Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8	$ 10	$ 16	$ 20
Interest cost	17	14	32	29
Expected return on plan assets	(23)	(26)	(48)	(52)
Amortization of net loss	7	10	14	19
Settlement cost (benefit)	30	(1)	30	(1)
Net periodic cost (benefit)	39	7	44	15
Total contributions expected in current year	7		7
Total contributions to the plans during the period	2		4
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	0	1	1
Interest cost	2	2	4	4
Expected return on plan assets	(1)	(1)	(2)	(2)
Amortization of prior service cost (credit)	0	(1)	(1)	(2)
Amortization of net loss	(1)	0	(2)	0
Net periodic cost (benefit)	0	0	0	1
Total contributions expected in current year	8		8
Total contributions to the plans during the period	2		4
Other Postretirement Benefits Plan | Houston Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	1	1	2	2
Expected return on plan assets	(1)	(1)	(2)	(2)
Amortization of prior service cost (credit)	(1)	(1)	(2)	(2)
Amortization of net loss	0	0	(1)	0
Net periodic cost (benefit)	(1)	(1)	(3)	(2)
Total contributions expected in current year	1		1
Total contributions to the plans during the period	1		1
Other Postretirement Benefits Plan | CERC
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	0	1
Interest cost	1	0	2	1
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	1	0	1	0
Amortization of net loss	(1)	0	(1)	0
Net periodic cost (benefit)	1	$ 1	2	$ 2
Total contributions expected in current year	4		4
Total contributions to the plans during the period	$ 2		$ 2