Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7	$ 9	$ 23	$ 29
Interest cost	20	15	52	44
Expected return on plan assets	(21)	(26)	(69)	(78)
Amortization of net loss	8	9	22	28
Settlement cost (benefit)	8	27	38	26
Net periodic cost (benefit)	22	34	66	49
Total contributions expected in current year	7		7
Total contributions to the plans during the period	2		6
Pension Benefits | Houston Electric
Defined Benefit Plan Disclosure [Line Items]
Total contributions expected in current year	0		0
Total contributions to the plans during the period	0		0
Pension Benefits | CERC
Defined Benefit Plan Disclosure [Line Items]
Total contributions expected in current year	0		0
Total contributions to the plans during the period	0		0
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	1	2
Interest cost	3	2	7	6
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of prior service cost (credit)	(1)	(1)	(2)	(3)
Amortization of net loss	(1)	0	(3)	0
Net periodic cost (benefit)	0	1	0	2
Total contributions expected in current year	8		8
Total contributions to the plans during the period	2		6
Other Postretirement Benefits Plan | Houston Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	1	1	3	3
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of prior service cost (credit)	(1)	(1)	(3)	(3)
Amortization of net loss	(1)	0	(2)	0
Net periodic cost (benefit)	(2)	(1)	(5)	(3)
Total contributions expected in current year	1		1
Total contributions to the plans during the period	0		1
Other Postretirement Benefits Plan | CERC
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	0	1	1
Interest cost	1	1	3	2
Expected return on plan assets	(1)	0	(1)	0
Amortization of prior service cost (credit)	0	0	1	0
Amortization of net loss	0	0	(1)	0
Net periodic cost (benefit)	1	$ 1	3	$ 3
Total contributions expected in current year	4		4
Total contributions to the plans during the period	$ 1		$ 3