Divestitures (CenterPoint Energy and CERC) (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2020		Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019		Dec. 31, 2019
Discontinued Operation, Additional Disclosures [Abstract]
Cash proceeds from sale					$ 1,136		$ 0
Goodwill Impairment		$ 0		$ 0	185		0
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Receivables, net									$ 637
Accrued unbilled revenues									117
Natural gas inventory									67
Materials and supplies									6
Non-trading derivative assets									136
Other									39
Total current assets held for sale		0			0				1,002
Property, plant and equipment, net									321
Goodwill									282
Non-trading derivative assets									58
Other									301
Total non-current assets held for sale		0			0				962
Total assets held for sale									1,964
Accounts payable									344
Taxes accrued									2
Non-trading derivative liabilities									44
Other									65
Total current liabilities held for sale		0			0				455
Non-trading derivative liabilities									14
Benefit obligations									4
Other									25
Total non-current liabilities held for sale		0			0				43
Total liabilities held for sale									498
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues		0		1,117	1,417		3,683
Non-utility cost of revenues		0		811	1,158		2,929
Operation and maintenance		0		252	218		577
Depreciation and amortization		0		18	0		49
Taxes other than income taxes		0		1	4		1
Total		0		1,082	1,380		3,556
Income (loss) from Discontinued Operations before income taxes		0		35	37		127
Gain (loss) on classification to held for sale, net (2)	[1]	(6)		0	(198)		0
Income tax expense (benefit)		0		16	21		38
Net income (loss) from Discontinued Operations		(6)		19	(182)		89
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization					0		49
Infrastructure Services Disposal Group [Member]
Discontinued Operation, Additional Disclosures [Abstract]
Sales price of outstanding equity interests		850			850
Cash proceeds from sale		850
Net deferred tax liabilities on sale recognized as deferred income tax benefit by CenterPoint Energy		127			127
Current tax expense (benefit) of cash taxes payable upon sale		2			(157)
Goodwill Impairment					82
Cost to sell					14
Pre-tax gain on sale		9			6
Maximum contractual exposure under Securities Purchase Agreement		21			21
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Receivables, net									192
Accrued unbilled revenues									109
Natural gas inventory									0
Materials and supplies									6
Non-trading derivative assets									0
Other									4
Total current assets held for sale									311
Property, plant and equipment, net									295
Goodwill									220
Non-trading derivative assets									0
Other									234
Total non-current assets held for sale									749
Total assets held for sale									1,060
Accounts payable									45
Taxes accrued									2
Non-trading derivative liabilities									0
Other									40
Total current liabilities held for sale									87
Non-trading derivative liabilities									0
Benefit obligations									0
Other									16
Total non-current liabilities held for sale									16
Total liabilities held for sale									103
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues		0		377	250		849	[2]
Non-utility cost of revenues		0		96	50		228	[2]
Operation and maintenance		0		235	184		526	[2]
Depreciation and amortization		0		15	0		39	[2]
Taxes other than income taxes		0		1	1		1	[2]
Total		0		347	235		794	[2]
Income (loss) from Discontinued Operations before income taxes		0		30	15		55	[2]
Gain (loss) on classification to held for sale, net (2)	[1]	(9)		0	(102)		0	[2]
Income tax expense (benefit)		(1)		15	24		21	[2]
Net income (loss) from Discontinued Operations		(8)		15	(111)		34	[2]
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization					0		39	[2]
Amortization of intangible assets in Non-utility cost of revenues					0		15	[2]
Write-down of natural gas inventory					0		0	[2]
Capital expenditures					16		53	[2]
Accounts payable related to capital expenditures					2		1	[2]
Discontinued Operation, Continuing Involvement [Abstract]
Pipeline construction and repair services capitalized		0	[3]	45	34	[3]	112	[4]
Pipeline construction and repair services charges		0	[3]	1	1	[3]	5	[4]
Energy Services Disposal Group [Member]
Discontinued Operation, Additional Disclosures [Abstract]
Sales price of outstanding equity interests		400			400
Cash proceeds from sale		286
Receivable from sale of disposal group		79			79
Net deferred tax liabilities on sale recognized as deferred income tax benefit by CenterPoint Energy		3			3
Current tax expense (benefit) of cash taxes payable upon sale		(1)			(4)
Goodwill Impairment					62
Loss from reclassification to held for sale		0			31
Cost to sell		0			6
Pre-tax gain on sale		(3)			(3)
Outstanding obligation related to AMAs		31			31				0
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Receivables, net									445
Accrued unbilled revenues									8
Natural gas inventory									67
Materials and supplies									0
Non-trading derivative assets									136
Other									35
Total current assets held for sale									691
Property, plant and equipment, net									26
Goodwill									62
Non-trading derivative assets									58
Other									67
Total non-current assets held for sale									213
Total assets held for sale									904
Accounts payable									299
Taxes accrued									0
Non-trading derivative liabilities									44
Other									25
Total current liabilities held for sale									368
Non-trading derivative liabilities									14
Benefit obligations									4
Other									9
Total non-current liabilities held for sale									27
Total liabilities held for sale									395
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues		0		740	1,167		2,834
Non-utility cost of revenues		0		715	1,108		2,701
Operation and maintenance		0		17	34		51
Depreciation and amortization		0		3	0		10
Taxes other than income taxes		0		0	3		0
Total		0		735	1,145		2,762
Income (loss) from Discontinued Operations before income taxes		0		5	22		72
Gain (loss) on classification to held for sale, net (2)	[1]	3		0	(96)		0
Income tax expense (benefit)		1		1	(3)		17
Net income (loss) from Discontinued Operations		2		4	(71)		55
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization					0		10
Amortization of intangible assets in Non-utility cost of revenues					0		0
Write-down of natural gas inventory					3		5
Capital expenditures					1		12
Accounts payable related to capital expenditures					4		1
Discontinued Operation, Continuing Involvement [Abstract]
Transportation revenue		0		33	34	[5]	81
Natural gas expense		0		10	48	[5]	90
CERC Corp [Member]
Discontinued Operation, Additional Disclosures [Abstract]
Cash proceeds from sale					286		0
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Total current assets held for sale		0			0				691
Total non-current assets held for sale		0			0				213
Total current liabilities held for sale		0			0				368
Total non-current liabilities held for sale		0			0				27
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Income tax expense (benefit)		1		2	(2)		15
Net income (loss) from Discontinued Operations		2		3	(66)		57
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization					0		10
CERC Corp [Member] | Infrastructure Services Disposal Group [Member]
Discontinued Operation, Continuing Involvement [Abstract]
Pipeline construction and repair services capitalized		0		3	0	[3]	12
Pipeline construction and repair services charges		0		1	1	[3]	2
CERC Corp [Member] | Energy Services Disposal Group [Member]
Discontinued Operation, Additional Disclosures [Abstract]
Net deferred tax liabilities on sale recognized as deferred income tax benefit by CenterPoint Energy		3			3
Current tax expense (benefit) of cash taxes payable upon sale		(1)			(4)
Goodwill Impairment					62
Pre-tax gain on sale		(3)			(3)
Outstanding obligation related to AMAs		31			31				0
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Receivables, net									445
Accrued unbilled revenues									8
Natural gas inventory									67
Materials and supplies									0
Non-trading derivative assets									136
Other									35
Total current assets held for sale									691
Property, plant and equipment, net									26
Goodwill									62
Non-trading derivative assets									58
Other									67
Total non-current assets held for sale									213
Total assets held for sale									904
Accounts payable									299
Taxes accrued									0
Non-trading derivative liabilities									44
Other									25
Total current liabilities held for sale									368
Non-trading derivative liabilities									14
Benefit obligations									4
Other									9
Total non-current liabilities held for sale									27
Total liabilities held for sale									$ 395
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues		0		740	1,167		2,834
Non-utility cost of revenues		0		715	1,108		2,701
Operation and maintenance		0		17	34		51
Depreciation and amortization		0		3	0		10
Taxes other than income taxes		0		0	3		0
Total		0		735	1,145		2,762
Income (loss) from Discontinued Operations before income taxes		0		5	22		72
Gain (loss) on classification to held for sale, net (2)	[1]	3		0	(90)		0
Income tax expense (benefit)		1		2	(2)		15
Net income (loss) from Discontinued Operations		2		3	(66)		57
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization					0		10
Amortization of intangible assets in Non-utility cost of revenues					0		0
Write-down of natural gas inventory					3		5
Capital expenditures					1		12
Accounts payable related to capital expenditures					4		1
Discontinued Operation, Continuing Involvement [Abstract]
Transportation revenue		0		33	34	[5]	81
Natural gas expense		$ 0		$ 10	$ 47	[5]	$ 89

[1] Loss from classification to held for sale is inclusive of goodwill impairment, gains and losses recognized upon sale, and for CenterPoint Energy, its costs to sell.

[2] Reflects February 1, 2019 to September 30, 2019 results only due to the Merger.

[3] Represents charges for the period January 1, 2020 until the closing of the sale of the Infrastructure Services Disposal Group.

[4] Represents charges for the period beginning February 1, 2019 due to the Merger.

[5] Represents charges for the period January 1, 2020 until the closing of the sale of the Energy Services Disposal Group.