Unconsolidated Affiliate (CenterPoint Energy and CERC) (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended
		May 05, 2020	Apr. 01, 2020	Mar. 31, 2020		Mar. 31, 2019	Dec. 31, 2019
Enable Units [Abstract]
Preferred units – unconsolidated affiliate				$ 363			$ 363
Percentage of sales that trigger right of first refusal				5.00%
Enable Distributions [Abstract]
Proceeds from Equity Method Investment, Distribution				$ 70		$ 74
Total distributions received from Enable				86		83
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
Equity in earnings of unconsolidated affiliate, net				(1,475)		62
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Investment in unconsolidated affiliates				$ 850			2,408
OGE [Member]
Enable Units [Abstract]
Percentage of sales that trigger right of first refusal				5.00%
Proliance Holdings LLC [Member]
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
Equity in earnings of unconsolidated affiliate, net				$ 0		0
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Investment in unconsolidated affiliates				$ 2			2
Enable Midstream Partners [Member]
Enable Partnership Interest [Abstract]
Ownership percentage of equity method investment	[1]			53.70%
Limited partner ownership interest	[1]			100.00%
Enable Units [Abstract]
Equity Method Investments, Fair Value Disclosure				$ 848
Maximum incentive distribution right				50.00%
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
Operating revenues				$ 648		795
Cost of sales, excluding depreciation and amortization				226		378
Depreciation and amortization				104		105
Equity Method Investment, Summarized Financial Information, Impairment of Goodwill and Long-Lived Assets				28		0
Operating income				146		165
Net income attributable to Enable common units				103		113
CenterPoint Energy’s interest				55		61
Basis difference amortization (1)	[2]			12		12
Dilution Loss, Equity Method Investment				(1)		(11)
Impairment of CenterPoint Energy’s equity method investment in Enable				(1,541)		0
Equity in earnings of unconsolidated affiliate, net				(1,475)		62
Equity Method Investment, Summarized Financial Information, Assets and Liabilities [Abstract]
Current assets				333			389
Non-current assets				11,784			11,877
Current liabilities				391			780
Non-current liabilities				4,374			4,077
Non-controlling interest				27			37
Preferred equity				362			362
Accumulated other comprehensive loss				(9)			(3)
Enable partners’ equity				6,972			7,013
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s ownership interest in Enable partners’ equity				3,739			3,767
CenterPoint Energy’s basis difference (1)				(2,891)	[3]		(1,361)
Investment in unconsolidated affiliates				848			2,406
Enable Midstream Partners [Member] | Common Units [Member]
Enable Distributions [Abstract]
Proceeds from Equity Method Investment, Distribution				$ 77		$ 74
Distribution per share of common units				$ 0.3305	[4]	$ 0.3180
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Enable Distributions [Abstract]
Distributions received from Enable cost method investment				$ 9		$ 9
Distribution per share of Series A preferred units				$ 0.6250		$ 0.6250
Enable Midstream Partners [Member] | OGE [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[1]			25.50%
Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[1]			20.80%
Minimum [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Incentive distribution per unit				$ 0.2875
Maximum [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Incentive distribution per unit				$ 0.330625
Common Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Limited partner interest units held	[5]			233,856,623
Limited partner interest units held	[5]			435,443,494
Common Units [Member] | Enable Midstream Partners [Member] | OGE [Member]
Enable Units [Abstract]
Limited partner interest units held	[5]			110,982,805
Common Units [Member] | Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Units [Abstract]
Limited partner interest units held	[5]			90,604,066
Series A Preferred Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Preferred Units Held	[6]			14,520,000
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Natural gas expenses, includes transportation and storage costs				$ 27		$ 27
Accounts payable for natural gas purchases from Enable				9			9
Natural Gas Expenses [Member] | Enable Midstream Partners [Member] | CERC Corp [Member]
Transactions with Enable [Abstract]
Natural gas expenses, includes transportation and storage costs				27		$ 27
Accounts payable for natural gas purchases from Enable				$ 9			$ 9
Enable GP, LLC [Member] | CenterPoint Energy [Member]
Enable Units [Abstract]
Management rights ownership percentage	[7],[8]			50.00%
Incentive Distribution Right, Percentage	[8],[9]			40.00%
Enable GP, LLC [Member] | OGE [Member]
Enable Units [Abstract]
Management rights ownership percentage	[7]			50.00%
Incentive Distribution Right, Percentage	[9]			60.00%
Common Units [Member] | Subsequent Event [Member] | Enable Midstream Partners [Member]
Enable Distributions [Abstract]
Proceeds from Equity Method Investment, Distribution		$ 39
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Percentage Reduction of Dividend or Distribution Amount			50.00%
Distribution Made to Limited Partner, Distributions Declared, Per Unit	[10]	$ 0.16525
Previous Dividend or Distribution [Member] | Common Units [Member] | Subsequent Event [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Distribution Made to Limited Partner, Distributions Declared, Per Unit			$ 0.3305
Revised Dividend or Distribution [Member] | Common Units [Member] | Subsequent Event [Member] | Enable Midstream Partners [Member]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Distribution Made to Limited Partner, Distributions Declared, Per Unit			$ 0.16525

[1] Excludes the Enable Series A Preferred Units owned by CenterPoint Energy.

[2] 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 through the year 2048.

[3] Includes the impairment of CenterPoint Energy’s equity method investment in Enable of $1,541 million recorded during the three months ended March 31, 2020. The basis difference is being amortized through the year 2048.

[4] On April 1, 2020, Enable announced a 50% reduction in its quarterly distribution per common unit from $0.3305 to $0.16525.

[5] Held indirectly through CNP Midstream by CenterPoint Energy.

[6] The carrying amount of the Enable Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of March 31, 2020 and $363 million as of December 31, 2019. No impairment charges or adjustment due to observable price changes were required or recorded during the current or prior reporting periods.

[7] 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.

[8] Held indirectly through CNP Midstream.

[9] Enable previously 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.

[10] On April 1, 2020, Enable announced a reduction in its quarterly distributions per common unit from $0.3305 distributed for the fourth quarter 2019 to $0.16525, representing a 50% reduction.