Equity (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended
		May 06, 2020	Apr. 24, 2020	Mar. 31, 2020	Mar. 31, 2019
Class of Stock [Line Items]
Dividends declared per share				$ 0.2900	$ 0.0000
Preferred stock dividend requirement				$ 29	$ 29
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance				(98)	(108)
Other comprehensive loss from unconsolidated affiliates, net of tax				(3)	0
Actuarial losses	[1]			2	2
Reclassification of deferred loss from cash flow hedges realized in net income				0	1
Tax expense				(1)	(1)
Net current period other comprehensive income (loss)				(2)	1
Ending Balance				$ (100)	$ (107)
Common Stock [Member]
Class of Stock [Line Items]
Dividends declared per share				$ 0.2875	$ 0.2775
Dividends paid per share				$ 0.2900	$ 0.2875
Total dividends paid				$ 145	$ 144
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividends declared				$ 30.6250	$ 0.0000
Dividends paid per share				$ 30.6250	$ 32.1563
Total dividends paid				$ 25	$ 26
Preferred stock dividend requirement				$ 12	$ 12
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividends declared				$ 17.5000	$ 0.0000
Dividends paid per share				$ 17.5000	$ 17.5000
Total dividends paid				$ 17	$ 17
Preferred stock dividend requirement				17	17
Houston Electric [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance				(15)	(14)
Other comprehensive loss from unconsolidated affiliates, net of tax				0	0
Actuarial losses	[1]			0	0
Reclassification of deferred loss from cash flow hedges realized in net income				0	0
Tax expense				0	0
Net current period other comprehensive income (loss)				0	(1)
Ending Balance				(15)	(15)
CERC Corp [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance				10	5
Other comprehensive loss from unconsolidated affiliates, net of tax				0	0
Actuarial losses	[1]			0	0
Reclassification of deferred loss from cash flow hedges realized in net income				0	0
Tax expense				0	0
Net current period other comprehensive income (loss)				0	0
Ending Balance				10	5
Interest Rate Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications	[2]			0	(1)
Interest Rate Contract [Member] | Houston Electric [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications	[2]			0	(1)
Interest Rate Contract [Member] | CERC Corp [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications	[2]			$ 0	$ 0
First Quarter 2020 [Member] | Common Stock [Member]
Class of Stock [Line Items]
Declaration Date				Feb. 03, 2020
Record Date				Feb. 20, 2020
Payment Date				Mar. 12, 2020
Dividends paid per share				$ 0.2900
Total dividends paid				$ 145
First Quarter 2020 [Member] | Series A Preferred Stock [Member]
Class of Stock [Line Items]
Declaration Date				Feb. 03, 2020
Record Date				Feb. 14, 2020
Payment Date				Mar. 02, 2020
Dividends paid per share				$ 30.6250
Total dividends paid				$ 25
First Quarter 2020 [Member] | Series B Preferred Stock [Member]
Class of Stock [Line Items]
Declaration Date				Feb. 03, 2020
Record Date				Feb. 14, 2020
Payment Date				Mar. 02, 2020
Dividends paid per share				$ 17.5000
Total dividends paid				$ 17
First Quarter 2019 [Member] | Common Stock [Member]
Class of Stock [Line Items]
Declaration Date					Dec. 12, 2018
Record Date					Feb. 21, 2019
Payment Date					Mar. 14, 2019
Dividends paid per share					$ 0.2875
Total dividends paid					$ 144
First Quarter 2019 [Member] | Series A Preferred Stock [Member]
Class of Stock [Line Items]
Declaration Date					Dec. 12, 2018
Record Date					Feb. 15, 2019
Payment Date					Mar. 01, 2019
Dividends paid per share					$ 32.1563
Total dividends paid					$ 26
First Quarter 2019 [Member] | Series B Preferred Stock [Member]
Class of Stock [Line Items]
Declaration Date					Dec. 12, 2018
Record Date					Feb. 15, 2019
Payment Date					Mar. 01, 2019
Dividends paid per share					$ 17.5000
Total dividends paid					$ 17
Subsequent Event [Member] | Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Issued		725,000
Convertible Preferred Stock, Shares Issued upon Conversion		47,354,670
Preferred Stock, Liquidation Preference Per Share		$ 1,000
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Proceeds from Issuance of Convertible Preferred Stock		$ 725
Preferred Stock, Convertible, Conversion Price		$ 15.31
Preferred Stock, Convertible, Conversion Limit		4.90%
Preferred Stock, Convertible, Percent Outstanding Shares To Amend		66 2/3%
Subsequent Event [Member] | Common Stock [Member]
Class of Stock [Line Items]
Dividends declared per share	[3]		$ 0.1500
Declaration Date			Apr. 24, 2020
Record Date			May 21, 2020
Payment Date			Jun. 11, 2020
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Stock Issued During Period, Shares, New Issues		41,977,612
Shares Issued, Price Per Share		$ 16.08
Proceeds from Issuance of Common Stock		$ 675
Subsequent Event [Member] | Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividends declared			$ 17.5000
Declaration Date			Apr. 24, 2020
Record Date			May 15, 2020
Payment Date			Jun. 01, 2020

[1] Amounts are included in the computation of net periodic cost and are reflected in Other income (expense), net in each of the Registrants’ respective Statements of Consolidated Income.

[2] Gains and losses are reclassified from Accumulated other comprehensive income into income when the hedged transactions affect earnings. The reclassification amounts are included in Interest and other finance charges in each of the Registrants’ respective Statements of Consolidated Income. Over the next twelve months estimated amortization from Accumulated Comprehensive Income into income is expected to be immaterial.

[3] On April 1, 2020, in response to the reduction in cash flow related to the reduction in Enable quarterly common unit distributions announced by Enable on April 1, 2020, CenterPoint Energy announced a reduction of its quarterly common stock dividend per share from $0.2900 to $0.1500.