Unconsolidated Affiliate (CenterPoint Energy and CERC) (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		9 Months Ended
		Apr. 01, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 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]
Distributions from unconsolidated affiliates					$ 109	$ 226
Total distributions received from Enable			48	$ 86	182	253
Income Statement [Abstract]
Operating revenues			1,622	1,658	5,364	5,545
Depreciation and amortization			306	316	885	938
Operating income			302	357	754	797
Net income attributable to Enable common units			69	241	(1,100)	546
Equity in earnings of unconsolidated affiliate, net			(67)	77	(1,499)	213
Assets [Abstract]
Current assets			2,785		2,785				3,937
Liabilities and Equity [Abstract]
Current liabilities			3,830		3,830				3,978
Enable partners’ equity			8,388	8,346	8,388	8,346			8,359
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Investment in unconsolidated affiliates			749		749				2,408
Common Units [Member]
Liabilities and Equity [Abstract]
Enable partners’ equity			5	5	5	5	$ 5		5	$ 5	$ 5
Series A Preferred Units [Member]
Liabilities and Equity [Abstract]
Enable partners’ equity			2,456	1,740	2,456	1,740	2,441		1,740	1,740	1,740
CERC Corp [Member]
Transactions with Enable [Abstract]
Natural gas expenses, including transportation and storage costs	[1]		23	0	23	0
Income Statement [Abstract]
Operating revenues			426	420	1,920	2,158
Depreciation and amortization			78	72	226	218
Operating income			14	18	256	205
Assets [Abstract]
Current assets			568		568				1,489
Liabilities and Equity [Abstract]
Current liabilities			606		606				1,111
Enable partners’ equity			2,345	2,483	2,345	2,483			2,641
CERC Corp [Member] | Common Units [Member]
Liabilities and Equity [Abstract]
Enable partners’ equity			$ 0	0	$ 0	0	$ 0		0	$ 0	$ 0
OGE [Member]
Enable Units [Abstract]
Percentage of sales that trigger right of first refusal					5.00%
Enable Midstream Partners [Member]
Enable Partnership Interest [Abstract]
Ownership percentage of equity method investment	[2]		53.70%		53.70%
Limited partner ownership interest	[2]				100.00%
Enable Units [Abstract]
Equity Method Investments, Fair Value Disclosure								$ 848
Maximum incentive distribution right					50.00%
Income Statement [Abstract]
Operating revenues			$ 596	699	$ 1,759	2,229
Cost of sales, excluding depreciation and amortization			250	263	653	958
Depreciation and amortization			105	108	314	323
Goodwill and Intangible Asset Impairment			0	0	28	0
Operating income			100	175	326	507
Net income attributable to Enable common units			(173)	123	(35)	351
CenterPoint Energy’s interest			(93)	66	(19)	189
Basis difference amortization (1)	[3]		26	11	62	35
Loss on dilution, net of proportional basis difference recognition			0	0	(1)	(11)
Impairment of CenterPoint Energy’s equity method investment in Enable			0	0	(1,541)	0
Equity in earnings of unconsolidated affiliate, net			(67)	77	(1,499)	213
Equity Method Investment's Impairment on an equity method investment					225
Assets [Abstract]
Current assets			373		373				389
Non-current assets			11,402		11,402				11,877
Liabilities and Equity [Abstract]
Current liabilities			644		644				780
Non-current liabilities			4,055		4,055				4,077
Non-controlling interest			26		26				37
Preferred equity			362		362				362
Accumulated other comprehensive loss			(7)		(7)				(3)
Enable partners’ equity			6,695		6,695				7,013
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s ownership interest in Enable partners’ equity			3,592		3,592				3,767
CenterPoint Energy’s basis difference (1)	[4]		(2,844)		(2,844)				(1,361)
Investment in unconsolidated affiliates			748		748				2,406
Enable Midstream Partners [Member] | Common Units [Member]
Enable Distributions [Abstract]
Distributions from unconsolidated affiliates	[5]		$ 39	$ 77	$ 155	$ 226
Distribution per share of common units	[5]		$ 0.16525	$ 0.3305	$ 0.6610	$ 0.9665
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Enable Distributions [Abstract]
Distributions received from Enable cost method investment			$ 9	$ 9	$ 27	$ 27
Distribution per share of Series A preferred units			$ 0.62500	$ 0.6250	$ 1.8750	$ 1.8750
Enable Midstream Partners [Member] | OGE [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[2]				25.50%
Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[2]				20.80%
Proliance Holdings LLC [Member]
Income Statement [Abstract]
Equity in earnings of unconsolidated affiliate, net			$ 0	$ 0	$ 0	$ 0
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Investment in unconsolidated affiliates			$ 1		$ 1				2
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	[6]		233,856,623		233,856,623
Limited partner interest units held	[6]		435,468,668		435,468,668
Common Units [Member] | Enable Midstream Partners [Member] | OGE [Member]
Enable Units [Abstract]
Limited partner interest units held	[6]		110,982,805		110,982,805
Preferred Units Held	[7]		0		0
Common Units [Member] | Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Units [Abstract]
Limited partner interest units held	[6]		90,629,240		90,629,240
Preferred Units Held	[7]		0		0
Series A Preferred Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Preferred Units Held	[7]		14,520,000		14,520,000
Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Accounts receivable for amounts billed for services provided to Enable			$ 1		$ 1				2
Enable Midstream Partners [Member] | CERC Corp [Member]
Transactions with Enable [Abstract]
Accounts receivable for amounts billed for services provided to Enable			1		1				2
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Natural gas expenses, including transportation and storage costs			17	17	61	62
Accounts payable for natural gas purchases from Enable			6		6				9
Natural Gas Expenses [Member] | Enable Midstream Partners [Member] | CERC Corp [Member]
Transactions with Enable [Abstract]
Natural gas expenses, including transportation and storage costs			17	$ 17	61	$ 62
Accounts payable for natural gas purchases from Enable			$ 6		$ 6				$ 9
Enable GP, LLC [Member] | CenterPoint Energy [Member]
Enable Units [Abstract]
Management rights ownership percentage	[8],[9]				50.00%
Incentive Distribution Right, Percentage	[9],[10]				40.00%
Enable GP, LLC [Member] | OGE [Member]
Enable Units [Abstract]
Management rights ownership percentage	[8]				50.00%
Incentive Distribution Right, Percentage	[10]				60.00%
Common Units [Member] | Enable Midstream Partners [Member]
Enable Distributions [Abstract]
Percentage Reduction of Dividend or Distribution Amount		50.00%
Previous Dividend or Distribution [Member] | Common Units [Member] | Enable Midstream Partners [Member]
Enable Distributions [Abstract]
Distribution Made to Limited Partner, Distributions Declared, Per Unit		$ 0.3305
Revised Dividend or Distribution [Member] | Common Units [Member] | Enable Midstream Partners [Member]
Enable Distributions [Abstract]
Distribution Made to Limited Partner, Distributions Declared, Per Unit		$ 0.16525

[1] Property, plant and equipment purchased from CenterPoint Energy at its net carrying value on the date of purchase.

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

[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 through the year 2048.

[4] Includes the impairment of CenterPoint Energy’s equity method investment in Enable of $1,541 million recorded during the nine months ended September 30, 2020. The basis difference is being amortized through the year 2048.

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

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

[7] The carrying amount of the Enable Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both September 30, 2020 and December 31, 2019. No impairment charges or adjustment due to observable price changes were required or recorded during the current or prior reporting periods.

[8] 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.

[9] Held indirectly through CNP Midstream.

[10] 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.