Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Benefits and compensation	$ 131	$ 121
Regulatory liabilities	365	378
Loss and credit carryforwards	76	84
Asset retirement obligations	96	95
Other	124	49
Valuation allowance	(10)	(10)
Total deferred tax assets	782	717
Deferred tax liabilities:
Property, plant and equipment	3,580	3,228
Regulatory assets	401	601
Investment in ZENS and equity securities related to ZENS	788	722
Other	92	152
Total deferred tax liabilities	4,861	4,703
Net deferred tax liabilities	4,079	3,986
Decreases related to tax positions of prior years	0	(3)
Houston Electric
Deferred tax assets:
Benefits and compensation	10	10
Regulatory liabilities	176	184
Asset retirement obligations	6	6
Other	18	13
Total deferred tax assets	210	213
Deferred tax liabilities:
Property, plant and equipment	1,497	1,330
Regulatory assets	119	112
Total deferred tax liabilities	1,616	1,442
Net deferred tax liabilities	1,406	1,229
CERC Corp
Deferred tax assets:
Benefits and compensation	21	9
Regulatory liabilities	145	151
Loss and credit carryforwards	276	466
Asset retirement obligations	86	86
Other	65	25
Total deferred tax assets	593	737
Deferred tax liabilities:
Property, plant and equipment	1,602	1,427
Regulatory assets	171	381
Other	66	191
Total deferred tax liabilities	1,839	1,999
Net deferred tax liabilities	$ 1,246	$ 1,262