of Inventory or Property, Plant and Equipment. The following tables summarize CenterPoint Energy’s LTIP activity for 2018 : Year Ended December 31, 2018 Shares (Thousands) Weighted-Average Grant Date Fair Value Remaining Average Contractual Life (Years) Aggregate Intrinsic Value (2) (Millions) Performance Awards (1) Outstanding and non-vested as of December 31, 2017 3,627 $ 22.15 Granted 1,321 26.74 Forfeited or canceled (721 ) 21.72 Vested and released to participants (409 ) 21.31 Outstanding and non-vested as of December 31, 2018 3,818 $ 23.91 1 $ 57 Stock Awards Outstanding and non-vested as of December 31, 2017 980 $ 22.68 Granted 409 26.62 Forfeited or canceled (29 ) 25.31 Vested and released to participants (300 ) 22.84 Outstanding and non-vested as of December 31, 2018 1,060 $ 24.08 1.1 $ 30 (1) Reflects maximum performance achievement. (2) Reflects the impact of current expectations of achievement and stock price. The weighted average grant date fair values per unit of awards granted were as follows for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 (In millions, except for per unit amounts) Performance Awards Weighted-average grant date fair value per unit of awards granted $ 26.74 $ 26.64 $ 18.98 Total intrinsic value of awards received by participants 12 7 7 Vested grant date fair value 9 5 7 Stock Awards Weighted-average grant date fair value per unit of awards granted $ 26.62 $ 26.77 $ 19.24 Total intrinsic value of awards received by participants 9 9 6 Vested grant date fair value 7 7 6 As of December 31, 2018 , there was $27 million of total unrecognized compensation cost related to non-vested performance and stock awards which is expected to be recognized over a weighted-average period of 1.7 years. (b) Pension Benefits (CenterPoint Energy) CenterPoint Energy maintains a non-contributory qualified defined benefit pension plan covering substantially all employees, with benefits determined using a cash balance formula. Substantially all of the Registrants’ employees participate in CenterPoint Energy’s non-contributory qualified defined benefit plan. Under the cash balance formula, participants accumulate a retirement benefit based upon 5% of eligible earnings and accrued interest. Participants are 100% vested in their benefit after completing three years of service. In addition to the non-contributory qualified defined benefit pension plans, CenterPoint Energy maintains unfunded non-qualified benefit restoration plans which allow participants to receive the benefits to which they would have been entitled under CenterPoint Energy’s non-contributory qualified pension plan except for federally mandated limits on qualified plan benefits or on the level of compensation on which qualified plan benefits may be calculated. CenterPoint Energy’s net periodic cost includes the following components relating to pension, including the non-qualified benefit restoration plan: Year Ended December 31, 2018 2017 2016 (in millions) Service cost (1) $ 37 $ 36 $ 38 Interest cost (2) 79 89 93 Expected return on plan assets (2) (107 ) (97 ) (101 ) Amortization of prior service cost (2) 9 9 9 Amortization of net loss (2) 43 58 63 Net periodic cost $ 61 $ 95 $ 102 (1) Amounts presented in the table above are included in Operation and maintenance expense in CenterPoint Energy’s Statements of Consolidated Income, net of regulatory deferrals and amounts capitalized. See Note 2(r). (2) Amounts presented in the table above are included in Other, net in CenterPoint Energy’s Statements of Consolidated Income, net of regulatory deferrals. See Note 2(r). CenterPoint Energy used the following assumptions to determine net periodic cost relating to pension benefits: Year Ended December 31, 2018 2017 2016 Discount rate 3.65 % 4.15 % 4.40 % Expected return on plan assets 6.00 6.00 6.25 Rate of increase in compensation levels 4.45 4.50 4.15 In determining net periodic benefit cost, CenterPoint Energy uses fair value, as of the beginning of the year, as its basis for determining expected return on plan assets. The following table summarizes changes in the benefit obligation, plan assets, the amounts recognized in the Consolidated Balance Sheets as well as the key assumptions of CenterPoint Energy’s pension plans. The measurement dates for plan assets and obligations were December 31, 2018 and 2017 . December 31, 2018 2017 (in millions, except for actuarial assumptions) Change in Benefit Obligation Benefit obligation, beginning of year $ 2,225 $ 2,197 Service cost 37 36 Interest cost 79 89 Benefits paid (201 ) (168 ) Actuarial (gain) loss (1) (127 ) 71 Benefit obligation, end of year 2,013 2,225 Change in Plan Assets Fair value of plan assets, beginning of year 1,801 1,656 Employer contributions 69 48 Benefits paid (201 ) (168 ) Actual investment return (153 ) 265 Fair value of plan assets, end of year 1,516 1,801 Funded status, end of year $ (497 ) $ (424 ) December 31, 2018 2017 (in millions, except for actuarial assumptions) Amounts Recognized in Balance Sheets Current liabilities-other $ (7 ) $ (7 ) Other liabilities-benefit obligations (490 ) (417 ) Net liability, end of year $ (497 ) $ (424 ) Actuarial Assumptions Discount rate (2) 4.35 % 3.65 % Expected return on plan assets (3) 6.00 6.00 Rate of increase in compensation levels 4.60 4.45 Interest crediting rate 3.75 3.75 (1) Significant sources of gain for 2018 include the increase in discount rate from 3.65% to 4.35% and the mortality projection scale change from MP2017 to MP2018. For 2017, the significant source of loss was the decrease in the discount rate from 4.15% to 3.65% . (2) The discount rate assumption was determined by matching the projected cash flows of CenterPoint Energy’s plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years. (3) The expected rate of return assumption was developed using the targeted asset allocation of CenterPoint Energy’s plans and the expected return for each asset class. The following table displays pension benefits related to CenterPoint Energy’s pension plans that have accumulated benefit obligations in excess of plan assets: December 31, 2018 2017 Pension (Qualified) Pension (Non-qualified) Pension Pension (in millions) Accumulated benefit obligation $ 1,930 $ 61 $ 2,090 $ 74 Projected benefit obligation 1,952 61 2,151 74 Fair value of plan assets 1,516 — 1,801 — The accumulated benefit obligation for all defined benefit pension plans on CenterPoint Energy’s Consolidated Balance Sheets was $1,991 million and $2,164 million as of December 31, 2018 and 2017 , respectively. (c) Postretirement Benefits CenterPoint Energy provides certain healthcare and life insurance benefits for retired employees on both a contributory and non-contributory basis. The Registrants’ employees who were hired before January 1, 2018 and who have met certain age and service requirements at retirement, as defined in the plans, are eligible to participate in these benefit plans. Employees hired on or after January 1, 2018 are not eligible for these benefits, except that employees represented by IBEW Local Union 66 are eligible to participate in certain of the benefits, subject to the applicable age and service requirements. With respect to retiree medical and prescription drug benefits, employees represented by the IBEW Local Union 66 who retire on or after January 1, 2017, and their dependents, receive any such benefits exclusively through the NECA/IBEW Family Medical Care Plan pursuant to the terms of the renegotiated collective bargaining agreement entered into in May 2016. Houston Electric and CERC are required to fund a portion of their obligations in accordance with rate orders. All other obligations are funded on a pay-as-you-go basis. Postretirement benefits are accrued over the active service period of employees. The net postretirement benefit cost includes the following components: Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ 2 $ — $ 1 $ 2 $ 1 $ 1 $ 2 $ 1 $ 1 Interest cost (2) 13 8 4 16 9 5 16 10 4 Expected return on plan assets (2) (5 ) (4 ) (1 ) (5 ) (4 ) (1 ) (6 ) (5 ) (1 ) Amortization of prior service cost (credit) (2) (5 ) (5 ) 1 (5 ) (6 ) 1 (3 ) (4 ) — Amortization of net loss (2) — — — — — — 1 1 1 Curtailment (3) — — — — — — (5 ) (4 ) (1 ) Net postretirement benefit cost (credit) $ 5 $ (1 ) $ 5 $ 8 $ — $ 6 $ 5 $ (1 ) $ 4 (1) Amounts presented in the table above are included in Operation and maintenance expense in CenterPoint Energy’s Statements of Consolidated Income, net of regulatory deferrals and amounts capitalized. See Note 2(r). (2) Amounts presented in the table above are included in Other, net in each of the Registrants’ respective Statements of Consolidated Income, net of regulatory deferrals. See Note 2(r). (3) A curtailment gain or loss is required when the expected future services of a significant number of current employees are reduced or eliminated for the accrual of benefits. During 2016, postretirement healthcare benefits were amended resulting in a net curtailment gain of $5 million . In May 2016, Houston Electric entered into a renegotiated collective bargaining agreement with the IBEW Local Union 66 that provides that for Houston Electric bargaining unit employees covered under the agreement who retire on or after January 1, 2017, retiree medical and prescription drug coverage will be provided exclusively through the NECA/IBEW Family Medical Care Plan in exchange for the payment of monthly premiums as determined under the agreement. As a result, the accrued postretirement benefits related to such future CenterPoint Energy and Houston Electric union retirees were eliminated. Houston Electric recognized a curtailment gain of $3 million as an accelerated recognition of the prior service credit that would otherwise be recognized in future periods for the postretirement plan. CenterPoint Energy also recognized an additional curtailment gain of $2 million in October 2016 related to other amendments in the postretirement plan. The following assumptions were used to determine net periodic cost relating to postretirement benefits: Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC Discount rate 3.60 % 3.60 % 3.60 % 4.15 % 4.15 % 4.15 % 4.35 % 4.35 % 4.35 % Expected return on plan assets 4.55 4.75 3.85 4.50 4.75 3.60 4.80 5.00 3.95 The following table summarizes changes in the benefit obligation, plan assets, the amounts recognized in consolidated balance sheets and the key assumptions of the postretirement plans. The measurement dates for plan assets and benefit obligations were December 31, 2018 and 2017 . December 31, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Change in Benefit Obligation Benefit obligation, beginning of year $ 386 $ 225 $ 109 $ 383 $ 217 $ 115 Service cost 2 — 1 2 1 1 Interest cost 13 8 4 16 9 5 Participant contributions 7 2 4 7 2 3 Benefits paid (25 ) (13 ) (9 ) (26 ) (14 ) (9 ) Actuarial (gain) loss (1) (52 ) (56 ) 1 4 10 (6 ) Benefit obligation, end of year 331 166 110 386 225 109 Change in Plan Assets Fair value of plan assets, beginning of year 120 93 26 113 88 25 Employer contributions 14 9 4 16 10 5 Participant contributions 7 2 4 7 2 3 Benefits paid (25 ) (13 ) (9 ) (26 ) (14 ) (9 ) Actual investment return (2 ) (2 ) — 10 7 2 Fair value of plan assets, end of year 114 89 25 120 93 26 Funded status, end of year $ (217 ) $ (77 ) $ (85 ) $ (266 ) $ (132 ) $ (83 ) Amounts Recognized in Balance Sheets Current liabilities-other $ (6 ) $ — $ (3 ) $ (6 ) $ — $ (4 ) Other liabilities-benefit obligations (211 ) (77 ) (82 ) (260 ) (132 ) (79 ) Net liability, end of year $ (217 ) $ (77 ) $ (85 ) $ (266 ) $ (132 ) $ (83 ) Actuarial Assumptions Discount rate (2) 4.35 % 4.35 % 4.35 % 3.60 % 3.60 % 3.60 % Expected return on plan assets (3) 4.60 4.70 4.15 4.55 4.75 3.85 Medical cost trend rate assumed for the next year - Pre-65 5.95 5.95 5.95 6.15 6.15 6.15 Medical/prescription drug cost trend rate assumed for the next year - Post-65 28.60 28.60 28.60 23.85 23.85 23.85 Prescription drug cost trend rate assumed for the next year - Pre-65 9.20 9.20 9.20 9.85 9.85 9.85 Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.50 4.50 4.50 4.50 4.50 4.50 Year that the cost trend rates reach the ultimate trend rate - Pre-65 2026 2026 2026 2026 2026 2026 Year that the cost trend rates reach the ultimate trend rate - Post-65 2027 2027 2027 2024 2024 2024 (1) Significant sources of gain for 2018 include the increase in the discount rate from 3.60% to 4.35% , favorable benefit claims experience and cost trend rates in addition to the change in mortality projection scale from MP2017 to MP2018. (2) The discount rate assumption was determined by matching the projected cash flows of the plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years. (3) The expected rate of return assumption was developed using the targeted asset allocation of the plans and the expected return for each asset class. (d) Accumulated Other Comprehensive Income (Loss) (CenterPoint Energy and CERC) CenterPoint Energy recognizes the funded status of its pension plans and other postretirement plans on its Consolidated Balance Sheets. To the extent this obligation exceeds amounts previously recognized in the Statements of Consolidated Income, CenterPoint Energy records a regulatory asset for that portion related to its rate regulated utilities. To the extent that excess liability does not relate to a rate regulated utility, the offset is recorded as a reduction to equity in accumulated other comprehensive income. Amounts recognized in accumulated other comprehensive loss (gain) consist of the following: December 31, 2018 2017 Pension Benefits Postretirement Benefits Pension Benefits Postretirement Benefits CenterPoint Energy CenterPoint Energy CERC CenterPoint Energy CenterPoint Energy CERC (in millions) Unrecognized actuarial loss (gain) $ 109 $ (7 ) $ (3 ) $ 94 $ (8 ) $ (2 ) Unrecognized prior service cost 1 5 5 1 6 6 Deferred tax benefit (1) — — (9 ) — — (11 ) Net amount recognized in accumulated other comprehensive loss (gain) $ 110 $ (2 ) $ (7 ) $ 95 $ (2 ) $ (7 ) (1) CenterPoint Energy’s and CERC’s postretirement benefit obligation is reduced by the impact of previously non-taxable government subsidies under the Medicare Prescription Drug Act. Because the subsidies were non-taxable, the temporary difference used in measuring the deferred tax impact was determined on the unrecognized losses excluding such subsidies. The changes in plan assets and benefit obligations recognized in other comprehensive income during 2018 are as follows: Pension Benefits Postretirement Benefits CenterPoint Energy CenterPoint Energy CERC (in millions) Net loss (gain) $ 22 $ — $ (1 ) Amortization of net loss (6 ) — — Amortization of prior service cost (1 ) — (1 ) Total recognized in comprehensive income $ 15 $ — $ (2 ) Total expense recognized in net periodic costs and Other comprehensive income $ 76 $ 5 $ 3 (e) Pension Plan Assets (CenterPoint Energy) In managing the investments associated with the benefit plans, CenterPoint Energy’s objective is to achieve and maintain a fully funded plan. This objective is expected to be achieved through an investment strategy that manages liquidity requirements while maintaining a long-term horizon in making investment decisions and efficient and effective management of plan assets. As part of the investment strategy discussed above, CenterPoint Energy maintained the following weighted average allocation targets for its pension plans as of December 31, 2018 : U.S. equity 12 - 28% International developed market equity 7 - 17% Emerging market equity 5 - 11% Fixed income 55 - 65% Cash 0 - 2% The following tables set forth by level, within the fair value hierarchy (see Note 10 ), CenterPoint Energy’s pension plan assets at fair value as of December 31, 2018 and 2017 : Fair Value Measurements as of December 31, 2018 2017 (Level 1) (Level 2) (Level 3) Total (Level 1) (Level 2) (Level 3) Total (in millions) Cash $ 19 $ — $ — $ 19 $ 18 $ — $ — $ 18 Corporate bonds: Investment grade or above — 368 — 368 — 432 — 432 Equity securities: U.S. companies 60 — — 60 76 — — 76 Cash received as collateral from securities lending 77 — — 77 76 — — 76 U.S. treasuries 196 — — 196 67 — — 67 Mortgage backed securities — 6 — 6 — 8 — 8 Asset backed securities — 1 — 1 — 1 — 1 Municipal bonds — 27 — 27 — 47 — 47 Mutual funds (2) 167 — — 167 211 — — 211 International government bonds — 16 — 16 — 17 — 17 Obligation to return cash received as collateral from securities lending (77 ) — — (77 ) (76 ) — — (76 ) Total investments at fair value $ 442 $ 418 $ — 860 $ 372 $ 505 $ — 877 Investments measured by net asset value per share or its equivalent (1) (2) 656 924 Total Investments $ 1,516 $ 1,801 (1) Represents investments in common collective trust funds. (2) The amounts invested in mutual funds and common collective trust funds were allocated as follows: As of December 31, 2018 2017 Mutual Funds Common Collective Trust Funds Mutual Funds Common Collective Trust Funds International equities 51 % 37 % 57 % 34 % Emerging market equities 34 % 4 % 30 % 5 % U.S. equities 15 % 5 % 13 % 6 % Fixed income — 54 % — 55 % The pension plan utilized both exchange traded and over-the-counter financial instruments such as futures, interest rate options and swaps that were marked to market daily with the gains/losses settled in the cash accounts. The pension plan did not include any holdings of CenterPoint Energy Common Stock as of December 31, 2018 or 2017 . (f) Postretirement Plan Assets In managing the investments associated with the postretirement plans, the Registrants’ objective is to achieve and maintain a fully funded plan. This objective is expected to be achieved through an investment strategy that manages liquidity requirements while maintaining a long-term horizon in making investment decisions and efficient and effective management of plan assets. As part of the investment strategy discussed above, the Registrants maintained the following weighted average allocation targets for the postretirement plans as of December 31, 2018 : CenterPoint Energy Houston Electric CERC U.S. equity 13 - 23% 13 - 23% 15 - 25% International developed market equity 3 - 13% 3 - 13% 2 - 12% Fixed income 69 - 79% 69 - 79% 68 - 78% Cash 0 - 2% 0 - 2% 0 - 2% The following table presents mutual funds by level, within the fair value hierarchy, the Registrants’ postretirement plan assets at fair value as of December 31, 2018 and 2017 : Fair Value Measurements as of December 31, 2018 2017 Mutual Funds (Level 1) (Level 2) (Level 3) Total Total (in millions) CenterPoint Energy $ 114 $ — $ — $ 114 $ 120 $ — $ — $ 120 Houston Electric 89 — — 89 93 — — 93 CERC 25 — — 25 26 — — 26 The amounts invested in mutual funds were allocated as follows: As of December 31, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC Fixed income 74 % 74 % 73 % 74 % 74 % 71 % U.S. equities 19 % 19 % 21 % 18 % 18 % 21 % International equities 7 % 7 % 6 % 8 % 8 % 8 % (g) Benefit Plan Contributions The Registrants made the following contributions in 2018 and expect to make the following minimum contributions in 2019 to the indicated benefit plans below: Contributions in 2018 Expected Minimum Contributions in 2019 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Qualified pension plan $ 60 $ — $ — $ 86 $ — $ — Non-qualified pension plan 9 — — 7 — — Postretirement benefit plan 14 9 4 17 10 4 The following benefit payments are expected to be paid by the pension and postretirement benefit plans: Pension Benefits Postretirement Benefits CenterPoint Energy CenterPoint Energy Houston Electric CERC (in millions) 2019 $ 141 $ 16 $ 9 $ 5 2020 146 19 10 6 2021 154 20 11 6 2022 155 21 11 7 2023 156 22 12 7 2024-2028 759 116 61 37 (h) Savings Plan The Registrants participate in CenterPoint Energy’s tax-qualified employee savings plan that includes a cash or deferred arrangement under Section 401(k) of the Internal Revenue Code of 1986, as amended (the Code), and an employee stock ownership plan under Section 4975(e)(7) of the Code. Under the plan, participating employees may make pre-tax or Roth contributions up to 50% , and after tax contributions up to 16% , of their eligible compensation, not to exceed certain federally mandated limits. The Registrants match 100% of the first 6% of each employee’s compensation contributed. The matching contributions are fully vested at all times. Effective January 1, 2016, the savings plan was amended to limit the percentage of future contributions that could be invested in Common Stock to 25% and to prohibit transfers of account balances where the transfer would result in more than 25% of a participant’s total account balance invested in Common Stock. The savings plan has significant holdings of Common Stock. As of December 31, 2018 , 12,062,915 shares of Common Stock were held by the savings plan, which represented approximately 16% of its investments. Given the concentration of the investments in Common Stock, the savings plan and its participants have market risk related to this investment. CenterPoint Energy allocates to Houston Electric and CERC the savings plan benefit expense related to their respective employees. The following table summarizes the Registrants’ savings plan benefit expense for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Savings plan benefit expenses $ 43 $ 17 $ 18 $ 41 $ 17 $ 17 $ 38 $ 15 $ 16 (i) Other Benefits Plans The Registrants participate in CenterPoint Energy’s plan that provides postemployment benefits for certain former or inactive employees, their beneficiaries and covered dependents, after employment but before retirement (primarily healthcare and life insurance benefits for participants in the long-term disability plan). The Registrants participate in CenterPoint Energy’s non-qualified deferred compensation plans that provide benefits payable to directors, officers and select employees or their designated beneficiaries at specified future dates or upon termination, retirement or death. Benefit payments are made from the general assets of the Registrants. Expenses related to other benefit plans were recorded as follows: Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Postemployment benefits $ 3 $ 4 $ 1 $ 6 $ 1 $ 4 $ 5 $ 3 $ 3 Deferred compensation plans 3 1 — 3 1 — 3 1 — Amounts related to other benefit plans were included in Benefit Obligations in the Registrants’ accompanying Consolidated Balance Sheets as follows: December 31, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Postemployment benefits $ 11 $ 3 $ 7 $ 20 $ 3 $ 14 Deferred compensation plans 42 9 3 45 10 3 Split-dollar life insurance arrangements 36 1 — 39 1 — (j) Change in Control Agreements and Other Employee Matters CenterPoint Energy has a change in control plan, which was amended and restated on May 1, 2017. The plan generally provides, to the extent applicable, in the case of a change in control of CenterPoint Energy and covered termination of employment, for severance benefits of up to three times annual base salary plus bonus, and other benefits. CenterPoint Energy officers, including the Executive Chairman, are participants under the plan. As of December 31, 2018 , the Registrants’ employees were covered by collective bargaining agreements as follows: Percentage of Employees Covered Agreement Expiration CenterPoint Energy Houston Electric CERC IBEW Local 66 May 2020 18 % 51 % — OPEIU Local 12 and Mankato March and May 2021 3 % — 3 % Gas Workers Union Local 340 April 2020 6 % — 12 % IBEW Local 949 December 2020 3 % — 7 % USW Locals 13-227 and 13-1 June and July 2022 5 % — 11 % Total 35 % 51 % 33 %

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 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 operating results and cash flows. (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 reportable 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. CenterPoint Energy’s and CERC’s NGD and CenterPoint Energy’s 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 CenterPoint Energy’s and CERC’s NGD’s results in Texas and on CenterPoint Energy’s 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 weather hedge gain (loss) activity: Year Ended December 31, Jurisdiction Winter Season Bilateral Cap 2018 2017 2016 (in millions) Certain NGD jurisdictions 2018 – 2019 $ 9 $ — $ — $ — Certain NGD jurisdictions 2017 – 2018 8 (2 ) — — Total CERC (1) (2 ) — — Electric operations’ Texas service territory 2018 – 2019 8 — — — Electric operations’ Texas service territory 2017 – 2018 9 (2 ) — — Electric operations’ Texas service territory 2016 – 2017 9 — (1 ) 1 Total CenterPoint Energy (1) $ (4 ) $ (1 ) $ 1 (1) Weather hedge gains (losses) are recorded in Revenues in the 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. As of December 31, 2018 and 2017 , the total outstanding notional amount of CenterPoint Energy’s and Houston Electric’s forward interest rate agreements related to cash flow hedges was $450 million and $-0- , respectively. The maximum length of time over which CenterPoint Energy and Houston Electric are exposed to the variability in future cash flows of the forecasted debt offerings is less than 12 months. For the impacts of cash flow hedges to accumulated other comprehensive income, see Note 13. 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 December 31, 2018 and 2017 , the Registrants did not have any outstanding forward interest rate agreements related to economic hedges. (b) Derivative Fair Values and Income Statement Impacts The following tables present information about derivative instruments and hedging activities. The first three tables provide a balance sheet overview of Derivative Assets and Liabilities as of December 31, 2018 and 2017 , while the last three tables provide a breakdown of the related income statement impacts for the years ending December 31, 2018 , 2017 and 2016. Fair Value of Derivative Instruments December 31, 2018 December 31, 2017 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivative Derivative (in millions) Derivatives designated as cash flow hedges: Interest rate derivatives Current Liabilities: Non-trading derivative liabilities $ — $ 24 $ — $ — Total Houston Electric — 24 — — Derivatives designated as fair value hedges: Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 1 7 13 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 103 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 62 173 38 78 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 16 25 9 24 Total CERC 220 208 218 107 Indexed debt securities derivative Current Liabilities — 601 — 668 Total CenterPoint Energy $ 220 $ 833 $ 218 $ 775 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,674 Bcf or a net 140 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of December 31, 2018 and 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 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 Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities is detailed in the Offsetting of Natural Gas Derivative Assets and Liabilities table below. (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) December 31, 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 (in millions) Hedged items in fair value hedge relationship: Natural gas inventory Current Assets: Natural gas inventory $ 57 $ 1 $ 80 $ 14 Total CenterPoint Energy and CERC $ 57 $ 1 $ 80 $ 14 Offsetting of Natural Gas Derivative Assets and Liabilities (CenterPoint Energy and CERC) December 31, 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 $ 166 $ (66 ) $ 100 $ 165 $ (55 ) $ 110 Other Assets: Non-trading derivative assets 54 (16 ) 38 53 (9 ) 44 Current Liabilities: Non-trading derivative liabilities (183 ) 81 (102 ) (83 ) 63 (20 ) Other Liabilities: Non-trading derivative liabilities (25 ) 20 (5 ) (24 ) 20 (4 ) Total $ 12 $ 19 $ 31 $ 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 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) Year Ended December 31, 2018 2017 2016 Location and Amount of Gain (Loss) recognized in Income on Hedging Relationship (2) Non-utility natural gas expense (in millions) Total amounts presented in the statements of income in which the effects of hedges are recorded $ 4,364 $ 3,785 $ 1,983 Gain (loss) on fair value hedging relationships: Commodity contracts: Hedged items - Natural gas inventory (13 ) 14 — Derivatives designated as hedging instruments 13 (14 ) — Amounts excluded from effectiveness testing recognized in earnings immediately (1) (149 ) (67 ) 70 (1) Upon adoption of ASU 2017-12 effective January 1, 2018 (see Note 2 for additional information), CenterPoint Energy and CERC elected to 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 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 the years ended December 31, 2018, 2017 and 2016, respectively. Year Ended December 31, Income Statement Location 2018 2017 2016 (in millions) Effects of derivatives not designated as hedging instruments on the income statement: Commodity contracts Gains (Losses) in Non-utility revenues $ 107 $ 211 $ (18 ) Total CERC 107 211 (18 ) Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (232 ) 49 (413 ) Interest rate derivatives Gains in Other Income (Expense) 2 — — Total CenterPoint Energy $ (123 ) $ 260 $ (431 ) (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 December 31, December 31, 2017 (in millions) Aggregate fair value of derivatives containing material adverse change provisions in a net liability position $ 1 $ 2 Fair value of collateral already posted — — Additional collateral required to be posted if credit risk contingent features triggered — 2 (d) Credit Quality of Counterparties In addition to the risk associated with price movements, credit risk is also inherent in CenterPoint Energy’s and CERC’s non-trading derivative activities. Credit risk relates to the risk of loss resulting from non-performance of contractual obligations by a counterparty. The following table shows the composition of counterparties to the non-trading derivative assets: CenterPoint Energy and CERC December 31, 2018 December 31, 2017 Investment Grade (1) Total (3) Investment Grade (1) Total (3) (in millions) Energy marketers $ 11 $ 24 $ 6 $ 45 End users (2) 30 114 17 109 Total $ 41 $ 138 $ 23 $ 154 (1) “Investment grade” is primarily determined using publicly available credit ratings and considers credit support (including parent company guarantees) and collateral (including cash and standby letters of credit). For unrated counterparties, CenterPoint Energy and CERC determine a synthetic credit rating by performing financial statement analysis and consider contractual rights and restrictions and collateral. (2) End users are comprised primarily of customers who have contracted to fix the price of a portion of their physical gas requirements for future periods. (3) The amounts reflected in the table above were not impacted by collateral netting.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements [Text Block]	Fair Value Measurements Assets and liabilities that are recorded at fair value in the Registrants’ 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 December 31, 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 are valued using a discounted cash flow model which includes illiquid forward price curve locations (ranging from $1.39 to $5.96 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 December 31, 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 and recognize transfers between levels 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 as of December 31, 2018 and December 31, 2017 , and indicate the fair value hierarchy of the valuation techniques utilized by the Registrants to determine such fair value. CenterPoint Energy December 31, 2018 December 31, 2017 Level 1 (4) Level 2 Level 3 Netting (1) Total Level 1 (4) Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 542 $ — $ — $ — $ 542 $ 963 $ — $ — $ — $ 963 Investments, including money market funds (2) 66 — — — 66 68 — — — 68 Natural gas derivatives (3)(4) — 173 47 (82 ) 138 — 161 57 (64 ) 154 Hedged portion of natural gas inventory 1 — — — 1 14 — — — 14 Total assets $ 609 $ 173 $ 47 $ (82 ) $ 747 $ 1,045 $ 161 $ 57 $ (64 ) $ 1,199 Liabilities Indexed debt securities derivative $ — $ 601 $ — $ — $ 601 $ — $ — $ 668 $ — $ 668 Interest rate derivatives 24 — — — 24 — — — — — Natural gas derivatives (3)(4) — 191 17 (101 ) 107 — 96 11 (83 ) 24 Total liabilities $ 24 $ 792 $ 17 $ (101 ) $ 732 $ — $ 96 $ 679 $ (83 ) $ 692 Houston Electric December 31, 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) $ 48 $ — $ — $ — $ 48 $ 51 $ — $ — $ — $ 51 Total assets $ 48 $ — $ — $ — $ 48 $ 51 $ — $ — $ — $ 51 Liabilities Interest rate derivatives $ 24 $ — $ — $ — $ 24 $ — $ — $ — $ — $ — Total liabilities $ 24 $ — $ — $ — $ 24 $ — $ — $ — $ — $ — CERC December 31, 2018 December 31, 2017 Level 2 Level 3 Netting (1) Total Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 2 $ — $ — $ — $ 2 $ 3 $ — $ — $ — $ 3 Investments, including money market funds (2) 11 — — — 11 11 — — — 11 Natural gas derivatives (3)(4) — 173 47 (82 ) 138 — 161 57 (64 ) 154 Hedged portion of natural gas inventory 1 — — — 1 14 — — — 14 Total assets $ 14 $ 173 $ 47 $ (82 ) $ 152 $ 28 $ 161 $ 57 $ (64 ) $ 182 Liabilities Natural gas derivatives (3)(4) $ — $ 191 $ 17 $ (101 ) $ 107 $ — $ 96 $ 11 $ (83 ) $ 24 Total liabilities $ — $ 191 $ 17 $ (101 ) $ 107 $ — $ 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 $19 million as of both December 31, 2018 and 2017 , respectively, posted with the same counterparties. (2) Amounts are included in Prepaid and Other Current Assets and Other Assets in the Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable. (4) Level 1 natural gas derivatives include exchange-traded derivatives cleared by the CME, which deems that financial instruments cleared by the CME are settled daily in connection with posted cash payments. As a result of this exchange rule, CME-related derivatives are considered to have no fair value at the balance sheet date for financial reporting purposes, and are presented in Level 1 net of posted cash; however, the derivatives remain outstanding and subject to future commodity price fluctuations until they are settled in accordance with their contractual terms. Derivative transactions cleared on exchanges other than the CME (e.g., the Intercontinental Exchange or ICE) continue to be reported on a gross basis. 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: Year Ended December 31, 2018 2017 2016 CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC (in millions) Beginning balance $ (622 ) $ 46 $ (704 ) $ 13 $ 12 $ 12 Purchases (1) — — — — 12 12 Total gains (losses) 30 30 96 47 12 12 Total settlements (39 ) (39 ) (11 ) (11 ) (27 ) (27 ) Transfers into Level 3 (2) 5 5 14 14 (712 ) 5 Transfers out of Level 3 (3) 656 (12 ) (17 ) (17 ) (1 ) (1 ) Ending balance (4) $ 30 $ 30 $ (622 ) $ 46 $ (704 ) $ 13 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: $ 18 $ 18 $ 87 $ 38 $ (402 ) $ 11 (1) Mark-to-market value of Level 3 derivative assets acquired through the purchase of AEM were less than $1 million at the acquisition date. (2) During 2016, CenterPoint Energy transferred its indexed debt securities from Level 2 to Level 3 to reflect changes in the significance of the unobservable inputs used in the valuation. (3) During 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. (4) CenterPoint Energy and CERC did not have significant Level 3 sales during any of the years ended December 31, 2018 , 2017 or 2016. Items Measured at Fair Value on a Nonrecurring Basis As of December 31, 2018 and 2017, there were no significant assets or liabilities measured at fair value on a nonrecurring basis. 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’ Consolidated Balance Sheets, but for which the fair value is disclosed, would be classified as Level 2 in the fair value hierarchy. December 31, 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 $ 9,140 $ 4,717 $ 2,371 $ 8,679 $ 4,753 $ 2,457 Fair value 9,308 4,770 2,488 9,220 5,034 2,708 (1) Includes Securitization Bond debt.

Unconsolidated Affiliate (Cente

Unconsolidated Affiliate (CenterPoint Energy and CERC)	12 Months Ended
	Dec. 31, 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, accounts for its 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 and CERC 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(r) for further discussion. Enable is considered to be a VIE because the power to direct the activities that most significantly impact Enable’s economic performance does not reside with the holders of equity investment at risk. However, CenterPoint Energy is not considered the primary beneficiary of Enable since it does not have the power to direct the activities of Enable that are considered most significant to the economic performance of Enable. As of December 31, 2018, CenterPoint Energy’s maximum exposure to loss related to Enable is limited to the equity investment, its investment in Enable Series A Preferred Units and outstanding current accounts receivable from Enable. 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. 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 21 for further discussion. 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 Consolidated Financial Statements as detailed below. Limited Partner Interest and Units Held in Enable (CenterPoint Energy and CERC): As of December 31, 2018 2017 Limited Partner Interest (1) Common Units Enable Series A Preferred Units (2) Limited Partner Interest (1) Common Units Enable Series A Preferred Units (2) CenterPoint Energy (3) 54.0 % 233,856,623 14,520,000 54.1 % 233,856,623 14,520,000 OGE 25.6 % 110,982,805 — 25.7 % 110,982,805 — Public unitholders 20.4 % 88,392,983 — 20.2 % 87,744,652 — (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 Consolidated Balance Sheets, was $363 million as of both December 31, 2018 and 2017 . No impairment charges or adjustment to carrying value were made as no observable price changes were identified in the current or prior reporting periods. See Note 2(r) for further discussion. (3) Prior to the Internal Spin on September 4, 2018 described above, CenterPoint Energy’s investment in Enable’s common units, excluding the Enable Series A Preferred Units held directly by CenterPoint Energy, was held indirectly through CERC. Generally, sales to any person or entity (including a series of sales to the same person or entity) of more than 5% of the aggregate of the common units CenterPoint Energy owns in Enable or sales to any person or entity (including a series of sales to the same person or entity) by OGE of more than 5% of the aggregate of the common units it owns in Enable are subject to mutual rights of first offer and first refusal set forth in Enable’s Agreement of Limited Partnership. Interests Held in Enable GP (CenterPoint Energy and CERC): CenterPoint Energy and OGE held the following interests in Enable GP as of both December 31, 2018 and 2017: Management Rights (1) Incentive Distribution Rights (2) CenterPoint Energy (3) 50 % 40 % OGE 50 % 60 % (1) As of December 31, 2018, 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) CenterPoint Energy held the management rights and incentive distributions rights in Enable GP indirectly through CERC until the Internal Spin on September 4, 2018 described above. Distributions Received from Enable (CenterPoint Energy and CERC): Year Ended December 31, 2018 2017 2016 Per Unit Cash Distribution Per Unit Cash Distribution Per Unit Cash Distribution (in millions, except per unit amounts) Enable common units (1) $ 0.9540 $ 223 $ 1.2720 $ 297 $ 1.2720 $ 297 Total CERC 223 297 297 Enable common units (1) 0.3180 74 — — — — Enable Series A Preferred Units (2) 2.5000 36 2.5000 36 1.5417 22 Total CenterPoint Energy $ 333 $ 333 $ 319 (1) Reflects CERC’s ownership of Enable common units up to September 4, 2018 when CERC completed the Internal Spin. After such date, distributions from Enable were received directly by CenterPoint Energy. (2) 2016 amounts represent the period from February 18, 2016 to December 31, 2016. Transactions with Enable (CenterPoint Energy and CERC): Year Ended December 31, 2018 2017 2016 CenterPoint Energy and CERC (in millions) Natural gas expenses, including transportation and storage costs $ 122 $ 115 $ 110 CenterPoint Energy Reimbursement of transition services (1) 4 4 7 (1) Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement. December 31, 2018 2017 CenterPoint Energy and CERC (in millions) Accounts payable for natural gas purchases from Enable $ 11 $ 13 CenterPoint Energy Accounts receivable for amounts billed for transition services 2 1 CERC’s continuing involvement with Enable subsequent to the Internal Spin is limited to its natural gas purchases from Enable. Summarized consolidated income (loss) information for Enable is as follows: Year Ended December 31, 2018 2017 2016 (in millions) Operating revenues $ 3,431 $ 2,803 $ 2,272 Cost of sales, excluding depreciation and amortization 1,819 1,381 1,017 Depreciation and amortization 398 366 338 Operating income 648 528 385 Net income attributable to Enable common units 485 400 290 Reconciliation of Equity in Earnings (Losses), net: CenterPoint Energy’s interest $ 262 $ 216 $ 160 Basis difference amortization (1) 47 49 48 Loss on dilution, net of proportional basis difference recognition (2 ) — — CenterPoint Energy’s equity in earnings, net $ 307 $ 265 $ 208 (1) Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s share of Enable earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s original investment in Enable and its underlying equity in net assets of Enable. The basis difference is being amortized over approximately 30 years, the remaining average life of the assets to which the basis difference is attributed. Summarized consolidated balance sheet information for Enable is as follows: December 31, 2018 2017 (in millions) Current assets $ 449 $ 416 Non-current assets 11,995 11,177 Current liabilities 1,615 1,279 Non-current liabilities 3,211 2,660 Non-controlling interest 38 12 Preferred equity 362 362 Enable partners’ equity 7,218 7,280 Reconciliation of Investment in Enable: CenterPoint Energy’s ownership interest in Enable partners’ equity $ 3,896 $ 3,935 CenterPoint Energy’s basis difference (1,414 ) (1,463 ) CenterPoint Energy’s equity method investment in Enable $ 2,482 $ 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 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 Consolidated Balance Sheets for the periods presented. The following table presents amounts included in Income from discontinued operations, net of tax in CERC’s Statements of Consolidated Income. Year Ended December 31, 2018 2017 2016 (in millions) Equity in earnings of unconsolidated affiliate, net $ 184 $ 265 $ 208 Income tax expense 46 104 81 Income from discontinued operations, net of tax $ 138 $ 161 $ 127

Indexed Debt Securities (ZENS)

Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy)	12 Months Ended
	Dec. 31, 2018
Indexed Debt 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 ZENS-Related 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 Statements of Consolidated Income. Shares Held at December 31, 2018 2017 AT&T Common 10,212,945 — Charter Common 872,912 872,503 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 remained outstanding as of December 31, 2018 . Each ZENS was originally exchangeable at the holder’s option at any time for an amount of cash equal to 95% of the market value of the reference shares of TW Common attributable to such note. The number and identity of the reference shares attributable to each ZENS are adjusted for certain corporate events. On October 22, 2016, AT&T announced that it had entered into a definitive agreement to acquire TW in a stock and cash transaction. On February 15, 2017, TW shareholders approved the announced transaction with AT&T. 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 ZENS 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 ZENS contingent principal amount. As a result, CenterPoint Energy recorded the following during the year ended December 31, 2018 related to the events discussed above: 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: December 31, 2018 2017 (in shares) AT&T Common 0.7185 — Charter Common 0.061382 0.061382 Time Common — 0.0625 TW Common — 0.5 CenterPoint Energy pays interest on the ZENS at an annual rate of 2% plus the amount of any quarterly cash dividends paid in respect of the reference shares attributable to the ZENS. The principal amount of ZENS is subject to being increased or decreased to the extent that the annual yield from interest and cash dividends on the reference shares is less than or more than 2.309% . The adjusted principal amount is defined in the ZENS instrument as “contingent principal.” At December 31, 2018 , ZENS having an original principal amount of $828 million and a contingent principal amount of $93 million were outstanding and were exchangeable, at the option of the holders, for cash equal to 95% of the market value of reference shares deemed to be attributable to the ZENS. As of December 31, 2018 , the market value of such shares was approximately $540 million , which would provide an exchange amount of $620 for each $1,000 original principal amount of ZENS. At maturity of the ZENS in 2029 , CenterPoint Energy will be obligated to pay in cash the higher of the contingent principal amount of the ZENS or an amount based on the then-current market value of the reference shares, which will include any additional publicly-traded securities distributed with respect to the current reference shares prior to maturity. The ZENS obligation is bifurcated into a debt component and a derivative component (the holder’s option to receive the appreciated value of the reference shares at maturity). The bifurcated debt component accretes through interest charges annually up to the contingent principal amount of the ZENS in 2029. Such accretion will be reduced by annual cash interest payments, as described above. The derivative component is recorded at fair value and changes in the fair value of the derivative component are recorded in CenterPoint Energy’s Statements of Consolidated Income. Changes in the fair value of the ZENS-Related Securities held by CenterPoint Energy are expected to substantially offset changes in the fair value of the derivative component of the ZENS. The following table sets forth summarized financial information regarding CenterPoint Energy’s investment in ZENS-Related Securities and each component of CenterPoint Energy’s ZENS obligation. ZENS-Related Securities Debt Component of ZENS Derivative Component of ZENS (in millions) Balance as of December 31, 2015 $ 805 $ 145 $ 442 Accretion of debt component of ZENS — 26 — 2% interest paid — (17 ) — Sale of ZENS-Related Securities (178 ) — — Distribution to ZENS holders — (40 ) (21 ) Loss on indexed debt securities — — 296 Gain on ZENS-Related Securities 326 — — Balance as of December 31, 2016 953 114 717 Accretion of debt component of ZENS — 27 — 2% interest paid — (17 ) — Distribution to ZENS holders — (2 ) — Gain on indexed debt securities — — (49 ) Gain on ZENS-Related Securities 7 — — Balance as of December 31, 2017 960 122 668 Accretion of debt component of ZENS — 21 — 2% interest paid — (17 ) — Sale of ZENS-Related Securities (398 ) — — Distribution to ZENS holders — (102 ) (46 ) Gain on indexed debt securities — — (21 ) Loss on ZENS-Related Securities (22 ) — — Balance as of December 31, 2018 $ 540 $ 24 $ 601

Equity (CenterPoint Energy)

Equity (CenterPoint Energy)	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Equity (CenterPoint Energy) [Text Block]	Equity (CenterPoint Energy) Dividends Declared CenterPoint Energy declared dividends on its Common Stock during 2018, 2017 and 2016 as presented in the table below: Declaration Date Record Date Payment Date Per Share Total (in millions) December 12, 2018 February 21, 2019 March 14, 2019 $ 0.2875 $ 144 October 23, 2018 November 15, 2018 December 13, 2018 0.2775 139 July 26, 2018 August 16, 2018 September 13, 2018 0.2775 120 April 26, 2018 May 17, 2018 June 14, 2018 0.2775 120 Total 2018 $ 1.1200 $ 523 December 13, 2017 February 15, 2018 March 8, 2018 $ 0.2775 $ 120 October 25, 2017 November 16, 2017 December 8, 2017 0.2675 116 July 27, 2017 August 16, 2017 September 8, 2017 0.2675 115 April 27, 2017 May 16, 2017 June 9, 2017 0.2675 115 January 5, 2017 February 16, 2017 March 10, 2017 0.2675 115 Total 2017 $ 1.3475 $ 581 Declaration Date Record Date Payment Date Per Share Total (in millions) October 27, 2016 November 16, 2016 December 9, 2016 $ 0.2575 $ 111 July 28, 2016 August 16, 2016 September 9, 2016 0.2575 111 April 28, 2016 May 16, 2016 June 10, 2016 0.2575 111 January 20, 2016 February 16, 2016 March 10, 2016 0.2575 110 Total 2016 $ 1.0300 $ 443 CenterPoint Energy declared dividends on its Series A Preferred Stock during 2018 as presented in the table below: Declaration Date Record Date Payment Date Per Share Total (in millions) December 12, 2018 February 15, 2019 March 1, 2019 $ 32.1563 $ 26 Total 2018 $ 32.1563 $ 26 CenterPoint Energy declared dividends on its Series B Preferred Stock during 2018 as presented in the table below: Declaration Date Record Date Payment Date Per Share Total (in millions) December 12, 2018 February 15, 2019 March 1, 2019 $ 17.5000 $ 17 October 23, 2018 November 15, 2018 December 1, 2018 11.6667 11 Total 2018 $ 29.1667 $ 28 There were no Series A Preferred Stock or Series B Preferred Stock outstanding or dividends declared in 2017 and 2016. Dividend Requirement on Preferred Stock Year Ended December 31, 2018 2017 2016 (in millions) Series A Preferred Stock $ 18 $ — $ — Series B Preferred Stock 17 — — Total preferred stock dividend requirement $ 35 $ — $ — 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 used the net proceeds from the Series A Preferred Stock offering to fund a portion of the 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 earned during the applicable periods are presented on CenterPoint Energy’s Statements of Consolidated Income as 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 used the net proceeds from the offering of depositary shares, each representing a 1/20th interest in a share of its Series B Preferred Stock, to fund a portion of the 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. Cumulative dividends earned during the applicable periods are presented on CenterPoint Energy’s Statements of Consolidated Income as Preferred stock dividend requirement. 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 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 used the net proceeds from the Common Stock offering to fund a portion of the Merger and to pay related fees and expenses. Undistributed Retained Earnings As of December 31, 2018 and 2017 , CenterPoint Energy’s consolidated retained earnings balance includes undistributed earnings from Enable of $31 million and $-0- , respectively. Accumulated Other Comprehensive Income (Loss) Changes in accumulated comprehensive income (loss) are as follows: Year Ended December 31, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Beginning Balance $ (68 ) $ — $ 6 $ (71 ) $ 1 $ 3 Other comprehensive income (loss) before reclassifications: Remeasurement of pension and other postretirement plans (19 ) — 1 4 — 7 Deferred loss from interest rate derivatives (1) (19 ) (18 ) (1 ) (5 ) (1 ) (2 ) Amounts reclassified from accumulated other comprehensive loss: Prior service cost (2) 1 — 1 1 — 1 Actuarial losses (2) 6 — — 7 — — Tax benefit (expense) 6 4 (1 ) (4 ) — (3 ) Net current period other comprehensive income (loss) (25 ) (14 ) — 3 (1 ) 3 Adoption of ASU 2018-02 (15 ) — (1 ) — — — Ending Balance $ (108 ) $ (14 ) $ 5 $ (68 ) $ — $ 6 (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 each of the Registrant’s respective Statements of Consolidated Income. Amounts are less than $1 million for each of the years ended December 31, 2018 and 2017, respectively. (2) Amounts are included in the computation of net periodic cost and are reflected in Other, net in each of the Registrants’ respective Statements of Consolidated Income.

Short Term Borrowings and Long

Short Term Borrowings and Long Term Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Short-term Borrowings and Long-term Debt [Text Block]	Short-term Borrowings and Long-term Debt December 31, December 31, Long-Term Current (1) Long-Term Current (1) (in millions) CERC (2) : Short-term borrowings: Inventory financing (3) $ — $ — $ — $ 39 Total short-term borrowings — — — 39 Long-term debt: Senior notes 3.55% to 6.625% due 2021 to 2047 2,193 — 1,593 — Commercial paper (4) 210 — 898 — Unamortized debt issuance costs (15 ) — (12 ) — Unamortized discount and premium, net (17 ) — (22 ) — Total CERC long-term debt 2,371 — 2,457 — Total CERC debt 2,371 — 2,457 39 Houston Electric: First mortgage bonds 9.15% due 2021 102 — 102 — General mortgage bonds 1.85% to 6.95% due 2021 to 2048 3,212 — 2,812 — Restoration Bond Company: System restoration bonds 4.243% due 2022 197 59 256 56 Bond Company II: Transition bonds 5.302% due 2019 — 208 208 194 Bond Company III: Transition bonds 5.234% due 2020 29 56 85 53 Bond Company IV: Transition bonds 2.161% to 3.028% due 2020 to 2024 753 135 888 131 Unamortized debt issuance costs (24 ) — (22 ) — Unamortized discount and premium, net (11 ) — (10 ) — Total Houston Electric debt 4,258 458 4,319 434 CenterPoint Energy: ZENS due 2029 (5) — 24 — 122 Senior notes 2.50% to 4.25% due 2021 to 2028 2,000 — 500 — Pollution control bonds 5.125% due 2028 (6) 68 — 68 50 Commercial paper (4) — — 855 — Unamortized debt issuance costs (13 ) — (4 ) — Unamortized discount and premium, net (2 ) — — — Total CenterPoint Energy long-term debt 8,682 482 8,195 606 Total CenterPoint Energy debt $ 8,682 $ 482 $ 8,195 $ 645 (1) Includes amounts due or exchangeable within one year of the date noted. (2) Issued by CERC Corp. (3) CenterPoint Energy’s and CERC’s 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. (4) Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted. (5) CenterPoint Energy’s ZENS obligation is bifurcated into a debt component and an embedded derivative component. For additional information regarding ZENS, see Note 12(b). As ZENS are exchangeable for cash at any time at the option of the holders, these notes are classified as a current portion of long-term debt. (6) $68 million and $118 million of these series of debt were secured by general mortgage bonds of Houston Electric as of December 31, 2018 and 2017 , respectively. Long-term Debt Debt Retirements. During the year ended December 31, 2018 , CenterPoint Energy retired the following debt instrument at maturity: Registrant Retirement Date Debt Instrument Aggregate Principal Amount (1) Interest Rate Maturity Date (in millions) CenterPoint Energy November 2018 Pollution control bonds $ 50 5.050% 2018 (1) Secured by general mortgage bonds of Houston Electric. Debt Issuances. During the year ended December 31, 2018 and in January 2019, the Registrants issued the following debt instruments: Registrant Issuance Date Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) Houston Electric (1) February 2018 General mortgage bonds $ 400 3.95% 2048 CERC (1) (2) March 2018 Unsecured senior notes 300 3.55% 2023 CERC (1) (2) March 2018 Unsecured senior notes 300 4.00% 2028 CenterPoint Energy (3) October 2018 Unsecured senior notes 500 3.60% 2021 CenterPoint Energy (3) October 2018 Unsecured senior notes 500 3.85% 2024 CenterPoint Energy (3) October 2018 Unsecured senior notes 500 4.25% 2028 Houston Electric (1) January 2019 General mortgage bonds 700 4.25% 2049 (1) Proceeds from these debt issuances were used for general limited liability company and corporate purposes, as applicable, including capital expenditures, repayment of portions of outstanding commercial paper and borrowings under CenterPoint Energy’s money pool. (2) Issued by CERC Corp. (3) Proceeds from these debt issuances were used to fund a portion of the Merger and to pay related fees and expenses. Securitization Bonds. As of December 31, 2018 , CenterPoint Energy and Houston Electric had special purpose subsidiaries consisting of the Bond Companies, which they consolidate. The consolidated special purpose subsidiaries are wholly-owned, bankruptcy remote entities that were formed solely for the purpose of purchasing and owning transition or system restoration property through the issuance of transition bonds or system restoration bonds and activities incidental thereto. These Securitization Bonds are payable only through the imposition and collection of “transition” or “system restoration” charges, as defined in the Texas Public Utility Regulatory Act, which are irrevocable, non-bypassable charges to provide recovery of authorized qualified costs. CenterPoint Energy and Houston Electric have no payment obligations in respect of the Securitization Bonds other than to remit the applicable transition or system restoration charges they collect as set forth in servicing agreements among Houston Electric, the Bond Companies and other parties. Each special purpose entity is the sole owner of the right to impose, collect and receive the applicable transition or system restoration charges securing the bonds issued by that entity. Creditors of CenterPoint Energy or Houston Electric have no recourse to any assets or revenues of the Bond Companies (including the transition and system restoration charges), and the holders of Securitization Bonds have no recourse to the assets or revenues of CenterPoint Energy or Houston Electric. Credit Facilities. In April 2018, CenterPoint Energy obtained commitments by lenders to provide a $5 billion Bridge Facility to provide flexibility for the timing of the long-term acquisition financing and fund, in part, amounts payable by CenterPoint Energy in connection with the Merger. 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 termination date of the revolving credit facility. In addition, the amendment provided 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% . As of December 31, 2018 and 2017 , the Registrants had the following revolving credit facilities and utilization of such facilities: December 31, 2018 December 31, 2017 Size of Loans Letters Commercial Weighted Average Interest Rate Size of Loans Letters Commercial Weighted Average Interest Rate (in millions, except weighted average interest rate) CenterPoint Energy $ 3,300 $ — $ 6 $ — — $ 1,700 $ — $ 6 $ 855 1.88 % Houston Electric 300 — 4 — — 300 — 4 — — CERC (1) 900 — 1 210 2.93 % 900 — 1 898 1.72 % Total $ 4,500 $ — $ 11 $ 210 $ 2,900 $ — $ 11 $ 1,753 (1) Issued by CERC Corp. In January 2019, CenterPoint Energy issued the following commercial paper in connection with the closing of the Merger: Registrant Issuance Date Debt Instrument Aggregate Principal Amount Weighted Average Interest Rate (in millions) CenterPoint Energy (1) (2) January 2019 Commercial paper $ 1,660 2.88% (1) Proceeds from these commercial paper issuances were used to fund a portion of the Merger and to pay related fees and expenses and were contributed to Vectren for its payment of its stub period cash dividend, long-term incentive payments and to fund the repayment of indebtedness of Vectren subsidiaries redeemed at the option of the holder as a result of the closing of the Merger. (2) The commercial paper notes were issued at various times in January 2019 with maturities up to and including 90 days as of the time of issuance, and, prior to their use as described in connection with the closing of the Merger, the net proceeds of such issuances were invested in short-term investments. Execution Date Registrant Size of Facility Draw Rate of LIBOR plus (1) Financial Covenant Limit on Debt for Borrowed Money to Capital Ratio (2) Debt for Borrowed Money to Capital Ratio as of December 31, 2018 (3) Termination Date (4) (in millions) March 3, 2016 CenterPoint Energy $ 3,300 (5) 1.250% 65% 44.9% March 3, 2022 March 3, 2016 Houston Electric 300 1.125% 65% 49.2% March 3, 2022 March 3, 2016 CERC (6) 900 1.125% 65% 46.8% March 3, 2022 (1) Based on credit ratings as of December 31, 2018. (2) For CenterPoint Energy 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. (3) As defined in the revolving credit facility agreement, excluding Securitization Bonds. (4) Amended on June 16, 2017 to extend the termination date. (5) 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. (6) Issued by CERC Corp. The Registrants were in compliance with all financial debt covenants as of December 31, 2018 . Maturities. As of December 31, 2018, maturities of long-term debt, capital leases and sinking fund requirements, excluding the ZENS obligation, are as follows: CenterPoint Energy (1) Houston Electric (1) CERC Securitization Bonds (in millions) 2019 $ 458 $ 458 $ — $ 458 2020 231 231 — 231 2021 1,706 613 593 211 2022 1,230 519 210 219 2023 656 356 300 156 (1) These maturities include Securitization Bonds principal repayments on scheduled payment dates. Liens. As of December 31, 2018 , Houston Electric’s assets were subject to liens securing approximately $102 million of first mortgage bonds. Sinking or improvement fund and replacement fund requirements on the first mortgage bonds may be satisfied by certification of property additions. Sinking fund and replacement fund requirements for 2018 , 2017 and 2016 have been satisfied by certification of property additions. The replacement fund requirement to be satisfied in 2019 is approximately $283 million , and the sinking fund requirement to be satisfied in 2019 is approximately $1.6 million . CenterPoint Energy expects Houston Electric to meet these 2019 obligations by certification of property additions. As of December 31, 2018 , Houston Electric’s assets were also subject to liens securing approximately $3.3 billion of general mortgage bonds, including approximately $68 million held in trust to secure pollution control bonds for which CenterPoint Energy is obligated. The lien of the general mortgage indenture is junior to that of the mortgage pursuant to which the first mortgage bonds are issued. Houston Electric may issue additional general mortgage bonds on the basis of retired bonds, 70% of property additions or cash deposited with the trustee. Approximately $4.3 billion of additional first mortgage bonds and general mortgage bonds could be issued on the basis of retired bonds and 70% of property additions as of December 31, 2018 . Houston Electric has contractually agreed that it will not issue additional first mortgage bonds, subject to certain exceptions.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes [Text Block]	Income Taxes The components of the Registrant’ income tax expense (benefit) were as follows: Year Ended December 31, 2018 2017 2016 (in millions) CenterPoint Energy Current income tax expense: Federal $ 89 $ 32 $ 23 State 9 9 18 Total current expense 98 41 41 Deferred income tax expense (benefit): Federal (25 ) (806 ) 185 State 73 36 28 Total deferred expense (benefit) 48 (770 ) 213 Total income tax expense (benefit) $ 146 $ (729 ) $ 254 Houston Electric Current income tax expense: Federal $ 109 $ 70 $ 165 State 18 19 18 Total current expense 127 89 183 Deferred income tax benefit: Federal (38 ) (98 ) (34 ) Total deferred benefit (38 ) (98 ) (34 ) Total income tax expense (benefit) $ 89 $ (9 ) $ 149 CERC - Continuing Operations Current income tax expense (benefit): Federal $ (9 ) $ (31 ) $ 21 State — (10 ) 4 Total current expense (benefit) (9 ) (41 ) 25 Deferred income tax expense (benefit): Federal 10 (249 ) 41 State 21 25 15 Total deferred expense (benefit) 31 (224 ) 56 Total income tax expense (benefit) $ 22 $ (265 ) $ 81 Year Ended December 31, 2018 2017 2016 (in millions) CERC - Discontinued Operations Current income tax expense (benefit): Federal $ 9 $ 31 $ (21 ) State 4 11 2 Total current expense (benefit) 13 42 (19 ) Deferred income tax expense: Federal 29 56 90 State 4 6 10 Total deferred expense 33 62 100 Total income tax expense $ 46 $ 104 $ 81 A reconciliation of income tax expense (benefit) using the federal statutory income tax rate to the actual income tax expense and resulting effective income tax rate is as follows: Year Ended December 31, 2018 2017 2016 (in millions) CenterPoint Energy (1) (2) (3) Income before income taxes $ 514 $ 1,063 $ 686 Federal statutory income tax rate 21 % 35 % 35 % Expected federal income tax expense 108 372 240 Increase (decrease) in tax expense resulting from: State income tax expense, net of federal income tax 22 26 27 State valuation allowance, net of federal income tax 11 3 3 State law change, net of federal income tax 32 — — Federal income tax rate reduction — (1,113 ) — Excess deferred income tax amortization (24 ) — — Other, net (3 ) (17 ) (16 ) Total 38 (1,101 ) 14 Total income tax expense (benefit) $ 146 $ (729 ) $ 254 Effective tax rate 28 % (69 )% 37 % Houston Electric (4) (5) Income before income taxes $ 425 $ 424 $ 425 Federal statutory income tax rate 21 % 35 % 35 % Expected federal income tax expense 89 148 149 Increase (decrease) in tax expense resulting from: State income tax expense, net of federal income tax 14 12 12 Federal income tax rate reduction — (158 ) — Excess deferred income tax amortization (9 ) — — Other, net (5 ) (11 ) (12 ) Total — (157 ) — Total income tax expense (benefit) $ 89 $ (9 ) $ 149 Effective tax rate 21 % (2 )% 35 % Year Ended December 31, 2018 2017 2016 (in millions) CERC - Continuing Operations (6) (7) Income before income taxes $ 92 $ 319 $ 199 Federal statutory income tax rate 21 % 35 % 35 % Expected federal income tax expense 19 112 70 Increase (decrease) in tax expense resulting from: State income tax expense, net of federal income tax 5 6 4 State law change, net of federal income tax — — 6 State valuation allowance, net of federal income tax 11 3 2 Federal income tax rate reduction — (396 ) — Excess deferred income tax amortization (15 ) — — Tax basis balance sheet adjustment — 11 — Other, net 2 (1 ) (1 ) Total 3 (377 ) 11 Total income tax expense (benefit) $ 22 $ (265 ) $ 81 Effective tax rate 24 % (83 )% 41 % CERC - Discontinued Operations (7) Income before income taxes $ 184 $ 265 $ 208 Federal statutory income tax rate 21 % 35 % 35 % Expected federal income tax expense 39 93 73 Increase in tax expense resulting from: State income tax expense, net of federal income tax 7 11 8 Total 7 11 8 Total income tax expense $ 46 $ 104 $ 81 Effective tax rate 25 % 39 % 39 % (1) Recognized a $32 million deferred tax expense due to state law changes that resulted in remeasurement of state deferred taxes in those jurisdictions. Also recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These items are partially offset by $24 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018. (2) Recognized a $1.1 billion deferred tax benefit from the remeasurement of CenterPoint Energy’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21% . For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below. (3) Recognized a $6 million deferred tax expense in 2016 due to Louisiana state law change and recorded an additional $3 million valuation allowance on certain state carryforwards. (4) Recognized $9 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018. (5) Recognized a $158 million deferred tax benefit from the remeasurement of Houston Electric’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21% . For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below. (6) Recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. This item is partially offset by $15 million of amortization of the net regulatory EDIT liability in certain jurisdictions as decreed by regulators beginning in 2018. (7) Recognized a $396 million deferred tax benefit from the remeasurement of CERC’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21% . ASC 740 requires tax impacts of changes in tax laws or rates be reported in continuing operations. Therefore, CERC’s federal income tax benefit generated by the remeasurement of the ADFIT liability for Enable during 2017 and state law changes during 2016 associated with its investment in Enable are reported in continuing operations on CERC’s Statements of Consolidated Income. The ADFIT liability associated with CERC’s investment in Enable is reported as discontinued operations on CERC’s Consolidated Balance Sheets. The tax effects of temporary differences that give rise to significant portions of deferred tax assets and liabilities were as follows: December 31, 2018 2017 (in millions) CenterPoint Energy Deferred tax assets: Benefits and compensation $ 160 $ 162 Regulatory liabilities 356 347 Loss and credit carryforwards 84 90 Asset retirement obligations 62 68 Other 29 16 Valuation allowance (18 ) (7 ) Total deferred tax assets 673 676 Deferred tax liabilities: Property, plant and equipment 1,894 1,808 Investment in unconsolidated affiliates 987 927 Regulatory assets 395 473 Investment in marketable securities and indexed debt 478 502 Indexed debt securities derivative 27 13 Other 131 127 Total deferred tax liabilities 3,912 3,850 Net deferred tax liabilities $ 3,239 $ 3,174 Houston Electric Deferred tax assets: Regulatory liabilities $ 205 $ 198 Benefits and compensation 17 28 Asset retirement obligations 7 7 Other 12 3 Total deferred tax assets 241 236 Deferred tax liabilities: Property, plant and equipment 1,087 1,030 Regulatory assets 177 265 Total deferred tax liabilities 1,264 1,295 Net deferred tax liabilities $ 1,023 $ 1,059 December 31, 2018 2017 (in millions) CERC - Continuing Operations Deferred tax assets: Benefits and compensation $ 27 $ 27 Regulatory liabilities 150 150 Loss and credit carryforwards 259 288 Asset retirement obligations 54 60 Other 20 18 Valuation allowance (18 ) (7 ) Total deferred tax assets 492 536 Deferred tax liabilities: Property, plant and equipment 773 745 Regulatory assets 41 38 Other 84 115 Total deferred tax liabilities 898 898 Net deferred tax liabilities $ 406 $ 362 CERC - Discontinued Operations Deferred tax liabilities: Investment in unconsolidated affiliates — 927 Net deferred tax liabilities $ — $ 927 Federal Tax Reform On December 22, 2017, President Trump signed into law comprehensive tax reform legislation informally called the Tax Cuts and Jobs Acts, or TCJA, which resulted in significant changes to federal tax laws effective January 1, 2018. The new legislation contained several key tax provisions that impacted the Registrants, including the reduction of the corporate income tax rate from 35% to 21% effective January 1, 2018. The legislation also includes a variety of other changes, such as, a limitation on the tax deductibility of interest expense, acceleration of business asset expensing and reduction in the amount of executive pay that may qualify for a tax deduction, among others. Several other provisions of the TCJA were not generally applicable to the public utility industry, including the limitation on the tax deductibility of interest expense and the acceleration of business asset expensing. While the effective date of the rate change in the legislation was January 1, 2018, ASC 740 requires that deferred tax balances be adjusted in the period of enactment to the rate in which those deferred taxes will reverse. During 2017, CenterPoint Energy’s EDIT from the rate change resulted in an adjustment to income tax expense of approximately $1.1 billion and creation of a net regulatory liability of $1.3 billion (includes $0.3 billion gross-up) for the amount that is likely to be returned to ratepayers. The major components of the $1.1 billion benefit to income tax expense are for the remeasurement of CenterPoint Energy's deferred taxes associated with its investment in Enable, investment in marketable securities (ZENS) and stranded costs related to the Securitization Bonds. During 2017, Houston Electric’s EDIT from the rate change resulted in an adjustment to income tax expense of $158 million and creation of a net regulatory liability of $829 million (includes $180 million gross-up) for the amount that is likely to be returned to ratepayers. The $158 million benefit to income tax expense is for the remeasurement of Houston Electric’s stranded costs related to the Securitization Bonds. During 2017, CERC’s EDIT from the rate change resulted in an adjustment to income tax expense of $396 million and creation of a net regulatory liability of $478 million (includes $121 million gross-up) for the amount that is likely to be returned to ratepayers. The major components of the $396 million benefit to income tax expense were for the remeasurement of CERC’s deferred taxes associated with its investment in Enable and federal net operating loss carryforwards. The amount and expected amortization of the net regulatory tax liability may differ from the Registrants’ estimates, possibly materially, due to, among other things, regulatory actions, interpretations and assumptions the Registrants have made, and any guidance that may be issued in the future. The Registrants will continue to assess the amount and expected amortization of the net regulatory tax liability as they have proceedings with regulators in future periods. Houston Electric and CERC are included in CenterPoint Energy’s U.S. federal consolidated income tax return. Houston Electric and CERC report their income tax provision on a separate entity basis pursuant to a tax sharing agreement with CenterPoint Energy. Tax Attribute Carryforwards and Valuation Allowance. CenterPoint Energy has no remaining federal net operating loss carryforward or federal tax credits as of December 31, 2018 . As of December 31, 2018, CenterPoint Energy had $802 million of state net operating loss carryforwards that expire between 2019 and 2038 and $18 million of state tax credits that do not expire. CenterPoint Energy reported a valuation allowance of $18 million because it is more likely than not that the benefit from certain state net operating loss carryforwards will not be realized. CERC has $951 million of federal net operating loss carryforwards which have an indefinite carryforward period, however, utilization is limited to 80 percent of taxable income in any given taxable year. CERC has $797 million of state net operating loss carryforwards which expire between 2019 and 2038 and $17 million of state tax credits which do not expire. CERC reported a valuation allowance of $18 million since it is more likely than not that the benefit from certain state net operating loss carryforwards will not be realized. Uncertain Income Tax Positions . The Registrants reported no uncertain tax liabilities as of December 31, 2018 , 2017 and 2016 . The Registrants expect no significant change to the uncertain tax liabilities over the next 12 months ending December 31, 2019. Tax Audits and Settlements. Tax years through 2016 have been audited and settled with the IRS, however, during 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, the Registrants are participants in the IRS’s Compliance Assurance Process.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 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 reportable 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 Consolidated Balance Sheets as of December 31, 2018 and 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 December 31, 2018 , minimum payment obligations for natural gas supply commitments are approximately: (in millions) 2019 $ 454 2020 430 2021 343 2022 231 2023 154 2024 and beyond 1,446 (b) AMAs (CenterPoint Energy and CERC) 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. Generally, AMAs are contracts between NGD and an asset manager that are intended to transfer the working capital obligation and maximize the utilization of the assets. In these AMAs, NGD agrees to release transportation and storage capacity to other parties to manage natural gas storage, supply and delivery arrangements for NGD and to use the released capacity for other purposes when it is not needed for NGD. NGD is compensated by the asset manager through payments made over the life of the AMAs. NGD has an obligation to purchase its winter storage requirements that have been released to the asset manager under these AMAs. (c) Lease Commitments The following table sets forth information concerning the Registrants’ obligations under non-cancelable long-term operating leases as of December 31, 2018 , which primarily consist of rental agreements for real property: CenterPoint Energy Houston Electric CERC (in millions) 2019 $ 6 $ 1 $ 5 2020 6 — 5 2021 5 — 4 2022 4 — 4 2023 3 — 3 2024 and beyond 12 — 11 Total $ 36 $ 1 $ 32 Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Lease expense $ 9 $ 1 $ 8 $ 10 $ 1 $ 9 $ 10 $ 1 $ 9 (d) Legal, Environmental and Other Matters Legal Matters (CenterPoint Energy and CERC) Gas Market Manipulation Cases . 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 (which review has been stayed pending approval of the settlement agreement described below). Under a master separation agreement between CenterPoint Energy and a former subsidiary, RRI, CenterPoint Energy and its subsidiaries are entitled to be indemnified by RRI and its successors for any losses, including certain attorneys’ fees and other costs, arising out of these lawsuits. 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. In December 2018, GenOn completed its reorganization and emerged from Chapter 11. 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. In January 2019, the bankruptcy court approved the settlement between CES and GenOn. If the settlement agreement between CES, GenOn and the plaintiffs is not approved by the federal district court, 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. 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 and CERC have reached confidential settlement agreements with some claimants. Additionally, CenterPoint Energy and CERC are cooperating with the ongoing investigation conducted by the National Transportation Safety Board. Further, CenterPoint Energy and CERC are 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 or CERC. CenterPoint Energy’s and CERC’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). CenterPoint Energy, CERC and its predecessors operated MGPs in the past. With respect to certain Minnesota MGP sites, CenterPoint Energy and CERC have completed state-ordered remediation and continue state-ordered monitoring and water treatment. As of December 31, 2018 , CenterPoint Energy and 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 CenterPoint Energy and CERC believe they may have responsibility was $5 million to $32 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 CenterPoint Energy or CERC or may have been owned by one of their 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)	12 Months Ended
	Dec. 31, 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 common share. Basic earnings per common share is determined by dividing Income available to common shareholders - basic by the Weighted average common shares outstanding - basic for the applicable period. Diluted earnings per common share is determined by the inclusion of potentially dilutive common stock equivalent shares that may occur if securities to issue Common Stock were exercised or converted into Common Stock. For the Year Ended December 31, 2018 2017 2016 (in millions, except per share and share amounts) Numerator: Income available to common shareholders - basic (1) $ 333 $ 1,792 $ 432 Add back: Series B Preferred Stock dividend — — — Income available to common shareholders - diluted (1) $ 333 $ 1,792 $ 432 Denominator: Weighted average common shares outstanding - basic 448,829,000 430,964,000 430,606,000 Plus: Incremental shares from assumed conversions: Restricted stock (2) 3,636,000 3,344,000 2,997,000 Series B Preferred Stock (3) — — — Weighted average common shares outstanding - diluted 452,465,000 434,308,000 433,603,000 Earnings per common share: Basic earnings per common share $ 0.74 $ 4.16 $ 1.00 Diluted earnings per common share $ 0.74 $ 4.13 $ 1.00 (1) Income available to common shareholders for the year ended December 31, 2017 includes a reduction in income tax expense of $1,113 million due to tax reform. See Note 15 for further discussion of the impacts of the TCJA. (2) The potentially dilutive impact from restricted stock awards applies the treasury stock method. Under this method, an increase in the average fair market value of Common Stock can result in a greater dilutive impact from these securities. (3) The potentially dilutive impact from Series B Preferred Stock applies the if-converted method in calculating diluted earnings per common share. Under this method, diluted earnings per common share is adjusted for the more dilutive effect of the Series B Preferred Stock as a result of either its accumulated dividend for the period in the numerator or the assumed-converted common share equivalent in the denominator. The computation of diluted earnings per common share outstanding for the year ended December 31, 2018 excludes 8,885,000 potentially dilutive shares because to include them would be anti-dilutive. However, these shares could be potentially dilutive in the future.

Unaudited Quarterly Information

Unaudited Quarterly Information	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Unaudited Quarterly Information [Text Block]	Unaudited Quarterly Information Summarized quarterly financial data is as follows: Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter (in millions, except per share amounts) CenterPoint Energy Revenues $ 3,155 $ 2,186 $ 2,212 $ 3,036 Operating income 251 187 226 167 Income (loss) available to common shareholders 165 (75 ) 153 90 Basic earnings (loss) per common share (1) 0.38 (0.17 ) 0.35 0.18 Diluted earnings (loss) per common share (1) 0.38 (0.17 ) 0.35 0.18 Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter (in millions, except per share amounts) Houston Electric Revenues 755 854 897 728 Operating income 119 181 227 98 Net income 52 101 143 40 CERC (4) Revenues 2,400 1,328 1,312 2,303 Operating income (loss) 131 22 (7 ) 76 Income (loss) from continuing operations 78 (8 ) (35 ) 35 Income (loss) from discontinued operations 52 44 44 (2 ) Net income 130 36 9 33 Year Ended December 31, 2017 First Quarter Second Third Quarter Fourth Quarter (in millions, except per share amounts) CenterPoint Energy Revenues $ 2,735 $ 2,143 $ 2,098 $ 2,638 Operating income (2) 291 240 297 308 Income available to common shareholders (3) 192 135 169 1,296 Basic earnings per common share (1) 0.45 0.31 0.39 3.01 Diluted earnings per common share (1) 0.44 0.31 0.39 2.99 Houston Electric Revenues 638 752 843 765 Operating income (2) 85 171 254 127 Net income (3) 18 75 130 210 CERC (4) Revenues 2,093 1,387 1,251 1,872 Operating income (2) 199 59 31 178 Income (loss) from continuing operations 102 17 (4 ) 469 Income from discontinued operations 45 37 42 37 Net income (3) 147 54 38 506 (1) Quarterly earnings (loss) per common share are based on the weighted average number of shares outstanding during the quarter, and the sum of the quarters may not equal annual earnings (loss) per common share. (2) Recast to reflect the adoption of ASU 2017-07. See Note 2(r) for further information. (3) Income available to common shareholders and Net income for the fourth quarter 2017 include a reduction in income tax expense of $1,113 million , $158 million and $396 million for CenterPoint Energy, Houston Electric and CERC, respectively, due to the TCJA. See Note 15 for further discussion of the impacts of tax reform implementation. (4) Amounts have been recast to reflect discontinued operations in all periods presented.

Reportable Segments

Reportable Segments	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Reportable Segments [Text Block]	Reportable Segments The Registrants’ determination of reportable 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 reportable segments other than Midstream Investments, where equity in earnings is used. As of December 31, 2018 , reportable 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) On September 4, 2018, CERC completed the Internal Spin. Previously, CERC’s equity method investment in Enable was included in CERC’s Midstream Investments reportable segment. CERC’s equity in earnings in Enable, net of basis difference amortization and income tax, have been classified as discontinued operations for all periods presented. See Note 11 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 segment, Electric Transmission & Distribution, and therefore is not included in the tabular reportable segment presentation below. Operating income (loss) amounts for 2017 and 2016 have been recast to reflect the adoption of ASU 2017-07 (see Note 2 (r) for further information). Long-lived assets include net property, plant and equipment, goodwill and other intangibles and equity investments in unconsolidated subsidiaries. Intersegment sales are eliminated in consolidation. Financial data for reportable segments and products and services are as follows: CenterPoint Energy Revenues from External Customers Intersegment Revenues Depreciation and Amortization Operating Income Total Assets Expenditures for Long-Lived Assets (in millions) As of and for the year ended December 31, 2018: Electric Transmission & Distribution $ 3,232 (1) $ — $ 917 $ 623 $ 10,509 $ 952 Natural Gas Distribution 2,931 36 277 266 6,956 638 Energy Services 4,411 110 16 (47 ) 1,558 20 Midstream Investments (2) — — — — 2,482 — Other Operations 15 — 33 (11 ) 6,156 (3) 110 Eliminations — (146 ) — — (652 ) — Consolidated $ 10,589 $ — $ 1,243 $ 831 $ 27,009 1,720 Reconciling items (69 ) Capital expenditures per Statements of Consolidated Cash Flows $ 1,651 Revenues from External Customers Intersegment Revenues Depreciation and Amortization Operating Income Total Assets Expenditures for Long-Lived Assets (in millions) As of and for the year ended December 31, 2017: Electric Transmission & Distribution $ 2,997 (1) $ — $ 724 $ 636 $ 10,292 $ 924 Natural Gas Distribution 2,606 33 260 348 6,608 523 Energy Services 3,997 52 19 126 1,521 11 Midstream Investments (2) — — — — 2,472 — Other Operations 14 — 33 26 2,497 (3) 36 Eliminations — (85 ) — — (654 ) — Consolidated $ 9,614 $ — $ 1,036 $ 1,136 $ 22,736 1,494 Reconciling items (68 ) Capital expenditures per Statements of Consolidated Cash Flows $ 1,426 As of and for the year ended December 31, 2016: Electric Transmission & Distribution $ 3,060 (1) $ — $ 838 $ 653 $ 10,211 $ 858 Natural Gas Distribution 2,380 29 242 321 6,099 510 Energy Services 2,073 26 7 21 1,102 5 Midstream Investments (2) — — — — 2,505 — Other Operations 15 — 39 28 2,681 (3) 33 Eliminations — (55 ) — — (769 ) — Consolidated $ 7,528 $ — $ 1,126 $ 1,023 $ 21,829 1,406 Reconciling items 8 Capital expenditures per Statements of Consolidated Cash Flows $ 1,414 (1) CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Year Ended December 31, 2018 2017 2016 (in millions) Affiliates of NRG $ 705 $ 713 $ 698 Affiliates of Vistra Energy Corp. 251 229 220 (2) CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows: Year Ended December 31, 2018 2017 2016 (in millions) Enable $ 307 $ 265 $ 208 (3) Total assets included pension and other postemployment-related regulatory assets of $665 million , $600 million and $759 million as of December 31, 2018 , 2017 and 2016 , respectively. Additionally, total assets as of December 31, 2018 included $3.9 billion of temporary investments included in Cash and cash equivalents on CenterPoint Energy’s Consolidated Balance Sheets. CERC Revenues from External Customers Intersegment Revenues Depreciation and Amortization Operating Income Total Assets (1) Expenditures for Long-Lived Assets (in millions) As of and for the year ended December 31, 2018: Natural Gas Distribution $ 2,931 $ 36 $ 277 $ 266 $ 6,956 $ 638 Energy Services 4,411 110 16 (47 ) 1,558 20 Other Operations 1 — — 3 66 — Eliminations — (146 ) — — (366 ) — Consolidated $ 7,343 $ — $ 293 $ 222 $ 8,214 658 Reconciling items (25 ) Capital expenditures per Statements of Consolidated Cash Flows $ 633 As of and for the year ended December 31, 2017: Natural Gas Distribution $ 2,606 $ 33 $ 260 $ 348 $ 6,608 $ 523 Energy Services 3,997 52 19 126 1,521 11 Discontinued operations — — — — 2,472 (1) — Other Operations — — — (7 ) 70 — Eliminations — (85 ) — — (559 ) — Consolidated $ 6,603 $ — $ 279 $ 467 $ 10,112 534 Reconciling items (21 ) Capital expenditures per Statements of Consolidated Cash Flows $ 513 As of and for the year ended December 31, 2016: Natural Gas Distribution $ 2,380 $ 29 $ 242 $ 321 $ 6,099 $ 510 Energy Services 2,073 26 7 21 1,102 5 Discontinued operations — — — — 2,505 (1) — Other Operations 1 — — (1 ) 75 — Eliminations — (55 ) — — (563 ) — Consolidated $ 4,454 $ — $ 249 $ 341 $ 9,218 515 Reconciling items 2 Capital expenditures per Statements of Consolidated Cash Flows $ 517 (1) On September 4, 2018, CERC completed the Internal Spin. For further information regarding the Internal Spin, see Note 11 . Year Ended December 31, 2018 2017 2016 Revenues by Products and Services: CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Electric delivery $ 3,232 $ 3,234 $ — $ 2,997 $ 2,998 $ — $ 3,060 $ 3,059 $ — Retail gas sales 4,161 — 4,161 3,634 — 3,634 3,329 — 3,329 Wholesale gas sales 3,008 — 3,008 2,811 — 2,811 977 — 977 Gas transportation and processing 32 — 32 29 — 29 23 — 23 Energy products and services 156 — 142 143 — 129 139 — 125 Total $ 10,589 $ 3,234 $ 7,343 $ 9,614 $ 2,998 $ 6,603 $ 7,528 $ 3,059 $ 4,454

Supplemental Disclosure of Cash

Supplemental Disclosure of Cash Flow Information	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosure of Cash Flow Information [Text Block]	Supplemental Disclosure of Cash Flow Information The tables below provide supplemental disclosure of cash flow information: 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Cash Payments/Receipts: Interest, net of capitalized interest $ 363 $ 200 $ 105 $ 378 $ 205 $ 116 $ 406 $ 209 $ 116 Income taxes (refunds), net 89 154 3 15 76 4 (104 ) 128 3 Non-cash transactions: Accounts payable related to capital expenditures 201 124 80 144 104 56 87 65 35 Capital distribution associated with the Internal Spin — — 1,473 — — — — — — The table below provides a reconciliation of cash, cash equivalents and restricted cash reported in the Consolidated Balance Sheets to the amount reported in the Statements of Consolidated Cash Flows: December 31, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Cash and cash equivalents (1) (2) $ 4,231 $ 335 $ 14 $ 260 $ 238 $ 12 Restricted cash included in Prepaid expenses and other current assets 46 34 11 35 35 — Restricted cash included in Other 1 1 — 1 1 — Total cash, cash equivalents and restricted cash shown in Statements of Consolidated Cash Flows $ 4,278 $ 370 $ 25 $ 296 $ 274 $ 12 (1) CenterPoint Energy’s Cash and cash equivalents as of December 31, 2018 included $3.9 billion of temporary investments resulting from the Merger financings. CenterPoint Energy recorded interest income of $28 million , $2 million and $1 million for the years ended December 31, 2018 , 2017 and 2016 , respectively, in Other, net on CenterPoint Energy’s Statements of Consolidated Income. See Notes 13 and 14 for further details related to the Merger financings. (2) Houston Electric’s Cash and cash equivalents as of December 31, 2018 and 2017 included $335 million and $230 million , respectively, of cash related to the Bond Companies. Houston Electric recorded interest income of $4 million , $2 million and $1 million for the years ended December 31, 2018 , 2017 and 2016 , respectively, in Other, net on Houston Electric’s Statement of Consolidated Income.

Related Party Transactions (Hou

Related Party Transactions (Houston Electric and CERC)	12 Months Ended
	Dec. 31, 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: December 31, 2018 December 31, 2017 Houston Electric CERC Houston Electric CERC (in millions) Money pool investments (borrowings) (1) $ (1 ) $ 114 $ (60 ) $ (570 ) Weighted average interest rate 2.42 % 2.42 % 1.90 % 1.90 % (1) Included in Accounts and notes receivable (payable)–affiliated companies in Houston Electric’s and CERC’s Consolidated Balance Sheets. Houston Electric and CERC affiliate-related net interest income (expense) were as follows: Year Ended December 31, 2018 2017 2016 Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Interest income (expense), net (1) $ 1 $ — $ 2 $ — $ (4 ) $ — (1) Interest income is included in Other, net and interest expense is included in Interest and other finance charges on Houston Electric’s and CERC’s respective 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: Year Ended December 31, 2018 2017 2016 Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Corporate service charges $ 190 $ 147 $ 188 $ 128 $ 179 $ 125 Net affiliate service charges (billings) (17 ) 17 (9 ) 9 (8 ) 8 The table below presents transactions among Houston Electric, CERC and their parent, Utility Holding. Year Ended December 31, 2018 2017 2016 Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Cash dividends paid to parent $ 209 $ 360 $ 180 $ 601 $ 135 $ 643 Cash contribution from parent 200 960 — 38 374 72 Capital distribution to parent associated with the Internal Spin — 1,473 — — — —

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Enable Distributions Declarations (CenterPoint Energy) Equity Instrument Declaration Date Record Date Payment Date Per Unit Distribution Expected Cash Distribution (in millions) Common units February 8, 2019 February 19, 2019 February 26, 2019 $ 0.318 $ 74 Enable Series A Preferred Units February 8, 2019 February 8, 2019 February 14, 2019 0.625 9

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates 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.
Principles of Consolidation	Principles of Consolidation The accounts of the Registrants and their wholly-owned and majority-owned subsidiaries are included in the consolidated financial statements. All intercompany transactions and balances are eliminated in consolidation. As of December 31, 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 solely 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 payable only 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.
Equity and Investments without a Readily Determinable Fair Value (CenterPoint Energy and CERC)	Equity and Investments without a Readily Determinable Fair Value (CenterPoint Energy and CERC) CenterPoint Energy and CERC generally use the equity method of accounting for investments in entities in which they have an ownership interest between 20% and 50% and exercise significant influence. CenterPoint Energy and CERC also use the equity method for investments in which they have ownership percentages greater than 50%, when they exercise significant influence, do not have control and are not considered the primary beneficiary, if applicable. Under the equity method, CenterPoint Energy and CERC adjust their investments each period for contributions made, distributions received, respective shares of comprehensive income and amortization of basis differences, as appropriate. CenterPoint Energy and CERC evaluate their equity method investments for impairment when events or changes in circumstances indicate there is a loss in value of the investment that is other than a temporary decline. CenterPoint Energy and CERC consider distributions received from equity method investments which do not exceed cumulative equity in earnings subsequent to the date of investment to be a return on investment and classify these distributions as operating activities in their respective Statements of Consolidated Cash Flows. CenterPoint Energy and CERC consider distributions received from equity method investments in excess of cumulative equity in earnings subsequent to the date of investment to be a return of investment and classify these distributions as investing activities in their respective Statements of Consolidated Cash Flows. On September 4, 2018, CERC completed the Internal Spin of its equity investment in Enable and Enable GP. For further information regarding the Internal Spin, see Note 11. Investments without a readily determinable fair value will be measured at cost, less impairment, plus or minus observable prices changes of an identical or similar investment of the same issuer.
Revenues	Revenues The Registrants record revenue for electricity delivery and natural gas sales and services under the accrual method and these revenues are recognized upon delivery to customers. Electricity deliveries not billed by month-end are accrued based on actual AMS data, daily supply volumes and applicable rates. Natural gas sales not billed by month-end are accrued based upon estimated purchased gas volumes, estimated lost and unaccounted for gas and currently effective tariff rates. For further discussion, see Note 5.
Long-lived Assets and Intangibles Subject to Amortization	Long-lived Assets and Intangibles Subject to Amortization The Registrants record property, plant and equipment at historical cost and expense repair and maintenance costs as incurred. The Registrants periodically evaluate long-lived assets, including property, plant and equipment, and specifically identifiable intangibles subject to amortization, when events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. The determination of whether an impairment has occurred is based on an estimate of undiscounted cash flows attributable to the assets compared to the carrying value of the assets.
Regulatory Assets and Liabilities	Regulatory Assets and Liabilities The Registrants apply the guidance for accounting for regulated operations to the Electric Transmission & Distribution reportable segment and the Natural Gas Distribution reportable segment. The Registrants’ rate-regulated subsidiaries may collect revenues subject to refund pending final determination in rate proceedings. In connection with such revenues, estimated rate refund liabilities are recorded which reflect management’s current judgment of the ultimate outcomes of the proceedings. The Registrants’ rate-regulated businesses recognize removal costs as a component of depreciation expense in accordance with regulatory treatment. In addition, a portion of the amount of removal costs collected from customers that relate to AROs has been reclassified from a regulatory liability to an asset retirement liability in accordance with accounting guidance for AROs. For further detail on the Registrants’ regulatory assets and liabilities, see Note 7.
Depreciation and Amortization Expense	Depreciation and Amortization Expense The Registrants compute depreciation and amortization using the straight-line method based on economic lives or regulatory-mandated recovery periods. Amortization expense includes amortization of certain regulatory assets and other intangibles.
Capitalization of Interest and AFUDC	Capitalization of Interest and AFUDC The Registrants capitalize interest and AFUDC as a component of projects under construction and amortize over the assets’ estimated useful lives once the assets are placed in service. AFUDC represents the composite interest cost of borrowed funds and a reasonable return on the equity funds used for construction for subsidiaries that apply the guidance for accounting for regulated operations. Although AFUDC increases both utility plant and earnings, it is realized in cash when the assets are included in rates. Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Interest and AFUDC debt (1) $ 8 $ 6 $ 2 $ 9 $ 6 $ 2 $ 8 $ 6 $ 2 AFUDC equity (2) 12 10 2 11 10 1 7 6 1 (1) Included in Interest and other finance charges on the Registrants’ respective Statements of Consolidated Income. (2) Included in Other Income (Expense) on the Registrants’ respective Statements of Consolidated Income.
Income Taxes	Income Taxes Houston Electric and CERC are included in CenterPoint Energy’s U.S. federal consolidated income tax return. Houston Electric and CERC report their income tax provision on a separate entity basis pursuant to a tax sharing agreement with CenterPoint Energy. Current federal and certain state income taxes are payable to or receivable from CenterPoint Energy. The Registrants use the asset and liability method of accounting for deferred income taxes. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. A valuation allowance is established against deferred tax assets for which management believes realization is not considered to be more likely than not. The Registrants recognize interest and penalties as a component of income tax expense (benefit), as applicable, in their respective Statements of Consolidated Income. CenterPoint Energy reports the income tax provision associated with its interest in Enable in income tax expense (benefit) in its Statements of Consolidated Income. On December 22, 2017, President Trump signed into law comprehensive tax reform legislation informally called the Tax Cuts and Jobs Acts, or TCJA, which resulted in significant changes to federal tax laws effective January 1, 2018. See Note 15 for further discussion of the impacts of tax reform implementation. To the extent certain EDIT of the Registrants’ rate-regulated subsidiaries may be recoverable or payable through future rates, regulatory assets and liabilities have been recorded, respectively. The Registrants use the portfolio approach to recognize income tax effects on other comprehensive income from accumulated other comprehensive income.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are recorded at the invoiced amount and do not bear interest. Management reviews the outstanding accounts receivable, as well as the bad debt write-offs experienced in the past, and establishes an allowance for doubtful accounts. Account balances are charged off against the allowance when management determines it is probable the receivable will not be recovered. The table below summarizes the Registrants’ provision for doubtful accounts for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Provision for doubtful accounts $ 16 $ — $ 16 $ 14 $ 1 $ 13 $ 7 $ — $ 7
Inventory	Inventory The Registrants’ inventory consists principally of materials and supplies and, for CERC, natural gas. Materials and supplies are valued at the lower of average cost or market. Materials and supplies are recorded to inventory when purchased and subsequently charged to expense or capitalized to plant when installed. Natural gas inventories of CERC’s Energy Services business segment at locations qualifying for and utilizing the fair value hedge accounting election are valued at fair value; inventories at locations not qualifying for or not utilizing the fair value hedge accounting election are valued at the lower of average cost or market. During 2018 , 2017 and 2016 , CERC recorded write-downs of natural gas inventory to the lower of average cost or market which are disclosed on the respective Statements of Consolidated Cash Flows.
Derivative Instruments	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 operating results and cash flows. Such derivatives are recognized in the Registrants’ Consolidated Balance Sheets at their fair value unless the Registrant elects the normal purchase and sales exemption for qualified physical transactions. A derivative may be designated as a normal purchase or normal sale if the intent is to physically receive or deliver the product for use or sale in the normal course of business. CenterPoint Energy has a Risk Oversight Committee composed of corporate and reportable 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’ risk management policies 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.
Investments in Equity Securities (CenterPoint Energy and CERC)	Investments in Equity Securities (CenterPoint Energy and CERC) CenterPoint Energy and CERC report equity securities at estimated fair value in their respective Consolidated Balance Sheets, and any unrealized holding gains and losses are recorded as Other Income (Expense) in their respective Statements of Consolidated Income.
Environmental Costs	Environmental Costs The Registrants expense or capitalize environmental expenditures, as appropriate, depending on their future economic benefit. The Registrants expense amounts that relate to an existing condition caused by past operations that do not have future economic benefit. The Registrants record undiscounted liabilities related to these future costs when environmental assessments and/or remediation activities are probable and the costs can be reasonably estimated.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents and Restricted Cash For purposes of reporting cash flows, the Registrants consider cash equivalents to be short-term, highly-liquid investments with maturities of three months or less from the date of purchase. Cash and cash equivalents held by the Bond Companies (VIEs) solely to support servicing the Securitization Bonds as of December 31, 2018 and 2017 are reflected on CenterPoint Energy’s and Houston Electric’s Consolidated Balance Sheets. In connection with the issuance of Securitization Bonds, CenterPoint Energy and Houston Electric were required to establish restricted cash accounts to collateralize the bonds that were issued in these financing transactions. These restricted cash accounts are not available for withdrawal until the maturity of the bonds and are not included in cash and cash equivalents. For more information on restricted cash see Note 20 .
Preferred Stock Dividends	Preferred Stock and Dividends Preferred stock is evaluated to determine balance sheet classification, and all conversion and redemption features are evaluated for bifurcation treatment. Proceeds received net of issuance costs are recognized on the settlement date. Cash dividends become a liability once declared. Income available to common stockholders is computed by deducting from net income the dividends accumulated and earned during the period on cumulative preferred stock.
Purchase Accounting	Purchase Accounting The Registrants evaluate acquisitions to determine when a set of acquired activities and assets represent a business. When control of a business is obtained, the Registrants apply the acquisition method of accounting and record the assets acquired, liabilities assumed and any non-controlling interest obtained based on fair value at the acquisition date. The excess of the fair value of purchase consideration over the fair value of the net assets acquired is recorded as goodwill. The results of operations of the acquired business are included in the Registrants’ respective Statements of Consolidated Income beginning on the date of the acquisition.
New Accounting Pronouncements	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 5 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. This standard also 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. Transition method: modified retrospective January 1, 2018 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. 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 11 for further discussion. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption 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 Statements of Consolidated Cash Flows reflect an increase in investing activities and a corresponding decrease in operating activities of $2 million, $4 million and $8 million for the years ended December 31, 2018, 2017 and 2016, respectively, due to the requirement that cash proceeds from COLI policies be classified as cash inflows from investing activity. ASU 2016-18- Statement of Cash Flows (Topic 230): Restricted Cash This standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. Transition method: retrospective January 1, 2018 The adoption of this standard did not have a material impact on the Registrants’ financial position, results of operations or disclosures. However, the Registrants’ respective Statements of Consolidated Cash Flows are reconciled to cash, cash equivalents and restricted cash, resulting in a decrease in investing activities of $11 million for each of CenterPoint Energy’s and CERC’s respective Statements of Consolidated Cash Flows for the year ended December 31, 2018. In addition, each of CenterPoint Energy and Houston Electric showed a decrease of $4 million and an increase of $5 million in investing activities for the years ended December 31, 2017 and 2016, respectively, in their respective Statements of Consolidated Cash Flows. See Note 20 for further discussion. 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 of net periodic costs previously capitalized in assets are recorded as regulatory assets by the Registrants’ rate-regulated businesses prospectively from date of adoption. ASU 2017-12- Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities This standard, including standards amending 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 9 reflects disclosures modified upon adoption. ASU 2018-02-Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA and requires entities to provide certain disclosures regarding stranded tax effects. Transition method : in the period of adoption October 1, 2018 The adoption of this standard did not impact the Registrants’ results of operations or cash flows. As a result of the adoption, CenterPoint Energy and CERC elected to reclassify a stranded tax benefit of $15 million and $1 million, respectively, primarily related to benefit plans, from accumulated other comprehensive loss and income to Retained earnings on their respective Consolidated Balance Sheets. The reclassification only encompasses the change in the federal corporate income tax rate due to the TCJA. 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 10 reflects the disclosures modified upon adoption. Recently Adopted 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 October 1, 2018 The adoption of this standard did not impact the Registrants’ financial position, results of operations, and cash flows. Note 8 reflects the disclosures modified upon adoption. The table below reflects the impact of adoption of ASU 2017-07 (Compensation—Retirement Benefits (Topic 715)) on each of the Registrants’ respective Statements of Consolidated Income: Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 47 $ 21 $ 11 $ 64 $ 26 $ 23 $ 64 $ 25 $ 23 Decrease to other income 47 21 11 64 26 23 64 25 23 Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Effective Date 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 2018-20- Leases (Topic 842)-Narrow-Scope Improvements for Lessors 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. ASU 2018-20 updates several narrow-scope changes for lessors, including sales taxes collected from lessees, lessor costs paid directly by lessees, and recognition of variable payments for contracts with lease and non-lease components. January 1, 2019 Early adoption is permitted The Registrants have completed the identification of leases under the revised definition. In addition to expanded disclosure for lessees and lessors, which will include qualitative disclosures of the nature of the lease population and additional quantitative information, the Registrants expect to recognize approximately $30 million, $1 million and $28 million of right-of-use assets and lease liabilities on the statements of financial position of CenterPoint Energy, Houston Electric and CERC, respectively, on the date of adoption but do not expect a material impact on their results of operations and cash flows. The Registrants elected the practical expedient for 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. ASU 2016-13- Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This standard, including standards amending 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 Early adoption is permitted starting January 1, 2019 The Registrants are currently assessing the impact that this standard will have on their financial position, results of operations, cash flows and disclosures. Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Effective Date Financial Statement Impact upon Adoption 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.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Public Utilities General Disclosures [Table Text Block]	The Registrants capitalize interest and AFUDC as a component of projects under construction and amortize over the assets’ estimated useful lives once the assets are placed in service. AFUDC represents the composite interest cost of borrowed funds and a reasonable return on the equity funds used for construction for subsidiaries that apply the guidance for accounting for regulated operations. Although AFUDC increases both utility plant and earnings, it is realized in cash when the assets are included in rates. Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Interest and AFUDC debt (1) $ 8 $ 6 $ 2 $ 9 $ 6 $ 2 $ 8 $ 6 $ 2 AFUDC equity (2) 12 10 2 11 10 1 7 6 1 (1) Included in Interest and other finance charges on the Registrants’ respective Statements of Consolidated Income. (2) Included in Other Income (Expense) on the Registrants’ respective Statements of Consolidated Income.
Provision for doubtful accounts [Table Text Block]	The table below summarizes the Registrants’ provision for doubtful accounts for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Provision for doubtful accounts $ 16 $ — $ 16 $ 14 $ 1 $ 13 $ 7 $ — $ 7
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 5 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. This standard also 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. Transition method: modified retrospective January 1, 2018 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. 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 11 for further discussion. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption 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 Statements of Consolidated Cash Flows reflect an increase in investing activities and a corresponding decrease in operating activities of $2 million, $4 million and $8 million for the years ended December 31, 2018, 2017 and 2016, respectively, due to the requirement that cash proceeds from COLI policies be classified as cash inflows from investing activity. ASU 2016-18- Statement of Cash Flows (Topic 230): Restricted Cash This standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. Transition method: retrospective January 1, 2018 The adoption of this standard did not have a material impact on the Registrants’ financial position, results of operations or disclosures. However, the Registrants’ respective Statements of Consolidated Cash Flows are reconciled to cash, cash equivalents and restricted cash, resulting in a decrease in investing activities of $11 million for each of CenterPoint Energy’s and CERC’s respective Statements of Consolidated Cash Flows for the year ended December 31, 2018. In addition, each of CenterPoint Energy and Houston Electric showed a decrease of $4 million and an increase of $5 million in investing activities for the years ended December 31, 2017 and 2016, respectively, in their respective Statements of Consolidated Cash Flows. See Note 20 for further discussion. 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 of net periodic costs previously capitalized in assets are recorded as regulatory assets by the Registrants’ rate-regulated businesses prospectively from date of adoption. ASU 2017-12- Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities This standard, including standards amending 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 9 reflects disclosures modified upon adoption. ASU 2018-02-Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA and requires entities to provide certain disclosures regarding stranded tax effects. Transition method : in the period of adoption October 1, 2018 The adoption of this standard did not impact the Registrants’ results of operations or cash flows. As a result of the adoption, CenterPoint Energy and CERC elected to reclassify a stranded tax benefit of $15 million and $1 million, respectively, primarily related to benefit plans, from accumulated other comprehensive loss and income to Retained earnings on their respective Consolidated Balance Sheets. The reclassification only encompasses the change in the federal corporate income tax rate due to the TCJA. 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 10 reflects the disclosures modified upon adoption. Recently Adopted 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 October 1, 2018 The adoption of this standard did not impact the Registrants’ financial position, results of operations, and cash flows. Note 8 reflects the disclosures modified upon adoption. The table below reflects the impact of adoption of ASU 2017-07 (Compensation—Retirement Benefits (Topic 715)) on each of the Registrants’ respective Statements of Consolidated Income: Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 47 $ 21 $ 11 $ 64 $ 26 $ 23 $ 64 $ 25 $ 23 Decrease to other income 47 21 11 64 26 23 64 25 23 Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Effective Date 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 2018-20- Leases (Topic 842)-Narrow-Scope Improvements for Lessors 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. ASU 2018-20 updates several narrow-scope changes for lessors, including sales taxes collected from lessees, lessor costs paid directly by lessees, and recognition of variable payments for contracts with lease and non-lease components. January 1, 2019 Early adoption is permitted The Registrants have completed the identification of leases under the revised definition. In addition to expanded disclosure for lessees and lessors, which will include qualitative disclosures of the nature of the lease population and additional quantitative information, the Registrants expect to recognize approximately $30 million, $1 million and $28 million of right-of-use assets and lease liabilities on the statements of financial position of CenterPoint Energy, Houston Electric and CERC, respectively, on the date of adoption but do not expect a material impact on their results of operations and cash flows. The Registrants elected the practical expedient for 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. ASU 2016-13- Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This standard, including standards amending 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 Early adoption is permitted starting January 1, 2019 The Registrants are currently assessing the impact that this standard will have on their financial position, results of operations, cash flows and disclosures. Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Effective Date Financial Statement Impact upon Adoption 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.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment [Table Text Block]	Property, plant and equipment includes the following: December 31, 2018 December 31, 2017 Weighted Average Useful Lives Property, Plant and Equipment, Gross Accumulated Depreciation & Amortization Property, Plant and Equipment, Net Property, Plant and Equipment, Gross Accumulated Depreciation & Amortization Property, Plant and Equipment, Net CenterPoint Energy (in years) (in millions) Electric Transmission & Distribution 35 $ 12,148 $ 3,746 $ 8,402 $ 11,496 $ 3,633 $ 7,863 Natural Gas Distribution 28 7,257 2,128 5,129 6,735 1,968 4,767 Energy Services 27 121 43 78 102 35 67 Other property 26 741 306 435 698 338 360 Total $ 20,267 $ 6,223 $ 14,044 $ 19,031 $ 5,974 $ 13,057 Houston Electric Electric Transmission 45 $ 3,077 $ 650 $ 2,427 $ 2,767 $ 620 $ 2,147 Electric Distribution 33 7,524 2,553 4,971 7,178 2,522 4,656 Other transmission & distribution property 18 1,547 543 1,004 1,551 491 1,060 Total $ 12,148 $ 3,746 $ 8,402 $ 11,496 $ 3,633 $ 7,863 CERC Natural Gas Distribution 28 $ 7,257 $ 2,128 $ 5,129 $ 6,735 $ 1,968 $ 4,767 Energy Services 27 121 43 78 102 35 67 Other property 23 53 34 19 51 33 18 Total $ 7,431 $ 2,205 $ 5,226 $ 6,888 $ 2,036 $ 4,852
Depreciation and Amortization [Table Text Block]	The following table presents depreciation and amortization expense for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Depreciation $ 626 $ 342 $ 264 $ 619 $ 354 $ 243 $ 607 $ 349 $ 230 Amortization of securitized regulatory assets 531 531 — 329 329 — 455 455 — Other amortization 86 44 29 88 41 36 64 34 19 Total $ 1,243 $ 917 $ 293 $ 1,036 $ 724 $ 279 $ 1,126 $ 838 $ 249
Asset Retirement Obligation [Table Text Block]	A reconciliation of the changes in the ARO liability recorded in Other non-current liabilities on each of the Registrants’ respective Consolidated Balance Sheets is as follows: December 31, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Beginning balance $ 281 $ 35 $ 243 $ 205 $ 33 $ 169 Accretion expense (1) 10 1 9 8 1 7 Revisions in estimates (2) (33 ) (2 ) (31 ) 68 1 67 Ending balance $ 258 $ 34 $ 221 $ 281 $ 35 $ 243 (1) Reflected in Regulatory assets on each of the Registrants’ respective Consolidated Balance Sheets. (2) In 2018, CenterPoint Energy and CERC reflected a decrease in their respective ARO liability which is primarily attributable to increases in the long-term interest rates used for discounting in the ARO calculation. In 2017, CenterPoint Energy and CERC reflected an increase in their respective ARO liability which is primarily attributable to decreases in the long-term interest rates used for discounting in the ARO calculation.

Mergers and Acquisitions (Table

Mergers and Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	The fair value of the identifiable intangible assets and related useful lives included in the final purchase price allocation is as follows: Fair Value Useful Life (in millions) (in years) Customer relationships $ 25 15
Business Acquisition, Pro Forma Information [Table Text Block]	The following unaudited pro forma financial information reflects the consolidated results of operations of CenterPoint Energy and CERC, assuming the AEM acquisition had taken place on January 1, 2016. The unaudited pro forma financial information has been presented for illustrative purposes only and is not necessarily indicative of the consolidated results of operations that would have been achieved had the acquisition taken place on the dates indicated or the future consolidated results of operations of the combined companies. Year Ended December 31, 2017 2016 CenterPoint Energy CERC CenterPoint Energy CERC (in millions) Revenues $ 9,614 $ 6,603 $ 8,541 $ 5,467 Net Income (1) 1,792 745 442 255 (1) Net income for the year ended December 31, 2017 includes a reduction in income tax expense of $1,113 million and $396 million due to the TCJA for CenterPoint Energy and CERC, respectively. See Note 15 for further discussion of the impacts of tax reform implementation.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	The following tables disaggregate revenues by reportable segment and major source: Year Ended December 31, 2018 CenterPoint Energy Houston Electric CERC Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 3,235 $ 3,011 $ 493 $ 6 $ 6,745 $ 3,235 $ 3,011 $ 493 $ 1 $ 3,505 Derivatives income (2 ) (2 ) 4,028 — 4,024 — (2 ) 4,028 — 4,026 Other (3) (1 ) (42 ) — 9 (34 ) (1 ) (42 ) — — (42 ) Eliminations — (36 ) (110 ) — (146 ) — (36 ) (110 ) — (146 ) Total revenues $ 3,232 $ 2,931 $ 4,411 $ 15 $ 10,589 $ 3,234 $ 2,931 $ 4,411 $ 1 $ 7,343 Year Ended December 31, 2017 CenterPoint Energy Houston Electric CERC Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 3,001 $ 2,638 $ 480 $ 5 $ 6,124 $ 3,001 $ 2,638 $ 480 $ — $ 3,118 Derivatives income (1 ) — 3,569 — 3,568 — — 3,569 — 3,569 Other (3) (3 ) 1 — 9 7 (3 ) 1 — — 1 Eliminations — (33 ) (52 ) — (85 ) — (33 ) (52 ) — (85 ) Total revenues $ 2,997 $ 2,606 $ 3,997 $ 14 $ 9,614 $ 2,998 $ 2,606 $ 3,997 $ — $ 6,603 Year Ended December 31, 2016 CenterPoint Energy Houston Electric CERC Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 3,050 $ 2,368 $ 288 $ 5 $ 5,711 $ 3,050 $ 2,368 $ 288 $ — $ 2,656 Derivatives income 1 — 1,811 — 1,812 — — 1,811 — 1,811 Other (3) 9 41 — 10 60 9 41 — 1 42 Eliminations — (29 ) (26 ) — (55 ) — (29 ) (26 ) — (55 ) Total revenues $ 3,060 $ 2,380 $ 2,073 $ 15 $ 7,528 $ 3,059 $ 2,380 $ 2,073 $ 1 $ 4,454 (1) Reflected in Utility revenues in the Statements of Consolidated Income. (2) Reflected in Non-utility revenues in the 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.

Goodwill and Other Intangible_2

Goodwill and Other Intangibles (CenterPoint Energy and CERC) (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill by Reportable Segments [Table Text Block]	CenterPoint Energy’s and CERC’s goodwill by reportable segment as of both December 31, 2018 and 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 finite lived intangible assets recorded in Other non-current assets on the Consolidated Balance Sheets. Finite lived intangible assets are amortized over their estimated useful lives. December 31, 2018 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Balance Gross Carrying Amount Accumulated Amortization Net Balance (in millions) Customer relationships $ 86 $ (27 ) $ 59 $ 86 $ (21 ) $ 65 Covenants not to compete 4 (3 ) 1 4 (2 ) 2 Other 16 (11 ) 5 15 (8 ) 7 Total $ 106 $ (41 ) $ 65 $ 105 $ (31 ) $ 74
Finite-lived Intangible Assets Amortization Expense [Table Text Block]	Year Ended December 31, 2018 2017 2016 (in millions) Amortization expense of intangible assets (1) $ 10 $ 13 $ 4 (1) Recorded in Depreciation and amortization expenses on CenterPoint Energy’s and CERC’s respective Statements of Consolidated Income.
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	CenterPoint Energy and CERC estimate that amortization expense of intangible assets with finite lives for the next five years will be as follows: Amortization Expense (in millions) 2019 $ 11 2020 6 2021 6 2022 6 2023 5

Regulatory Accounting (Tables)

Regulatory Accounting (Tables)	12 Months Ended
	Dec. 31, 2018
Regulated Operations [Abstract]
Schedule of Regulatory Assets and Liabilities [Table Text Block]	The following is a list of regulatory assets and liabilities reflected on the Registrants’ respective Consolidated Balance Sheets as of December 31, 2018 and 2017 : December 31, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Regulatory Assets: Current regulatory assets (1) $ 77 $ — $ 77 $ 130 $ — $ 130 Non-current regulatory assets: Securitized regulatory assets 1,059 1,059 — 1,590 1,590 — Unrecognized equity return (2) (213 ) (213 ) — (287 ) (287 ) — Unamortized loss on reacquired debt 68 68 — 75 75 — Pension and postretirement-related regulatory asset (3) 725 33 30 646 31 20 Hurricane Harvey restoration costs (4) 68 64 4 64 58 6 Regulatory assets related to TCJA (5) 33 23 10 48 33 15 Other long-term regulatory assets (6) 227 90 137 211 70 140 Total non-current regulatory assets 1,967 1,124 181 2,347 1,570 181 Total regulatory assets 2,044 1,124 258 2,477 1,570 311 Regulatory Liabilities: Current regulatory liabilities (7) 38 17 21 24 22 2 Non-current regulatory liabilities: Regulatory liabilities related to TCJA (5) 1,323 847 476 1,354 862 492 Estimated removal costs 886 269 617 878 285 593 Other long-term regulatory liabilities 316 182 134 232 116 116 Total non-current regulatory liabilities 2,525 1,298 1,227 2,464 1,263 1,201 Total regulatory liabilities 2,563 1,315 1,248 2,488 1,285 1,203 Total regulatory assets and liabilities, net $ (519 ) $ (191 ) $ (990 ) $ (11 ) $ 285 $ (892 ) (1) Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ respective Consolidated Balance Sheets. (2) The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the years ended December 31, 2018 , 2017 and 2016 , Houston Electric recognized approximately $74 million , $42 million and $64 million , respectively, of the allowed equity return. The timing of 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 Houston Electric’s and CERC’s 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 $33 million and $4 million as of December 31, 2018 , respectively, and $31 million and $7 million as of December 31, 2017 , respectively, were not earning a return. (4) The Registrants suffered damage as a result of Hurricane Harvey, a major storm classified as a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale, that first struck the Texas coast on Friday, August 25, 2017 and remained over the Houston area for the next several days. The unprecedented flooding from torrential amounts of rainfall accompanying the storm caused significant damage to or destruction of residences and businesses served by the Registrants. The Registrants deferred the uninsured storm restoration costs as management believed it was probable that such costs will be recovered through traditional rate adjustment mechanisms for capital costs and through the next base rate proceeding for operation and maintenance expenses. As a result, storm restoration costs did not materially affect the Registrants’ reported net income for 2017. 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. See Note 15 for additional information. (6) Other long-term regulatory assets that are not earning a return were not material as of December 31, 2018 and 2017 . (7) Current regulatory liabilities are included in Other current liabilities in each of the Registrants’ respective Consolidated Balance Sheets.

Stock-Based Incentive Compens_2

Stock-Based Incentive Compensation Plans and Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]	The following table summarizes CenterPoint Energy’s expenses related to LTIPs for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 (in millions) LTIP Compensation expense (1) $ 26 $ 21 $ 19 Income tax benefit recognized 6 8 7 Actual tax benefit realized for tax deductions 5 6 5 (1) Included in Operation and maintenance expense in CenterPoint Energy’s Statements of Consolidated Income and not capitalized as a part of Inventory or Property, Plant and Equipment.
Share-Based Compensation, Activity [Table Text Block]	The following tables summarize CenterPoint Energy’s LTIP activity for 2018 : Year Ended December 31, 2018 Shares (Thousands) Weighted-Average Grant Date Fair Value Remaining Average Contractual Life (Years) Aggregate Intrinsic Value (2) (Millions) Performance Awards (1) Outstanding and non-vested as of December 31, 2017 3,627 $ 22.15 Granted 1,321 26.74 Forfeited or canceled (721 ) 21.72 Vested and released to participants (409 ) 21.31 Outstanding and non-vested as of December 31, 2018 3,818 $ 23.91 1 $ 57 Stock Awards Outstanding and non-vested as of December 31, 2017 980 $ 22.68 Granted 409 26.62 Forfeited or canceled (29 ) 25.31 Vested and released to participants (300 ) 22.84 Outstanding and non-vested as of December 31, 2018 1,060 $ 24.08 1.1 $ 30 (1) Reflects maximum performance achievement. (2) Reflects the impact of current expectations of achievement and stock price.
Share-Based Compensation Arrangement By Award, Weighted Average Grant Date Fair Value, Grant Date Intrinsic Value, and Vested Grant Date Fair Value [Table Text Block]	The weighted average grant date fair values per unit of awards granted were as follows for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 (In millions, except for per unit amounts) Performance Awards Weighted-average grant date fair value per unit of awards granted $ 26.74 $ 26.64 $ 18.98 Total intrinsic value of awards received by participants 12 7 7 Vested grant date fair value 9 5 7 Stock Awards Weighted-average grant date fair value per unit of awards granted $ 26.62 $ 26.77 $ 19.24 Total intrinsic value of awards received by participants 9 9 6 Vested grant date fair value 7 7 6
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Amounts recognized in accumulated other comprehensive loss (gain) consist of the following: December 31, 2018 2017 Pension Benefits Postretirement Benefits Pension Benefits Postretirement Benefits CenterPoint Energy CenterPoint Energy CERC CenterPoint Energy CenterPoint Energy CERC (in millions) Unrecognized actuarial loss (gain) $ 109 $ (7 ) $ (3 ) $ 94 $ (8 ) $ (2 ) Unrecognized prior service cost 1 5 5 1 6 6 Deferred tax benefit (1) — — (9 ) — — (11 ) Net amount recognized in accumulated other comprehensive loss (gain) $ 110 $ (2 ) $ (7 ) $ 95 $ (2 ) $ (7 ) (1) CenterPoint Energy’s and CERC’s postretirement benefit obligation is reduced by the impact of previously non-taxable government subsidies under the Medicare Prescription Drug Act. Because the subsidies were non-taxable, the temporary difference used in measuring the deferred tax impact was determined on the unrecognized losses excluding such subsidies. Changes in accumulated comprehensive income (loss) are as follows: Year Ended December 31, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Beginning Balance $ (68 ) $ — $ 6 $ (71 ) $ 1 $ 3 Other comprehensive income (loss) before reclassifications: Remeasurement of pension and other postretirement plans (19 ) — 1 4 — 7 Deferred loss from interest rate derivatives (1) (19 ) (18 ) (1 ) (5 ) (1 ) (2 ) Amounts reclassified from accumulated other comprehensive loss: Prior service cost (2) 1 — 1 1 — 1 Actuarial losses (2) 6 — — 7 — — Tax benefit (expense) 6 4 (1 ) (4 ) — (3 ) Net current period other comprehensive income (loss) (25 ) (14 ) — 3 (1 ) 3 Adoption of ASU 2018-02 (15 ) — (1 ) — — — Ending Balance $ (108 ) $ (14 ) $ 5 $ (68 ) $ — $ 6 (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 each of the Registrant’s respective Statements of Consolidated Income. Amounts are less than $1 million for each of the years ended December 31, 2018 and 2017, respectively. (2) Amounts are included in the computation of net periodic cost and are reflected in Other, net in each of the Registrants’ respective Statements of Consolidated Income.
Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	The changes in plan assets and benefit obligations recognized in other comprehensive income during 2018 are as follows: Pension Benefits Postretirement Benefits CenterPoint Energy CenterPoint Energy CERC (in millions) Net loss (gain) $ 22 $ — $ (1 ) Amortization of net loss (6 ) — — Amortization of prior service cost (1 ) — (1 ) Total recognized in comprehensive income $ 15 $ — $ (2 ) Total expense recognized in net periodic costs and Other comprehensive income $ 76 $ 5 $ 3
Benefit Plan Contributions [Table Text Block]	The Registrants made the following contributions in 2018 and expect to make the following minimum contributions in 2019 to the indicated benefit plans below: Contributions in 2018 Expected Minimum Contributions in 2019 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Qualified pension plan $ 60 $ — $ — $ 86 $ — $ — Non-qualified pension plan 9 — — 7 — — Postretirement benefit plan 14 9 4 17 10 4
Schedule of Expected Benefit Payments [Table Text Block]	The following benefit payments are expected to be paid by the pension and postretirement benefit plans: Pension Benefits Postretirement Benefits CenterPoint Energy CenterPoint Energy Houston Electric CERC (in millions) 2019 $ 141 $ 16 $ 9 $ 5 2020 146 19 10 6 2021 154 20 11 6 2022 155 21 11 7 2023 156 22 12 7 2024-2028 759 116 61 37
Defined Contribution Plan Disclosures [Table Text Block]	CenterPoint Energy allocates to Houston Electric and CERC the savings plan benefit expense related to their respective employees. The following table summarizes the Registrants’ savings plan benefit expense for 2018 , 2017 and 2016 : Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Savings plan benefit expenses $ 43 $ 17 $ 18 $ 41 $ 17 $ 17 $ 38 $ 15 $ 16
Other Benefit Plans [Table Text Block]	Expenses related to other benefit plans were recorded as follows: Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Postemployment benefits $ 3 $ 4 $ 1 $ 6 $ 1 $ 4 $ 5 $ 3 $ 3 Deferred compensation plans 3 1 — 3 1 — 3 1 — Amounts related to other benefit plans were included in Benefit Obligations in the Registrants’ accompanying Consolidated Balance Sheets as follows: December 31, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Postemployment benefits $ 11 $ 3 $ 7 $ 20 $ 3 $ 14 Deferred compensation plans 42 9 3 45 10 3 Split-dollar life insurance arrangements 36 1 — 39 1 —
Other Employee Matters [Table Text Block]	As of December 31, 2018 , the Registrants’ employees were covered by collective bargaining agreements as follows: Percentage of Employees Covered Agreement Expiration CenterPoint Energy Houston Electric CERC IBEW Local 66 May 2020 18 % 51 % — OPEIU Local 12 and Mankato March and May 2021 3 % — 3 % Gas Workers Union Local 340 April 2020 6 % — 12 % IBEW Local 949 December 2020 3 % — 7 % USW Locals 13-227 and 13-1 June and July 2022 5 % — 11 % Total 35 % 51 % 33 %
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Net Benefit Costs [Table Text Block]	CenterPoint Energy’s net periodic cost includes the following components relating to pension, including the non-qualified benefit restoration plan: Year Ended December 31, 2018 2017 2016 (in millions) Service cost (1) $ 37 $ 36 $ 38 Interest cost (2) 79 89 93 Expected return on plan assets (2) (107 ) (97 ) (101 ) Amortization of prior service cost (2) 9 9 9 Amortization of net loss (2) 43 58 63 Net periodic cost $ 61 $ 95 $ 102 (1) Amounts presented in the table above are included in Operation and maintenance expense in CenterPoint Energy’s Statements of Consolidated Income, net of regulatory deferrals and amounts capitalized. See Note 2(r). (2) Amounts presented in the table above are included in Other, net in CenterPoint Energy’s Statements of Consolidated Income, net of regulatory deferrals. See Note 2(r).
Schedule of Assumptions Used [Table Text Block]	CenterPoint Energy used the following assumptions to determine net periodic cost relating to pension benefits: Year Ended December 31, 2018 2017 2016 Discount rate 3.65 % 4.15 % 4.40 % Expected return on plan assets 6.00 6.00 6.25 Rate of increase in compensation levels 4.45 4.50 4.15
Schedule of Net Pension and Post-retirement Benefit Costs [Table Text Block]	The following table summarizes changes in the benefit obligation, plan assets, the amounts recognized in the Consolidated Balance Sheets as well as the key assumptions of CenterPoint Energy’s pension plans. The measurement dates for plan assets and obligations were December 31, 2018 and 2017 . December 31, 2018 2017 (in millions, except for actuarial assumptions) Change in Benefit Obligation Benefit obligation, beginning of year $ 2,225 $ 2,197 Service cost 37 36 Interest cost 79 89 Benefits paid (201 ) (168 ) Actuarial (gain) loss (1) (127 ) 71 Benefit obligation, end of year 2,013 2,225 Change in Plan Assets Fair value of plan assets, beginning of year 1,801 1,656 Employer contributions 69 48 Benefits paid (201 ) (168 ) Actual investment return (153 ) 265 Fair value of plan assets, end of year 1,516 1,801 Funded status, end of year $ (497 ) $ (424 ) December 31, 2018 2017 (in millions, except for actuarial assumptions) Amounts Recognized in Balance Sheets Current liabilities-other $ (7 ) $ (7 ) Other liabilities-benefit obligations (490 ) (417 ) Net liability, end of year $ (497 ) $ (424 ) Actuarial Assumptions Discount rate (2) 4.35 % 3.65 % Expected return on plan assets (3) 6.00 6.00 Rate of increase in compensation levels 4.60 4.45 Interest crediting rate 3.75 3.75 (1) Significant sources of gain for 2018 include the increase in discount rate from 3.65% to 4.35% and the mortality projection scale change from MP2017 to MP2018. For 2017, the significant source of loss was the decrease in the discount rate from 4.15% to 3.65% . (2) The discount rate assumption was determined by matching the projected cash flows of CenterPoint Energy’s plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years. (3) The expected rate of return assumption was developed using the targeted asset allocation of CenterPoint Energy’s plans and the expected return for each asset class.
Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]	The following table displays pension benefits related to CenterPoint Energy’s pension plans that have accumulated benefit obligations in excess of plan assets: December 31, 2018 2017 Pension (Qualified) Pension (Non-qualified) Pension Pension (in millions) Accumulated benefit obligation $ 1,930 $ 61 $ 2,090 $ 74 Projected benefit obligation 1,952 61 2,151 74 Fair value of plan assets 1,516 — 1,801 —
Target Allocation of Plan Assets [Table Text Block]	As part of the investment strategy discussed above, CenterPoint Energy maintained the following weighted average allocation targets for its pension plans as of December 31, 2018 : U.S. equity 12 - 28% International developed market equity 7 - 17% Emerging market equity 5 - 11% Fixed income 55 - 65% Cash 0 - 2%
Schedule of Allocation of Plan Assets [Table Text Block]	The following tables set forth by level, within the fair value hierarchy (see Note 10 ), CenterPoint Energy’s pension plan assets at fair value as of December 31, 2018 and 2017 : Fair Value Measurements as of December 31, 2018 2017 (Level 1) (Level 2) (Level 3) Total (Level 1) (Level 2) (Level 3) Total (in millions) Cash $ 19 $ — $ — $ 19 $ 18 $ — $ — $ 18 Corporate bonds: Investment grade or above — 368 — 368 — 432 — 432 Equity securities: U.S. companies 60 — — 60 76 — — 76 Cash received as collateral from securities lending 77 — — 77 76 — — 76 U.S. treasuries 196 — — 196 67 — — 67 Mortgage backed securities — 6 — 6 — 8 — 8 Asset backed securities — 1 — 1 — 1 — 1 Municipal bonds — 27 — 27 — 47 — 47 Mutual funds (2) 167 — — 167 211 — — 211 International government bonds — 16 — 16 — 17 — 17 Obligation to return cash received as collateral from securities lending (77 ) — — (77 ) (76 ) — — (76 ) Total investments at fair value $ 442 $ 418 $ — 860 $ 372 $ 505 $ — 877 Investments measured by net asset value per share or its equivalent (1) (2) 656 924 Total Investments $ 1,516 $ 1,801 (1) Represents investments in common collective trust funds. (2) The amounts invested in mutual funds and common collective trust funds were allocated as follows: As of December 31, 2018 2017 Mutual Funds Common Collective Trust Funds Mutual Funds Common Collective Trust Funds International equities 51 % 37 % 57 % 34 % Emerging market equities 34 % 4 % 30 % 5 % U.S. equities 15 % 5 % 13 % 6 % Fixed income — 54 % — 55 %
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Net Benefit Costs [Table Text Block]	Postretirement benefits are accrued over the active service period of employees. The net postretirement benefit cost includes the following components: Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ 2 $ — $ 1 $ 2 $ 1 $ 1 $ 2 $ 1 $ 1 Interest cost (2) 13 8 4 16 9 5 16 10 4 Expected return on plan assets (2) (5 ) (4 ) (1 ) (5 ) (4 ) (1 ) (6 ) (5 ) (1 ) Amortization of prior service cost (credit) (2) (5 ) (5 ) 1 (5 ) (6 ) 1 (3 ) (4 ) — Amortization of net loss (2) — — — — — — 1 1 1 Curtailment (3) — — — — — — (5 ) (4 ) (1 ) Net postretirement benefit cost (credit) $ 5 $ (1 ) $ 5 $ 8 $ — $ 6 $ 5 $ (1 ) $ 4 (1) Amounts presented in the table above are included in Operation and maintenance expense in CenterPoint Energy’s Statements of Consolidated Income, net of regulatory deferrals and amounts capitalized. See Note 2(r). (2) Amounts presented in the table above are included in Other, net in each of the Registrants’ respective Statements of Consolidated Income, net of regulatory deferrals. See Note 2(r). (3) A curtailment gain or loss is required when the expected future services of a significant number of current employees are reduced or eliminated for the accrual of benefits. During 2016, postretirement healthcare benefits were amended resulting in a net curtailment gain of $5 million . In May 2016, Houston Electric entered into a renegotiated collective bargaining agreement with the IBEW Local Union 66 that provides that for Houston Electric bargaining unit employees covered under the agreement who retire on or after January 1, 2017, retiree medical and prescription drug coverage will be provided exclusively through the NECA/IBEW Family Medical Care Plan in exchange for the payment of monthly premiums as determined under the agreement. As a result, the accrued postretirement benefits related to such future CenterPoint Energy and Houston Electric union retirees were eliminated. Houston Electric recognized a curtailment gain of $3 million as an accelerated recognition of the prior service credit that would otherwise be recognized in future periods for the postretirement plan. CenterPoint Energy also recognized an additional curtailment gain of $2 million in October 2016 related to other amendments in the postretirement plan.
Schedule of Assumptions Used [Table Text Block]	The following assumptions were used to determine net periodic cost relating to postretirement benefits: Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC Discount rate 3.60 % 3.60 % 3.60 % 4.15 % 4.15 % 4.15 % 4.35 % 4.35 % 4.35 % Expected return on plan assets 4.55 4.75 3.85 4.50 4.75 3.60 4.80 5.00 3.95
Schedule of Net Pension and Post-retirement Benefit Costs [Table Text Block]	The following table summarizes changes in the benefit obligation, plan assets, the amounts recognized in consolidated balance sheets and the key assumptions of the postretirement plans. The measurement dates for plan assets and benefit obligations were December 31, 2018 and 2017 . December 31, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Change in Benefit Obligation Benefit obligation, beginning of year $ 386 $ 225 $ 109 $ 383 $ 217 $ 115 Service cost 2 — 1 2 1 1 Interest cost 13 8 4 16 9 5 Participant contributions 7 2 4 7 2 3 Benefits paid (25 ) (13 ) (9 ) (26 ) (14 ) (9 ) Actuarial (gain) loss (1) (52 ) (56 ) 1 4 10 (6 ) Benefit obligation, end of year 331 166 110 386 225 109 Change in Plan Assets Fair value of plan assets, beginning of year 120 93 26 113 88 25 Employer contributions 14 9 4 16 10 5 Participant contributions 7 2 4 7 2 3 Benefits paid (25 ) (13 ) (9 ) (26 ) (14 ) (9 ) Actual investment return (2 ) (2 ) — 10 7 2 Fair value of plan assets, end of year 114 89 25 120 93 26 Funded status, end of year $ (217 ) $ (77 ) $ (85 ) $ (266 ) $ (132 ) $ (83 ) Amounts Recognized in Balance Sheets Current liabilities-other $ (6 ) $ — $ (3 ) $ (6 ) $ — $ (4 ) Other liabilities-benefit obligations (211 ) (77 ) (82 ) (260 ) (132 ) (79 ) Net liability, end of year $ (217 ) $ (77 ) $ (85 ) $ (266 ) $ (132 ) $ (83 ) Actuarial Assumptions Discount rate (2) 4.35 % 4.35 % 4.35 % 3.60 % 3.60 % 3.60 % Expected return on plan assets (3) 4.60 4.70 4.15 4.55 4.75 3.85 Medical cost trend rate assumed for the next year - Pre-65 5.95 5.95 5.95 6.15 6.15 6.15 Medical/prescription drug cost trend rate assumed for the next year - Post-65 28.60 28.60 28.60 23.85 23.85 23.85 Prescription drug cost trend rate assumed for the next year - Pre-65 9.20 9.20 9.20 9.85 9.85 9.85 Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.50 4.50 4.50 4.50 4.50 4.50 Year that the cost trend rates reach the ultimate trend rate - Pre-65 2026 2026 2026 2026 2026 2026 Year that the cost trend rates reach the ultimate trend rate - Post-65 2027 2027 2027 2024 2024 2024 (1) Significant sources of gain for 2018 include the increase in the discount rate from 3.60% to 4.35% , favorable benefit claims experience and cost trend rates in addition to the change in mortality projection scale from MP2017 to MP2018. (2) The discount rate assumption was determined by matching the projected cash flows of the plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years. (3) The expected rate of return assumption was developed using the targeted asset allocation of the plans and the expected return for each asset class.
Target Allocation of Plan Assets [Table Text Block]	As part of the investment strategy discussed above, the Registrants maintained the following weighted average allocation targets for the postretirement plans as of December 31, 2018 : CenterPoint Energy Houston Electric CERC U.S. equity 13 - 23% 13 - 23% 15 - 25% International developed market equity 3 - 13% 3 - 13% 2 - 12% Fixed income 69 - 79% 69 - 79% 68 - 78% Cash 0 - 2% 0 - 2% 0 - 2%
Schedule of Allocation of Plan Assets [Table Text Block]	The following table presents mutual funds by level, within the fair value hierarchy, the Registrants’ postretirement plan assets at fair value as of December 31, 2018 and 2017 : Fair Value Measurements as of December 31, 2018 2017 Mutual Funds (Level 1) (Level 2) (Level 3) Total Total (in millions) CenterPoint Energy $ 114 $ — $ — $ 114 $ 120 $ — $ — $ 120 Houston Electric 89 — — 89 93 — — 93 CERC 25 — — 25 26 — — 26 The amounts invested in mutual funds were allocated as follows: As of December 31, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC Fixed income 74 % 74 % 73 % 74 % 74 % 71 % U.S. equities 19 % 19 % 21 % 18 % 18 % 21 % International equities 7 % 7 % 6 % 8 % 8 % 8 %

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The table below summarizes CenterPoint Energy’s and CERC’s weather hedge gain (loss) activity: Year Ended December 31, Jurisdiction Winter Season Bilateral Cap 2018 2017 2016 (in millions) Certain NGD jurisdictions 2018 – 2019 $ 9 $ — $ — $ — Certain NGD jurisdictions 2017 – 2018 8 (2 ) — — Total CERC (1) (2 ) — — Electric operations’ Texas service territory 2018 – 2019 8 — — — Electric operations’ Texas service territory 2017 – 2018 9 (2 ) — — Electric operations’ Texas service territory 2016 – 2017 9 — (1 ) 1 Total CenterPoint Energy (1) $ (4 ) $ (1 ) $ 1 (1) Weather hedge gains (losses) are recorded in Revenues in the 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 three tables provide a balance sheet overview of Derivative Assets and Liabilities as of December 31, 2018 and 2017 , while the last three tables provide a breakdown of the related income statement impacts for the years ending December 31, 2018 , 2017 and 2016. Fair Value of Derivative Instruments December 31, 2018 December 31, 2017 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivative Derivative (in millions) Derivatives designated as cash flow hedges: Interest rate derivatives Current Liabilities: Non-trading derivative liabilities $ — $ 24 $ — $ — Total Houston Electric — 24 — — Derivatives designated as fair value hedges: Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 1 7 13 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 103 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 62 173 38 78 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 16 25 9 24 Total CERC 220 208 218 107 Indexed debt securities derivative Current Liabilities — 601 — 668 Total CenterPoint Energy $ 220 $ 833 $ 218 $ 775 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,674 Bcf or a net 140 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of December 31, 2018 and 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 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 Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities is detailed in the Offsetting of Natural Gas Derivative Assets and Liabilities table below. (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) December 31, 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 (in millions) Hedged items in fair value hedge relationship: Natural gas inventory Current Assets: Natural gas inventory $ 57 $ 1 $ 80 $ 14 Total CenterPoint Energy and CERC $ 57 $ 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) December 31, 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 $ 166 $ (66 ) $ 100 $ 165 $ (55 ) $ 110 Other Assets: Non-trading derivative assets 54 (16 ) 38 53 (9 ) 44 Current Liabilities: Non-trading derivative liabilities (183 ) 81 (102 ) (83 ) 63 (20 ) Other Liabilities: Non-trading derivative liabilities (25 ) 20 (5 ) (24 ) 20 (4 ) Total $ 12 $ 19 $ 31 $ 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 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) Year Ended December 31, 2018 2017 2016 Location and Amount of Gain (Loss) recognized in Income on Hedging Relationship (2) Non-utility natural gas expense (in millions) Total amounts presented in the statements of income in which the effects of hedges are recorded $ 4,364 $ 3,785 $ 1,983 Gain (loss) on fair value hedging relationships: Commodity contracts: Hedged items - Natural gas inventory (13 ) 14 — Derivatives designated as hedging instruments 13 (14 ) — Amounts excluded from effectiveness testing recognized in earnings immediately (1) (149 ) (67 ) 70 (1) Upon adoption of ASU 2017-12 effective January 1, 2018 (see Note 2 for additional information), CenterPoint Energy and CERC elected to 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 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 the years ended December 31, 2018, 2017 and 2016, respectively. Year Ended December 31, Income Statement Location 2018 2017 2016 (in millions) Effects of derivatives not designated as hedging instruments on the income statement: Commodity contracts Gains (Losses) in Non-utility revenues $ 107 $ 211 $ (18 ) Total CERC 107 211 (18 ) Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (232 ) 49 (413 ) Interest rate derivatives Gains in Other Income (Expense) 2 — — Total CenterPoint Energy $ (123 ) $ 260 $ (431 )
Credit Quality of Counterparties [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 December 31, December 31, 2017 (in millions) Aggregate fair value of derivatives containing material adverse change provisions in a net liability position $ 1 $ 2 Fair value of collateral already posted — — Additional collateral required to be posted if credit risk contingent features triggered — 2 (d) Credit Quality of Counterparties In addition to the risk associated with price movements, credit risk is also inherent in CenterPoint Energy’s and CERC’s non-trading derivative activities. Credit risk relates to the risk of loss resulting from non-performance of contractual obligations by a counterparty. The following table shows the composition of counterparties to the non-trading derivative assets: CenterPoint Energy and CERC December 31, 2018 December 31, 2017 Investment Grade (1) Total (3) Investment Grade (1) Total (3) (in millions) Energy marketers $ 11 $ 24 $ 6 $ 45 End users (2) 30 114 17 109 Total $ 41 $ 138 $ 23 $ 154 (1) “Investment grade” is primarily determined using publicly available credit ratings and considers credit support (including parent company guarantees) and collateral (including cash and standby letters of credit). For unrated counterparties, CenterPoint Energy and CERC determine a synthetic credit rating by performing financial statement analysis and consider contractual rights and restrictions and collateral. (2) End users are comprised primarily of customers who have contracted to fix the price of a portion of their physical gas requirements for future periods. (3) The amounts reflected in the table above were not impacted by collateral netting.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value, Assets 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 as of December 31, 2018 and December 31, 2017 , and indicate the fair value hierarchy of the valuation techniques utilized by the Registrants to determine such fair value. CenterPoint Energy December 31, 2018 December 31, 2017 Level 1 (4) Level 2 Level 3 Netting (1) Total Level 1 (4) Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 542 $ — $ — $ — $ 542 $ 963 $ — $ — $ — $ 963 Investments, including money market funds (2) 66 — — — 66 68 — — — 68 Natural gas derivatives (3)(4) — 173 47 (82 ) 138 — 161 57 (64 ) 154 Hedged portion of natural gas inventory 1 — — — 1 14 — — — 14 Total assets $ 609 $ 173 $ 47 $ (82 ) $ 747 $ 1,045 $ 161 $ 57 $ (64 ) $ 1,199 Liabilities Indexed debt securities derivative $ — $ 601 $ — $ — $ 601 $ — $ — $ 668 $ — $ 668 Interest rate derivatives 24 — — — 24 — — — — — Natural gas derivatives (3)(4) — 191 17 (101 ) 107 — 96 11 (83 ) 24 Total liabilities $ 24 $ 792 $ 17 $ (101 ) $ 732 $ — $ 96 $ 679 $ (83 ) $ 692 Houston Electric December 31, 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) $ 48 $ — $ — $ — $ 48 $ 51 $ — $ — $ — $ 51 Total assets $ 48 $ — $ — $ — $ 48 $ 51 $ — $ — $ — $ 51 Liabilities Interest rate derivatives $ 24 $ — $ — $ — $ 24 $ — $ — $ — $ — $ — Total liabilities $ 24 $ — $ — $ — $ 24 $ — $ — $ — $ — $ — CERC December 31, 2018 December 31, 2017 Level 2 Level 3 Netting (1) Total Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 2 $ — $ — $ — $ 2 $ 3 $ — $ — $ — $ 3 Investments, including money market funds (2) 11 — — — 11 11 — — — 11 Natural gas derivatives (3)(4) — 173 47 (82 ) 138 — 161 57 (64 ) 154 Hedged portion of natural gas inventory 1 — — — 1 14 — — — 14 Total assets $ 14 $ 173 $ 47 $ (82 ) $ 152 $ 28 $ 161 $ 57 $ (64 ) $ 182 Liabilities Natural gas derivatives (3)(4) $ — $ 191 $ 17 $ (101 ) $ 107 $ — $ 96 $ 11 $ (83 ) $ 24 Total liabilities $ — $ 191 $ 17 $ (101 ) $ 107 $ — $ 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 $19 million as of both December 31, 2018 and 2017 , respectively, posted with the same counterparties. (2) Amounts are included in Prepaid and Other Current Assets and Other Assets in the Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable. (4) Level 1 natural gas derivatives include exchange-traded derivatives cleared by the CME, which deems that financial instruments cleared by the CME are settled daily in connection with posted cash payments. As a result of this exchange rule, CME-related derivatives are considered to have no fair value at the balance sheet date for financial reporting purposes, and are presented in Level 1 net of posted cash; however, the derivatives remain outstanding and subject to future commodity price fluctuations until they are settled in accordance with their contractual terms. Derivative transactions cleared on exchanges other than the CME (e.g., the Intercontinental Exchange or ICE) continue to be reported on a gross basis.
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: Year Ended December 31, 2018 2017 2016 CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC (in millions) Beginning balance $ (622 ) $ 46 $ (704 ) $ 13 $ 12 $ 12 Purchases (1) — — — — 12 12 Total gains (losses) 30 30 96 47 12 12 Total settlements (39 ) (39 ) (11 ) (11 ) (27 ) (27 ) Transfers into Level 3 (2) 5 5 14 14 (712 ) 5 Transfers out of Level 3 (3) 656 (12 ) (17 ) (17 ) (1 ) (1 ) Ending balance (4) $ 30 $ 30 $ (622 ) $ 46 $ (704 ) $ 13 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: $ 18 $ 18 $ 87 $ 38 $ (402 ) $ 11 (1) Mark-to-market value of Level 3 derivative assets acquired through the purchase of AEM were less than $1 million at the acquisition date. (2) During 2016, CenterPoint Energy transferred its indexed debt securities from Level 2 to Level 3 to reflect changes in the significance of the unobservable inputs used in the valuation. (3) During 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. (4) CenterPoint Energy and CERC did not have significant Level 3 sales during any of the years ended December 31, 2018 , 2017 or 2016.
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’ Consolidated Balance Sheets, but for which the fair value is disclosed, would be classified as Level 2 in the fair value hierarchy. December 31, 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 $ 9,140 $ 4,717 $ 2,371 $ 8,679 $ 4,753 $ 2,457 Fair value 9,308 4,770 2,488 9,220 5,034 2,708 (1) Includes Securitization Bond debt.

Unconsolidated Affiliate (Cen_2

Unconsolidated Affiliate (CenterPoint Energy and CERC) (Tables)	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments [Table Text Block]	CenterPoint Energy and OGE held the following interests in Enable GP as of both December 31, 2018 and 2017: Management Rights (1) Incentive Distribution Rights (2) CenterPoint Energy (3) 50 % 40 % OGE 50 % 60 % (1) As of December 31, 2018, 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) CenterPoint Energy held the management rights and incentive distributions rights in Enable GP indirectly through CERC until the Internal Spin on September 4, 2018 described above. Distributions Received from Enable (CenterPoint Energy and CERC): Year Ended December 31, 2018 2017 2016 Per Unit Cash Distribution Per Unit Cash Distribution Per Unit Cash Distribution (in millions, except per unit amounts) Enable common units (1) $ 0.9540 $ 223 $ 1.2720 $ 297 $ 1.2720 $ 297 Total CERC 223 297 297 Enable common units (1) 0.3180 74 — — — — Enable Series A Preferred Units (2) 2.5000 36 2.5000 36 1.5417 22 Total CenterPoint Energy $ 333 $ 333 $ 319 (1) Reflects CERC’s ownership of Enable common units up to September 4, 2018 when CERC completed the Internal Spin. After such date, distributions from Enable were received directly by CenterPoint Energy. (2) 2016 amounts represent the period from February 18, 2016 to December 31, 2016. Transactions with Enable (CenterPoint Energy and CERC): Year Ended December 31, 2018 2017 2016 CenterPoint Energy and CERC (in millions) Natural gas expenses, including transportation and storage costs $ 122 $ 115 $ 110 CenterPoint Energy Reimbursement of transition services (1) 4 4 7 (1) Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement. December 31, 2018 2017 CenterPoint Energy and CERC (in millions) Accounts payable for natural gas purchases from Enable $ 11 $ 13 CenterPoint Energy Accounts receivable for amounts billed for transition services 2 1 CERC’s continuing involvement with Enable subsequent to the Internal Spin is limited to its natural gas purchases from Enable. Summarized consolidated income (loss) information for Enable is as follows: Year Ended December 31, 2018 2017 2016 (in millions) Operating revenues $ 3,431 $ 2,803 $ 2,272 Cost of sales, excluding depreciation and amortization 1,819 1,381 1,017 Depreciation and amortization 398 366 338 Operating income 648 528 385 Net income attributable to Enable common units 485 400 290 Reconciliation of Equity in Earnings (Losses), net: CenterPoint Energy’s interest $ 262 $ 216 $ 160 Basis difference amortization (1) 47 49 48 Loss on dilution, net of proportional basis difference recognition (2 ) — — CenterPoint Energy’s equity in earnings, net $ 307 $ 265 $ 208 (1) Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s share of Enable earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s original investment in Enable and its underlying equity in net assets of Enable. The basis difference is being amortized over approximately 30 years, the remaining average life of the assets to which the basis difference is attributed. Summarized consolidated balance sheet information for Enable is as follows: December 31, 2018 2017 (in millions) Current assets $ 449 $ 416 Non-current assets 11,995 11,177 Current liabilities 1,615 1,279 Non-current liabilities 3,211 2,660 Non-controlling interest 38 12 Preferred equity 362 362 Enable partners’ equity 7,218 7,280 Reconciliation of Investment in Enable: CenterPoint Energy’s ownership interest in Enable partners’ equity $ 3,896 $ 3,935 CenterPoint Energy’s basis difference (1,414 ) (1,463 ) CenterPoint Energy’s equity method investment in Enable $ 2,482 $ 2,472 Limited Partner Interest and Units Held in Enable (CenterPoint Energy and CERC): As of December 31, 2018 2017 Limited Partner Interest (1) Common Units Enable Series A Preferred Units (2) Limited Partner Interest (1) Common Units Enable Series A Preferred Units (2) CenterPoint Energy (3) 54.0 % 233,856,623 14,520,000 54.1 % 233,856,623 14,520,000 OGE 25.6 % 110,982,805 — 25.7 % 110,982,805 — Public unitholders 20.4 % 88,392,983 — 20.2 % 87,744,652 — (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 Consolidated Balance Sheets, was $363 million as of both December 31, 2018 and 2017 . No impairment charges or adjustment to carrying value were made as no observable price changes were identified in the current or prior reporting periods. See Note 2(r) for further discussion. (3) Prior to the Internal Spin on September 4, 2018 described above, CenterPoint Energy’s investment in Enable’s common units, excluding the Enable Series A Preferred Units held directly by CenterPoint Energy, was held indirectly through CERC.
Disposal Groups, Including Discontinued Operations [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 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 Consolidated Balance Sheets for the periods presented. The following table presents amounts included in Income from discontinued operations, net of tax in CERC’s Statements of Consolidated Income. Year Ended December 31, 2018 2017 2016 (in millions) Equity in earnings of unconsolidated affiliate, net $ 184 $ 265 $ 208 Income tax expense 46 104 81 Income from discontinued operations, net of tax $ 138 $ 161 $ 127

Indexed Debt Securities (ZENS_2

Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) (Tables)	12 Months Ended
	Dec. 31, 2018
Indexed Debt Securities [Abstract]
Summarized Financial Information on Investment in Time Warner Securities and Indexed Debt Security Obligation [Table Text Block]	In 1995, CenterPoint Energy sold a cable television subsidiary to TW and received certain ZENS-Related 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 Statements of Consolidated Income. Shares Held at December 31, 2018 2017 AT&T Common 10,212,945 — Charter Common 872,912 872,503 Time Common — 888,392 TW Common — 7,107,130 The following table sets forth summarized financial information regarding CenterPoint Energy’s investment in ZENS-Related Securities and each component of CenterPoint Energy’s ZENS obligation. ZENS-Related Securities Debt Component of ZENS Derivative Component of ZENS (in millions) Balance as of December 31, 2015 $ 805 $ 145 $ 442 Accretion of debt component of ZENS — 26 — 2% interest paid — (17 ) — Sale of ZENS-Related Securities (178 ) — — Distribution to ZENS holders — (40 ) (21 ) Loss on indexed debt securities — — 296 Gain on ZENS-Related Securities 326 — — Balance as of December 31, 2016 953 114 717 Accretion of debt component of ZENS — 27 — 2% interest paid — (17 ) — Distribution to ZENS holders — (2 ) — Gain on indexed debt securities — — (49 ) Gain on ZENS-Related Securities 7 — — Balance as of December 31, 2017 960 122 668 Accretion of debt component of ZENS — 21 — 2% interest paid — (17 ) — Sale of ZENS-Related Securities (398 ) — — Distribution to ZENS holders — (102 ) (46 ) Gain on indexed debt securities — — (21 ) Loss on ZENS-Related Securities (22 ) — — Balance as of December 31, 2018 $ 540 $ 24 $ 601 As a result, CenterPoint Energy recorded the following during the year ended December 31, 2018 related to the events discussed above: 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: December 31, 2018 2017 (in shares) AT&T Common 0.7185 — Charter Common 0.061382 0.061382 Time Common — 0.0625 TW Common — 0.5

Equity (CenterPoint Energy) (Ta

Equity (CenterPoint Energy) (Tables)	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Dividends Declared [Table Text Block]	CenterPoint Energy declared dividends on its Common Stock during 2018, 2017 and 2016 as presented in the table below: Declaration Date Record Date Payment Date Per Share Total (in millions) December 12, 2018 February 21, 2019 March 14, 2019 $ 0.2875 $ 144 October 23, 2018 November 15, 2018 December 13, 2018 0.2775 139 July 26, 2018 August 16, 2018 September 13, 2018 0.2775 120 April 26, 2018 May 17, 2018 June 14, 2018 0.2775 120 Total 2018 $ 1.1200 $ 523 December 13, 2017 February 15, 2018 March 8, 2018 $ 0.2775 $ 120 October 25, 2017 November 16, 2017 December 8, 2017 0.2675 116 July 27, 2017 August 16, 2017 September 8, 2017 0.2675 115 April 27, 2017 May 16, 2017 June 9, 2017 0.2675 115 January 5, 2017 February 16, 2017 March 10, 2017 0.2675 115 Total 2017 $ 1.3475 $ 581 Declaration Date Record Date Payment Date Per Share Total (in millions) October 27, 2016 November 16, 2016 December 9, 2016 $ 0.2575 $ 111 July 28, 2016 August 16, 2016 September 9, 2016 0.2575 111 April 28, 2016 May 16, 2016 June 10, 2016 0.2575 111 January 20, 2016 February 16, 2016 March 10, 2016 0.2575 110 Total 2016 $ 1.0300 $ 443 CenterPoint Energy declared dividends on its Series A Preferred Stock during 2018 as presented in the table below: Declaration Date Record Date Payment Date Per Share Total (in millions) December 12, 2018 February 15, 2019 March 1, 2019 $ 32.1563 $ 26 Total 2018 $ 32.1563 $ 26 CenterPoint Energy declared dividends on its Series B Preferred Stock during 2018 as presented in the table below: Declaration Date Record Date Payment Date Per Share Total (in millions) December 12, 2018 February 15, 2019 March 1, 2019 $ 17.5000 $ 17 October 23, 2018 November 15, 2018 December 1, 2018 11.6667 11 Total 2018 $ 29.1667 $ 28 There were no Series A Preferred Stock or Series B Preferred Stock outstanding or dividends declared in 2017 and 2016. Dividend Requirement on Preferred Stock Year Ended December 31, 2018 2017 2016 (in millions) Series A Preferred Stock $ 18 $ — $ — Series B Preferred Stock 17 — — Total preferred stock dividend requirement $ 35 $ — $ —
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
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Amounts recognized in accumulated other comprehensive loss (gain) consist of the following: December 31, 2018 2017 Pension Benefits Postretirement Benefits Pension Benefits Postretirement Benefits CenterPoint Energy CenterPoint Energy CERC CenterPoint Energy CenterPoint Energy CERC (in millions) Unrecognized actuarial loss (gain) $ 109 $ (7 ) $ (3 ) $ 94 $ (8 ) $ (2 ) Unrecognized prior service cost 1 5 5 1 6 6 Deferred tax benefit (1) — — (9 ) — — (11 ) Net amount recognized in accumulated other comprehensive loss (gain) $ 110 $ (2 ) $ (7 ) $ 95 $ (2 ) $ (7 ) (1) CenterPoint Energy’s and CERC’s postretirement benefit obligation is reduced by the impact of previously non-taxable government subsidies under the Medicare Prescription Drug Act. Because the subsidies were non-taxable, the temporary difference used in measuring the deferred tax impact was determined on the unrecognized losses excluding such subsidies. Changes in accumulated comprehensive income (loss) are as follows: Year Ended December 31, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Beginning Balance $ (68 ) $ — $ 6 $ (71 ) $ 1 $ 3 Other comprehensive income (loss) before reclassifications: Remeasurement of pension and other postretirement plans (19 ) — 1 4 — 7 Deferred loss from interest rate derivatives (1) (19 ) (18 ) (1 ) (5 ) (1 ) (2 ) Amounts reclassified from accumulated other comprehensive loss: Prior service cost (2) 1 — 1 1 — 1 Actuarial losses (2) 6 — — 7 — — Tax benefit (expense) 6 4 (1 ) (4 ) — (3 ) Net current period other comprehensive income (loss) (25 ) (14 ) — 3 (1 ) 3 Adoption of ASU 2018-02 (15 ) — (1 ) — — — Ending Balance $ (108 ) $ (14 ) $ 5 $ (68 ) $ — $ 6 (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 each of the Registrant’s respective Statements of Consolidated Income. Amounts are less than $1 million for each of the years ended December 31, 2018 and 2017, respectively. (2) Amounts are included in the computation of net periodic cost and are reflected in Other, net in each of the Registrants’ respective Statements of Consolidated Income.

Short Term Borrowings and Lon_2

Short Term Borrowings and Long Term Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Short-term Borrowings and Long-term Debt [Table Text Block]	December 31, December 31, Long-Term Current (1) Long-Term Current (1) (in millions) CERC (2) : Short-term borrowings: Inventory financing (3) $ — $ — $ — $ 39 Total short-term borrowings — — — 39 Long-term debt: Senior notes 3.55% to 6.625% due 2021 to 2047 2,193 — 1,593 — Commercial paper (4) 210 — 898 — Unamortized debt issuance costs (15 ) — (12 ) — Unamortized discount and premium, net (17 ) — (22 ) — Total CERC long-term debt 2,371 — 2,457 — Total CERC debt 2,371 — 2,457 39 Houston Electric: First mortgage bonds 9.15% due 2021 102 — 102 — General mortgage bonds 1.85% to 6.95% due 2021 to 2048 3,212 — 2,812 — Restoration Bond Company: System restoration bonds 4.243% due 2022 197 59 256 56 Bond Company II: Transition bonds 5.302% due 2019 — 208 208 194 Bond Company III: Transition bonds 5.234% due 2020 29 56 85 53 Bond Company IV: Transition bonds 2.161% to 3.028% due 2020 to 2024 753 135 888 131 Unamortized debt issuance costs (24 ) — (22 ) — Unamortized discount and premium, net (11 ) — (10 ) — Total Houston Electric debt 4,258 458 4,319 434 CenterPoint Energy: ZENS due 2029 (5) — 24 — 122 Senior notes 2.50% to 4.25% due 2021 to 2028 2,000 — 500 — Pollution control bonds 5.125% due 2028 (6) 68 — 68 50 Commercial paper (4) — — 855 — Unamortized debt issuance costs (13 ) — (4 ) — Unamortized discount and premium, net (2 ) — — — Total CenterPoint Energy long-term debt 8,682 482 8,195 606 Total CenterPoint Energy debt $ 8,682 $ 482 $ 8,195 $ 645 (1) Includes amounts due or exchangeable within one year of the date noted. (2) Issued by CERC Corp. (3) CenterPoint Energy’s and CERC’s 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. (4) Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted. (5) CenterPoint Energy’s ZENS obligation is bifurcated into a debt component and an embedded derivative component. For additional information regarding ZENS, see Note 12(b). As ZENS are exchangeable for cash at any time at the option of the holders, these notes are classified as a current portion of long-term debt. (6) $68 million and $118 million of these series of debt were secured by general mortgage bonds of Houston Electric as of December 31, 2018 and 2017 , respectively. Long-term Debt Debt Retirements. During the year ended December 31, 2018 , CenterPoint Energy retired the following debt instrument at maturity: Registrant Retirement Date Debt Instrument Aggregate Principal Amount (1) Interest Rate Maturity Date (in millions) CenterPoint Energy November 2018 Pollution control bonds $ 50 5.050% 2018 (1) Secured by general mortgage bonds of Houston Electric. Debt Issuances. During the year ended December 31, 2018 and in January 2019, the Registrants issued the following debt instruments: Registrant Issuance Date Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) Houston Electric (1) February 2018 General mortgage bonds $ 400 3.95% 2048 CERC (1) (2) March 2018 Unsecured senior notes 300 3.55% 2023 CERC (1) (2) March 2018 Unsecured senior notes 300 4.00% 2028 CenterPoint Energy (3) October 2018 Unsecured senior notes 500 3.60% 2021 CenterPoint Energy (3) October 2018 Unsecured senior notes 500 3.85% 2024 CenterPoint Energy (3) October 2018 Unsecured senior notes 500 4.25% 2028 Houston Electric (1) January 2019 General mortgage bonds 700 4.25% 2049 (1) Proceeds from these debt issuances were used for general limited liability company and corporate purposes, as applicable, including capital expenditures, repayment of portions of outstanding commercial paper and borrowings under CenterPoint Energy’s money pool. (2) Issued by CERC Corp. (3) Proceeds from these debt issuances were used to fund a portion of the Merger and to pay related fees and expenses.
Schedule of Revolving Credit Facilities and Utilization of Such Facilities [Table Text Block]	As of December 31, 2018 and 2017 , the Registrants had the following revolving credit facilities and utilization of such facilities: December 31, 2018 December 31, 2017 Size of Loans Letters Commercial Weighted Average Interest Rate Size of Loans Letters Commercial Weighted Average Interest Rate (in millions, except weighted average interest rate) CenterPoint Energy $ 3,300 $ — $ 6 $ — — $ 1,700 $ — $ 6 $ 855 1.88 % Houston Electric 300 — 4 — — 300 — 4 — — CERC (1) 900 — 1 210 2.93 % 900 — 1 898 1.72 % Total $ 4,500 $ — $ 11 $ 210 $ 2,900 $ — $ 11 $ 1,753 (1) Issued by CERC Corp. In January 2019, CenterPoint Energy issued the following commercial paper in connection with the closing of the Merger: Registrant Issuance Date Debt Instrument Aggregate Principal Amount Weighted Average Interest Rate (in millions) CenterPoint Energy (1) (2) January 2019 Commercial paper $ 1,660 2.88% (1) Proceeds from these commercial paper issuances were used to fund a portion of the Merger and to pay related fees and expenses and were contributed to Vectren for its payment of its stub period cash dividend, long-term incentive payments and to fund the repayment of indebtedness of Vectren subsidiaries redeemed at the option of the holder as a result of the closing of the Merger. (2) The commercial paper notes were issued at various times in January 2019 with maturities up to and including 90 days as of the time of issuance, and, prior to their use as described in connection with the closing of the Merger, the net proceeds of such issuances were invested in short-term investments. Execution Date Registrant Size of Facility Draw Rate of LIBOR plus (1) Financial Covenant Limit on Debt for Borrowed Money to Capital Ratio (2) Debt for Borrowed Money to Capital Ratio as of December 31, 2018 (3) Termination Date (4) (in millions) March 3, 2016 CenterPoint Energy $ 3,300 (5) 1.250% 65% 44.9% March 3, 2022 March 3, 2016 Houston Electric 300 1.125% 65% 49.2% March 3, 2022 March 3, 2016 CERC (6) 900 1.125% 65% 46.8% March 3, 2022 (1) Based on credit ratings as of December 31, 2018. (2) For CenterPoint Energy 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. (3) As defined in the revolving credit facility agreement, excluding Securitization Bonds. (4) Amended on June 16, 2017 to extend the termination date. (5) 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. (6) Issued by CERC Corp.
Schedule of Maturities of Long-term Debt [Table Text Block]	Maturities. As of December 31, 2018, maturities of long-term debt, capital leases and sinking fund requirements, excluding the ZENS obligation, are as follows: CenterPoint Energy (1) Houston Electric (1) CERC Securitization Bonds (in millions) 2019 $ 458 $ 458 $ — $ 458 2020 231 231 — 231 2021 1,706 613 593 211 2022 1,230 519 210 219 2023 656 356 300 156 (1) These maturities include Securitization Bonds principal repayments on scheduled payment dates.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Tax Expense [Table Text Block]	The components of the Registrant’ income tax expense (benefit) were as follows: Year Ended December 31, 2018 2017 2016 (in millions) CenterPoint Energy Current income tax expense: Federal $ 89 $ 32 $ 23 State 9 9 18 Total current expense 98 41 41 Deferred income tax expense (benefit): Federal (25 ) (806 ) 185 State 73 36 28 Total deferred expense (benefit) 48 (770 ) 213 Total income tax expense (benefit) $ 146 $ (729 ) $ 254 Houston Electric Current income tax expense: Federal $ 109 $ 70 $ 165 State 18 19 18 Total current expense 127 89 183 Deferred income tax benefit: Federal (38 ) (98 ) (34 ) Total deferred benefit (38 ) (98 ) (34 ) Total income tax expense (benefit) $ 89 $ (9 ) $ 149 CERC - Continuing Operations Current income tax expense (benefit): Federal $ (9 ) $ (31 ) $ 21 State — (10 ) 4 Total current expense (benefit) (9 ) (41 ) 25 Deferred income tax expense (benefit): Federal 10 (249 ) 41 State 21 25 15 Total deferred expense (benefit) 31 (224 ) 56 Total income tax expense (benefit) $ 22 $ (265 ) $ 81 Year Ended December 31, 2018 2017 2016 (in millions) CERC - Discontinued Operations Current income tax expense (benefit): Federal $ 9 $ 31 $ (21 ) State 4 11 2 Total current expense (benefit) 13 42 (19 ) Deferred income tax expense: Federal 29 56 90 State 4 6 10 Total deferred expense 33 62 100 Total income tax expense $ 46 $ 104 $ 81
Reconciliation of Expected Federal Income Tax Expense to Actual [Table Text Block]	A reconciliation of income tax expense (benefit) using the federal statutory income tax rate to the actual income tax expense and resulting effective income tax rate is as follows: Year Ended December 31, 2018 2017 2016 (in millions) CenterPoint Energy (1) (2) (3) Income before income taxes $ 514 $ 1,063 $ 686 Federal statutory income tax rate 21 % 35 % 35 % Expected federal income tax expense 108 372 240 Increase (decrease) in tax expense resulting from: State income tax expense, net of federal income tax 22 26 27 State valuation allowance, net of federal income tax 11 3 3 State law change, net of federal income tax 32 — — Federal income tax rate reduction — (1,113 ) — Excess deferred income tax amortization (24 ) — — Other, net (3 ) (17 ) (16 ) Total 38 (1,101 ) 14 Total income tax expense (benefit) $ 146 $ (729 ) $ 254 Effective tax rate 28 % (69 )% 37 % Houston Electric (4) (5) Income before income taxes $ 425 $ 424 $ 425 Federal statutory income tax rate 21 % 35 % 35 % Expected federal income tax expense 89 148 149 Increase (decrease) in tax expense resulting from: State income tax expense, net of federal income tax 14 12 12 Federal income tax rate reduction — (158 ) — Excess deferred income tax amortization (9 ) — — Other, net (5 ) (11 ) (12 ) Total — (157 ) — Total income tax expense (benefit) $ 89 $ (9 ) $ 149 Effective tax rate 21 % (2 )% 35 % Year Ended December 31, 2018 2017 2016 (in millions) CERC - Continuing Operations (6) (7) Income before income taxes $ 92 $ 319 $ 199 Federal statutory income tax rate 21 % 35 % 35 % Expected federal income tax expense 19 112 70 Increase (decrease) in tax expense resulting from: State income tax expense, net of federal income tax 5 6 4 State law change, net of federal income tax — — 6 State valuation allowance, net of federal income tax 11 3 2 Federal income tax rate reduction — (396 ) — Excess deferred income tax amortization (15 ) — — Tax basis balance sheet adjustment — 11 — Other, net 2 (1 ) (1 ) Total 3 (377 ) 11 Total income tax expense (benefit) $ 22 $ (265 ) $ 81 Effective tax rate 24 % (83 )% 41 % CERC - Discontinued Operations (7) Income before income taxes $ 184 $ 265 $ 208 Federal statutory income tax rate 21 % 35 % 35 % Expected federal income tax expense 39 93 73 Increase in tax expense resulting from: State income tax expense, net of federal income tax 7 11 8 Total 7 11 8 Total income tax expense $ 46 $ 104 $ 81 Effective tax rate 25 % 39 % 39 % (1) Recognized a $32 million deferred tax expense due to state law changes that resulted in remeasurement of state deferred taxes in those jurisdictions. Also recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These items are partially offset by $24 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018. (2) Recognized a $1.1 billion deferred tax benefit from the remeasurement of CenterPoint Energy’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21% . For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below. (3) Recognized a $6 million deferred tax expense in 2016 due to Louisiana state law change and recorded an additional $3 million valuation allowance on certain state carryforwards. (4) Recognized $9 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018. (5) Recognized a $158 million deferred tax benefit from the remeasurement of Houston Electric’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21% . For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below. (6) Recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. This item is partially offset by $15 million of amortization of the net regulatory EDIT liability in certain jurisdictions as decreed by regulators beginning in 2018. (7) Recognized a $396 million deferred tax benefit from the remeasurement of CERC’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21% . ASC 740 requires tax impacts of changes in tax laws or rates be reported in continuing operations. Therefore, CERC’s federal income tax benefit generated by the remeasurement of the ADFIT liability for Enable during 2017 and state law changes during 2016 associated with its investment in Enable are reported in continuing operations on CERC’s Statements of Consolidated Income. The ADFIT liability associated with CERC’s investment in Enable is reported as discontinued operations on CERC’s Consolidated Balance Sheets.
Tax Assets and Liabilities [Table Text Block]	The tax effects of temporary differences that give rise to significant portions of deferred tax assets and liabilities were as follows: December 31, 2018 2017 (in millions) CenterPoint Energy Deferred tax assets: Benefits and compensation $ 160 $ 162 Regulatory liabilities 356 347 Loss and credit carryforwards 84 90 Asset retirement obligations 62 68 Other 29 16 Valuation allowance (18 ) (7 ) Total deferred tax assets 673 676 Deferred tax liabilities: Property, plant and equipment 1,894 1,808 Investment in unconsolidated affiliates 987 927 Regulatory assets 395 473 Investment in marketable securities and indexed debt 478 502 Indexed debt securities derivative 27 13 Other 131 127 Total deferred tax liabilities 3,912 3,850 Net deferred tax liabilities $ 3,239 $ 3,174 Houston Electric Deferred tax assets: Regulatory liabilities $ 205 $ 198 Benefits and compensation 17 28 Asset retirement obligations 7 7 Other 12 3 Total deferred tax assets 241 236 Deferred tax liabilities: Property, plant and equipment 1,087 1,030 Regulatory assets 177 265 Total deferred tax liabilities 1,264 1,295 Net deferred tax liabilities $ 1,023 $ 1,059 December 31, 2018 2017 (in millions) CERC - Continuing Operations Deferred tax assets: Benefits and compensation $ 27 $ 27 Regulatory liabilities 150 150 Loss and credit carryforwards 259 288 Asset retirement obligations 54 60 Other 20 18 Valuation allowance (18 ) (7 ) Total deferred tax assets 492 536 Deferred tax liabilities: Property, plant and equipment 773 745 Regulatory assets 41 38 Other 84 115 Total deferred tax liabilities 898 898 Net deferred tax liabilities $ 406 $ 362 CERC - Discontinued Operations Deferred tax liabilities: Investment in unconsolidated affiliates — 927 Net deferred tax liabilities $ — $ 927

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Long-term Purchase Commitment [Table Text Block]	As of December 31, 2018 , minimum payment obligations for natural gas supply commitments are approximately: (in millions) 2019 $ 454 2020 430 2021 343 2022 231 2023 154 2024 and beyond 1,446
Lease Commitments [Table Text Block]	The following table sets forth information concerning the Registrants’ obligations under non-cancelable long-term operating leases as of December 31, 2018 , which primarily consist of rental agreements for real property: CenterPoint Energy Houston Electric CERC (in millions) 2019 $ 6 $ 1 $ 5 2020 6 — 5 2021 5 — 4 2022 4 — 4 2023 3 — 3 2024 and beyond 12 — 11 Total $ 36 $ 1 $ 32
Schedule of Rent Expense [Table Text Block]	Year Ended December 31, 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Lease expense $ 9 $ 1 $ 8 $ 10 $ 1 $ 9 $ 10 $ 1 $ 9

Earnings Per Share (CenterPoi_2

Earnings Per Share (CenterPoint Energy) (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Basic and Diluted Earnings Per Share [Table Text Block]	The following table reconciles numerators and denominators of CenterPoint Energy’s basic and diluted earnings per common share. Basic earnings per common share is determined by dividing Income available to common shareholders - basic by the Weighted average common shares outstanding - basic for the applicable period. Diluted earnings per common share is determined by the inclusion of potentially dilutive common stock equivalent shares that may occur if securities to issue Common Stock were exercised or converted into Common Stock. For the Year Ended December 31, 2018 2017 2016 (in millions, except per share and share amounts) Numerator: Income available to common shareholders - basic (1) $ 333 $ 1,792 $ 432 Add back: Series B Preferred Stock dividend — — — Income available to common shareholders - diluted (1) $ 333 $ 1,792 $ 432 Denominator: Weighted average common shares outstanding - basic 448,829,000 430,964,000 430,606,000 Plus: Incremental shares from assumed conversions: Restricted stock (2) 3,636,000 3,344,000 2,997,000 Series B Preferred Stock (3) — — — Weighted average common shares outstanding - diluted 452,465,000 434,308,000 433,603,000 Earnings per common share: Basic earnings per common share $ 0.74 $ 4.16 $ 1.00 Diluted earnings per common share $ 0.74 $ 4.13 $ 1.00 (1) Income available to common shareholders for the year ended December 31, 2017 includes a reduction in income tax expense of $1,113 million due to tax reform. See Note 15 for further discussion of the impacts of the TCJA. (2) The potentially dilutive impact from restricted stock awards applies the treasury stock method. Under this method, an increase in the average fair market value of Common Stock can result in a greater dilutive impact from these securities. (3) The potentially dilutive impact from Series B Preferred Stock applies the if-converted method in calculating diluted earnings per common share. Under this method, diluted earnings per common share is adjusted for the more dilutive effect of the Series B Preferred Stock as a result of either its accumulated dividend for the period in the numerator or the assumed-converted common share equivalent in the denominator. The computation of diluted earnings per common share outstanding for the year ended December 31, 2018 excludes 8,885,000 potentially dilutive shares because to include them would be anti-dilutive. However, these shares could be potentially dilutive in the future.

Unaudited Quarterly Informati_2

Unaudited Quarterly Information (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data [Table Text Block]	Summarized quarterly financial data is as follows: Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter (in millions, except per share amounts) CenterPoint Energy Revenues $ 3,155 $ 2,186 $ 2,212 $ 3,036 Operating income 251 187 226 167 Income (loss) available to common shareholders 165 (75 ) 153 90 Basic earnings (loss) per common share (1) 0.38 (0.17 ) 0.35 0.18 Diluted earnings (loss) per common share (1) 0.38 (0.17 ) 0.35 0.18 Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter (in millions, except per share amounts) Houston Electric Revenues 755 854 897 728 Operating income 119 181 227 98 Net income 52 101 143 40 CERC (4) Revenues 2,400 1,328 1,312 2,303 Operating income (loss) 131 22 (7 ) 76 Income (loss) from continuing operations 78 (8 ) (35 ) 35 Income (loss) from discontinued operations 52 44 44 (2 ) Net income 130 36 9 33 Year Ended December 31, 2017 First Quarter Second Third Quarter Fourth Quarter (in millions, except per share amounts) CenterPoint Energy Revenues $ 2,735 $ 2,143 $ 2,098 $ 2,638 Operating income (2) 291 240 297 308 Income available to common shareholders (3) 192 135 169 1,296 Basic earnings per common share (1) 0.45 0.31 0.39 3.01 Diluted earnings per common share (1) 0.44 0.31 0.39 2.99 Houston Electric Revenues 638 752 843 765 Operating income (2) 85 171 254 127 Net income (3) 18 75 130 210 CERC (4) Revenues 2,093 1,387 1,251 1,872 Operating income (2) 199 59 31 178 Income (loss) from continuing operations 102 17 (4 ) 469 Income from discontinued operations 45 37 42 37 Net income (3) 147 54 38 506 (1) Quarterly earnings (loss) per common share are based on the weighted average number of shares outstanding during the quarter, and the sum of the quarters may not equal annual earnings (loss) per common share. (2) Recast to reflect the adoption of ASU 2017-07. See Note 2(r) for further information. (3) Income available to common shareholders and Net income for the fourth quarter 2017 include a reduction in income tax expense of $1,113 million , $158 million and $396 million for CenterPoint Energy, Houston Electric and CERC, respectively, due to the TCJA. See Note 15 for further discussion of the impacts of tax reform implementation. (4) Amounts have been recast to reflect discontinued operations in all periods presented.

Reportable Segments (Tables)

Reportable Segments (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Financial Data for Business Segments [Table Text Block]	As of December 31, 2018 , reportable 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) On September 4, 2018, CERC completed the Internal Spin. Previously, CERC’s equity method investment in Enable was included in CERC’s Midstream Investments reportable segment. CERC’s equity in earnings in Enable, net of basis difference amortization and income tax, have been classified as discontinued operations for all periods presented. See Note 11 for further discussion on the Internal Spin and the associated discontinued operations presentation. Financial data for reportable segments and products and services are as follows: CenterPoint Energy Revenues from External Customers Intersegment Revenues Depreciation and Amortization Operating Income Total Assets Expenditures for Long-Lived Assets (in millions) As of and for the year ended December 31, 2018: Electric Transmission & Distribution $ 3,232 (1) $ — $ 917 $ 623 $ 10,509 $ 952 Natural Gas Distribution 2,931 36 277 266 6,956 638 Energy Services 4,411 110 16 (47 ) 1,558 20 Midstream Investments (2) — — — — 2,482 — Other Operations 15 — 33 (11 ) 6,156 (3) 110 Eliminations — (146 ) — — (652 ) — Consolidated $ 10,589 $ — $ 1,243 $ 831 $ 27,009 1,720 Reconciling items (69 ) Capital expenditures per Statements of Consolidated Cash Flows $ 1,651 Revenues from External Customers Intersegment Revenues Depreciation and Amortization Operating Income Total Assets Expenditures for Long-Lived Assets (in millions) As of and for the year ended December 31, 2017: Electric Transmission & Distribution $ 2,997 (1) $ — $ 724 $ 636 $ 10,292 $ 924 Natural Gas Distribution 2,606 33 260 348 6,608 523 Energy Services 3,997 52 19 126 1,521 11 Midstream Investments (2) — — — — 2,472 — Other Operations 14 — 33 26 2,497 (3) 36 Eliminations — (85 ) — — (654 ) — Consolidated $ 9,614 $ — $ 1,036 $ 1,136 $ 22,736 1,494 Reconciling items (68 ) Capital expenditures per Statements of Consolidated Cash Flows $ 1,426 As of and for the year ended December 31, 2016: Electric Transmission & Distribution $ 3,060 (1) $ — $ 838 $ 653 $ 10,211 $ 858 Natural Gas Distribution 2,380 29 242 321 6,099 510 Energy Services 2,073 26 7 21 1,102 5 Midstream Investments (2) — — — — 2,505 — Other Operations 15 — 39 28 2,681 (3) 33 Eliminations — (55 ) — — (769 ) — Consolidated $ 7,528 $ — $ 1,126 $ 1,023 $ 21,829 1,406 Reconciling items 8 Capital expenditures per Statements of Consolidated Cash Flows $ 1,414 (1) CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Year Ended December 31, 2018 2017 2016 (in millions) Affiliates of NRG $ 705 $ 713 $ 698 Affiliates of Vistra Energy Corp. 251 229 220 (2) CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows: Year Ended December 31, 2018 2017 2016 (in millions) Enable $ 307 $ 265 $ 208 (3) Total assets included pension and other postemployment-related regulatory assets of $665 million , $600 million and $759 million as of December 31, 2018 , 2017 and 2016 , respectively. Additionally, total assets as of December 31, 2018 included $3.9 billion of temporary investments included in Cash and cash equivalents on CenterPoint Energy’s Consolidated Balance Sheets. CERC Revenues from External Customers Intersegment Revenues Depreciation and Amortization Operating Income Total Assets (1) Expenditures for Long-Lived Assets (in millions) As of and for the year ended December 31, 2018: Natural Gas Distribution $ 2,931 $ 36 $ 277 $ 266 $ 6,956 $ 638 Energy Services 4,411 110 16 (47 ) 1,558 20 Other Operations 1 — — 3 66 — Eliminations — (146 ) — — (366 ) — Consolidated $ 7,343 $ — $ 293 $ 222 $ 8,214 658 Reconciling items (25 ) Capital expenditures per Statements of Consolidated Cash Flows $ 633 As of and for the year ended December 31, 2017: Natural Gas Distribution $ 2,606 $ 33 $ 260 $ 348 $ 6,608 $ 523 Energy Services 3,997 52 19 126 1,521 11 Discontinued operations — — — — 2,472 (1) — Other Operations — — — (7 ) 70 — Eliminations — (85 ) — — (559 ) — Consolidated $ 6,603 $ — $ 279 $ 467 $ 10,112 534 Reconciling items (21 ) Capital expenditures per Statements of Consolidated Cash Flows $ 513 As of and for the year ended December 31, 2016: Natural Gas Distribution $ 2,380 $ 29 $ 242 $ 321 $ 6,099 $ 510 Energy Services 2,073 26 7 21 1,102 5 Discontinued operations — — — — 2,505 (1) — Other Operations 1 — — (1 ) 75 — Eliminations — (55 ) — — (563 ) — Consolidated $ 4,454 $ — $ 249 $ 341 $ 9,218 515 Reconciling items 2 Capital expenditures per Statements of Consolidated Cash Flows $ 517 (1) On September 4, 2018, CERC completed the Internal Spin. For further information regarding the Internal Spin, see Note 11 .
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: Year Ended December 31, 2018 2017 2016 (in millions) Affiliates of NRG $ 705 $ 713 $ 698 Affiliates of Vistra Energy Corp. 251 229 220
Midstream Investments [Table Text Block]	CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows: Year Ended December 31, 2018 2017 2016 (in millions) Enable $ 307 $ 265 $ 208
Revenues by Products and Services [Table Text Block]	Year Ended December 31, 2018 2017 2016 Revenues by Products and Services: CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Electric delivery $ 3,232 $ 3,234 $ — $ 2,997 $ 2,998 $ — $ 3,060 $ 3,059 $ — Retail gas sales 4,161 — 4,161 3,634 — 3,634 3,329 — 3,329 Wholesale gas sales 3,008 — 3,008 2,811 — 2,811 977 — 977 Gas transportation and processing 32 — 32 29 — 29 23 — 23 Energy products and services 156 — 142 143 — 129 139 — 125 Total $ 10,589 $ 3,234 $ 7,343 $ 9,614 $ 2,998 $ 6,603 $ 7,528 $ 3,059 $ 4,454

Supplemental Disclosure of Ca_2

Supplemental Disclosure of Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]	The tables below provide supplemental disclosure of cash flow information: 2018 2017 2016 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Cash Payments/Receipts: Interest, net of capitalized interest $ 363 $ 200 $ 105 $ 378 $ 205 $ 116 $ 406 $ 209 $ 116 Income taxes (refunds), net 89 154 3 15 76 4 (104 ) 128 3 Non-cash transactions: Accounts payable related to capital expenditures 201 124 80 144 104 56 87 65 35 Capital distribution associated with the Internal Spin — — 1,473 — — — — — — The table below provides a reconciliation of cash, cash equivalents and restricted cash reported in the Consolidated Balance Sheets to the amount reported in the Statements of Consolidated Cash Flows: December 31, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Cash and cash equivalents (1) (2) $ 4,231 $ 335 $ 14 $ 260 $ 238 $ 12 Restricted cash included in Prepaid expenses and other current assets 46 34 11 35 35 — Restricted cash included in Other 1 1 — 1 1 — Total cash, cash equivalents and restricted cash shown in Statements of Consolidated Cash Flows $ 4,278 $ 370 $ 25 $ 296 $ 274 $ 12 (1) CenterPoint Energy’s Cash and cash equivalents as of December 31, 2018 included $3.9 billion of temporary investments resulting from the Merger financings. CenterPoint Energy recorded interest income of $28 million , $2 million and $1 million for the years ended December 31, 2018 , 2017 and 2016 , respectively, in Other, net on CenterPoint Energy’s Statements of Consolidated Income. See Notes 13 and 14 for further details related to the Merger financings. (2) Houston Electric’s Cash and cash equivalents as of December 31, 2018 and 2017 included $335 million and $230 million , respectively, of cash related to the Bond Companies. Houston Electric recorded interest income of $4 million , $2 million and $1 million for the years ended December 31, 2018 , 2017 and 2016 , respectively, in Other, net on Houston Electric’s Statement of Consolidated Income.

Related Party Transactions (H_2

Related Party Transactions (Houston Electric and CERC) (Tables)	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Schedule of Money Pool Investment and Borrowing [Table Text Block]	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: December 31, 2018 December 31, 2017 Houston Electric CERC Houston Electric CERC (in millions) Money pool investments (borrowings) (1) $ (1 ) $ 114 $ (60 ) $ (570 ) Weighted average interest rate 2.42 % 2.42 % 1.90 % 1.90 % (1) Included in Accounts and notes receivable (payable)–affiliated companies in Houston Electric’s and CERC’s Consolidated Balance Sheets.
Schedule of Related Party Transactions [Table Text Block]	Houston Electric and CERC affiliate-related net interest income (expense) were as follows: Year Ended December 31, 2018 2017 2016 Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Interest income (expense), net (1) $ 1 $ — $ 2 $ — $ (4 ) $ — (1) Interest income is included in Other, net and interest expense is included in Interest and other finance charges on Houston Electric’s and CERC’s respective Statements of Consolidated Income. Amounts charged for these services were as follows and are included primarily in operation and maintenance expenses: Year Ended December 31, 2018 2017 2016 Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Corporate service charges $ 190 $ 147 $ 188 $ 128 $ 179 $ 125 Net affiliate service charges (billings) (17 ) 17 (9 ) 9 (8 ) 8 The table below presents transactions among Houston Electric, CERC and their parent, Utility Holding. Year Ended December 31, 2018 2017 2016 Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Cash dividends paid to parent $ 209 $ 360 $ 180 $ 601 $ 135 $ 643 Cash contribution from parent 200 960 — 38 374 72 Capital distribution to parent associated with the Internal Spin — 1,473 — — — —

Subsequent Events (Tables)

Subsequent Events (Tables)	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Schedule of Subsequent Events [Table Text Block]	Enable Distributions Declarations (CenterPoint Energy) Equity Instrument Declaration Date Record Date Payment Date Per Unit Distribution Expected Cash Distribution (in millions) Common units February 8, 2019 February 19, 2019 February 26, 2019 $ 0.318 $ 74 Enable Series A Preferred Units February 8, 2019 February 8, 2019 February 14, 2019 0.625 9

Background (Details)

Background (Details) $ in Billions		Feb. 01, 2019USD ($)	Dec. 31, 2018stateshares	Dec. 31, 2017
Vectren [Member] | Subsequent Event [Member]
Cash paid to acquire Vectren | $		$ 6
Enable Midstream Partners [Member]
Ownership percentage of equity method investment	[1],[2]		54.00%	54.10%
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Preferred units held | shares			14,520,000
Enable GP, LLC [Member]
Management rights ownership percentage			50.00%
Incentive distribution right			40.00%
CERC Corp [Member] | Enable Midstream Partners [Member]
Ownership percentage of equity method investment	[1],[2]			54.10%
CERC Corp [Member] | Enable GP, LLC [Member]
Management rights ownership percentage	[3],[4]			50.00%
Incentive distribution right	[4],[5]			40.00%
CERC Corp [Member] | Natural Gas Distribution [Member]
Number of states in which entity operates			6
CERC Corp [Member] | Energy Services [Member]
Number of states in which entity operates			30
CenterPoint Energy [Member] | Enable GP, LLC [Member]
Management rights ownership percentage	[3],[4]		50.00%	50.00%
Incentive distribution right	[4],[5]		40.00%	40.00%
[1]	Excludes the Enable Series A Preferred Units owned by CenterPoint Energy.
[2]	Prior to the Internal Spin on September 4, 2018 described above, CenterPoint Energy’s investment in Enable’s common units, excluding the Enable Series A Preferred Units held directly by CenterPoint Energy, was held indirectly through CERC.
[3]	As of December 31, 2018, 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.
[4]	CenterPoint Energy held the management rights and incentive distributions rights in Enable GP indirectly through CERC until the Internal Spin on September 4, 2018 described above.
[5]	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.

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Significant Accounting Policies [Line Items]
Provision for doubtful accounts		$ 16	$ 14	$ 7
Interest Expense [Member]
Significant Accounting Policies [Line Items]
Interest and AFUDC debt (1)	[1]	8	9	8
Other Income (Expense) [Member]
Significant Accounting Policies [Line Items]
AFUDC equity (2)	[2]	12	11	7
Houston Electric [Member]
Significant Accounting Policies [Line Items]
Provision for doubtful accounts		0	1	0
Houston Electric [Member] | Interest Expense [Member]
Significant Accounting Policies [Line Items]
Interest and AFUDC debt (1)	[1]	6	6	6
Houston Electric [Member] | Other Income (Expense) [Member]
Significant Accounting Policies [Line Items]
AFUDC equity (2)	[2]	10	10	6
CERC Corp [Member]
Significant Accounting Policies [Line Items]
Provision for doubtful accounts		16	13	7
CERC Corp [Member] | Interest Expense [Member]
Significant Accounting Policies [Line Items]
Interest and AFUDC debt (1)	[1]	2	2	2
CERC Corp [Member] | Other Income (Expense) [Member]
Significant Accounting Policies [Line Items]
AFUDC equity (2)	[2]	2	1	1
Accounting Standards Update 2016-02 [Member]
Significant Accounting Policies [Line Items]
Amount of right-of-use assets and liabilities to recognize on the statement of financial position upon adoption of ASU 2016-02		30
Accounting Standards Update 2016-02 [Member] | Houston Electric [Member]
Significant Accounting Policies [Line Items]
Amount of right-of-use assets and liabilities to recognize on the statement of financial position upon adoption of ASU 2016-02		1
Accounting Standards Update 2016-02 [Member] | CERC Corp [Member]
Significant Accounting Policies [Line Items]
Amount of right-of-use assets and liabilities to recognize on the statement of financial position upon adoption of ASU 2016-02		28
Accounting Standards Update 2016-15 [Member]
Significant Accounting Policies [Line Items]
Effect of change on cash flow activities due to adoption of new ASU		2	4	8
Accounting Standards Update 2016-15 [Member] | Houston Electric [Member]
Significant Accounting Policies [Line Items]
Effect of change on cash flow activities due to adoption of new ASU		2	4	8
Accounting Standards Update 2016-18 [Member]
Significant Accounting Policies [Line Items]
Effect of change on cash flow activities due to adoption of new ASU		(11)	(4)	5
Accounting Standards Update 2016-18 [Member] | Houston Electric [Member]
Significant Accounting Policies [Line Items]
Effect of change on cash flow activities due to adoption of new ASU			(4)	5
Accounting Standards Update 2016-18 [Member] | CERC Corp [Member]
Significant Accounting Policies [Line Items]
Effect of change on cash flow activities due to adoption of new ASU		(11)
Accounting Standards Update 2017-07 [Member] | Operating Income [Member]
Significant Accounting Policies [Line Items]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07		47	64	64
Accounting Standards Update 2017-07 [Member] | Other Income [Member]
Significant Accounting Policies [Line Items]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07		(47)	(64)	(64)
Accounting Standards Update 2017-07 [Member] | Houston Electric [Member] | Operating Income [Member]
Significant Accounting Policies [Line Items]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07		21	26	25
Accounting Standards Update 2017-07 [Member] | Houston Electric [Member] | Other Income [Member]
Significant Accounting Policies [Line Items]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07		(21)	(26)	(25)
Accounting Standards Update 2017-07 [Member] | CERC Corp [Member] | Operating Income [Member]
Significant Accounting Policies [Line Items]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07		11	23	23
Accounting Standards Update 2017-07 [Member] | CERC Corp [Member] | Other Income [Member]
Significant Accounting Policies [Line Items]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07		(11)	(23)	$ (23)
Accounting Standards Update 2018-02 [Member]
Significant Accounting Policies [Line Items]
Tax (benefit) expense reclassification adjustment related to adoption of ASU 2018-02		(15)	0
Accounting Standards Update 2018-02 [Member] | Houston Electric [Member]
Significant Accounting Policies [Line Items]
Tax (benefit) expense reclassification adjustment related to adoption of ASU 2018-02		0	0
Accounting Standards Update 2018-02 [Member] | CERC Corp [Member]
Significant Accounting Policies [Line Items]
Tax (benefit) expense reclassification adjustment related to adoption of ASU 2018-02		$ (1)	$ 0
[1]	Included in Interest and other finance charges on the Registrants’ respective Statements of Consolidated Income.
[2]	Included in Other Income (Expense) on the Registrants’ respective Statements of Consolidated Income.

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 20,267	$ 19,031
Accumulated Depreciation & Amortization		6,223	5,974
Property, Plant and Equipment, Net		14,044	13,057
Depreciation and Amortization [Abstract]
Depreciation		626	619	$ 607
Amortization of securitized regulatory assets		531	329	455
Other amortization		86	88	64
Total		1,243	1,036	1,126
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance		281	205
Accretion expense (1)	[1]	10	8
Revisions in estimates (2)	[2]	(33)	68
Ending balance		258	281	205
Houston Electric [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		12,148	11,496
Accumulated Depreciation & Amortization		3,746	3,633
Property, Plant and Equipment, Net		8,402	7,863
Depreciation and Amortization [Abstract]
Depreciation		342	354	349
Amortization of securitized regulatory assets		531	329	455
Other amortization		44	41	34
Total		917	724	838
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance		35	33
Accretion expense (1)	[1]	1	1
Revisions in estimates (2)	[2]	(2)	1
Ending balance		34	35	33
CERC Corp [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		7,431	6,888
Accumulated Depreciation & Amortization		2,205	2,036
Property, Plant and Equipment, Net		5,226	4,852
Depreciation and Amortization [Abstract]
Depreciation		264	243	230
Other amortization		29	36	19
Total		293	279	249
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance		243	169
Accretion expense (1)	[1]	9	7
Revisions in estimates (2)	[2]	(31)	67
Ending balance		221	243	$ 169
Electric Transmission and Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		12,148	11,496
Accumulated Depreciation & Amortization		3,746	3,633
Property, Plant and Equipment, Net		$ 8,402	7,863
Electric Transmission and Distribution [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		35 years
Electric Transmission [Member] | Houston Electric [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 3,077	2,767
Accumulated Depreciation & Amortization		650	620
Property, Plant and Equipment, Net		$ 2,427	2,147
Electric Transmission [Member] | Houston Electric [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		45 years
Electric Distribution [Member] | Houston Electric [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 7,524	7,178
Accumulated Depreciation & Amortization		2,553	2,522
Property, Plant and Equipment, Net		$ 4,971	4,656
Electric Distribution [Member] | Houston Electric [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		33 years
Natural Gas Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 7,257	6,735
Accumulated Depreciation & Amortization		2,128	1,968
Property, Plant and Equipment, Net		$ 5,129	4,767
Natural Gas Distribution [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		28 years
Natural Gas Distribution [Member] | CERC Corp [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 7,257	6,735
Accumulated Depreciation & Amortization		2,128	1,968
Property, Plant and Equipment, Net		$ 5,129	4,767
Natural Gas Distribution [Member] | CERC Corp [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		28 years
Energy Services [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 121	102
Accumulated Depreciation & Amortization		43	35
Property, Plant and Equipment, Net		$ 78	67
Energy Services [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		27 years
Energy Services [Member] | CERC Corp [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 121	102
Accumulated Depreciation & Amortization		43	35
Property, Plant and Equipment, Net		$ 78	67
Energy Services [Member] | CERC Corp [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		27 years
Other property [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 741	698
Accumulated Depreciation & Amortization		306	338
Property, Plant and Equipment, Net		$ 435	360
Other property [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		26 years
Other property [Member] | Houston Electric [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 1,547	1,551
Accumulated Depreciation & Amortization		543	491
Property, Plant and Equipment, Net		$ 1,004	1,060
Other property [Member] | Houston Electric [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		18 years
Other property [Member] | CERC Corp [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross		$ 53	51
Accumulated Depreciation & Amortization		34	33
Property, Plant and Equipment, Net		$ 19	$ 18
Other property [Member] | CERC Corp [Member] | Weighted Average [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Useful Lives		23 years
[1]	Reflected in Regulatory assets on each of the Registrants’ respective Consolidated Balance Sheets.
[2]	In 2018, CenterPoint Energy and CERC reflected a decrease in their respective ARO liability which is primarily attributable to increases in the long-term interest rates used for discounting in the ARO calculation. In 2017, CenterPoint Energy and CERC reflected an increase in their respective ARO liability which is primarily attributable to decreases in the long-term interest rates used for discounting in the ARO calculation.

Mergers and Acquisitions (Detai

Mergers and Acquisitions (Details) - USD ($) $ / shares in Units, $ in Millions		Feb. 01, 2019	Jan. 03, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Dividends declared per share				$ 1.12		$ 1.3475		$ 1.03
Total short-term borrowings				$ 0		$ 39
Goodwill				867		867
Reduction in income taxes due to tax reform				0	[1]	1,113	[2]	$ 0	[3]
CERC Corp [Member]
Total short-term borrowings	[4],[5]			0		39
Goodwill				867		867
Vectren [Member]
Total short-term borrowings				167
Long-term debt including current maturities				2,200
Vectren [Member] | Operation And Maintenance Expense [Member]
Transaction costs				28
Integration costs				$ 18
Atmos Energy Marketing [Member]
Purchase price consideration			$ 147
Goodwill			5
Operating Revenue						9,614		8,541
Net Income (1)	[6]					1,792		442
Atmos Energy Marketing [Member] | Customer Relationships [Member]
Intangibles estimated fair value			$ 25
Intangibles estimated useful life			15 years
Atmos Energy Marketing [Member] | CERC Corp [Member]
Goodwill			$ 5
Operating Revenue						6,603		5,467
Net Income (1)	[6]					745		$ 255
Reduction in income taxes due to tax reform						$ 396
Atmos Energy Marketing [Member] | CERC Corp [Member] | Customer Relationships [Member]
Intangibles estimated fair value			$ 25
Intangibles estimated useful life			15 years
Subsequent Event [Member] | Vectren [Member]
Effective date of acquisition		Feb. 1, 2019
Purchase price consideration		$ 6,000
Cash paid per share of Vectren common stock at closing of the Merger		$ 72
Subsequent Event [Member] | Vectren [Member] | Stub period [Member]
Dividends declared per share		$ 0.41145
Declaration Date		Jan. 16, 2019
Record Date		Feb. 1, 2019
[1]	Recognized a $32 million deferred tax expense due to state law changes that resulted in remeasurement of state deferred taxes in those jurisdictions. Also recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These items are partially offset by $24 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018.
[2]	Recognized a $1.1 billion deferred tax benefit from the remeasurement of CenterPoint Energy’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21%. For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below.
[3]	Recognized a $6 million deferred tax expense in 2016 due to Louisiana state law change and recorded an additional $3 million valuation allowance on certain state carryforwards.
[4]	Includes amounts due or exchangeable within one year of the date noted.
[5]	Issued by CERC Corp.
[6]	Net income for the year ended December 31, 2017 includes a reduction in income tax expense of $1,113 million and $396 million due to the TCJA for CenterPoint Energy and CERC, respectively. See Note 15 for further discussion of the impacts of tax reform implementation.

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue from contracts										$ 6,745	$ 6,124	$ 5,711
Derivatives income										4,024	3,568	1,812
Other (3)	[1]									(34)	7	60
Total revenues		$ 3,036	$ 2,212	$ 2,186	$ 3,155	$ 2,638	$ 2,098	$ 2,143	$ 2,735	10,589	9,614	7,528
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues										(146)	(85)	(55)
Electric Transmission & Distribution [Member]
Disaggregation of Revenue [Line Items]
Total revenues	[2]									3,232	2,997	3,060
Electric Transmission & Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues										0	0	0
Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Total revenues										2,931	2,606	2,380
Natural Gas Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues										(36)	(33)	(29)
Energy Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues										4,411	3,997	2,073
Energy Services [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues										(110)	(52)	(26)
Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues										15	14	15
Corporate and Other [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues										0	0	0
Reportable Subsegments [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]									(36)	(33)	(29)
Derivatives income	[4]									(110)	(52)	(26)
Total revenues										(146)	(85)	(55)
Reportable Subsegments [Member] | Electric Transmission & Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]									3,235	3,001	3,050
Derivatives income	[3]									(2)	(1)	1
Other (3)	[1],[3]									(1)	(3)	9
Total revenues	[3]									3,232	2,997	3,060
Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]									3,011	2,638	2,368
Derivatives income	[3]									(2)	0	0
Other (3)	[1],[3]									(42)	1	41
Total revenues	[3]									2,931	2,606	2,380
Reportable Subsegments [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]									493	480	288
Derivatives income	[4]									4,028	3,569	1,811
Other (3)	[1],[4]									0	0	0
Total revenues	[4]									4,411	3,997	2,073
Reportable Subsegments [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]									6	5	5
Derivatives income	[4]									0	0	0
Other (3)	[1],[4]									9	9	10
Total revenues	[4]									15	14	15
Houston Electric [Member]
Disaggregation of Revenue [Line Items]
Total revenues		$ 728	$ 897	$ 854	$ 755	$ 765	$ 843	$ 752	$ 638	3,234	2,998	3,059
Houston Electric [Member] | Reportable Subsegments [Member] | Electric Transmission & Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts										3,235	3,001	3,050
Derivatives income										0	0	0
Other (3)	[1]									(1)	(3)	9
Total revenues										3,234	2,998	3,059
CERC Corp [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts										3,505	3,118	2,656
Derivatives income										4,026	3,569	1,811
Other (3)	[1]									(42)	1	42
Total revenues										7,343	6,603	4,454
CERC Corp [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues										(146)	(85)	(55)
CERC Corp [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Total revenues										2,931	2,606	2,380
CERC Corp [Member] | Natural Gas Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues										(36)	(33)	(29)
CERC Corp [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues										4,411	3,997	2,073
CERC Corp [Member] | Energy Services [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues										(110)	(52)	(26)
CERC Corp [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues										1	0	1
CERC Corp [Member] | Corporate and Other [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues										0	0	0
CERC Corp [Member] | Reportable Subsegments [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]									(36)	(33)	(29)
Derivatives income	[4]									(110)	(52)	(26)
Total revenues										(146)	(85)	(55)
CERC Corp [Member] | Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]									3,011	2,638	2,368
Derivatives income	[3]									(2)	0	0
Other (3)	[1],[3]									(42)	1	41
Total revenues	[3]									2,931	2,606	2,380
CERC Corp [Member] | Reportable Subsegments [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]									493	480	288
Derivatives income	[4]									4,028	3,569	1,811
Other (3)	[1],[4]									0	0	0
Total revenues	[4]									4,411	3,997	2,073
CERC Corp [Member] | Reportable Subsegments [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]									1	0	0
Derivatives income	[4]									0	0	0
Other (3)	[1],[4]									0	0	1
Total revenues	[4]									$ 1	$ 0	$ 1
[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: Year Ended December 31, 2018 2017 2016 (in millions)Affiliates of NRG $705 $713 $698Affiliates of Vistra Energy Corp. 251 229 220
[3]	Reflected in Utility revenues in the Statements of Consolidated Income.
[4]	Reflected in Non-utility revenues in the Statements of Consolidated Income.

Goodwill and Other Intangible_3

Goodwill and Other Intangibles (CenterPoint Energy and CERC) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill		$ 867,000,000	$ 867,000,000
Goodwill impairment charge recorded from annual impairment test		0	0
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount		106,000,000	105,000,000
Accumulated Amortization		(41,000,000)	(31,000,000)
Net Balance		65,000,000	74,000,000
Amortization expense of intangible assets (1)	[1]	10,000,000	13,000,000	$ 4,000,000
Estimated amortization expense over next twelve months		11,000,000
Estimated amortization expense in two years		6,000,000
Estimated amortization expense in three years		6,000,000
Estimated amortization expense in four years		6,000,000
Estimated amortization expense in five years		5,000,000
Customer Relationships [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount		86,000,000	86,000,000
Accumulated Amortization		(27,000,000)	(21,000,000)
Net Balance		59,000,000	65,000,000
Covenants Not To Compete [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount		4,000,000	4,000,000
Accumulated Amortization		(3,000,000)	(2,000,000)
Net Balance		1,000,000	2,000,000
Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount		16,000,000	15,000,000
Accumulated Amortization		(11,000,000)	(8,000,000)
Net Balance		5,000,000	7,000,000
Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill		746,000,000	746,000,000
Energy Services [Member]
Goodwill [Line Items]
Goodwill	[2]	110,000,000	110,000,000
Accumulated goodwill impairment charge recorded in 2012		252,000,000	252,000,000
Corporate and Other [Member]
Goodwill [Line Items]
Goodwill		11,000,000	11,000,000
CERC Corp [Member]
Goodwill [Line Items]
Goodwill		867,000,000	867,000,000
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount		106,000,000	105,000,000
Accumulated Amortization		(41,000,000)	(31,000,000)
Net Balance		65,000,000	74,000,000
Amortization expense of intangible assets (1)	[1]	10,000,000	13,000,000	$ 4,000,000
Estimated amortization expense over next twelve months		11,000,000
Estimated amortization expense in two years		6,000,000
Estimated amortization expense in three years		6,000,000
Estimated amortization expense in four years		6,000,000
Estimated amortization expense in five years		5,000,000
CERC Corp [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount		86,000,000	86,000,000
Accumulated Amortization		(27,000,000)	(21,000,000)
Net Balance		59,000,000	65,000,000
CERC Corp [Member] | Covenants Not To Compete [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount		4,000,000	4,000,000
Accumulated Amortization		(3,000,000)	(2,000,000)
Net Balance		1,000,000	2,000,000
CERC Corp [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount		16,000,000	15,000,000
Accumulated Amortization		(11,000,000)	(8,000,000)
Net Balance		5,000,000	7,000,000
CERC Corp [Member] | Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill		746,000,000	746,000,000
CERC Corp [Member] | Energy Services [Member]
Goodwill [Line Items]
Goodwill	[2]	110,000,000	110,000,000
Accumulated goodwill impairment charge recorded in 2012		252,000,000	252,000,000
CERC Corp [Member] | Corporate and Other [Member]
Goodwill [Line Items]
Goodwill		$ 11,000,000	$ 11,000,000
[1]	Recorded in Depreciation and amortization expenses on CenterPoint Energy’s and CERC’s respective Statements of Consolidated Income.
[2]	Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012.

Regulatory Accounting (Details)

Regulatory Accounting (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Regulatory Assets and Liabilities [Line Items]
Securitized regulatory assets		$ 1,059	$ 1,590
Unrecognized equity return (2)	[1]	(213)	(287)
Unamortized loss on reacquired debt		68	75
Non-current regulatory assets		1,967	2,347
Total regulatory assets		2,044	2,477
Non-current regulatory liabilities		2,525	2,464
Total regulatory liabilities		2,563	2,488
Total regulatory assets and liabilities, net		(519)	(11)
Amount of allowed equity return on the true-up balance that was recognized in the period		74	42	$ 64
Prepaid Expenses and Other Current Assets [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory assets (1)	[2]	77	130
Other Current Liabilities [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory liabilities (7)	[3]	38	24
Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities	[4]	1,323	1,354
Removal Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		886	878
Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		316	232
Pension and Other Postretirement Plans Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[5]	725	646
Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[4]	33	48
Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[6]	227	211
Hurricane Harvey [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[7]	68	64
Natural Gas Distribution [Member] | Pension and Other Postretirement Plans Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		4	7
Electric Transmission & Distribution [Member] | Pension and Other Postretirement Plans Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		33	31
Houston Electric [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Securitized regulatory assets		1,059	1,590
Unrecognized equity return (2)	[1]	(213)	(287)
Unamortized loss on reacquired debt		68	75
Non-current regulatory assets		1,124	1,570
Total regulatory assets		1,124	1,570
Non-current regulatory liabilities		1,298	1,263
Total regulatory liabilities		1,315	1,285
Total regulatory assets and liabilities, net		(191)	285
Amount of allowed equity return on the true-up balance that was recognized in the period		74	42	$ 64
Houston Electric [Member] | Prepaid Expenses and Other Current Assets [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory assets (1)	[2]	0	0
Houston Electric [Member] | Other Current Liabilities [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory liabilities (7)	[3]	17	22
Houston Electric [Member] | Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities	[4]	847	862
Houston Electric [Member] | Removal Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		269	285
Houston Electric [Member] | Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		182	116
Houston Electric [Member] | Pension and Other Postretirement Plans Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[5]	33	31
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		33	31
Houston Electric [Member] | Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[4]	23	33
Houston Electric [Member] | Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[6]	90	70
Houston Electric [Member] | Hurricane Harvey [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[7]	64	58
CERC Corp [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Securitized regulatory assets		0	0
Unrecognized equity return (2)	[1]	0	0
Unamortized loss on reacquired debt		0	0
Non-current regulatory assets		181	181
Total regulatory assets		258	311
Non-current regulatory liabilities		1,227	1,201
Total regulatory liabilities		1,248	1,203
Total regulatory assets and liabilities, net		(990)	(892)
CERC Corp [Member] | Prepaid Expenses and Other Current Assets [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory assets (1)	[2]	77	130
CERC Corp [Member] | Other Current Liabilities [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current regulatory liabilities (7)	[3]	21	2
CERC Corp [Member] | Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities	[4]	476	492
CERC Corp [Member] | Removal Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		617	593
CERC Corp [Member] | Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory liabilities		134	116
CERC Corp [Member] | Pension and Other Postretirement Plans Costs [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[5]	30	20
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		4	7
CERC Corp [Member] | Amounts related to TCJA [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[4]	10	15
CERC Corp [Member] | Other Regulatory Assets (Liabilities) [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[6]	137	140
CERC Corp [Member] | Hurricane Harvey [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-current regulatory assets	[7]	$ 4	$ 6
[1]	The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the years ended December 31, 2018, 2017 and 2016, Houston Electric recognized approximately $74 million, $42 million and $64 million, respectively, of the allowed equity return. The timing of 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]	Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ respective Consolidated Balance Sheets.
[3]	Current regulatory liabilities are included in Other current liabilities in each of the Registrants’ respective Consolidated Balance Sheets.
[4]	The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities. See Note 15 for additional information.
[5]	Includes a portion of Houston Electric’s and CERC’s 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 $33 million and $4 million as of December 31, 2018, respectively, and $31 million and $7 million as of December 31, 2017, respectively, were not earning a return.
[6]	Other long-term regulatory assets that are not earning a return were not material as of December 31, 2018 and 2017.
[7]	The Registrants suffered damage as a result of Hurricane Harvey, a major storm classified as a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale, that first struck the Texas coast on Friday, August 25, 2017 and remained over the Houston area for the next several days. The unprecedented flooding from torrential amounts of rainfall accompanying the storm caused significant damage to or destruction of residences and businesses served by the Registrants. The Registrants deferred the uninsured storm restoration costs as management believed it was probable that such costs will be recovered through traditional rate adjustment mechanisms for capital costs and through the next base rate proceeding for operation and maintenance expenses. As a result, storm restoration costs did not materially affect the Registrants’ reported net income for 2017. The Registrants are not earning a return on Hurricane Harvey restoration costs.

Stock-Based Incentive Compens_3

Stock-Based Incentive Compensation Plans and Employee Benefit Plans Stock Based Incentive Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance under long-term incentive plans (in shares)		14,000
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Income tax benefit recognized related to LTIPs		$ 6		$ 8	$ 7
Actual tax benefit realized for tax deductions		$ 5		$ 6	$ 5
Performance Awards [Member]
Summary of nonvested shares [Roll Forward]
Nonvested, beginning of period (in shares)	[1]	3,627
Granted (in shares)	[1]	1,321
Forfeited or cancelled (in shares)	[1]	(721)
Vested and released to participants (in shares)	[1]	(409)
Nonvested, end of period (in shares)	[1]	3,818		3,627
Weighted average grant date fair value, nonvested, beginning of period (in dollars per share)	[1]	$ 22.15
Weighted average grant date fair values of awards granted (in dollars per share)		26.74	[1]	$ 26.64	$ 18.98
Weighted average grant date fair value, forfeited or cancelled (in dollars per share)	[1]	21.72
Weighted average grant date fair value, vested and released to participants (in dollars per share)	[1]	21.31
Weighted average grant date fair value, nonvested, end of period (in dollars per share)	[1]	$ 23.91		$ 22.15
Remaining average contractual life of nonvested shares outstanding (in years)	[1]	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested	[1],[2]	$ 57
Total intrinsic value of awards received by participants		12		$ 7	$ 7
Total grant date fair values of performance and stock awards which vested during the period		$ 9		$ 5	$ 7
Stock Awards [Member]
Summary of nonvested shares [Roll Forward]
Nonvested, beginning of period (in shares)		980
Granted (in shares)		409
Forfeited or cancelled (in shares)		(29)
Vested and released to participants (in shares)		(300)
Nonvested, end of period (in shares)		1,060		980
Weighted average grant date fair value, nonvested, beginning of period (in dollars per share)		$ 22.68
Weighted average grant date fair values of awards granted (in dollars per share)		26.62		$ 26.77	$ 19.24
Weighted average grant date fair value, forfeited or cancelled (in dollars per share)		25.31
Weighted average grant date fair value, vested and released to participants (in dollars per share)		22.84
Weighted average grant date fair value, nonvested, end of period (in dollars per share)		$ 24.08		$ 22.68
Remaining average contractual life of nonvested shares outstanding (in years)		1 year 1 month
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested	[2]	$ 30
Total intrinsic value of awards received by participants		9		$ 9	$ 6
Total grant date fair values of performance and stock awards which vested during the period		7		7	6
Performance and Stock Awards [Member]
Summary of nonvested shares [Roll Forward]
Unrecognized compensation cost related to non-vested performance and stock awards		$ 27
Weighted average period of recognition (in years)		1 year 8 months
Operation And Maintenance Expense [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
LTIP compensation expense	[3]	$ 26		$ 21	$ 19
[1]	Reflects maximum performance achievement.
[2]	Reflects the impact of current expectations of achievement and stock price.
[3]	Included in Operation and maintenance expense in CenterPoint Energy’s Statements of Consolidated Income and not capitalized as a part of Inventory or Property, Plant and Equipment.

Stock-Based Incentive Compens_4

Stock-Based Incentive Compensation Plans and Employee Benefit Plans Pension and Postretirement Benefits (Details) - USD ($) $ in Millions		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Pension and Postretirement Benefits [Abstract]
Percentage of eligible earnings used to determine retirement benefits (in hundredths)		5.00%				5.00%
Percent vested						100.00%
Pension plan minimum vesting period (in years)						3 years
Amounts recognized in balance sheets
Other liabilities-benefit obligations		$ (796)		$ (785)		$ (796)		$ (785)
Changes in plan assets and benefit obligations recognized in other comprehensive income
Amortization of net loss	[1]					(6)		(7)
Prior service cost (2)	[1]					(1)		(1)
Pension Plan [Member]
Components of net periodic costs [Abstract]
Service cost (1)	[2]					37		36		$ 38
Interest cost (2)	[3]					79		89		93
Expected return on plan assets (2)	[3]					(107)		(97)		(101)
Amortization of prior service cost (credit)	[3]					9		9		9
Amortization of net loss (2)	[3]					43		58		63
Net periodic cost (credit)						$ 61		$ 95		$ 102
Assumptions used to determine net periodic benefit (income) cost
Discount rate						3.65%		4.15%		4.40%
Expected return on plan assets						6.00%	[4]	6.00%	[4]	6.25%
Rate of increase in compensation levels						4.45%		4.50%		4.15%
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year						$ 2,225		$ 2,197
Service cost (1)	[2]					37		36		$ 38
Interest cost (2)	[3]					79		89		93
Benefits paid						(201)		(168)
Actuarial (gain) loss (1)	[5]					(127)		71
Benefit obligation, end of year		2,013		2,225		2,013		2,225		2,197
Change in plan assets [Rollforward]
Fair value of plan assets, beginning of year						1,801		1,656
Employer contributions						69		48
Benefits paid						(201)		(168)
Actual investment return						(153)		265
Fair value of plan assets, end of year		1,516		1,801		1,516		1,801		$ 1,656
Funded status of plan
Funded status, end of year		(497)		(424)		(497)		(424)
Amounts recognized in balance sheets
Current liabilities-other		(7)		(7)		(7)		(7)
Other liabilities-benefit obligations		(490)		(417)		(490)		(417)
Net liability, end of year		$ (497)		$ (424)		$ (497)		$ (424)
Discount rate (2)		4.35%	[6]	3.65%	[6]	4.35%	[6]	3.65%	[6]	4.15%
Expected return on plan assets (3)						6.00%	[4]	6.00%	[4]	6.25%
Rate of increase in compensation levels		4.60%		4.45%		4.60%		4.45%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate		3.75%		3.75%		3.75%		3.75%
Annualized individual discount rates based on time period, minimum						6 months
Annualized individual discount rates based on time period, maximum						99 years
Amounts recognized in accumulated other comprehensive loss
Unrecognized actuarial loss (gain)		$ 109		$ 94		$ 109		$ 94
Unrecognized prior service cost		1		1		1		1
Deferred Tax Benefit On Accumulated Other Comprehensive Income	[7]	0		0		0		0
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax		110		95		110		95
Changes in plan assets and benefit obligations recognized in other comprehensive income
Net loss (gain)						22
Amortization of net loss						(6)
Prior service cost (2)						(1)
Total recognized in comprehensive income						15
Total expense recognized in net periodic cost and other comprehensive income						76
Pension benefits that have accumulated benefit obligations in excess of plan assets
Accumulated benefit obligation		1,930		2,090		1,930		2,090
Projected benefit obligation		1,952		2,151		1,952		2,151
Fair value of plan assets		1,516		1,801		1,516		1,801
Accumulated benefit obligation for all defined benefit pension plans		$ 1,991		$ 2,164		1,991		2,164
Postretirement Benefits [Member]
Components of net periodic costs [Abstract]
Service cost (1)	[8]					2		2		$ 2
Interest cost (2)	[9]					13		16		16
Expected return on plan assets (2)	[9]					(5)		(5)		(6)
Amortization of prior service cost (credit)	[9]					(5)		(5)		(3)
Amortization of net loss (2)	[9]					0		0		1
Curtailment (1)	[10]					0		0		(5)
Net periodic cost (credit)						$ 5		$ 8		$ 5
Assumptions used to determine net periodic benefit (income) cost
Discount rate						3.60%		4.15%		4.35%
Expected return on plan assets		4.60%	[11]	4.55%	[11]	4.55%		4.50%		4.80%
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year						$ 386		$ 383
Service cost (1)	[8]					2		2		$ 2
Interest cost (2)	[9]					13		16		16
Participant contributions						7		7
Benefits paid						(25)		(26)
Actuarial (gain) loss (1)	[12]					(52)		4
Benefit obligation, end of year		$ 331		$ 386		331		386		383
Change in plan assets [Rollforward]
Fair value of plan assets, beginning of year						120		113
Employer contributions						14		16
Participant contributions						7		7
Benefits paid						(25)		(26)
Actual investment return						(2)		10
Fair value of plan assets, end of year		114		120		114		120		$ 113
Funded status of plan
Funded status, end of year		(217)		(266)		(217)		(266)
Amounts recognized in balance sheets
Current liabilities-other		(6)		(6)		(6)		(6)
Other liabilities-benefit obligations		(211)		(260)		(211)		(260)
Net liability, end of year		$ (217)		$ (266)		$ (217)		$ (266)
Discount rate (2)	[13]	4.35%		3.60%		4.35%		3.60%
Expected return on plan assets (3)		4.60%	[11]	4.55%	[11]	4.55%		4.50%		4.80%
Prescription drug cost trend rate assumed for the next year - Pre-65						9.20%		9.85%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)		4.50%		4.50%		4.50%		4.50%
Annualized individual discount rates based on time period, minimum						6 months
Annualized individual discount rates based on time period, maximum						99 years
Amounts recognized in accumulated other comprehensive loss
Unrecognized actuarial loss (gain)		$ (7)		$ (8)		$ (7)		$ (8)
Unrecognized prior service cost		5		6		5		6
Deferred Tax Benefit On Accumulated Other Comprehensive Income	[7]	0		0		0		0
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax		(2)		(2)		(2)		(2)
Changes in plan assets and benefit obligations recognized in other comprehensive income
Net loss (gain)						0
Amortization of net loss						0
Prior service cost (2)						0
Total recognized in comprehensive income						0
Total expense recognized in net periodic cost and other comprehensive income						5
Non-qualified Pension Plan [Member]
Change in plan assets [Rollforward]
Employer contributions						9
Pension benefits that have accumulated benefit obligations in excess of plan assets
Accumulated benefit obligation		61		74		61		74
Projected benefit obligation		61		74		61		74
Fair value of plan assets		0		0		0		0
U.S. Equity [Member] | Pension Plan [Member]
Change in plan assets [Rollforward]
Fair value of plan assets, beginning of year						76
Fair value of plan assets, end of year		60		76		60		76
Cash and Cash Equivalents [Member] | Pension Plan [Member]
Change in plan assets [Rollforward]
Fair value of plan assets, beginning of year						18
Fair value of plan assets, end of year		$ 19		$ 18		$ 19		$ 18
Minimum [Member] | Postretirement Benefits [Member]
Amounts recognized in balance sheets
Health care cost trend rate assumed for the next year		5.95%		6.15%		5.95%		6.15%
Year that the cost trend rates reach the ultimate trend rate						2,026		2,026
Minimum [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		12.00%				12.00%
Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%				13.00%
Minimum [Member] | International Developed Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		7.00%				7.00%
Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		3.00%				3.00%
Minimum [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		5.00%				5.00%
Minimum [Member] | Fixed Income [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		55.00%				55.00%
Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		69.00%				69.00%
Minimum [Member] | Cash and Cash Equivalents [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%				0.00%
Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%				0.00%
Maximum [Member] | Postretirement Benefits [Member]
Amounts recognized in balance sheets
Health care cost trend rate assumed for the next year		28.60%		23.85%		28.60%		23.85%
Year that the cost trend rates reach the ultimate trend rate						2,027		2,024
Maximum [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		28.00%				28.00%
Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		23.00%				23.00%
Maximum [Member] | International Developed Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		17.00%				17.00%
Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%				13.00%
Maximum [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		11.00%				11.00%
Maximum [Member] | Fixed Income [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		65.00%				65.00%
Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		79.00%				79.00%
Maximum [Member] | Cash and Cash Equivalents [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%				2.00%
Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%				2.00%
Parent Company [Member] | Postretirement Benefits [Member]
Components of net periodic costs [Abstract]
Curtailment (1)										$ (2)
Houston Electric [Member]
Amounts recognized in balance sheets
Other liabilities-benefit obligations		$ (91)		$ (146)		$ (91)		$ (146)
Changes in plan assets and benefit obligations recognized in other comprehensive income
Amortization of net loss	[1]					0		0
Prior service cost (2)	[1]					0		0
Houston Electric [Member] | Postretirement Benefits [Member]
Components of net periodic costs [Abstract]
Service cost (1)	[8]					0		1		1
Interest cost (2)	[9]					8		9		10
Expected return on plan assets (2)	[9]					(4)		(4)		(5)
Amortization of prior service cost (credit)	[9]					(5)		(6)		(4)
Amortization of net loss (2)	[9]					0		0		1
Curtailment (1)	[10]					0		0		(4)
Net periodic cost (credit)						$ (1)		$ 0		$ (1)
Assumptions used to determine net periodic benefit (income) cost
Discount rate						3.60%		4.15%		4.35%
Expected return on plan assets		4.70%	[11]	4.75%	[11]	4.75%		4.75%		5.00%
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year						$ 225		$ 217
Service cost (1)	[8]					0		1		$ 1
Interest cost (2)	[9]					8		9		10
Participant contributions						2		2
Benefits paid						(13)		(14)
Actuarial (gain) loss (1)	[12]					(56)		10
Benefit obligation, end of year		$ 166		$ 225		166		225		217
Change in plan assets [Rollforward]
Fair value of plan assets, beginning of year						93		88
Employer contributions						9		10
Participant contributions						2		2
Benefits paid						(13)		(14)
Actual investment return						(2)		7
Fair value of plan assets, end of year		89		93		89		93		$ 88
Funded status of plan
Funded status, end of year		(77)		(132)		(77)		(132)
Amounts recognized in balance sheets
Current liabilities-other		0		0		0		0
Other liabilities-benefit obligations		(77)		(132)		(77)		(132)
Net liability, end of year		$ (77)		$ (132)		$ (77)		$ (132)
Discount rate (2)	[13]	4.35%		3.60%		4.35%		3.60%
Expected return on plan assets (3)		4.70%	[11]	4.75%	[11]	4.75%		4.75%		5.00%
Prescription drug cost trend rate assumed for the next year - Pre-65						9.20%		9.85%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)		4.50%		4.50%		4.50%		4.50%
Annualized individual discount rates based on time period, minimum						6 months
Annualized individual discount rates based on time period, maximum						99 years
Houston Electric [Member] | Non-qualified Pension Plan [Member]
Change in plan assets [Rollforward]
Employer contributions						$ 0
Houston Electric [Member] | Minimum [Member] | Postretirement Benefits [Member]
Amounts recognized in balance sheets
Health care cost trend rate assumed for the next year		5.95%		6.15%		5.95%		6.15%
Year that the cost trend rates reach the ultimate trend rate						2,026		2,026
Houston Electric [Member] | Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%				13.00%
Houston Electric [Member] | Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		3.00%				3.00%
Houston Electric [Member] | Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		69.00%				69.00%
Houston Electric [Member] | Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%				0.00%
Houston Electric [Member] | Maximum [Member] | Postretirement Benefits [Member]
Amounts recognized in balance sheets
Health care cost trend rate assumed for the next year		28.60%		23.85%		28.60%		23.85%
Year that the cost trend rates reach the ultimate trend rate						2,027		2,024
Houston Electric [Member] | Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		23.00%				23.00%
Houston Electric [Member] | Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%				13.00%
Houston Electric [Member] | Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		79.00%				79.00%
Houston Electric [Member] | Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%				2.00%
CERC Corp [Member]
Amounts recognized in balance sheets
Other liabilities-benefit obligations		$ (93)		$ (97)		$ (93)		$ (97)
Changes in plan assets and benefit obligations recognized in other comprehensive income
Amortization of net loss	[1]					0		0
Prior service cost (2)	[1]					(1)		(1)
CERC Corp [Member] | Postretirement Benefits [Member]
Components of net periodic costs [Abstract]
Service cost (1)	[8]					1		1		$ 1
Interest cost (2)	[9]					4		5		4
Expected return on plan assets (2)	[9]					(1)		(1)		(1)
Amortization of prior service cost (credit)	[9]					1		1		0
Amortization of net loss (2)	[9]					0		0		1
Curtailment (1)	[10]					0		0		(1)
Net periodic cost (credit)						$ 5		$ 6		$ 4
Assumptions used to determine net periodic benefit (income) cost
Discount rate						3.60%		4.15%		4.35%
Expected return on plan assets		4.15%	[11]	3.85%	[11]	3.85%		3.60%		3.95%
Change in benefit obligation [Roll Forward]
Benefit obligation, beginning of year						$ 109		$ 115
Service cost (1)	[8]					1		1		$ 1
Interest cost (2)	[9]					4		5		4
Participant contributions						4		3
Benefits paid						(9)		(9)
Actuarial (gain) loss (1)	[12]					1		(6)
Benefit obligation, end of year		$ 110		$ 109		110		109		115
Change in plan assets [Rollforward]
Fair value of plan assets, beginning of year						26		25
Employer contributions						4		5
Participant contributions						4		3
Benefits paid						(9)		(9)
Actual investment return						0		2
Fair value of plan assets, end of year		25		26		25		26		$ 25
Funded status of plan
Funded status, end of year		(85)		(83)		(85)		(83)
Amounts recognized in balance sheets
Current liabilities-other		(3)		(4)		(3)		(4)
Other liabilities-benefit obligations		(82)		(79)		(82)		(79)
Net liability, end of year		$ (85)		$ (83)		$ (85)		$ (83)
Discount rate (2)	[13]	4.35%		3.60%		4.35%		3.60%
Expected return on plan assets (3)		4.15%	[11]	3.85%	[11]	3.85%		3.60%		3.95%
Prescription drug cost trend rate assumed for the next year - Pre-65						9.20%		9.85%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)		4.50%		4.50%		4.50%		4.50%
Annualized individual discount rates based on time period, minimum						6 months
Annualized individual discount rates based on time period, maximum						99 years
Amounts recognized in accumulated other comprehensive loss
Unrecognized actuarial loss (gain)		$ (3)		$ (2)		$ (3)		$ (2)
Unrecognized prior service cost		5		6		5		6
Deferred Tax Benefit On Accumulated Other Comprehensive Income	[7]	(9)		(11)		(9)		(11)
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax		$ (7)		$ (7)		(7)		$ (7)
Changes in plan assets and benefit obligations recognized in other comprehensive income
Net loss (gain)						(1)
Amortization of net loss						0
Prior service cost (2)						(1)
Total recognized in comprehensive income						(2)
Total expense recognized in net periodic cost and other comprehensive income						3
CERC Corp [Member] | Non-qualified Pension Plan [Member]
Change in plan assets [Rollforward]
Employer contributions						$ 0
CERC Corp [Member] | Minimum [Member] | Postretirement Benefits [Member]
Amounts recognized in balance sheets
Health care cost trend rate assumed for the next year		5.95%		6.15%		5.95%		6.15%
Year that the cost trend rates reach the ultimate trend rate						2,026		2,026
CERC Corp [Member] | Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		15.00%				15.00%
CERC Corp [Member] | Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%				2.00%
CERC Corp [Member] | Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		68.00%				68.00%
CERC Corp [Member] | Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%				0.00%
CERC Corp [Member] | Maximum [Member] | Postretirement Benefits [Member]
Amounts recognized in balance sheets
Health care cost trend rate assumed for the next year		28.60%		23.85%		28.60%		23.85%
Year that the cost trend rates reach the ultimate trend rate						2,027		2,024
CERC Corp [Member] | Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		25.00%				25.00%
CERC Corp [Member] | Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		12.00%				12.00%
CERC Corp [Member] | Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		78.00%				78.00%
CERC Corp [Member] | Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%				2.00%
IBEW Local Union 66 [Member] | Houston Electric [Member] | Postretirement Benefits [Member]
Components of net periodic costs [Abstract]
Curtailment (1)										$ (3)
[1]	Amounts are included in the computation of net periodic cost and are reflected in Other, net in each of the Registrants’ respective Statements of Consolidated Income.
[2]	Amounts presented in the table above are included in Operation and maintenance expense in CenterPoint Energy’s Statements of Consolidated Income, net of regulatory deferrals and amounts capitalized. See Note 2(r).
[3]	Amounts presented in the table above are included in Other, net in CenterPoint Energy’s Statements of Consolidated Income, net of regulatory deferrals. See Note 2(r).
[4]	The expected rate of return assumption was developed using the targeted asset allocation of CenterPoint Energy’s plans and the expected return for each asset class.
[5]	Significant sources of gain for 2018 include the increase in discount rate from 3.65% to 4.35% and the mortality projection scale change from MP2017 to MP2018. For 2017, the significant source of loss was the decrease in the discount rate from 4.15% to 3.65%.
[6]	The discount rate assumption was determined by matching the projected cash flows of CenterPoint Energy’s plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years.
[7]	CenterPoint Energy’s and CERC’s postretirement benefit obligation is reduced by the impact of previously non-taxable government subsidies under the Medicare Prescription Drug Act. Because the subsidies were non-taxable, the temporary difference used in measuring the deferred tax impact was determined on the unrecognized losses excluding such subsidies.
[8]	Amounts presented in the table above are included in Operation and maintenance expense in CenterPoint Energy’s Statements of Consolidated Income, net of regulatory deferrals and amounts capitalized. See Note 2(r).
[9]	Amounts presented in the table above are included in Other, net in each of the Registrants’ respective Statements of Consolidated Income, net of regulatory deferrals. See Note 2(r).
[10]	A curtailment gain or loss is required when the expected future services of a significant number of current employees are reduced or eliminated for the accrual of benefits. During 2016, postretirement healthcare benefits were amended resulting in a net curtailment gain of $5 million. In May 2016, Houston Electric entered into a renegotiated collective bargaining agreement with the IBEW Local Union 66 that provides that for Houston Electric bargaining unit employees covered under the agreement who retire on or after January 1, 2017, retiree medical and prescription drug coverage will be provided exclusively through the NECA/IBEW Family Medical Care Plan in exchange for the payment of monthly premiums as determined under the agreement. As a result, the accrued postretirement benefits related to such future CenterPoint Energy and Houston Electric union retirees were eliminated. Houston Electric recognized a curtailment gain of $3 million as an accelerated recognition of the prior service credit that would otherwise be recognized in future periods for the postretirement plan. CenterPoint Energy also recognized an additional curtailment gain of $2 million in October 2016 related to other amendments in the postretirement plan.
[11]	The expected rate of return assumption was developed using the targeted asset allocation of the plans and the expected return for each asset class.
[12]	Significant sources of gain for 2018 include the increase in the discount rate from 3.60% to 4.35%, favorable benefit claims experience and cost trend rates in addition to the change in mortality projection scale from MP2017 to MP2018.
[13]	The discount rate assumption was determined by matching the projected cash flows of the plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years.

Stock-Based Incentive Compens_5

Stock-Based Incentive Compensation Plans and Employee Benefit Plans Plan Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Savings Plan [Abstract]
Maximum percentage of eligible compensation employees may contribute to the savings plan (in hundredths)		50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		6.00%
Defined Contribution Plan, Cost		$ 43		$ 41		$ 38
Postemployment Benefits [Abstract]
Postemployment Benefits, Period Expense		3		6		5
Other Non-Qualified Plans [Abstract]
Benefit expense related to deferred compensation plans		3		$ 3		$ 3
Non-qualified Pension Plan [Member]
Total contributions to the plans during the period		9
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		$ 7
Pension Plan [Member]
Discount Rate		4.35%	[1]	3.65%	[1]	4.15%
Plan assets, fair value		$ 1,516		$ 1,801		$ 1,656
Defined Benefits Plan, Fair Value Of Plan Assets, Excluding Investments Measured at Net Asset Value		860		877
Obligation To Return Cash Received As Collateral From Securities Lending,		(77)		(76)
Defined Benefit Plan, Contribution by Employer, Qualified Plan		60
Total contributions to the plans during the period		69		$ 48
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		86
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2019		141
Pension benefit payments 2020		146
Pension benefit payments 2021		154
Pension benefit payments 2022		155
Pension benefit payments 2023		156
Pension benefit payments 2024 - 2028		$ 759
Other Non-Qualified Plans [Abstract]
Annualized individual discount rates based on time period, minimum		6 months
Annualized individual discount rates based on time period, maximum		99 years
Postretirement Benefits [Member]
Discount Rate	[2]	4.35%		3.60%
Plan assets, fair value		$ 114		$ 120		113
Total contributions to the plans during the period		14		16
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		17
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2019		16
Pension benefit payments 2020		19
Pension benefit payments 2021		20
Pension benefit payments 2022		21
Pension benefit payments 2023		22
Pension benefit payments 2024 - 2028		$ 116
Other Non-Qualified Plans [Abstract]
Annualized individual discount rates based on time period, minimum		6 months
Annualized individual discount rates based on time period, maximum		99 years
Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		$ 442		372
Obligation To Return Cash Received As Collateral From Securities Lending,		(77)		(76)
Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		418		505
Obligation To Return Cash Received As Collateral From Securities Lending,		0		0
Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Obligation To Return Cash Received As Collateral From Securities Lending,		0		0
U.S. Equity [Member] | Pension Plan [Member]
Plan assets, fair value		60		76
U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		60		76
U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Cash and Cash Equivalents [Member] | Pension Plan [Member]
Plan assets, fair value		19		18
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		19		18
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Common Collective Trust Funds [Member] | Pension Plan [Member]
Plan assets, fair value	[3],[4]	$ 656		$ 924
Common Collective Trust Funds [Member] | International Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		37.00%		34.00%
Common Collective Trust Funds [Member] | Fixed Income Funds [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		54.00%		55.00%
Common Collective Trust Funds [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		5.00%		6.00%
Common Collective Trust Funds [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		4.00%		5.00%
Investment grade or above [Member] | Pension Plan [Member]
Plan assets, fair value		$ 368		$ 432
Investment grade or above [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Investment grade or above [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		368		432
Investment grade or above [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Cash received as collateral from securities [Member] | Pension Plan [Member]
Plan assets, fair value		77		76
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		77		76
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Cash received as collateral from securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
U.S. treasuries [Member] | Pension Plan [Member]
Plan assets, fair value		196		67
U.S. treasuries [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		196		67
U.S. treasuries [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
U.S. treasuries [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mortgage backed securities [Member] | Pension Plan [Member]
Plan assets, fair value		6		8
Mortgage backed securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mortgage backed securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		6		8
Mortgage backed securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Asset backed securities [Member] | Pension Plan [Member]
Plan assets, fair value		1		1
Asset backed securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Asset backed securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		1		1
Asset backed securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Municipal bonds [Member] | Pension Plan [Member]
Plan assets, fair value		27		47
Municipal bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Municipal bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		27		47
Municipal bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mutual funds [Member] | Pension Plan [Member]
Plan assets, fair value		167		211
Mutual funds [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 114		$ 120
Mutual funds [Member] | International Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		51.00%		57.00%
Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		7.00%		8.00%
Mutual funds [Member] | Fixed Income Funds [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		0.00%		0.00%
Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		74.00%		74.00%
Mutual funds [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		15.00%		13.00%
Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		19.00%		18.00%
Mutual funds [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		34.00%		30.00%
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		$ 167		$ 211
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		114		120
Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
International government bonds [Member] | Pension Plan [Member]
Plan assets, fair value		16		17
International government bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
International government bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Plan assets, fair value		16		17
International government bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Plan assets, fair value		0		0
Benefit Obligation [Member]
Postemployment Benefits [Abstract]
Postemployment benefit obligations		11		20
Other Non-Qualified Plans [Abstract]
Other non-qualified plans benefit obligations deferred compensation		42		45
Benefit obligations related to split-dollar life insurance arrangements		$ 36		39
Minimum [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		12.00%
Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%
Minimum [Member] | International Developed Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		7.00%
Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		3.00%
Minimum [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		5.00%
Minimum [Member] | Fixed Income [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		55.00%
Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		69.00%
Minimum [Member] | Cash and Cash Equivalents [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%
Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%
Maximum [Member] | U.S. Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		28.00%
Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		23.00%
Maximum [Member] | International Developed Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		17.00%
Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%
Maximum [Member] | Emerging Market Equity [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		11.00%
Maximum [Member] | Fixed Income [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		65.00%
Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		79.00%
Maximum [Member] | Cash and Cash Equivalents [Member] | Pension Plan [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
Common Stock [Member] | CenterPoint Energy [Member]
Savings Plan [Abstract]
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage		25.00%
Number of Common stock held by the savings plan (in shares)		12,062,915
Percentage of investment in common stocks (in hundredths)		16.00%
Houston Electric [Member]
Savings Plan [Abstract]
Maximum percentage of eligible compensation employees may contribute to the savings plan (in hundredths)		50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		6.00%
Defined Contribution Plan, Cost		$ 17		17		15
Postemployment Benefits [Abstract]
Postemployment Benefits, Period Expense		4		1		3
Other Non-Qualified Plans [Abstract]
Benefit expense related to deferred compensation plans		1		$ 1		1
Houston Electric [Member] | Non-qualified Pension Plan [Member]
Total contributions to the plans during the period		0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		0
Houston Electric [Member] | Pension Plan [Member]
Defined Benefit Plan, Contribution by Employer, Qualified Plan		0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		$ 0
Houston Electric [Member] | Postretirement Benefits [Member]
Discount Rate	[2]	4.35%		3.60%
Plan assets, fair value		$ 89		$ 93		88
Total contributions to the plans during the period		9		10
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		10
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2019		9
Pension benefit payments 2020		10
Pension benefit payments 2021		11
Pension benefit payments 2022		11
Pension benefit payments 2023		12
Pension benefit payments 2024 - 2028		$ 61
Other Non-Qualified Plans [Abstract]
Annualized individual discount rates based on time period, minimum		6 months
Annualized individual discount rates based on time period, maximum		99 years
Houston Electric [Member] | Mutual funds [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 89		$ 93
Houston Electric [Member] | Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		7.00%		8.00%
Houston Electric [Member] | Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		74.00%		74.00%
Houston Electric [Member] | Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		19.00%		18.00%
Houston Electric [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 89		$ 93
Houston Electric [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
Houston Electric [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
Houston Electric [Member] | Benefit Obligation [Member]
Postemployment Benefits [Abstract]
Postemployment benefit obligations		3		3
Other Non-Qualified Plans [Abstract]
Other non-qualified plans benefit obligations deferred compensation		9		10
Benefit obligations related to split-dollar life insurance arrangements		$ 1		1
Houston Electric [Member] | Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%
Houston Electric [Member] | Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		3.00%
Houston Electric [Member] | Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		69.00%
Houston Electric [Member] | Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%
Houston Electric [Member] | Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		23.00%
Houston Electric [Member] | Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%
Houston Electric [Member] | Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		79.00%
Houston Electric [Member] | Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
Houston Electric [Member] | Common Stock [Member] | CenterPoint Energy [Member]
Savings Plan [Abstract]
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage		25.00%
Number of Common stock held by the savings plan (in shares)		12,062,915
Percentage of investment in common stocks (in hundredths)		16.00%
CERC Corp [Member]
Savings Plan [Abstract]
Maximum percentage of eligible compensation employees may contribute to the savings plan (in hundredths)		50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		6.00%
Defined Contribution Plan, Cost		$ 18		17		16
Postemployment Benefits [Abstract]
Postemployment Benefits, Period Expense		1		4		3
Other Non-Qualified Plans [Abstract]
Benefit expense related to deferred compensation plans		0		$ 0		0
CERC Corp [Member] | Non-qualified Pension Plan [Member]
Total contributions to the plans during the period		0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		0
CERC Corp [Member] | Pension Plan [Member]
Defined Benefit Plan, Contribution by Employer, Qualified Plan		0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		$ 0
CERC Corp [Member] | Postretirement Benefits [Member]
Discount Rate	[2]	4.35%		3.60%
Plan assets, fair value		$ 25		$ 26		$ 25
Total contributions to the plans during the period		4		5
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		4
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Pension benefit payments 2019		5
Pension benefit payments 2020		6
Pension benefit payments 2021		6
Pension benefit payments 2022		7
Pension benefit payments 2023		7
Pension benefit payments 2024 - 2028		$ 37
Other Non-Qualified Plans [Abstract]
Annualized individual discount rates based on time period, minimum		6 months
Annualized individual discount rates based on time period, maximum		99 years
CERC Corp [Member] | Mutual funds [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 25		$ 26
CERC Corp [Member] | Mutual funds [Member] | International Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		6.00%		8.00%
CERC Corp [Member] | Mutual funds [Member] | Fixed Income Funds [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		73.00%		71.00%
CERC Corp [Member] | Mutual funds [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		21.00%		21.00%
CERC Corp [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		$ 25		$ 26
CERC Corp [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
CERC Corp [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Postretirement Benefits [Member]
Plan assets, fair value		0		0
CERC Corp [Member] | Benefit Obligation [Member]
Postemployment Benefits [Abstract]
Postemployment benefit obligations		7		14
Other Non-Qualified Plans [Abstract]
Other non-qualified plans benefit obligations deferred compensation		3		3
Benefit obligations related to split-dollar life insurance arrangements		$ 0		$ 0
CERC Corp [Member] | Minimum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		15.00%
CERC Corp [Member] | Minimum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
CERC Corp [Member] | Minimum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		68.00%
CERC Corp [Member] | Minimum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0.00%
CERC Corp [Member] | Maximum [Member] | U.S. Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		25.00%
CERC Corp [Member] | Maximum [Member] | International Developed Market Equity [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		12.00%
CERC Corp [Member] | Maximum [Member] | Fixed Income [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		78.00%
CERC Corp [Member] | Maximum [Member] | Cash and Cash Equivalents [Member] | Postretirement Benefits [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%
CERC Corp [Member] | Common Stock [Member] | CenterPoint Energy [Member]
Savings Plan [Abstract]
Defined Contribution Plan, Maximum Limit Of Account Balance In Company Stock, Percentage		25.00%
Number of Common stock held by the savings plan (in shares)		12,062,915
Percentage of investment in common stocks (in hundredths)		16.00%
[1]	The discount rate assumption was determined by matching the projected cash flows of CenterPoint Energy’s plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years.
[2]	The discount rate assumption was determined by matching the projected cash flows of the plans against a hypothetical yield curve of high-quality corporate bonds represented by a series of annualized individual discount rates from one-half to 99 years.
[3]	Represents investments in common collective trust funds.
[4]	The amounts invested in mutual funds and common collective trust funds were allocated as follows: As of December 31, 2018 2017 Mutual Funds Common Collective Trust Funds Mutual Funds Common Collective Trust FundsInternational equities51% 37% 57% 34%Emerging market equities34% 4% 30% 5%U.S. equities15% 5% 13% 6%Fixed income— 54% — 55%

Stock-Based Incentive Compens_6

Stock-Based Incentive Compensation Plans and Employee Benefit Plans Change in Control Agreements and Other Employee Matters (Details)	12 Months Ended
	Dec. 31, 2018salary_severance_benefits
Concentration Risk [Line Items]
Maximum Number Of Times Annual Salary Included In Severance Benefits	3
Workforce Subject to Collective Bargaining Arrangements Expiring in May 2020 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	18.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in March and May 2021 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	3.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in April 2020 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	6.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in December 2020 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	3.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in June and July 2022 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	5.00%
Workforce Subject to Collective Bargaining Arrangements [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	35.00%
Houston Electric [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in May 2020 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	51.00%
Houston Electric [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in March and May 2021 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.00%
Houston Electric [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in April 2020 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.00%
Houston Electric [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in December 2020 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.00%
Houston Electric [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in June and July 2022 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.00%
Houston Electric [Member] | Workforce Subject to Collective Bargaining Arrangements [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	51.00%
CERC Corp [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in May 2020 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.00%
CERC Corp [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in March and May 2021 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	3.00%
CERC Corp [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in April 2020 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	12.00%
CERC Corp [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in December 2020 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	7.00%
CERC Corp [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring in June and July 2022 [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	11.00%
CERC Corp [Member] | Workforce Subject to Collective Bargaining Arrangements [Member] | Employees Subject To Collective Bargaining Agreements [Member] | Labor Force Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	33.00%

Derivative Instruments Derivati

Derivative Instruments Derivatives and Hedging (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weather hedges term		10 years
Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member]
Recognized gain (loss) on weather hedges	[1]	$ (4)	$ (1)	$ 1
2018 to 2019 [Member] | Natural Gas Distribution [Member]
Weather hedge bilateral cap amount		9
2018 to 2019 [Member] | Electric Transmission & Distribution [Member]
Weather hedge bilateral cap amount		8
2018 to 2019 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Natural Gas Distribution [Member]
Recognized gain (loss) on weather hedges		0	0	0
2018 to 2019 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission & Distribution [Member]
Recognized gain (loss) on weather hedges		0	0	0
2017 to 2018 [Member] | Natural Gas Distribution [Member]
Weather hedge bilateral cap amount		8
2017 to 2018 [Member] | Electric Transmission & Distribution [Member]
Weather hedge bilateral cap amount		9
2017 to 2018 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Natural Gas Distribution [Member]
Recognized gain (loss) on weather hedges		(2)	0	0
2017 to 2018 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission & Distribution [Member]
Recognized gain (loss) on weather hedges		(2)	0	0
2016 to 2017 [Member] | Electric Transmission & Distribution [Member]
Weather hedge bilateral cap amount		9
2016 to 2017 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission & Distribution [Member]
Recognized gain (loss) on weather hedges		$ 0	(1)	1
CERC Corp [Member]
Weather hedges term		10 years
CERC Corp [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member]
Recognized gain (loss) on weather hedges	[1]	$ (2)	0	0
CERC Corp [Member] | 2018 to 2019 [Member] | Natural Gas Distribution [Member]
Weather hedge bilateral cap amount		9
CERC Corp [Member] | 2018 to 2019 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Natural Gas Distribution [Member]
Recognized gain (loss) on weather hedges		0	0	0
CERC Corp [Member] | 2017 to 2018 [Member] | Natural Gas Distribution [Member]
Weather hedge bilateral cap amount		8
CERC Corp [Member] | 2017 to 2018 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Natural Gas Distribution [Member]
Recognized gain (loss) on weather hedges		(2)	0	$ 0
Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Aggregate notional amount		450	0
Cash Flow Hedging [Member] | CERC Corp [Member] | Interest Rate Contract [Member]
Aggregate notional amount		$ 450	$ 0
[1]	Weather hedge gains (losses) are recorded in Revenues in the Statements of Consolidated Income.

Derivative Instruments Summary

Derivative Instruments Summary of Derivative Activity (Details) $ in Millions		12 Months Ended
		Dec. 31, 2018USD ($)Bcf	Dec. 31, 2017USD ($)Bcf		Dec. 31, 2016USD ($)
Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative gross volume notional amount (in Bcf) | Bcf		1,674	1,795
Gross Amounts Recognized	[1]	$ 12	$ 111
Gross Amounts Offset in the Consolidated Balance Sheets		19	19
Net Amount Presented in the Consolidated Balance Sheets	[2]	31	130
Derivative Assets Fair Value		220	218
Derivative Liabilities Fair Value		833	775
Derivative Asset		57	80
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item		1	14
Income Statement Impact of Derivative Activity [Abstract]
Total amounts presented in the statements of income in which the effects of hedges are recorded	[3]	4,364	3,785		$ 1,983
Gain (loss) on derivative instruments not designated as hedging instruments		(123)	260		(431)
Derivative, Credit Risk Related Contingent Features [Abstract]
Aggregate fair value of derivatives containing material adverse change provisions in a net liability position		1	2
Fair value of collateral already posted		0	0
Additional collateral required to be posted if credit risk contingent features triggered		0	2
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[4]	138	154
Energy Marketers [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[4]	24	45
Retail End Users [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[4],[5]	114	109
External Credit Rating, Investment Grade [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[6]	41	23
External Credit Rating, Investment Grade [Member] | Energy Marketers [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[6]	11	6
External Credit Rating, Investment Grade [Member] | Retail End Users [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[5],[6]	30	17
Current Assets [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset	[2]	100	110
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item		1	14
Gross Amounts Recognized	[1]	166	165
Gross Amounts Offset		(66)	(55)
Other Noncurrent Assets [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset	[2]	38	44
Gross Amounts Recognized	[1]	54	53
Gross Amounts Offset		(16)	(9)
Current Liabilities [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Gross Amounts Recognized	[1]	(183)	(83)
Gross Amounts Offset		81	63
Derivative Liability	[2]	(102)	(20)
Other Noncurrent Liabilities [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Gross Amounts Recognized	[1]	(25)	(24)
Gross Amounts Offset		20	20
Derivative Liability	[2]	(5)	(4)
Not Designated as Hedging Instrument [Member] | Current Liabilities [Member] | IDS Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Assets Fair Value		0	0
Derivative Liabilities Fair Value		$ 601	$ 668
Long [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative gross volume notional amount (in Bcf) | Bcf		140	224
Houston Electric [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Assets Fair Value		$ 0	$ 0
Derivative Liabilities Fair Value		$ 24	$ 0
CERC Corp [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative gross volume notional amount (in Bcf) | Bcf		1,674	1,795
Gross Amounts Recognized	[1]	$ 12	$ 111
Gross Amounts Offset in the Consolidated Balance Sheets		19	19
Net Amount Presented in the Consolidated Balance Sheets	[2]	31	130
CERC Corp [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Assets Fair Value		220	218
Derivative Liabilities Fair Value		208	107
Derivative Asset		57	80
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item		1	14
Income Statement Impact of Derivative Activity [Abstract]
Total amounts presented in the statements of income in which the effects of hedges are recorded		4,364	3,785		1,983
Gain (loss) on derivative instruments not designated as hedging instruments		107	211		(18)
Derivative, Credit Risk Related Contingent Features [Abstract]
Aggregate fair value of derivatives containing material adverse change provisions in a net liability position		1	2
Fair value of collateral already posted		0	0
Additional collateral required to be posted if credit risk contingent features triggered		0	2
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[4]	138	154
CERC Corp [Member] | Energy Marketers [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[4]	24	45
CERC Corp [Member] | Retail End Users [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[4],[5]	114	109
CERC Corp [Member] | External Credit Rating, Investment Grade [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[6]	41	23
CERC Corp [Member] | External Credit Rating, Investment Grade [Member] | Energy Marketers [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties		11	6	[6]
CERC Corp [Member] | External Credit Rating, Investment Grade [Member] | Retail End Users [Member]
Credit Risk Derivatives, at Fair Value, Net [Abstract]
Total credit risk of counterparties	[5]	30	17	[6]
CERC Corp [Member] | Current Assets [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset	[2]	100	110
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Item		1	14
Gross Amounts Recognized	[1]	166	165
Gross Amounts Offset		(66)	(55)
CERC Corp [Member] | Other Noncurrent Assets [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset	[2]	38	44
Gross Amounts Recognized	[1]	54	53
Gross Amounts Offset		(16)	(9)
CERC Corp [Member] | Current Liabilities [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Gross Amounts Recognized	[1]	(183)	(83)
Gross Amounts Offset		81	63
Derivative Liability	[2]	(102)	(20)
CERC Corp [Member] | Other Noncurrent Liabilities [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Gross Amounts Recognized	[1]	(25)	(24)
Gross Amounts Offset		20	20
Derivative Liability	[2]	(5)	(4)
CERC Corp [Member] | Not Designated as Hedging Instrument [Member] | Current Assets [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Assets Fair Value	[7],[8],[9]	103	114
Derivative Liabilities Fair Value	[7],[8],[9]	3	4
CERC Corp [Member] | Not Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Assets Fair Value	[7],[8],[9]	38	44
Derivative Liabilities Fair Value	[7],[8],[9]	0	0
CERC Corp [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Assets Fair Value	[7],[8],[9]	62	38
Derivative Liabilities Fair Value	[7],[8],[9]	173	78
CERC Corp [Member] | Not Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Assets Fair Value	[7],[8],[9]	16	9
Derivative Liabilities Fair Value	[7],[8],[9]	$ 25	$ 24
CERC Corp [Member] | Long [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative gross volume notional amount (in Bcf) | Bcf		140	224
Cash Flow Hedging [Member] | Houston Electric [Member] | Designated as Hedging Instrument [Member] | Current Liabilities [Member] | Interest Rate Contract [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Assets Fair Value		$ 0	$ 0
Derivative Liabilities Fair Value		24	0
Fair Value Hedging [Member] | Current Assets [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset		57	80
Fair Value Hedging [Member] | CERC Corp [Member] | Current Assets [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Asset		57	80
Fair Value Hedging [Member] | CERC Corp [Member] | Designated as Hedging Instrument [Member] | Current Liabilities [Member] | Energy Related Derivative [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Derivative Assets Fair Value	[7],[8],[9]	1	13
Derivative Liabilities Fair Value	[7],[8],[9]	7	1
Gains (Losses) in Revenue [Member] | CERC Corp [Member] | Energy Related Derivative [Member]
Income Statement Impact of Derivative Activity [Abstract]
Gain (loss) on derivative instruments not designated as hedging instruments		107	211		(18)
Natural Gas Expenses [Member] | Fair Value Hedging [Member] | Energy Related Derivative [Member]
Income Statement Impact of Derivative Activity [Abstract]
Change in unrealized gain (loss) on fair value hedging instruments	[3]	(13)	14		0
Amounts excluded from effectiveness testing recognized in earnings immediately (1)	[3],[10]	(149)	(67)		70
Natural Gas Expenses [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member]
Income Statement Impact of Derivative Activity [Abstract]
Change in unrealized gain (loss) on fair value hedging instruments	[3]	13	(14)		0
Natural Gas Expenses [Member] | Fair Value Hedging [Member] | CERC Corp [Member] | Energy Related Derivative [Member]
Income Statement Impact of Derivative Activity [Abstract]
Change in unrealized gain (loss) on fair value hedging instruments	[3]	(13)	14		0
Amounts excluded from effectiveness testing recognized in earnings immediately (1)	[3],[10]	(149)	(67)		70
Natural Gas Expenses [Member] | Fair Value Hedging [Member] | CERC Corp [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member]
Income Statement Impact of Derivative Activity [Abstract]
Change in unrealized gain (loss) on fair value hedging instruments	[3]	13	(14)		0
Gains (Losses) in Other Income (Expense) [Member] | Interest Rate Contract [Member]
Income Statement Impact of Derivative Activity [Abstract]
Gain (loss) on derivative instruments not designated as hedging instruments		2	0		0
Gains (Losses) in Other Income (Expense) [Member] | IDS Derivative [Member]
Income Statement Impact of Derivative Activity [Abstract]
Gain (loss) on derivative instruments not designated as hedging instruments		$ (232)	$ 49		$ (413)
[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 Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
[3]	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 the years ended December 31, 2018, 2017 and 2016, respectively.
[4]	The amounts reflected in the table above were not impacted by collateral netting.
[5]	End users are comprised primarily of customers who have contracted to fix the price of a portion of their physical gas requirements for future periods.
[6]	“Investment grade” is primarily determined using publicly available credit ratings and considers credit support (including parent company guarantees) and collateral (including cash and standby letters of credit). For unrated counterparties, CenterPoint Energy and CERC determine a synthetic credit rating by performing financial statement analysis and consider contractual rights and restrictions and collateral.
[7]	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
[8]	Natural gas contracts are presented on a net basis in the 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 Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities is detailed in the Offsetting of Natural Gas Derivative Assets and Liabilities table below
[9]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,674 Bcf or a net 140 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of December 31, 2018 and 2017, respectively. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure.
[10]	Upon adoption of ASU 2017-12 effective January 1, 2018 (see Note 2 for additional information), CenterPoint Energy and CERC elected to 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 Statements of Consolidated Income.

Fair Value Measurements (Detail

Fair Value Measurements (Details) $ in Millions		12 Months Ended
		Dec. 31, 2018USD ($)		Dec. 31, 2017USD ($)		Dec. 31, 2016USD ($)
Assets
Natural gas derivatives (3)(4)		$ 57		$ 80
Total derivative assets, netting adjustment	[1]	(82)		(64)
Total assets		747		1,199
Liabilities
Total derivative liabilities, netting adjustment	[1]	(101)		(83)
Total liabilities		732		692
Fair value measurement using significant unobservable input (level 3) reconciliation [Roll Forward]
Beginning balance		(622)	[2]	(704)	[2]	$ 12
Purchases (1)	[3]	0		0		12
Total gains (losses)		30		96		12
Total settlements		(39)		(11)		(27)
Transfers into Level 3 (2)	[4]	5		14		(712)
Transfers out of Level 3 (3)	[5]	656		(17)		(1)
Ending balance (4)	[2]	30		(622)		(704)
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date (3)		$ 18		87		(402)
Atmos Energy Marketing [Member]
Fair value measurement using significant unobservable input (level 3) reconciliation [Roll Forward]
Mark-to-market value of Level 3 derivative assets acquired		less than $1 million
Carrying amount [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[6]	$ 9,140		8,679
Fair value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[6]	9,308		9,220
Natural gas [Member]
Liabilities
Derivative fair value offsets, net		19		19
Fair Value, Inputs, Level 1 [Member]
Assets
Total assets	[7]	609		1,045
Liabilities
Total liabilities	[7]	24		0
Fair Value, Inputs, Level 2 [Member]
Assets
Total assets		173		161
Liabilities
Total liabilities		792		96
Fair Value, Inputs, Level 3 [Member]
Assets
Total assets		47		57
Liabilities
Total liabilities		$ 17		679
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Minimum [Member]
Fair Value, assets and liabilities measured on recurring basis, financial statement captions
Fair value inputs (price per MMBtu)		1.39
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Maximum [Member]
Fair Value, assets and liabilities measured on recurring basis, financial statement captions
Fair value inputs (price per MMBtu)		5.96
Fair Value, Measurements, Recurring [Member]
Assets
Corporate equities		$ 542		963
Investments, including money market funds (2)	[8]	66		68
Hedged portion of natural gas inventory		1		14
Fair Value, Measurements, Recurring [Member] | Natural gas [Member]
Assets
Natural gas derivative netting adjustment	[1],[9]	(82)		(64)
Natural gas derivatives (3)(4)	[9]	138		154
Liabilities
Derivative liabilities, netting adjustment	[1],[9]	(101)		(83)
Derivative liabilities	[9]	107		24
Fair Value, Measurements, Recurring [Member] | IDS Derivative [Member]
Liabilities
Derivative liabilities, netting adjustment	[1]	0		0
Derivative liabilities		601		668
Fair Value, Measurements, Recurring [Member] | Interest Rate Contract [Member]
Liabilities
Derivative liabilities		24		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Corporate equities	[7]	542		963
Investments, including money market funds (2)	[7],[8]	66		68
Hedged portion of natural gas inventory	[7]	1		14
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Natural gas [Member]
Assets
Natural gas derivatives (3)(4)	[7],[9]	0		0
Liabilities
Derivative liabilities	[7],[9]	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | IDS Derivative [Member]
Liabilities
Derivative liabilities	[7]	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Contract [Member]
Liabilities
Derivative liabilities	[7]	24		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Corporate equities		0		0
Investments, including money market funds (2)	[8]	0		0
Hedged portion of natural gas inventory		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Natural gas [Member]
Assets
Natural gas derivatives (3)(4)	[9]	173		161
Liabilities
Derivative liabilities	[9]	191		96
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | IDS Derivative [Member]
Liabilities
Derivative liabilities		601		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Contract [Member]
Liabilities
Derivative liabilities		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Corporate equities		0		0
Investments, including money market funds (2)	[8]	0		0
Hedged portion of natural gas inventory		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Natural gas [Member]
Assets
Natural gas derivatives (3)(4)	[9]	47		57
Liabilities
Derivative liabilities	[9]	17		11
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | IDS Derivative [Member]
Liabilities
Derivative liabilities		0		668
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Contract [Member]
Liabilities
Derivative liabilities		0		0
Houston Electric [Member]
Assets
Total derivative assets, netting adjustment		0		0
Total assets		48		51
Liabilities
Total derivative liabilities, netting adjustment		0		0
Total liabilities		24		0
Houston Electric [Member] | Carrying amount [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[6]	4,717		4,753
Houston Electric [Member] | Fair value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[6]	4,770		5,034
Houston Electric [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Total assets		48		51
Liabilities
Total liabilities		24		0
Houston Electric [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Total assets		0		0
Liabilities
Total liabilities		0		0
Houston Electric [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Total assets		0		0
Liabilities
Total liabilities		0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Investments, including money market funds (2)	[8]	48		51
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Contract [Member]
Liabilities
Derivative liabilities		24		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Investments, including money market funds (2)	[8]	48		51
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Contract [Member]
Liabilities
Derivative liabilities		24		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Investments, including money market funds (2)	[8]	0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Contract [Member]
Liabilities
Derivative liabilities		0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Investments, including money market funds (2)	[8]	0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Contract [Member]
Liabilities
Derivative liabilities		0		0
CERC Corp [Member]
Assets
Natural gas derivatives (3)(4)		57		80
Total derivative assets, netting adjustment	[1]	(82)		(64)
Total assets		152		182
Liabilities
Total derivative liabilities, netting adjustment	[1]	(101)		(83)
Total liabilities		107		24
Fair value measurement using significant unobservable input (level 3) reconciliation [Roll Forward]
Beginning balance		46	[2]	13	[2]	12
Purchases (1)	[3]	0		0		12
Total gains (losses)		30		47		12
Total settlements		(39)		(11)		(27)
Transfers into Level 3 (2)	[4]	5		14		5
Transfers out of Level 3 (3)	[5]	(12)		(17)		(1)
Ending balance (4)	[2]	30		46		13
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date (3)		18		38		$ 11
CERC Corp [Member] | Carrying amount [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities		2,371		2,457
CERC Corp [Member] | Fair value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities		2,488		2,708
CERC Corp [Member] | Natural gas [Member]
Liabilities
Derivative fair value offsets, net		19		19
CERC Corp [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Total assets	[7]	14		28
Liabilities
Total liabilities	[7]	0		0
CERC Corp [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Total assets		173		161
Liabilities
Total liabilities		191		96
CERC Corp [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Total assets		47		57
Liabilities
Total liabilities		$ 17		11
CERC Corp [Member] | Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Minimum [Member]
Fair Value, assets and liabilities measured on recurring basis, financial statement captions
Fair value inputs (price per MMBtu)		1.39
CERC Corp [Member] | Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Maximum [Member]
Fair Value, assets and liabilities measured on recurring basis, financial statement captions
Fair value inputs (price per MMBtu)		5.96
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Corporate equities		$ 2		3
Investments, including money market funds (2)	[8]	11		11
Hedged portion of natural gas inventory		1		14
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Natural gas [Member]
Assets
Natural gas derivative netting adjustment	[1],[9]	(82)		(64)
Natural gas derivatives (3)(4)	[9]	138		154
Liabilities
Derivative liabilities, netting adjustment	[1],[9]	(101)		(83)
Derivative liabilities	[9]	107		24
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Corporate equities	[7]	2		3
Investments, including money market funds (2)	[7],[8]	11		11
Hedged portion of natural gas inventory	[7]	1		14
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Natural gas [Member]
Assets
Natural gas derivatives (3)(4)	[7],[9]	0		0
Liabilities
Derivative liabilities	[7],[9]	0		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Corporate equities		0		0
Investments, including money market funds (2)	[8]	0		0
Hedged portion of natural gas inventory		0		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Natural gas [Member]
Assets
Natural gas derivatives (3)(4)	[9]	173		161
Liabilities
Derivative liabilities	[9]	191		96
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Corporate equities		0		0
Investments, including money market funds (2)	[8]	0		0
Hedged portion of natural gas inventory		0		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Natural gas [Member]
Assets
Natural gas derivatives (3)(4)	[9]	47		57
Liabilities
Derivative liabilities	[9]	$ 17		$ 11
[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 $19 million as of both December 31, 2018 and 2017, respectively, posted with the same counterparties.
[2]	CenterPoint Energy and CERC did not have significant Level 3 sales during any of the years ended December 31, 2018, 2017 or 2016.
[3]	Mark-to-market value of Level 3 derivative assets acquired through the purchase of AEM were less than $1 million at the acquisition date.
[4]	During 2016, CenterPoint Energy transferred its indexed debt securities from Level 2 to Level 3 to reflect changes in the significance of the unobservable inputs used in the valuation.
[5]	During 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.
[6]	Includes Securitization Bond debt.
[7]	Level 1 natural gas derivatives include exchange-traded derivatives cleared by the CME, which deems that financial instruments cleared by the CME are settled daily in connection with posted cash payments. As a result of this exchange rule, CME-related derivatives are considered to have no fair value at the balance sheet date for financial reporting purposes, and are presented in Level 1 net of posted cash; however, the derivatives remain outstanding and subject to future commodity price fluctuations until they are settled in accordance with their contractual terms. Derivative transactions cleared on exchanges other than the CME (e.g., the Intercontinental Exchange or ICE) continue to be reported on a gross basis.
[8]	Amounts are included in Prepaid and Other Current Assets and Other Assets in the Consolidated Balance Sheets.
[9]	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	12 Months Ended
		Dec. 31, 2018		Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016		Sep. 04, 2018
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					$ 333	333		$ 319
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
CenterPoint Energy’s equity in earnings, net					307	265		208
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s equity method investment in Enable		2,482			2,482	2,472
CERC Corp [Member]
Investment in unconsolidated affiliates - discontinued operations		0			0	2,472
Deferred income taxes, net - discontinued operations		$ 0			0	927
Contribution from parent					960	38		72
Enable Distributions [Abstract]
Total distributions received from Enable					223	297		297
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Income tax expense					46	104		81
Income (loss) from discontinued operations, net of tax					$ 138	$ 161		127
Enable Midstream Partners [Member]
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Basis difference amortization period					30 years
OGE [Member]
Enable Units [Abstract]
Percentage of sales that trigger right of first refusal					5.00%
Enable Midstream Partners [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[1],[2]	54.00%			54.00%	54.10%
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Operating revenues					$ 3,431	$ 2,803		2,272
Cost of sales, excluding depreciation and amortization					1,819	1,381		1,017
Depreciation and amortization					398	366		338
Operating income					648	528		385
Net income attributable to Enable common units					485	400		290
CenterPoint Energy’s interest					262	216		160
Basis difference amortization (1)	[3]				47	49		48
Loss on dilution, net of proportional basis difference recognition					(2)	0		0
CenterPoint Energy’s equity in earnings, net	[4]				307	265		$ 208
Equity Method Investment, Summarized Financial Information [Abstract]
Current assets		$ 449			449	416
Non-current assets		11,995			11,995	11,177
Current liabilities		1,615			1,615	1,279
Non-current liabilities		3,211			3,211	2,660
Non-controlling interest		38			38	12
Preferred equity		362			362	362
Enable partners’ equity		7,218			7,218	7,280
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s ownership interest in Enable partners’ equity		3,896			3,896	3,935
CenterPoint Energy’s basis difference		(1,414)			(1,414)	(1,463)
CenterPoint Energy’s equity method investment in Enable		$ 2,482			$ 2,482	$ 2,472
Enable Midstream Partners [Member] | Common Units [Member]
Enable Distributions [Abstract]
Distribution per share of common units	[5]	$ 0.3180		$ 0.9540		$ 1.2720		$ 1.2720
Distributions received from equity method investment		$ 74	[5]	$ 223		$ 297		$ 297
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Enable Distributions [Abstract]
Distribution per share of Series A preferred units	[6]				$ 2.5000	$ 2.5000		$ 1.5417
Distributions received from Enable cost method investment	[6]				$ 36	$ 36		$ 22
Enable Midstream Partners [Member] | CERC Corp [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[1],[2]					54.10%
Enable Midstream Partners [Member] | CERC Corp [Member] | Common Units [Member]
Enable Distributions [Abstract]
Distribution per share of common units				$ 0.9540		$ 1.2720		$ 1.2720
Distributions received from equity method investment	[5]				$ 223	$ 297		$ 297
Common Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Limited partner interest units held	[2]	233,856,623			233,856,623	233,856,623
Common Units [Member] | Enable Midstream Partners [Member] | CERC Corp [Member]
Enable Units [Abstract]
Limited partner interest units held	[2]					233,856,623
Series A Preferred Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Preferred units held	[2],[7]	14,520,000			14,520,000	14,520,000
Enable Internal Spin [Member] | CERC Corp [Member]
Contribution from parent					$ 600
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Transaction with Enable [Abstract]
Natural gas expenses, including transportation and storage costs					122	$ 115		110
Accounts payable for natural gas purchases from Enable		$ 11			11	13
Natural Gas Expenses [Member] | Enable Midstream Partners [Member] | CERC Corp [Member]
Transaction with Enable [Abstract]
Natural gas expenses, including transportation and storage costs						115		110
Accounts payable for natural gas purchases from Enable						13
Transitional Service [Member] | Enable Midstream Partners [Member]
Transaction with Enable [Abstract]
Reimbursement of transition services (1)	[4]				4	4		7
Accounts receivable for amounts billed for transition services		$ 2			$ 2	$ 1
Enable Midstream Partners [Member]
Enable Units [Abstract]
Maximum incentive distribution right					50.00%
Enable Midstream Partners [Member] | OGE [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[1]				25.60%	25.70%
Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[1]				20.40%	20.20%
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] | OGE [Member]
Enable Units [Abstract]
Limited partner interest units held		110,982,805			110,982,805	110,982,805
Enable Midstream Partners [Member] | Common Units [Member] | Public unitholders [Member]
Enable Units [Abstract]
Limited partner interest units held		88,392,983			88,392,983	87,744,652
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] | Enable Midstream Partners [Member] | CERC Corp [Member]
Investment in unconsolidated affiliates - discontinued operations						$ 2,472	[8]	2,505	[8]	$ 2,400
Deferred income taxes, net - discontinued operations										$ 974
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Equity in earnings of unconsolidated affiliate, net					$ 184	265		208
Income tax expense					46	104		81
Income (loss) from discontinued operations, net of tax					$ 138	$ 161		$ 127
Enable GP, LLC [Member]
Enable Units [Abstract]
Management rights ownership percentage					50.00%
Incentive distribution right					40.00%
Enable GP, LLC [Member] | CERC Corp [Member]
Enable Units [Abstract]
Management rights ownership percentage	[9],[10]					50.00%
Incentive distribution right	[10],[11]					40.00%
Enable GP, LLC [Member] | CenterPoint Energy [Member]
Enable Units [Abstract]
Management rights ownership percentage	[9],[10]				50.00%	50.00%
Incentive distribution right	[10],[11]				40.00%	40.00%
Enable GP, LLC [Member] | OGE [Member]
Enable Units [Abstract]
Management rights ownership percentage	[9]				50.00%	50.00%
Incentive distribution right	[11]				60.00%	60.00%
[1]	Excludes the Enable Series A Preferred Units owned by CenterPoint Energy.
[2]	Prior to the Internal Spin on September 4, 2018 described above, CenterPoint Energy’s investment in Enable’s common units, excluding the Enable Series A Preferred Units held directly by CenterPoint Energy, was held indirectly through CERC.
[3]	Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s share of Enable earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s original investment in Enable and its underlying equity in net assets of Enable. The basis difference is being amortized over approximately 30 years, the remaining average life of the assets to which the basis difference is attributed.
[4]	Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement.
[5]	Reflects CERC’s ownership of Enable common units up to September 4, 2018 when CERC completed the Internal Spin. After such date, distributions from Enable were received directly by CenterPoint Energy.
[6]	2016 amounts represent the period from February 18, 2016 to December 31, 2016.
[7]	The carrying amount of the Enable Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Consolidated Balance Sheets, was $363 million as of both December 31, 2018 and 2017. No impairment charges or adjustment to carrying value were made as no observable price changes were identified in the current or prior reporting periods. See Note 2(r) for further discussion.
[8]	On September 4, 2018, CERC completed the Internal Spin. For further information regarding the Internal Spin, see Note 11.
[9]	As of December 31, 2018, 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]	CenterPoint Energy held the management rights and incentive distributions rights in Enable GP indirectly through CERC until the Internal Spin on September 4, 2018 described above.
[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.

Indexed Debt Securities (ZENS_3

Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) (Details)	12 Months Ended
	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)	Jun. 14, 2018$ / sharesshares	Jan. 31, 2018$ / shares	Nov. 26, 2017$ / shares
ZENS-Related Securities
ZENS-Related Securities	$ 960,000,000
Proceeds from sale and maturity of marketable securities	(398,000,000)	$ 0	$ (178,000,000)
Gain (loss) on ZENS-Related Securities	(22,000,000)	7,000,000	326,000,000
ZENS-Related Securities	540,000,000	960,000,000
Debt component of ZENS
Debt Component of ZENS	122,000,000
Distribution to ZENS holders	398,000,000	0	178,000,000
Debt Component of ZENS	24,000,000	122,000,000
Derivative component of ZENS
Derivative Component of ZENS	668,000,000
Distribution to ZENS holders	398,000,000	0	178,000,000
Loss (gain) on indexed debt securities	232,000,000	(49,000,000)	413,000,000
Derivative Component of ZENS	$ 601,000,000	$ 668,000,000
AT&T Common [Member]
Indexed Debt Securities [Line Items]
Balance of investment owned (in shares) | shares	10,212,945
Charter Common [Member]
Indexed Debt Securities [Line Items]
Balance of investment owned (in shares) | shares	872,912	872,503
Time Common [Member]
Indexed Debt Securities [Line Items]
Balance of investment owned (in shares) | shares		888,392
ZENS early exchange ratio					100.00%
TW Common [Member]
Indexed Debt Securities [Line Items]
Balance of investment owned (in shares) | shares		7,107,130
ZENS-Related Securities [Member]
ZENS-Related Securities
ZENS-Related Securities	$ 960,000,000	$ 953,000,000	805,000,000
Proceeds from sale and maturity of marketable securities	(398,000,000)		(178,000,000)
Gain (loss) on ZENS-Related Securities	(22,000,000)	7,000,000	326,000,000
ZENS-Related Securities	540,000,000	960,000,000	953,000,000
Debt Component Of ZENS [Member]
Debt component of ZENS
Debt Component of ZENS	122,000,000	114,000,000	145,000,000
Accretion of debt component of ZENS	21,000,000	27,000,000	26,000,000
2 % interest paid	(17,000,000)	(17,000,000)	(17,000,000)
Distribution to ZENS holders	102,000,000	2,000,000	40,000,000
Debt Component of ZENS	24,000,000	122,000,000	114,000,000
Derivative component of ZENS
Distribution to ZENS holders	102,000,000	2,000,000	40,000,000
Derivative Component Of ZENS [Member]
Debt component of ZENS
Distribution to ZENS holders	46,000,000	0	21,000,000
Derivative component of ZENS
Derivative Component of ZENS	668,000,000	717,000,000	442,000,000
Distribution to ZENS holders	46,000,000	0	21,000,000
Loss (gain) on indexed debt securities	(21,000,000)	(49,000,000)	296,000,000
Derivative Component of ZENS	601,000,000	$ 668,000,000	$ 717,000,000
Subordinated Debt ZENS Member
Indexed Debt Securities [Line Items]
Principal amount of debt issued	1,000,000,000
Outstanding debt balance	$ 828,000,000
Subordinated note cash exchangeable percentage of fair value	95.00%
ZENS annual interest rate	2.00%
Target annual yield on referenced shares before increase or decrease of principal amount of subordinated note	2.309%
Contingent principal amount of indexed debt securities issued by CenterPoint Energy in September 1999 and outstanding and exchangeable	$ 93,000,000
The cash exchange amount from referenced shares per $1,000 face amount of individual notes	620
Face amount of each indexed debt security notes issued by CenterPoint Energy in September 1999	$ 1,000
Subordinated Debt ZENS Member | AT&T Common [Member]
Indexed Debt Securities [Line Items]
Number of shares referenced in exchangeable subordinated note | shares	0.7185
Subordinated Debt ZENS Member | Charter Common [Member]
Indexed Debt Securities [Line Items]
Number of shares referenced in exchangeable subordinated note | shares	0.061382	0.061382
Subordinated Debt ZENS Member | Time Common [Member]
Indexed Debt Securities [Line Items]
Number of shares referenced in exchangeable subordinated note | shares		0.0625
Subordinated Debt ZENS Member | TW Common [Member]
Indexed Debt Securities [Line Items]
Number of shares referenced in exchangeable subordinated note | shares		0.5
AT&T To Acquire Time Warner [Member]
Indexed Debt Securities [Line Items]
Indexed debt – reduction	$ (95,000,000)
Indexed debt securities derivative – reduction	(45,000,000)
Loss on indexed debt securities	242,000,000
Debt component of ZENS
Distribution to ZENS holders	382,000,000
Derivative component of ZENS
Distribution to ZENS holders	382,000,000
AT&T To Acquire Time Warner [Member] | AT&T Common [Member]
Indexed Debt Securities [Line Items]
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	382,000,000
Total AT&T shares received in exchange for TW Common shares held | shares				10,212,945
Meredith to acquire time [Member]
Indexed Debt Securities [Line Items]
Indexed debt – reduction	(4,000,000)
Indexed debt securities derivative – reduction	(1,000,000)
Loss on indexed debt securities	11,000,000
Debt component of ZENS
Distribution to ZENS holders	16,000,000
Derivative component of ZENS
Distribution to ZENS holders	16,000,000
Meredith to acquire time [Member] | Time Common [Member]
Indexed Debt Securities [Line Items]
Cash paid per share exchanged | $ / shares					$ 18.50	$ 18.50
Cash proceeds received for shares exchanged	$ 16,000,000

Equity (CenterPoint Energy) (De

Equity (CenterPoint Energy) (Details)		Dec. 12, 2018USD ($)$ / shares	Oct. 23, 2018USD ($)$ / shares	Oct. 01, 2018USD ($)$ / sharesshares	Aug. 22, 2018USD ($)$ / sharesshares	Jul. 26, 2018USD ($)$ / shares	Apr. 26, 2018USD ($)$ / shares	Dec. 13, 2017USD ($)$ / shares	Oct. 25, 2017USD ($)$ / shares	Jul. 27, 2017USD ($)$ / shares	Apr. 27, 2017USD ($)$ / shares	Jan. 05, 2017USD ($)$ / shares	Oct. 27, 2016USD ($)$ / shares	Jul. 28, 2016USD ($)$ / shares	Apr. 28, 2016USD ($)$ / shares	Jan. 20, 2016USD ($)$ / shares	Dec. 31, 2018USD ($)day$ / sharesshares	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016USD ($)$ / shares
Dividends declared per share | $ / shares																	$ 1.12	$ 1.3475	$ 1.03
Preferred stock dividend requirement																	$ 35,000,000	$ 0	$ 0
Preferred stock par value (in dollars per share) | $ / shares																	$ 0.01	$ 0.01	$ 0.01
Proceeds from the issuance of Series A Preferred Stock, net					$ 790,000,000												$ 1,740,000,000	$ 0	$ 0
Proceeds from issuance of common stock																	1,844,000,000	0	0
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance																	(68,000,000)	(71,000,000)
Prior service cost (2)	[1]																1,000,000	1,000,000
Actuarial losses (2)	[1]																6,000,000	7,000,000
Tax benefit (expense)																	6,000,000	(4,000,000)
Net current period other comprehensive income (loss)																	(25,000,000)	3,000,000	(5,000,000)
Ending Balance																	(108,000,000)	(68,000,000)	$ (71,000,000)
Enable Midstream Partners [Member]
Undistributed earnings from equity method investments included in retained earnings																	$ 31,000,000	$ 0
Common Stock [Member]
Declaration Date		Dec. 12, 2018	Oct. 23, 2018			Jul. 26, 2018	Apr. 26, 2018	Dec. 13, 2017	Oct. 25, 2017	Jul. 27, 2017	Apr. 27, 2017	Jan. 5, 2017	Oct. 27, 2016	Jul. 28, 2016	Apr. 28, 2016	Jan. 20, 2016
Record Date		Feb. 21, 2019	Nov. 15, 2018			Aug. 16, 2018	May 17, 2018	Feb. 15, 2018	Nov. 16, 2017	Aug. 16, 2017	May 16, 2017	Feb. 16, 2017	Nov. 16, 2016	Aug. 16, 2016	May 16, 2016	Feb. 16, 2016
Payment Date		Mar. 14, 2019	Dec. 13, 2018			Sep. 13, 2018	Jun. 14, 2018	Mar. 8, 2018	Dec. 8, 2017	Sep. 8, 2017	Jun. 9, 2017	Mar. 10, 2017	Dec. 9, 2016	Sep. 9, 2016	Jun. 10, 2016	Mar. 10, 2016
Dividends declared per share | $ / shares		$ 0.2875	$ 0.2775			$ 0.2775	$ 0.2775	$ 0.2775	$ 0.2675	$ 0.2675	$ 0.2675	$ 0.2675	$ 0.2575	$ 0.2575	$ 0.2575	$ 0.2575	$ 1.1200	$ 1.3475	$ 1.0300
Dividends declared		$ 144,000,000	$ 139,000,000			$ 120,000,000	$ 120,000,000	$ 120,000,000	$ 116,000,000	$ 115,000,000	$ 115,000,000	$ 115,000,000	$ 111,000,000	$ 111,000,000	$ 111,000,000	$ 110,000,000	$ 523,000,000	$ 581,000,000	$ 443,000,000
Stock issued (in shares) | shares				69,633,027
Common stock issued per share price | $ / shares				$ 27.25
Proceeds from issuance of common stock				$ 1,844,000,000
Series A Preferred Stock [Member]
Declaration Date		Dec. 12, 2018
Record Date		Feb. 15, 2019
Payment Date		Mar. 1, 2019
Dividends declared per share | $ / shares		$ 32.1563															$ 32.1563	$ 0	$ 0
Dividends declared		$ 26,000,000															$ 26,000,000
Preferred stock dividend requirement																	$ 18,000,000	$ 0	$ 0
Stock issued (in shares) | shares					800,000
Preferred stock par value (in dollars per share) | $ / shares					$ 1,000												$ 0.01	$ 0
Preferred stock liquidation preference																	$ 800,000,000	$ 0
Preferred stock liquidation preference (per share) | $ / shares																	$ 1,000
Preferred stock dividend rate																	6.125%
Preferred stock redemption price (per share) | $ / shares																	$ 1,000
Preferred stock convertible threshold (in days) | day																	120
Series B Preferred Stock [Member]
Declaration Date		Dec. 12, 2018	Oct. 23, 2018
Record Date		Feb. 15, 2019	Nov. 15, 2018
Payment Date		Mar. 1, 2019	Dec. 1, 2018
Dividends declared per share | $ / shares		$ 17.5000	$ 11.6667														$ 29.1667	$ 0	$ 0
Dividends declared		$ 17,000,000	$ 11,000,000														$ 28,000,000
Preferred stock dividend requirement																	$ 17,000,000	$ 0	$ 0
Preferred stock par value (in dollars per share) | $ / shares																	$ 0.01	$ 0
Preferred stock liquidation preference																	$ 977,500,000	$ 0
Preferred stock liquidation preference (per share) | $ / shares																	$ 1,000
Preferred stock dividend rate																	7.00%
Proceeds from the issuance of Series B Preferred Stock, net				$ 950,000,000
Depositary Share, Conversion Ratio																	0.05
Preferred Stock, Convertible, Conversion Price | $ / shares																	$ 1,000
Preferred stock threshold consecutive calendar days | day																	20
Depositary Share [Member]
Stock issued (in shares) | shares				19,550,000
Depositary share par value (in dollars per depositary share) | $ / shares				$ 50													$ 50
Number of depositary shares eligible for conversion (in shares) | shares																	20
120 Days After Conclusion of Review or Appeal [Member] | Series A Preferred Stock [Member]
Preferred stock redemption price (per share) | $ / shares																	$ 1,020
Preferred stock redemption percentage liquidation value																	102.00%
London Interbank Offered Rate (LIBOR) [Member] | Series A Preferred Stock [Member]
Preferred stock dividend rate																	3.27%
Over-Allotment Option [Member] | Common Stock [Member]
Stock issued (in shares) | shares				9,082,568
Over-Allotment Option [Member] | Series B [Member]
Stock issued (in shares) | shares				2,550,000
Minimum [Member] | Series B Preferred Stock [Member]
Preferred Stock, Convertible, Stock Price Trigger | $ / shares																	$ 27.2494
Conversion rate per share | shares																	30.5820
Minimum [Member] | Series B [Member]
Preferred Stock, Convertible, Stock Price Trigger | $ / shares																	$ 27.2494
Minimum [Member] | Depositary Share [Member]
Conversion rate per share | shares																	1.5291
Maximum [Member] | Series B Preferred Stock [Member]
Preferred Stock, Convertible, Stock Price Trigger | $ / shares																	$ 32.6990
Conversion rate per share | shares																	36.6980
Maximum [Member] | Series B [Member]
Preferred Stock, Convertible, Stock Price Trigger | $ / shares																	$ 32.6990
Maximum [Member] | Depositary Share [Member]
Conversion rate per share | shares																	1.8349
Interest Rate Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications:	[2]																$ (19,000,000)	(5,000,000)
Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Gain (loss) reclassified from accumulated OCI into income																	1,000,000	1,000,000
Houston Electric [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance																	0	1,000,000
Prior service cost (2)	[1]																0	0
Actuarial losses (2)	[1]																0	0
Tax benefit (expense)																	4,000,000	0
Net current period other comprehensive income (loss)																	(14,000,000)	(1,000,000)	1,000,000
Ending Balance																	(14,000,000)	0	1,000,000
Houston Electric [Member] | Interest Rate Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications:	[2]																(18,000,000)	(1,000,000)
Houston Electric [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Gain (loss) reclassified from accumulated OCI into income																	1,000,000	1,000,000
CERC Corp [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance																	6,000,000	3,000,000
Prior service cost (2)	[1]																1,000,000	1,000,000
Actuarial losses (2)	[1]																0	0
Tax benefit (expense)																	(1,000,000)	(3,000,000)
Net current period other comprehensive income (loss)																	0	3,000,000	(6,000,000)
Ending Balance																	5,000,000	6,000,000	$ 3,000,000
CERC Corp [Member] | Interest Rate Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications:	[2]																(1,000,000)	(2,000,000)
CERC Corp [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Gain (loss) reclassified from accumulated OCI into income																	1,000,000	1,000,000
Pension and Other Postretirement Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications:																	(19,000,000)	4,000,000
Pension and Other Postretirement Plans [Member] | Houston Electric [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications:																	0	0
Pension and Other Postretirement Plans [Member] | CERC Corp [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications:																	1,000,000	7,000,000
Adoption of ASU 2018-02 [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Adoption of ASU 2018-02																	(15,000,000)	0
Adoption of ASU 2018-02 [Member] | Houston Electric [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Adoption of ASU 2018-02																	0	0
Adoption of ASU 2018-02 [Member] | CERC Corp [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Adoption of ASU 2018-02																	$ (1,000,000)	$ 0
[1]	Amounts are included in the computation of net periodic cost and are reflected in Other, net in each of the Registrants’ respective Statements of Consolidated Income.
[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 each of the Registrant’s respective Statements of Consolidated Income. Amounts are less than $1 million for each of the years ended December 31, 2018 and 2017, respectively.

Short Term Borrowings and Lon_3

Short Term Borrowings and Long Term Debt Schedule of Debt (Details) - USD ($) $ in Millions		Dec. 31, 2018	Nov. 01, 2018	Dec. 31, 2017
Short term borrowings:
Total short-term borrowings		$ 0		$ 39
Long-term debt:
Long-term Debt, Excluding Current Maturities		8,682		8,195
Long-term Debt		8,682		8,195
Debt, Current	[1]	$ 482		645
ZENS due 2029 (5)
Long-term debt:
Debt instrument interest rate		2.00%
Parent Company [Member]
Long-term debt:
Unamortized Issuance Costs		$ (13)		(4)
Unamortized Discount (Premium), Net		(2)		0
Long-term Debt, Excluding Current Maturities		8,682		8,195
Long-term Debt, Current Maturities	[1]	482		606
Parent Company [Member] | Commercial paper (4)
Long-term debt:
Long-Term	[2]	0		855
Current	[1],[2]	0		0
Parent Company [Member] | ZENS due 2029 (5)
Long-term debt:
Long-Term	[3]	0		0
Current	[1],[3]	24		122
Parent Company [Member] | Senior notes 2.50% to 4.25% due 2021 to 2028
Long-term debt:
Long-Term		2,000		500
Current	[1]	$ 0		0
Parent Company [Member] | Senior notes 2.50% to 4.25% due 2021 to 2028 | Minimum [Member]
Long-term debt:
Debt instrument interest rate		2.50%
Parent Company [Member] | Senior notes 2.50% to 4.25% due 2021 to 2028 | Maximum [Member]
Long-term debt:
Debt instrument interest rate		4.25%
Parent Company [Member] | Pollution control bonds 5.125% due 2028 (6)
Long-term debt:
Long-Term	[4]	$ 68		68
Current	[1],[4]	$ 0		50
Debt instrument interest rate		5.125%	5.05%
Amount of debt secured by general mortgage bonds		$ 68		118
Houston Electric [Member]
Long-term debt:
Unamortized Issuance Costs		(24)		(22)
Unamortized Discount (Premium), Net		(11)		(10)
Long-term Debt, Excluding Current Maturities		4,258		4,319
Long-term Debt		4,258		4,319
Debt, Current	[1]	458		434
Houston Electric [Member] | First mortgage bonds 9.15% due 2021
Long-term debt:
Long-Term		102		102
Current	[1]	$ 0		0
Debt instrument interest rate		9.15%
Amount of debt secured by general mortgage bonds		$ 102
Houston Electric [Member] | General mortgage bonds 1.85% to 6.95% due 2021 to 2048
Long-term debt:
Long-Term		3,212		2,812
Current	[1]	0		0
Amount of debt secured by general mortgage bonds		$ 3,300
Houston Electric [Member] | General mortgage bonds 1.85% to 6.95% due 2021 to 2048 | Minimum [Member]
Long-term debt:
Debt instrument interest rate		1.85%
Houston Electric [Member] | General mortgage bonds 1.85% to 6.95% due 2021 to 2048 | Maximum [Member]
Long-term debt:
Debt instrument interest rate		6.95%
Houston Electric [Member] | System restoration bonds 4.243% due 2022
Long-term debt:
Long-Term		$ 197		256
Current	[1]	$ 59		56
Debt instrument interest rate		4.243%
Houston Electric [Member] | Transition bonds 5.302% due 2019
Long-term debt:
Long-Term		$ 0		208
Current	[1]	$ 208		194
Debt instrument interest rate		5.302%
Houston Electric [Member] | Transition bonds 5.234% due 2020
Long-term debt:
Long-Term		$ 29		85
Current	[1]	$ 56		53
Debt instrument interest rate		5.234%
Houston Electric [Member] | Transition bonds 2.161% to 3.028% due 2020 to 2024
Long-term debt:
Long-Term		$ 753		888
Current	[1]	$ 135		131
Houston Electric [Member] | Transition bonds 2.161% to 3.028% due 2020 to 2024 | Minimum [Member]
Long-term debt:
Debt instrument interest rate		2.161%
Houston Electric [Member] | Transition bonds 2.161% to 3.028% due 2020 to 2024 | Maximum [Member]
Long-term debt:
Debt instrument interest rate		3.028%
CERC Corp [Member]
Short term borrowings:
Total short-term borrowings	[1],[5]	$ 0		39
Long-term debt:
Unamortized Issuance Costs	[5]	(15)		(12)
Unamortized Discount (Premium), Net	[5]	(17)		(22)
Long-term Debt, Excluding Current Maturities	[5]	2,371		2,457
Long-term Debt, Current Maturities	[1],[5]	0		0
Long-term Debt	[5]	2,371		2,457
Debt, Current	[1],[5]	0		39
CERC Corp [Member] | Senior notes 3.55% to 6.625% due 2021 to 2047
Long-term debt:
Long-Term	[5]	2,193		1,593
Current	[1],[5]	$ 0		0
CERC Corp [Member] | Senior notes 3.55% to 6.625% due 2021 to 2047 | Minimum [Member]
Long-term debt:
Debt instrument interest rate		3.55%
CERC Corp [Member] | Senior notes 3.55% to 6.625% due 2021 to 2047 | Maximum [Member]
Long-term debt:
Debt instrument interest rate		6.625%
CERC Corp [Member] | Commercial paper (4)
Long-term debt:
Long-Term	[2],[5]	$ 210		898
Current	[1],[2],[5]	0		0
CERC Corp [Member] | Product Financing Arrangement [Member]
Short term borrowings:
Total short-term borrowings	[1],[5],[6]	$ 0		$ 39
[1]	Includes amounts due or exchangeable within one year of the date noted.
[2]	Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted.
[3]	CenterPoint Energy’s ZENS obligation is bifurcated into a debt component and an embedded derivative component. For additional information regarding ZENS, see Note 12(b). As ZENS are exchangeable for cash at any time at the option of the holders, these notes are classified as a current portion of long-term debt.
[4]	$68 million and $118 million of these series of debt were secured by general mortgage bonds of Houston Electric as of December 31, 2018 and 2017, respectively.
[5]	Issued by CERC Corp.
[6]	CenterPoint Energy’s and CERC’s 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.

Short Term Borrowings and Lon_4

Short Term Borrowings and Long Term Debt Long-term Debt (Details)		Jan. 15, 2019USD ($)	Nov. 01, 2018USD ($)	Oct. 05, 2018USD ($)	Mar. 26, 2018USD ($)	Feb. 28, 2018USD ($)	Jan. 31, 2019USD ($)	Dec. 31, 2018USD ($)		Dec. 31, 2017USD ($)
Line of Credit Facility [Abstract]
Size of credit facility								$ 4,500,000,000		$ 2,900,000,000
Senior Notes Due 2021 [Member]
Long-term debt:
Debt instrument interest rate	[1]			3.60%
Maturity date of debt issued	[1]			Nov. 1, 2021
Principal amount of debt issued	[1]			$ 500,000,000
Senior Notes Due 2024 [Member]
Long-term debt:
Debt instrument interest rate	[1]			3.85%
Maturity date of debt issued	[1]			Feb. 1, 2024
Principal amount of debt issued	[1]			$ 500,000,000
Senior Notes Due 2028 [Member]
Long-term debt:
Debt instrument interest rate	[1]			4.25%
Maturity date of debt issued	[1]			Nov. 1, 2028
Principal amount of debt issued	[1]			$ 500,000,000
Securitization Bonds [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
2,018								458,000,000
2,019								231,000,000
2,020								211,000,000
2,021								219,000,000
2,022								156,000,000
Long term Debt Excluding ZENS [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
2,018	[2]							458,000,000
2,019	[2]							231,000,000
2,020	[2]							1,706,000,000
2,021	[2]							1,230,000,000
2,022	[2]							656,000,000
Houston Electric [Member]
Line of Credit Facility [Abstract]
Size of credit facility								300,000,000		300,000,000
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
2,018	[2]							458,000,000
2,019	[2]							231,000,000
2,020	[2]							613,000,000
2,021	[2]							519,000,000
2,022	[2]							356,000,000
Additional first mortgage bonds and general mortgage bonds that could be issued								$ 4,300,000,000
Percentage of property additions								70.00%
Houston Electric [Member] | General Mortgage Bonds Due 2048 [Member]
Long-term debt:
Debt instrument interest rate	[3]					3.95%
Maturity date of debt issued	[3]					Mar. 1, 2048
Principal amount of debt issued	[3]					$ 400,000,000
Houston Electric [Member] | First mortgage bonds 9.15% due 2021
Long-term debt:
Debt instrument interest rate								9.15%
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Secured debt amount with asset liens								$ 102,000,000
Replacement fund requirements to be satisfied in 2018								283,000,000
Sinking fund requirements to be satisfied in 2018								1,600,000
Long-Term								102,000,000		102,000,000
Houston Electric [Member] | General mortgage bonds 1.85% to 6.95% due 2021 to 2048
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Secured debt amount with asset liens								3,300,000,000
Long-Term								3,212,000,000		2,812,000,000
CERC Corp [Member]
Line of Credit Facility [Abstract]
Size of credit facility								900,000,000	[4]	900,000,000	[5]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
2,018								0
2,019								0
2,020								593,000,000
2,021								210,000,000
2,022								300,000,000
CERC Corp [Member] | Senior Notes Due 2023 [Member]
Long-term debt:
Debt instrument interest rate	[3],[6]				3.55%
Maturity date of debt issued	[3],[6]				Apr. 1, 2023
Principal amount of debt issued	[3],[6]				$ 300,000,000
CERC Corp [Member] | Senior Notes Due 2028 [Member]
Long-term debt:
Debt instrument interest rate	[3],[6]				4.00%
Maturity date of debt issued	[3],[6]				Apr. 1, 2028
Principal amount of debt issued	[3],[6]				$ 300,000,000
CERC Corp [Member] | Commercial paper (4)
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-Term	[7],[8]							210,000,000		898,000,000
Revolving Credit Facility [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit								0		0
Revolving Credit Facility [Member] | Houston Electric [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit								0		0
Revolving Credit Facility [Member] | CERC Corp [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit	[5]							$ 0		0
Line of Credit [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	[9]							65.00%
Ratio of indebtedness to net capital	[10]							0.492
Line of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	[4],[9]							65.00%
Ratio of indebtedness to net capital	[4],[10]							0.468
Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[11]							1.125%
Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[4],[11]							1.125%
Letter of Credit [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit								$ 11,000,000		11,000,000
Letter of Credit [Member] | Houston Electric [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit								4,000,000		4,000,000
Letter of Credit [Member] | CERC Corp [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit	[5]							1,000,000		1,000,000
Commercial paper (4)
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit								210,000,000		1,753,000,000
Commercial paper (4) | Houston Electric [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit								0		0
Commercial paper (4) | CERC Corp [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit	[5]							$ 210,000,000		$ 898,000,000
Debt, Weighted Average Interest Rate	[5]							2.93%		1.72%
Subsequent Event [Member] | Houston Electric [Member] | General Mortgage Bonds Due 2049 [Member]
Long-term debt:
Debt instrument interest rate	[3]	4.25%
Maturity date of debt issued	[3]	Feb. 1, 2049
Principal amount of debt issued	[3]	$ 700,000,000
Subsequent Event [Member] | Vectren [Member]
Line of Credit Facility [Abstract]
Long-term line of credit							90
Subsequent Event [Member] | Vectren [Member] | Commercial paper (4)
Line of Credit Facility [Abstract]
Weighted average interest rate of commercial paper issued in connection with the Merger	[12],[13]						2.88%
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit	[12],[13]						$ 1,660,000,000
Parent Company [Member]
Line of Credit Facility [Abstract]
Size of credit facility								$ 3,300,000,000	[14]	$ 1,700,000,000
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Temporary increased line of credit facility, maximum borrowing capacity								3,300,000,000
Parent Company [Member] | Commercial paper (4)
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-Term	[7]							$ 0		855,000,000
Parent Company [Member] | Pollution control bonds 5.125% due 2028 (6)
Long-term debt:
Amount of debt retired	[15]		$ 50,000,000
Debt instrument interest rate			5.05%					5.125%
Maturity date of debt issued			Nov. 1, 2018
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Secured debt amount with asset liens								$ 68,000,000		118,000,000
Long-Term	[16]							68,000,000		68,000,000
Parent Company [Member] | Revolving Credit Facility [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit								$ 0		0
Parent Company [Member] | Line of Credit [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	[9]							65.00%
Ratio of indebtedness to net capital	[10]							0.449
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)								70.00%
System restoration costs threshold for increase in permitted debt to EBITDA covenant ratio								$ 100,000,000
Consecutive period for system restoration costs to exceed $100 million (in months)								12
Parent Company [Member] | Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[11]							1.25%
Parent Company [Member] | Letter of Credit [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit								$ 6,000,000		6,000,000
Parent Company [Member] | Commercial paper (4)
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Long-term Line of Credit								$ 0		$ 855,000,000
Debt, Weighted Average Interest Rate								0.00%		1.88%
Parent Company [Member] | Vectren acquisition [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Bridge Loan								$ 5,000,000,000
Parent Company [Member] | Vectren acquisition [Member] | Line of Credit [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)								75.00%
Parent Company [Member] | April 2018 [Member]
Line of Credit Facility [Abstract]
Size of credit facility								$ 1,700,000,000
Parent Company [Member] | April 2018 [Member] | Vectren acquisition [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Temporary increased line of credit facility, maximum borrowing capacity								3,300,000,000
Parent Company [Member] | October 2018 [Member]
Line of Credit Facility [Abstract]
Size of credit facility								1,700,000,000
Parent Company [Member] | October 2018 [Member] | Vectren acquisition [Member]
Annual maturities of long term debt, capital leases, and sinking fund requirements, excluding ZENS obligations [Abstract]
Temporary increased line of credit facility, maximum borrowing capacity								$ 3,300,000,000
[1]	Proceeds from these debt issuances were used to fund a portion of the Merger and to pay related fees and expenses.
[2]	These maturities include Securitization Bonds principal repayments on scheduled payment dates.
[3]	Proceeds from these debt issuances were used for general limited liability company and corporate purposes, as applicable, including capital expenditures, repayment of portions of outstanding commercial paper and borrowings under CenterPoint Energy’s money pool.
[4]	Issued by CERC Corp.
[5]	Issued by CERC Corp.
[6]	Issued by CERC Corp.
[7]	Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted.
[8]	Issued by CERC Corp.
[9]	For CenterPoint Energy 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.
[10]	As defined in the revolving credit facility agreement, excluding Securitization Bonds.
[11]	Based on credit ratings as of December 31, 2018.
[12]	Proceeds from these commercial paper issuances were used to fund a portion of the Merger and to pay related fees and expenses and were contributed to Vectren for its payment of its stub period cash dividend, long-term incentive payments and to fund the repayment of indebtedness of Vectren subsidiaries redeemed at the option of the holder as a result of the closing of the Merger.
[13]	The commercial paper notes were issued at various times in January 2019 with maturities up to and including 90 days as of the time of issuance, and, prior to their use as described in connection with the closing of the Merger, the net proceeds of such issuances were invested in short-term investments.
[14]	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.
[15]	Secured by general mortgage bonds of Houston Electric.
[16]	$68 million and $118 million of these series of debt were secured by general mortgage bonds of Houston Electric as of December 31, 2018 and 2017, respectively.

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Current income tax expense (benefit):
Federal	$ 89		$ 32		$ 23
State	9		9		18
Total current expense (benefit)	98		41		41
Deferred income tax expense (benefit):
Federal	(25)		(806)		185
State	73		36		28
Total deferred expense (benefit)	48		(770)		213
Total income tax expense (benefit)	146	[1]	(729)	[2]	254	[3]
Income tax reconciliation [Abstract]
Income before income taxes	$ 514	[1]	$ 1,063	[2]	$ 686	[3]
Federal statutory income tax rate	21.00%	[1]	35.00%	[2]	35.00%	[3]
Expected federal income tax expense	$ 108	[1]	$ 372	[2]	$ 240	[3]
Increase (decrease) in tax expense resulting from:
State income tax expense, net of federal income tax	22	[1]	26	[2]	27	[3]
Other adjustments	11	[1]	3	[2]	3	[3]
State law change, net of federal income tax	32	[1]	0	[2]	0	[3]
Federal income tax rate reduction	0	[1]	(1,113)	[2]	0	[3]
Excess deferred income tax amortization	(24)	[1]	0	[2]	0	[3]
Other, net	(3)	[1]	(17)	[2]	(16)	[3]
Total	38	[1]	(1,101)	[2]	14	[3]
Total income tax expense (benefit)	$ 146	[1]	$ (729)	[2]	$ 254	[3]
Effective tax rate (in hundredths)	28.00%	[1]	(69.00%)	[2]	37.00%	[3]
Valuation allowance on certain state carryforwards					$ 3
Deferred tax assets:
Benefits and compensation	$ 160		$ 162
Regulatory liabilities	356		347
Loss and credit carryforwards	84		90
Asset retirement obligations	62		68
Other	29		16
Valuation allowance	(18)		(7)
Total deferred tax assets	673		676
Deferred tax liabilities:
Property, plant, and equipment	1,894		1,808
Investment in unconsolidated affiliates	987		927
Regulatory assets	395		473
Investment in marketable securities and indexed debt	478		502
Indexed debt securities derivative	27		13
Other	131		127
Total deferred tax liabilities	3,912		3,850
Net deferred tax liabilities	3,239		3,174
State and Local Jurisdiction [Member]
Increase (decrease) in tax expense resulting from:
State law change, net of federal income tax					6
Deferred tax liabilities:
Operating loss carryforwards	802
Deferred tax assets tax credit carryforwards	18
Houston Electric [Member]
Current income tax expense (benefit):
Federal	109		70		165
State	18		19		18
Total current expense (benefit)	127		89		183
Deferred income tax expense (benefit):
Federal	(38)		(98)		(34)
Total deferred expense (benefit)	(38)		(98)		(34)
Total income tax expense (benefit)	89	[4]	(9)	[5]	149
Income tax reconciliation [Abstract]
Income before income taxes	$ 425	[4]	$ 424	[5]	$ 425
Federal statutory income tax rate	21.00%	[4]	35.00%	[5]	35.00%
Expected federal income tax expense	$ 89	[4]	$ 148	[5]	$ 149
Increase (decrease) in tax expense resulting from:
State income tax expense, net of federal income tax	14	[4]	12	[5]	12
Federal income tax rate reduction	0	[4]	(158)	[5]	0
Excess deferred income tax amortization	(9)	[4]	0	[5]	0
Other, net	(5)	[4]	(11)	[5]	(12)
Total	0	[4]	(157)	[5]	0
Total income tax expense (benefit)	$ 89	[4]	$ (9)	[5]	$ 149
Effective tax rate (in hundredths)	21.00%	[4]	(2.00%)	[5]	35.00%
Deferred tax assets:
Benefits and compensation	$ 17		$ 28
Regulatory liabilities	205		198
Asset retirement obligations	7		7
Other	12		3
Total deferred tax assets	241		236
Deferred tax liabilities:
Property, plant, and equipment	1,087		1,030
Regulatory assets	177		265
Total deferred tax liabilities	1,264		1,295
Net deferred tax liabilities	1,023		1,059
CERC Corp [Member]
Deferred income tax expense (benefit):
Total deferred expense (benefit)	31		(224)		$ 56
Total income tax expense (benefit)	22		(265)		81
Income tax reconciliation [Abstract]
Income before income taxes	92		319		199
Increase (decrease) in tax expense resulting from:
Total income tax expense (benefit)	22		(265)		81
Deferred tax assets:
Valuation allowance	(18)
CERC Corp [Member] | State and Local Jurisdiction [Member]
Deferred tax liabilities:
Operating loss carryforwards	797
Deferred tax assets tax credit carryforwards	17
CERC Corp [Member] | Internal Revenue Service (IRS) [Member]
Deferred tax liabilities:
Operating loss carryforwards	$ 951
Earliest Tax Year [Member] | State and Local Jurisdiction [Member]
Deferred tax liabilities:
Tax credit carryforward expiration date	Dec. 31, 2019
Earliest Tax Year [Member] | CERC Corp [Member] | State and Local Jurisdiction [Member]
Deferred tax liabilities:
Tax credit carryforward expiration date	Dec. 31, 2019
Latest Tax Year [Member] | State and Local Jurisdiction [Member]
Deferred tax liabilities:
Tax credit carryforward expiration date	Dec. 31, 2038
Latest Tax Year [Member] | CERC Corp [Member] | State and Local Jurisdiction [Member]
Deferred tax liabilities:
Tax credit carryforward expiration date	Dec. 31, 2038
Excess deferred income taxes [Member]
Deferred tax liabilities:
Net regulatory liability			1,300
Net regulatory liabilities gross-up			300
Excess deferred income taxes [Member] | Houston Electric [Member]
Deferred tax liabilities:
Net regulatory liability			829
Net regulatory liabilities gross-up			180
Excess deferred income taxes [Member] | CERC Corp [Member]
Deferred tax liabilities:
Net regulatory liability			478
Net regulatory liabilities gross-up			$ 121
Federal Income Tax Rate Prior To TCJA [Member]
Income tax reconciliation [Abstract]
Federal statutory income tax rate			35.00%
Federal Income Tax Rate Prior To TCJA [Member] | Houston Electric [Member]
Income tax reconciliation [Abstract]
Federal statutory income tax rate			35.00%
Federal Income Tax Rate Prior To TCJA [Member] | CERC Corp [Member]
Income tax reconciliation [Abstract]
Federal statutory income tax rate			35.00%
Federal Income Tax Rate After TCJA [Member]
Income tax reconciliation [Abstract]
Federal statutory income tax rate			21.00%
Federal Income Tax Rate After TCJA [Member] | Houston Electric [Member]
Income tax reconciliation [Abstract]
Federal statutory income tax rate			21.00%
Federal Income Tax Rate After TCJA [Member] | CERC Corp [Member]
Income tax reconciliation [Abstract]
Federal statutory income tax rate			21.00%
Continuing Operations [Member] | CERC Corp [Member]
Current income tax expense (benefit):
Federal	$ (9)		$ (31)		21
State	0		(10)		4
Total current expense (benefit)	(9)		(41)		25
Deferred income tax expense (benefit):
Federal	10		(249)		41
State	21		25		15
Total deferred expense (benefit)	31		(224)		56
Total income tax expense (benefit)	22	[6]	(265)	[7]	81
Income tax reconciliation [Abstract]
Income before income taxes	$ 92	[6]	$ 319	[7]	$ 199
Federal statutory income tax rate	21.00%	[6]	35.00%	[7]	35.00%
Expected federal income tax expense	$ 19	[6]	$ 112	[7]	$ 70
Increase (decrease) in tax expense resulting from:
State income tax expense, net of federal income tax	5	[6]	6	[7]	4
State law change, net of federal income tax	0	[6]	0	[7]	6
Federal income tax rate reduction	0	[6]	(396)	[7]	0
Excess deferred income tax amortization	(15)	[6]	0	[7]	0
Other, net	2	[6]	(1)	[7]	(1)
Total	3	[6]	(377)	[7]	11
Total income tax expense (benefit)	$ 22	[6]	$ (265)	[7]	$ 81
Effective tax rate (in hundredths)	24.00%	[6]	(83.00%)	[7]	41.00%
Deferred tax assets:
Benefits and compensation	$ 27		$ 27
Regulatory liabilities	150		150
Loss and credit carryforwards	259		288
Asset retirement obligations	54		60
Other	20		18
Valuation allowance	(18)		(7)
Total deferred tax assets	492		536
Deferred tax liabilities:
Property, plant, and equipment	773		745
Regulatory assets	41		38
Other	84		115
Total deferred tax liabilities	898		898
Net deferred tax liabilities	406		362
Discontinued Operations [Member] | CERC Corp [Member]
Current income tax expense (benefit):
Federal	9		31		$ (21)
State	4		11		2
Total current expense (benefit)	13		42		(19)
Deferred income tax expense (benefit):
Federal	29		56		90
State	4		6		10
Total deferred expense (benefit)	33		62		100
Total income tax expense (benefit)	46		104		81
Income tax reconciliation [Abstract]
Income before income taxes	$ 184		$ 265		$ 208
Federal statutory income tax rate	21.00%		35.00%		35.00%
Expected federal income tax expense	$ 39		$ 93		$ 73
Increase (decrease) in tax expense resulting from:
State income tax expense, net of federal income tax	7		11		8
Total	7		11		8
Total income tax expense (benefit)	$ 46		$ 104		$ 81
Effective tax rate (in hundredths)	25.00%		39.00%		39.00%
Deferred tax liabilities:
Investment in unconsolidated affiliates	$ 0		$ 927
Net deferred tax liabilities	0		927
State Valuation Allowance, net of Federal Income Taxes [Member] | Continuing Operations [Member] | CERC Corp [Member]
Increase (decrease) in tax expense resulting from:
Other adjustments	11	[6]	3	[7]	$ 2
Tax Basis Balance Sheet Adjustment [Member] | Continuing Operations [Member] | CERC Corp [Member]
Increase (decrease) in tax expense resulting from:
Other adjustments	$ 0	[6]	$ 11	[7]	$ 0
[1]	Recognized a $32 million deferred tax expense due to state law changes that resulted in remeasurement of state deferred taxes in those jurisdictions. Also recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These items are partially offset by $24 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018.
[2]	Recognized a $1.1 billion deferred tax benefit from the remeasurement of CenterPoint Energy’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21%. For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below.
[3]	Recognized a $6 million deferred tax expense in 2016 due to Louisiana state law change and recorded an additional $3 million valuation allowance on certain state carryforwards.
[4]	Recognized $9 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018.
[5]	Recognized a $158 million deferred tax benefit from the remeasurement of Houston Electric’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21%. For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below.
[6]	Recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. This item is partially offset by $15 million of amortization of the net regulatory EDIT liability in certain jurisdictions as decreed by regulators beginning in 2018.
[7]	Recognized a $396 million deferred tax benefit from the remeasurement of CERC’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21%. ASC 740 requires tax impacts of changes in tax laws or rates be reported in continuing operations. Therefore, CERC’s federal income tax benefit generated by the remeasurement of the ADFIT liability for Enable during 2017 and state law changes during 2016 associated with its investment in Enable are reported in continuing operations on CERC’s Statements of Consolidated Income. The ADFIT liability associated with CERC’s investment in Enable is reported as discontinued operations on CERC’s Consolidated Balance Sheets.

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leases, Future Minimum Payments Due [Abstract]
2,019	$ 6,000,000
2,020	6,000,000
2,021	5,000,000
2,022	4,000,000
2,023	3,000,000
2024 and beyond	12,000,000
Total	36,000,000
Total lease expense for all operating leases	9,000,000	$ 10,000,000	$ 10,000,000
Minnesota Service Territory [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Liability recorded for remediation of Minnesota sites	7,000,000
Minnesota Service Territory [Member] | Minimum [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Estimated remediation costs for the Minnesota sites	$ 5,000,000
Years to resolve contingency	30
Minnesota Service Territory [Member] | Maximum [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Estimated remediation costs for the Minnesota sites	$ 32,000,000
Years to resolve contingency	50
Minnehaha Academy Gas Explosion [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Contested amount of fines imposed	$ 200,000
Natural Gas Supply Commitments [Member]
Long-term Purchase Commitment [Line Items]
2,019	454,000,000
2,020	430,000,000
2,021	343,000,000
2,022	231,000,000
2,023	154,000,000
2024 and beyond	1,446,000,000
CERC Corp [Member] | Minnesota Service Territory [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Liability recorded for remediation of Minnesota sites	7,000,000
CERC Corp [Member] | Minnesota Service Territory [Member] | Minimum [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Estimated remediation costs for the Minnesota sites	$ 5,000,000
Years to resolve contingency	30
CERC Corp [Member] | Minnesota Service Territory [Member] | Maximum [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Estimated remediation costs for the Minnesota sites	$ 32,000,000
Years to resolve contingency	50
CERC Corp [Member] | Minnehaha Academy Gas Explosion [Member]
Legal Environmental And Other Regulatory Matters Legal Matters Gas Market Manipulation Cases Abstract
Contested amount of fines imposed	$ 200,000
CERC Corp [Member] | Natural Gas Supply Commitments [Member]
Long-term Purchase Commitment [Line Items]
2,019	454,000,000
2,020	430,000,000
2,021	343,000,000
2,022	231,000,000
2,023	154,000,000
2024 and beyond	1,446,000,000
Houston Electric [Member]
Operating Leases, Future Minimum Payments Due [Abstract]
2,019	1,000,000
2,020	0
2,021	0
2,022	0
2,023	0
2024 and beyond	0
Total	1,000,000
Total lease expense for all operating leases	1,000,000	1,000,000	1,000,000
CERC Corp [Member]
Operating Leases, Future Minimum Payments Due [Abstract]
2,019	5,000,000
2,020	5,000,000
2,021	4,000,000
2,022	4,000,000
2,023	3,000,000
2024 and beyond	11,000,000
Total	32,000,000
Total lease expense for all operating leases	$ 8,000,000	$ 9,000,000	$ 9,000,000

Earnings Per Share (CenterPoi_3

Earnings Per Share (CenterPoint Energy) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended																12 Months Ended
		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Numerator:
Income available to common shareholders - basic (1)		$ 90		$ 153		$ (75)		$ 165		$ 1,296	[1]	$ 169	[1]	$ 135	[1]	$ 192	[1]	$ 333	[2]	$ 1,792	[2]	$ 432	[2]
Add back: Series B Preferred Stock dividend																		35		0		0
Income available to common shareholders - diluted (1)	[2]																	$ 333		$ 1,792		$ 432
Denominator:
Weighted average common shares outstanding - basic																		448,829,000		430,964,000		430,606,000
Plus: Incremental shares from assumed conversions:
Weighted average common shares outstanding - diluted																		452,465,000		434,308,000		433,603,000
Basic Earnings Per Common Share		$ 0.18	[3]	$ 0.35	[3]	$ (0.17)	[3]	$ 0.38	[3]	$ 3.01	[3]	$ 0.39	[3]	$ 0.31	[3]	$ 0.45	[3]	$ 0.74		$ 4.16		$ 1
Diluted Earnings Per Common Share		$ 0.18	[3]	$ 0.35	[3]	$ (0.17)	[3]	$ 0.38	[3]	$ 2.99	[3]	$ 0.39	[3]	$ 0.31	[3]	$ 0.44	[3]	$ 0.74		$ 4.13		$ 1
Reduction in income taxes due to tax reform																		$ 0	[4]	$ 1,113	[5]	$ 0	[6]
Restricted Stock [Member]
Plus: Incremental shares from assumed conversions:
Restricted stock (2)	[7]																	3,636,000		3,344,000		2,997,000
Series B Preferred Stock [Member]
Numerator:
Add back: Series B Preferred Stock dividend																		$ 0		$ 0		$ 0
Plus: Incremental shares from assumed conversions:
Series B Preferred Stock (3)	[8]																	0		0		0
Amount of antidilutive securities excluded from computation of earnings per share																		8,885,000
[1]	Income available to common shareholders and Net income for the fourth quarter 2017 include a reduction in income tax expense of $1,113 million, $158 million and $396 million for CenterPoint Energy, Houston Electric and CERC, respectively, due to the TCJA. See Note 15 for further discussion of the impacts of tax reform implementation.
[2]	Income available to common shareholders for the year ended December 31, 2017 includes a reduction in income tax expense of $1,113 million due to tax reform. See Note 15 for further discussion of the impacts of the TCJA.
[3]	Quarterly earnings (loss) per common share are based on the weighted average number of shares outstanding during the quarter, and the sum of the quarters may not equal annual earnings (loss) per common share.
[4]	Recognized a $32 million deferred tax expense due to state law changes that resulted in remeasurement of state deferred taxes in those jurisdictions. Also recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These items are partially offset by $24 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018.
[5]	Recognized a $1.1 billion deferred tax benefit from the remeasurement of CenterPoint Energy’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21%. For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below.
[6]	Recognized a $6 million deferred tax expense in 2016 due to Louisiana state law change and recorded an additional $3 million valuation allowance on certain state carryforwards.
[7]	The potentially dilutive impact from restricted stock awards applies the treasury stock method. Under this method, an increase in the average fair market value of Common Stock can result in a greater dilutive impact from these securities.
[8]	The potentially dilutive impact from Series B Preferred Stock applies the if-converted method in calculating diluted earnings per common share. Under this method, diluted earnings per common share is adjusted for the more dilutive effect of the Series B Preferred Stock as a result of either its accumulated dividend for the period in the numerator or the assumed-converted common share equivalent in the denominator. The computation of diluted earnings per common share outstanding for the year ended December 31, 2018 excludes 8,885,000 potentially dilutive shares because to include them would be anti-dilutive. However, these shares could be potentially dilutive in the future.

Unaudited Quarterly Informati_3

Unaudited Quarterly Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended																12 Months Ended
		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Revenues		$ 3,036		$ 2,212		$ 2,186		$ 3,155		$ 2,638		$ 2,098		$ 2,143		$ 2,735		$ 10,589		$ 9,614		$ 7,528
Operating income (loss)		167		226		187		251		308	[1]	297	[1]	240	[1]	291	[1]	831		1,136		1,023
Income (loss) available to common shareholders		$ 90		$ 153		$ (75)		$ 165		$ 1,296	[2]	$ 169	[2]	$ 135	[2]	$ 192	[2]	$ 333	[3]	$ 1,792	[3]	$ 432	[3]
Basic earnings (loss) per common share (1)		$ 0.18	[4]	$ 0.35	[4]	$ (0.17)	[4]	$ 0.38	[4]	$ 3.01	[4]	$ 0.39	[4]	$ 0.31	[4]	$ 0.45	[4]	$ 0.74		$ 4.16		$ 1
Diluted earnings (loss) per common share (1)		$ 0.18	[4]	$ 0.35	[4]	$ (0.17)	[4]	$ 0.38	[4]	$ 2.99	[4]	$ 0.39	[4]	$ 0.31	[4]	$ 0.44	[4]	$ 0.74		$ 4.13		$ 1
Net income																		$ 368		$ 1,792		$ 432
Reduction in income taxes due to tax reform																		0	[5]	1,113	[6]	0	[7]
Houston Electric [Member]
Revenues		$ 728		$ 897		$ 854		$ 755		$ 765		$ 843		$ 752		$ 638		3,234		2,998		3,059
Operating income (loss)		98		227		181		119		127	[1]	254	[1]	171	[1]	85	[1]	625		637		652
Net income		40		143		101		52		210	[2]	130	[2]	75	[2]	18	[2]	336		433		276
Reduction in income taxes due to tax reform																		$ 0	[8]	158	[9]	$ 0
CERC Corp [Member]
Revenues	[10]	2,303		1,312		1,328		2,400		1,872		1,251		1,387		2,093
Operating income (loss)	[10]	76		(7)		22		131		178	[1]	31	[1]	59	[1]	199	[1]
Income (loss) from continuing operations	[10]	35		(35)		(8)		78		469		(4)		17		102
Income (loss) from discontinued operations, net of tax	[10]	(2)		44		44		52		37		42		37		45
Net income	[10]	$ 33		$ 9		$ 36		$ 130		$ 506	[2]	$ 38	[2]	$ 54	[2]	$ 147	[2]
Reduction in income taxes due to tax reform																				$ 396
[1]	Recast to reflect the adoption of ASU 2017-07. See Note 2(r) for further information.
[2]	Income available to common shareholders and Net income for the fourth quarter 2017 include a reduction in income tax expense of $1,113 million, $158 million and $396 million for CenterPoint Energy, Houston Electric and CERC, respectively, due to the TCJA. See Note 15 for further discussion of the impacts of tax reform implementation.
[3]	Income available to common shareholders for the year ended December 31, 2017 includes a reduction in income tax expense of $1,113 million due to tax reform. See Note 15 for further discussion of the impacts of the TCJA.
[4]	Quarterly earnings (loss) per common share are based on the weighted average number of shares outstanding during the quarter, and the sum of the quarters may not equal annual earnings (loss) per common share.
[5]	Recognized a $32 million deferred tax expense due to state law changes that resulted in remeasurement of state deferred taxes in those jurisdictions. Also recorded an additional $11 million valuation allowance on certain state net operating loss deferred tax assets that are no longer expected to be utilized prior to expiration after the Internal Spin. These items are partially offset by $24 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018.
[6]	Recognized a $1.1 billion deferred tax benefit from the remeasurement of CenterPoint Energy’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21%. For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below.
[7]	Recognized a $6 million deferred tax expense in 2016 due to Louisiana state law change and recorded an additional $3 million valuation allowance on certain state carryforwards.
[8]	Recognized $9 million of amortization of the net regulatory EDIT liability as decreed by regulators in certain jurisdictions beginning in 2018.
[9]	Recognized a $158 million deferred tax benefit from the remeasurement of Houston Electric’s ADFIT liability as a result of the enactment of the TCJA on December 22, 2017, which reduced the U.S. corporate income tax rate from 35% to 21%. For additional information on the 2017 impacts of the TCJA, please see the discussion following the deferred tax assets and liabilities table below.
[10]	Amounts have been recast to reflect discontinued operations in all periods presented.

Reportable Segments (Details)

Reportable Segments (Details) - USD ($) $ in Millions		3 Months Ended													12 Months Ended
		Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016		Sep. 04, 2018
Segment Reporting Information [Line Items]
Revenues		$ 3,036		$ 2,212	$ 2,186	$ 3,155	$ 2,638		$ 2,098		$ 2,143		$ 2,735		$ 10,589		$ 9,614		$ 7,528
Depreciation and Amortization															1,243		1,036		1,126
Operating Income (Loss)		167		226	187	251	308	[1]	297	[1]	240	[1]	291	[1]	831		1,136		1,023
Total Assets		27,009					22,736								27,009		22,736		21,829
Expenditures for Long-Lived Assets															1,720		1,494		1,406
Capital expenditures per Statements of Consolidated Cash Flows															1,651		1,426		1,414
Midstream Investments’ equity earnings, net															307		265		208
Total regulatory assets		2,044					2,477								2,044		2,477
Enable Midstream Partners [Member]
Segment Reporting Information [Line Items]
Midstream Investments’ equity earnings, net	[2]														307		265		208
Electric Transmission & Distribution [Member]
Segment Reporting Information [Line Items]
Revenues	[3]														3,232		2,997		3,060
Depreciation and Amortization															917		724		838
Operating Income (Loss)															623		636		653
Expenditures for Long-Lived Assets															952		924		858
Electric Transmission & Distribution [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues															705		713		698
Electric Transmission & Distribution [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues															251		229		220
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues															2,931		2,606		2,380
Depreciation and Amortization															277		260		242
Operating Income (Loss)															266		348		321
Expenditures for Long-Lived Assets															638		523		510
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues															4,411		3,997		2,073
Depreciation and Amortization															16		19		7
Operating Income (Loss)															(47)		126		21
Expenditures for Long-Lived Assets															20		11		5
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[4]														0		0		0
Depreciation and Amortization	[4]														0		0		0
Operating Income (Loss)	[4]														0		0		0
Expenditures for Long-Lived Assets	[4]														0		0		0
Midstream Investments [Member] | Enable Midstream Partners [Member]
Segment Reporting Information [Line Items]
Midstream Investments’ equity earnings, net															307		265		208
Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues															15		14		15
Depreciation and Amortization															33		33		39
Operating Income (Loss)															(11)		26		28
Expenditures for Long-Lived Assets															110		36		33
Operating Segments [Member] | Electric Transmission & Distribution [Member]
Segment Reporting Information [Line Items]
Total Assets		10,509					10,292								10,509		10,292		10,211
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Total Assets		6,956					6,608								6,956		6,608		6,099
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Total Assets		1,558					1,521								1,558		1,521		1,102
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Total Assets	[4]	2,482					2,472								2,482		2,472		2,505
Operating Segments [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Total Assets	[5]	6,156					2,497								6,156		2,497		2,681
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues															(146)		(85)		(55)
Total Assets		(652)					(654)								(652)		(654)		(769)
Intersegment Eliminations [Member] | Electric Transmission & Distribution [Member]
Segment Reporting Information [Line Items]
Revenues															0		0		0
Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues															(36)		(33)		(29)
Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues															(110)		(52)		(26)
Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[4]														0		0		0
Intersegment Eliminations [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues															0		0		0
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Expenditures for Long-Lived Assets															(69)		(68)		8
Pension and Other Postretirement Plans Costs [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Total regulatory assets		665					600								665		600		759
Cash and Cash Equivalents [Member]
Segment Reporting Information [Line Items]
Temporary investments		3,900													3,900
Houston Electric [Member]
Segment Reporting Information [Line Items]
Revenues		728		897	854	755	765		843		752		638		3,234		2,998		3,059
Depreciation and Amortization															917		724		838
Operating Income (Loss)		98		$ 227	$ 181	$ 119	127	[1]	$ 254	[1]	$ 171	[1]	$ 85	[1]	625		637		652
Total Assets		10,507					10,292								10,507		10,292
Capital expenditures per Statements of Consolidated Cash Flows															922		875		862
Total regulatory assets		1,124					1,570								1,124		1,570
Houston Electric [Member] | Electric Transmission & Distribution [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues															705		713		698
Houston Electric [Member] | Electric Transmission & Distribution [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues															251		229		220
CERC Corp [Member]
Segment Reporting Information [Line Items]
Revenues															7,343		6,603		4,454
Depreciation and Amortization															293		279		249
Operating Income (Loss)															222		467		341
Total Assets		8,214	[6]				10,112								8,214	[6]	10,112		9,218
Investment in unconsolidated affiliates - discontinued operations		0					2,472								0		2,472
Expenditures for Long-Lived Assets															658		534		515
Capital expenditures per Statements of Consolidated Cash Flows															633		513		517
Total regulatory assets		258					311								258		311
CERC Corp [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues															2,931		2,606		2,380
Depreciation and Amortization															277		260		242
Operating Income (Loss)															266		348		321
Expenditures for Long-Lived Assets															638		523		510
CERC Corp [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues															4,411		3,997		2,073
Depreciation and Amortization															16		19		7
Operating Income (Loss)															(47)		126		21
Expenditures for Long-Lived Assets															20		11		5
CERC Corp [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues															1		0		1
Depreciation and Amortization															0		0		0
Operating Income (Loss)															3		(7)		(1)
Expenditures for Long-Lived Assets															0		0		0
CERC Corp [Member] | Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Total Assets		6,956	[6]				6,608								6,956	[6]	6,608		6,099
CERC Corp [Member] | Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Total Assets		1,558	[6]				1,521								1,558	[6]	1,521		1,102
CERC Corp [Member] | Operating Segments [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Total Assets		66	[6]				70								66	[6]	70		75
CERC Corp [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues															(146)		(85)		(55)
Total Assets		$ (366)	[6]				(559)								(366)	[6]	(559)		(563)
CERC Corp [Member] | Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues															(36)		(33)		(29)
CERC Corp [Member] | Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues															(110)		(52)		(26)
CERC Corp [Member] | Intersegment Eliminations [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues															0		0		0
CERC Corp [Member] | Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Expenditures for Long-Lived Assets															$ (25)		(21)		2
Enable Midstream Partners [Member] | Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] | CERC Corp [Member]
Segment Reporting Information [Line Items]
Revenues																	0		0
Depreciation and Amortization																	0		0
Operating Income (Loss)																	0		0
Investment in unconsolidated affiliates - discontinued operations							$ 2,472	[6]									2,472	[6]	2,505	[6]	$ 2,400
Expenditures for Long-Lived Assets																	$ 0		$ 0
[1]	Recast to reflect the adoption of ASU 2017-07. See Note 2(r) for further information.
[2]	Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement.
[3]	CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Year Ended December 31, 2018 2017 2016 (in millions)Affiliates of NRG $705 $713 $698Affiliates of Vistra Energy Corp. 251 229 220
[4]	CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows: Year Ended December 31, 2018 2017 2016 (in millions)Enable $307 $265 $208
[5]	Total assets included pension and other postemployment-related regulatory assets of $665 million, $600 million and $759 million as of December 31, 2018, 2017 and 2016, respectively. Additionally, total assets as of December 31, 2018 included $3.9 billion of temporary investments included in Cash and cash equivalents on CenterPoint Energy’s Consolidated Balance Sheets.
[6]	On September 4, 2018, CERC completed the Internal Spin. For further information regarding the Internal Spin, see Note 11.

Reportable Segments Revenues by

Reportable Segments Revenues by Products and Services (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues by Products and Services:
Revenues	$ 3,036	$ 2,212	$ 2,186	$ 3,155	$ 2,638	$ 2,098	$ 2,143	$ 2,735	$ 10,589	$ 9,614	$ 7,528
Electric Delivery [Member]
Revenues by Products and Services:
Revenues									3,232	2,997	3,060
Retail Gas Sales [Member]
Revenues by Products and Services:
Revenues									4,161	3,634	3,329
Wholesale Gas Sales [Member]
Revenues by Products and Services:
Revenues									3,008	2,811	977
Gas Transportation and Processing [Member]
Revenues by Products and Services:
Revenues									32	29	23
Energy Products Or Services [Member]
Revenues by Products and Services:
Revenues									156	143	139
Houston Electric [Member]
Revenues by Products and Services:
Revenues	$ 728	$ 897	$ 854	$ 755	$ 765	$ 843	$ 752	$ 638	3,234	2,998	3,059
Houston Electric [Member] | Electric Delivery [Member]
Revenues by Products and Services:
Revenues									3,234	2,998	3,059
Houston Electric [Member] | Retail Gas Sales [Member]
Revenues by Products and Services:
Revenues									0	0	0
Houston Electric [Member] | Wholesale Gas Sales [Member]
Revenues by Products and Services:
Revenues									0	0	0
Houston Electric [Member] | Gas Transportation and Processing [Member]
Revenues by Products and Services:
Revenues									0	0	0
Houston Electric [Member] | Energy Products Or Services [Member]
Revenues by Products and Services:
Revenues									0	0	0
CERC Corp [Member]
Revenues by Products and Services:
Revenues									7,343	6,603	4,454
CERC Corp [Member] | Electric Delivery [Member]
Revenues by Products and Services:
Revenues									0	0	0
CERC Corp [Member] | Retail Gas Sales [Member]
Revenues by Products and Services:
Revenues									4,161	3,634	3,329
CERC Corp [Member] | Wholesale Gas Sales [Member]
Revenues by Products and Services:
Revenues									3,008	2,811	977
CERC Corp [Member] | Gas Transportation and Processing [Member]
Revenues by Products and Services:
Revenues									32	29	23
CERC Corp [Member] | Energy Products Or Services [Member]
Revenues by Products and Services:
Revenues									$ 142	$ 129	$ 125

Supplemental Disclosure of Ca_3

Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest, net of capitalized interest		$ 363	$ 378	$ 406
Income taxes (refunds), net		89	15	(104)
Accounts payable related to capital expenditures		201	144	87
Capital distribution associated with the Internal Spin		0	0	0
Cash and cash equivalents	[1]	4,231	260
Total cash, cash equivalents and restricted cash shown in Statements of Consolidated Cash Flows		4,278	296	381	$ 300
Other, net [Member]
Interest income		28	2	1
Cash and Cash Equivalents [Member]
Temporary investments		3,900
Prepaid Expenses and Other Current Assets [Member]
Restricted cash		46	35
Other Noncurrent Assets [Member]
Restricted cash		1	1
Houston Electric [Member]
Interest, net of capitalized interest		200	205	209
Income taxes (refunds), net		154	76	128
Accounts payable related to capital expenditures		124	104	65
Capital distribution associated with the Internal Spin		0	0	0
Cash and cash equivalents	[2]	335	238
Total cash, cash equivalents and restricted cash shown in Statements of Consolidated Cash Flows		370	274	381	$ 299
Houston Electric [Member] | Other, net [Member]
Interest Income, Other		4	2	1
Houston Electric [Member] | Prepaid Expenses and Other Current Assets [Member]
Restricted cash		34	35
Houston Electric [Member] | Other Noncurrent Assets [Member]
Restricted cash		1	1
CERC Corp [Member]
Interest, net of capitalized interest		105	116	116
Income taxes (refunds), net		3	4	3
Accounts payable related to capital expenditures		80	56	35
Capital distribution associated with the Internal Spin		1,473	0	$ 0
Cash and cash equivalents		14	12
Total cash, cash equivalents and restricted cash shown in Statements of Consolidated Cash Flows		25	12
CERC Corp [Member] | Prepaid Expenses and Other Current Assets [Member]
Restricted cash		11	0
CERC Corp [Member] | Other Noncurrent Assets [Member]
Restricted cash		0	0
Bond Companies [Member] | Houston Electric [Member]
Cash and cash equivalents		$ 335	$ 230
[1]	CenterPoint Energy’s Cash and cash equivalents as of December 31, 2018 included $3.9 billion of temporary investments resulting from the Merger financings. CenterPoint Energy recorded interest income of $28 million, $2 million and $1 million for the years ended December 31, 2018, 2017 and 2016, respectively, in Other, net on CenterPoint Energy’s Statements of Consolidated Income. See Notes 13 and 14 for further details related to the Merger financings.
[2]	Houston Electric’s Cash and cash equivalents as of December 31, 2018 and 2017 included $335 million and $230 million, respectively, of cash related to the Bond Companies. Houston Electric recorded interest income of $4 million, $2 million and $1 million for the years ended December 31, 2018, 2017 and 2016, respectively, in Other, net on Houston Electric’s Statement of Consolidated Income.

Related Party Transactions (H_3

Related Party Transactions (Houston Electric and CERC) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Capital distribution to parent associated with the Internal Spin		$ 0	$ 0	$ 0
Houston Electric [Member]
Related Party Transaction [Line Items]
Cash dividends paid to parent		209	180	135
Cash contribution from parent		200	0	374
Capital distribution to parent associated with the Internal Spin		0	0	0
Houston Electric [Member] | Other, net [Member]
Related Party Transaction [Line Items]
Interest income (expense), net (1)	[1]	1	2	(4)
Houston Electric [Member] | Operation And Maintenance Expense [Member]
Related Party Transaction [Line Items]
Net affiliate service charges (billings)		(17)	(9)	(8)
Houston Electric [Member] | Operation And Maintenance Expense [Member] | CenterPoint Energy [Member]
Related Party Transaction [Line Items]
Corporate service charges		190	188	179
Houston Electric [Member] | Accounts and notes receivable (payable) - affiliate companies [Member]
Related Party Transaction [Line Items]
Money pool investments (borrowings) (1)	[2]	$ (1)	$ (60)
Houston Electric [Member] | Investments [Member]
Related Party Transaction [Line Items]
Weighted average interest rate		2.42%	1.90%
CERC Corp [Member]
Related Party Transaction [Line Items]
Cash dividends paid to parent		$ 360	$ 601	643
Cash contribution from parent		960	38	72
Capital distribution to parent associated with the Internal Spin		1,473	0	0
CERC Corp [Member] | Other, net [Member]
Related Party Transaction [Line Items]
Interest income (expense), net (1)	[1]	0	0	0
CERC Corp [Member] | Operation And Maintenance Expense [Member]
Related Party Transaction [Line Items]
Net affiliate service charges (billings)		17	9	8
CERC Corp [Member] | Operation And Maintenance Expense [Member] | CenterPoint Energy [Member]
Related Party Transaction [Line Items]
Corporate service charges		147	128	$ 125
CERC Corp [Member] | Accounts and notes receivable (payable) - affiliate companies [Member]
Related Party Transaction [Line Items]
Money pool investments (borrowings) (1)	[2]	$ 114	$ (570)
CERC Corp [Member] | Investments [Member]
Related Party Transaction [Line Items]
Weighted average interest rate		2.42%	1.90%
[1]	Interest income is included in Other, net and interest expense is included in Interest and other finance charges on Houston Electric’s and CERC’s respective Statements of Consolidated Income.
[2]	Included in Accounts and notes receivable (payable)–affiliated companies in Houston Electric’s and CERC’s Consolidated Balance Sheets.

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event [Member] - Enable Midstream Partners [Member] $ / shares in Units, $ in Millions	Feb. 08, 2019USD ($)$ / shares
Series A Preferred Units [Member]
Subsequent Event [Line Items]
Declaration Date	Feb. 8, 2019
Record Date	Feb. 8, 2019
Payment Date	Feb. 14, 2019
Distributions Declared, Per Unit | $ / shares	$ 0.625
Expected cash distribution on Enable's Series A Preferred Units | $	$ 9
Common Units [Member]
Subsequent Event [Line Items]
Declaration Date	Feb. 8, 2019
Record Date	Feb. 19, 2019
Payment Date	Feb. 26, 2019
Distributions Declared, Per Unit | $ / shares	$ 0.318
Expected cash distribution on Enable Common Units | $	$ 74