Unconsolidated Affiliate (CenterPoint Energy and CERC) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Feb. 16, 2021	Dec. 31, 2020
Enable Units [Abstract]
Proceeds from Merger - Interest			$ 5
Merger Exchange Ratio			0.8595
Proceeds from Merger - Preferred Units			$ 385
Preferred units – unconsolidated affiliate	$ 363			$ 363
Percentage of sales that trigger right of first refusal	5.00%
Enable Distributions [Abstract]
Distributions from unconsolidated affiliates	$ 39	$ 70
Total distributions received from Enable	48	86
Enable Income Statement [Abstract]
Operating revenues	2,547	2,167
Depreciation and amortization	307	282
Operating income	453	217
Net income attributable to Enable common units	334	(1,228)
Reconciliation of Equity in Earnings (Losses), net [Abstract]
Equity in earnings of unconsolidated affiliate, net	108	(1,475)
Assets [Abstract]
Current assets	3,219			2,920
Liabilities and Equity [Abstract]
Current liabilities	4,326			4,825
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Investment in unconsolidated affiliates	853			783
CERC Corp [Member]
Enable Income Statement [Abstract]
Operating revenues	1,177	1,011
Depreciation and amortization	80	74
Operating income	218	200
Assets [Abstract]
Current assets	1,000			707
Liabilities and Equity [Abstract]
Current liabilities	$ 654			726
Enable Midstream Partners [Member]
Enable Units [Abstract]
Share Price	$ 6.48
Enable Income Statement [Abstract]
Operating revenues	$ 970	648
Cost of sales, excluding depreciation and amortization	519	226
Depreciation and amortization	106	104
Goodwill and Intangible Asset Impairment	0	28
Operating income	206	146
Net income attributable to Enable common units	155	103
Assets [Abstract]
Current assets	449			381
Non-current assets	11,315			11,348
Liabilities and Equity [Abstract]
Current liabilities	1,334			582
Non-current liabilities	3,249			4,052
Non-controlling interest	26			26
Preferred equity	362			362
Accumulated other comprehensive loss	(5)			(6)
Enable partners' equity	$ 6,798			6,713
OGE [Member]
Enable Units [Abstract]
Payment upon termination of partnership			$ 30
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	100.00%
Enable Units [Abstract]
Maximum incentive distribution right	50.00%
Reconciliation of Equity in Earnings (Losses), net [Abstract]
CenterPoint Energy’s interest	$ 83	55
Basis difference amortization (1)	25	12
Loss on dilution, net of proportional basis difference recognition	0	(1)
Impairment of CenterPoint Energy’s equity method investment in Enable	0	(1,541)
Equity in earnings of unconsolidated affiliate, net	108	(1,475)
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s ownership interest in Enable partners’ equity	3,645			3,601
CenterPoint Energy’s basis difference (1)	(2,793)			(2,819)
Investment in unconsolidated affiliates	852			782
Incentive Distribution	$ 0
Enable Midstream Partners [Member] | Variable Interest Entity, Not Primary Beneficiary
Enable Partnership Interest [Abstract]
Ownership percentage of equity method investment	53.70%
Enable Midstream Partners [Member] | Common Units [Member]
Enable Distributions [Abstract]
Distributions from unconsolidated affiliates	$ 39	$ 77
Distribution per share of common units	$ 0.16525	$ 0.3305
Enable Midstream Partners [Member] | Preferred Stock [Member]
Enable Distributions [Abstract]
Distributions received from Enable cost method investment	$ 9	$ 9
Distribution per share of Series A preferred units	$ 0.62500	$ 0.6250
Enable Midstream Partners [Member] | OGE [Member]
Enable Partnership Interest [Abstract]
Ownership percentage of equity method investment	25.50%
Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Partnership Interest [Abstract]
Ownership percentage of equity method investment	20.80%
Enable Midstream Partners [Member] | CenterPoint Energy and OGE [Member]
Enable Partnership Interest [Abstract]
Ownership percentage of equity method investment	79.20%
Other [Member]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Investment in unconsolidated affiliates	$ 1			1
Maximum [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Incentive distribution per unit	$ 0.330625
Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Accounts receivable for amounts billed for services provided to Enable	$ 1			1
Enable Midstream Partners [Member] | CERC Corp [Member]
Transactions with Enable [Abstract]
Accounts receivable for amounts billed for services provided to Enable	1			1
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Natural gas expenses, including transportation and storage costs	32	$ 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, including transportation and storage costs	32	$ 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	50.00%
Incentive Distribution Right, Percentage	40.00%
Enable GP, LLC [Member] | OGE [Member]
Enable Units [Abstract]
Management rights ownership percentage	50.00%
Incentive Distribution Right, Percentage	60.00%
Common Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Limited partner interest units held	435,846,766
Common Units [Member] | Enable Midstream Partners [Member] | Variable Interest Entity, Not Primary Beneficiary
Enable Units [Abstract]
Limited partner interest units held	233,856,623
Common Units [Member] | Enable Midstream Partners [Member] | OGE [Member]
Enable Units [Abstract]
Limited partner interest units held	110,982,805
Common Units [Member] | Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Units [Abstract]
Limited partner interest units held	91,007,338
Series A Preferred Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Preferred Units Held	14,520,000
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Cost-method Investments, Other than Temporary Impairment	$ 0
Series A Preferred Units [Member] | Enable Midstream Partners [Member] | OGE [Member]
Enable Units [Abstract]
Preferred Units Held	0
Series A Preferred Units [Member] | Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Units [Abstract]
Limited partner interest units held	0