Held for Sale and Discontinued Operations (CenterPoint Energy and CERC) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019		Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred Tax Liabilities, Net		$ 125
Goodwill Impairment		185	$ 0
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Receivables, net		571			$ 637
Accrued unbilled revenues		59			117
Natural gas inventory		52			67
Materials and supplies		6			6
Non-trading derivative assets		213			136
Property, plant and equipment, net		342
Goodwill		138
Loss on assets held for sale		(70)
Other		336			39
Total current assets held for sale		1,647			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			962
Total assets held for sale					1,964
Accounts payable		252			344
Taxes accrued		2			2
Non-trading derivative liabilities		36			44
Benefit obligations		4
Other		89			65
Total current liabilities held for sale		383			455
Non-trading derivative liabilities					14
Benefit obligations					4
Other					25
Total non-current liabilities held for sale		0			43
Total liabilities held for sale					498
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues		1,108	1,388
Non-utility cost of revenues		852	1,228
Operation and maintenance		183	113
Depreciation and amortization		0	13
Taxes other than income taxes		2	0
Total		1,037	1,354
Income (loss) from Discontinued Operations before income taxes		71	34
Loss from reclassification to held for sale	[1]	234
Income tax expense (benefit)		(17)	8
Net income (loss) from Discontinued Operations		(146)	26
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization		0	13
Infrastructure Services [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill Impairment		82
Cost to sell		14
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Receivables, net		216			192
Accrued unbilled revenues		57			109
Materials and supplies		6			6
Property, plant and equipment, net		313
Goodwill		138
Loss on assets held for sale		0
Other		242			4
Total current assets held for sale		972			311
Property, plant and equipment, net					295
Goodwill					220
Other					234
Total non-current assets held for sale					749
Total assets held for sale					1,060
Accounts payable		46			45
Taxes accrued		2			2
Other		60			40
Total current liabilities held for sale		108			87
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		222	146	[2]
Non-utility cost of revenues		44	43	[2]
Operation and maintenance		163	96	[2]
Depreciation and amortization		0	9	[2]
Taxes other than income taxes		1	0	[2]
Total		208	148	[2]
Income (loss) from Discontinued Operations before income taxes		14	(2)	[2]
Loss from reclassification to held for sale	[1]	96
Income tax expense (benefit)		(5)
Net income (loss) from Discontinued Operations		(77)	(2)	[2]
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization		0	9
Amortization of intangible assets in Non-utility cost of revenues			2
Capital expenditures		16	27
Accounts payable related to capital expenditures		2	3
Discontinued Operation, Continuing Involvement [Abstract]
Pipeline construction and repair services charges		1	4	[3]
Pipeline construction and repair services capitalized		34	19	[3]
Energy Services [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill Impairment		62
Loss from reclassification to held for sale		70
Cost to sell		6
Deferred Tax Asset		3
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Receivables, net		355			445
Accrued unbilled revenues		2			8
Natural gas inventory		52			67
Non-trading derivative assets		213			136
Property, plant and equipment, net		29
Loss on assets held for sale		(70)
Other		94			35
Total current assets held for sale		675			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		206			299
Taxes accrued		0			0
Non-trading derivative liabilities		36			44
Benefit obligations		4
Other		29			25
Total current liabilities held for sale		275			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		886	1,242
Non-utility cost of revenues		808	1,185
Operation and maintenance		20	17
Depreciation and amortization		0	4
Taxes other than income taxes		1	0
Total		829	1,206
Income (loss) from Discontinued Operations before income taxes		57	36
Loss from reclassification to held for sale	[1]	138
Income tax expense (benefit)		(12)	8
Net income (loss) from Discontinued Operations		(69)	28
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization			4
Write-down of natural gas inventory		3	1
Capital expenditures		1	1
Accounts payable related to capital expenditures		4	6
Discontinued Operation, Continuing Involvement [Abstract]
Transportation revenue		16	16
Natural gas expense		45	64
CERC Corp [Member]
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Total current assets held for sale		675			691
Total non-current assets held for sale		0			213
Total current liabilities held for sale		275			368
Total non-current liabilities held for sale		0			27
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Income tax expense (benefit)		(11)	8
Net income (loss) from Discontinued Operations		(64)	28
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization		0	4
CERC Corp [Member] | Infrastructure Services [Member]
Discontinued Operation, Continuing Involvement [Abstract]
Pipeline construction and repair services charges		1	1	[3]
Pipeline construction and repair services capitalized		0	1	[3]
CERC Corp [Member] | Energy Services [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill Impairment		62
Loss from reclassification to held for sale		70
Cost to sell		6
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Receivables, net		355			445
Accrued unbilled revenues		2			8
Natural gas inventory		52			67
Non-trading derivative assets		213			136
Property, plant and equipment, net		29
Loss on assets held for sale		(70)
Other		94			35
Total current assets held for sale		675			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		206			299
Taxes accrued		0			0
Non-trading derivative liabilities		36			44
Benefit obligations		4
Other		29			25
Total current liabilities held for sale		275			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		886	1,242
Non-utility cost of revenues		808	1,185
Operation and maintenance		20	17
Depreciation and amortization		0	4
Taxes other than income taxes		1	0
Total		829	1,206
Income (loss) from Discontinued Operations before income taxes		57	36
Loss from reclassification to held for sale	[1]	132
Income tax expense (benefit)		(11)	8
Net income (loss) from Discontinued Operations		(64)	28
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization			4
Write-down of natural gas inventory		3	1
Capital expenditures		1	1
Accounts payable related to capital expenditures		4	6
Discontinued Operation, Continuing Involvement [Abstract]
Transportation revenue		16	16
Natural gas expense		$ 44	$ 63

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

[2] Reflects February 1, 2019 to March 31, 2019 results only due to the Merger.

[3] Represents charges for the period February 1, 2019 through March 31, 2019 only due to the Merger.