Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Discretionary contribution			$ 24
Pension plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6	$ 7	19	$ 23
Interest cost	19	20	57	52
Expected return on plan assets	(19)	(21)	(57)	(69)
Amortization of net loss	7	8	21	22
Settlement cost (benefit)	0	8	0	38
Net periodic cost (benefit)	13	22	40	66
Total contributions expected in current year	31		31
Total contributions to the plans during the period	26		30
Pension plans | 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 plans | 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
Postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	3	3	9	7
Expected return on plan assets	(1)	(1)	(4)	(3)
Amortization of prior service cost (credit)	(1)	(1)	(2)	(2)
Amortization of net loss	(2)	(1)	(6)	(3)
Net periodic cost (benefit)	(1)	0	(2)	0
Total contributions expected in current year	8		8
Total contributions to the plans during the period	1		5
Postretirement benefit plans | Houston Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	1	1	4	3
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of prior service cost (credit)	(1)	(1)	(4)	(3)
Amortization of net loss	(1)	(1)	(3)	(2)
Net periodic cost (benefit)	(2)	(2)	(6)	(5)
Total contributions expected in current year	1		1
Total contributions to the plans during the period	0		0
Postretirement benefit plans | CERC
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	0	1
Interest cost	1	1	3	3
Expected return on plan assets	0	(1)	0	(1)
Amortization of prior service cost (credit)	1	0	2	1
Amortization of net loss	(1)	0	(2)	(1)
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