Leases (Details) $ in Millions	12 Months Ended			24 Months Ended
	Dec. 31, 2022 USD ($) MW	Dec. 31, 2021 USD ($) MW	Dec. 31, 2020 USD ($)	Dec. 31, 2022 USD ($) MW	Mar. 31, 2020 USD ($)
Lease Disclosure [Line Items]
Operating lease income	$ 5	$ 6
Disallowance of regulatory asset	53			$ 53
Lease, Cost [Abstract]
Operating lease cost	6	8
Short-term lease cost	167	119
Total lease cost	173	127
Operating Leases, Lease Income [Abstract]
Operating lease income	5	6
Variable lease income	2	1
Total lease income	7	7
Assets and Liabilities, Lessee [Abstract]
Operating ROU assets	19	22		19
Finance ROU assets	621	179		621
Total leased assets	640	201		640
Current operating lease liability	5	6		5
Non-current operating lease liability	14	17		14
Total leased liabilities	$ 19	$ 23		$ 19
Weighted-average remaining lease term (in years) - operating leases	4 years 3 months 18 days	6 years 2 months 12 days		4 years 3 months 18 days
Weighted-average discount rate - operating leases (as a percent)	3.80%	3.10%		3.80%
Weighted-average remaining lease term (in years) - finance leases	6 years 6 months	7 years 6 months		6 years 6 months
Weighted-average discount rate - finance leases (as a percent)	3.60%	2.21%		3.60%
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other non-current assets	Other non-current assets		Other non-current assets
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property, Plant and Equipment, net	Property, Plant and Equipment, net		Property, Plant and Equipment, net
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other	Other		Other
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other	Other		Other
Operating Lease Liabilities, Payments Due [Abstract]
2023	$ 5			$ 5
2024	5			5
2025	4			4
2026	4			4
2027	2			2
2028 and beyond	1			1
Total lease payments	21			21
Less: Interest	2			2
Present value of lease liabilities	19	$ 23		19
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2023	7			7
2024	7			7
2025	7			7
2026	7			7
2027	7			7
2028 and beyond	159			159
Total lease payments to be received	194			194
Other Information Related to Leases [Abstract]
Operating cash flows from operating leases included in the measurement of lease liabilities	6
Financing cash flows from finance leases included in the measurement of lease liabilities	485	179	$ 0
Level 2 | Energy Services Disposal Group
Other Information Related to Leases [Abstract]
Fair value of disposal group					$ 402
Houston Electric
Lease Disclosure [Line Items]
Expenses associated with short-term lease	$ 103	$ 20		$ 103
Number of megawatts of mobile generation | MW	505			505
Number of megawatts of mobile generation delivered | MW	380	125		380
Cash payment	$ 485	$ 179		$ 664
Operating lease income	1	1
Escrow deposit	113			113
Expenses associated with long term lease	$ 60	1		$ 60
Right to terminate, lease costs refunded (as a percent)	75.00%			75.00%
Disallowance of reimbursement clause exercised	85.00%
Disallowance of regulatory asset	$ 53			$ 53
Lease, Cost [Abstract]
Operating lease cost	1	1
Short-term lease cost	166	118
Total lease cost	167	119
Operating Leases, Lease Income [Abstract]
Operating lease income	1	1
Variable lease income	0	0
Total lease income	1	1
Assets and Liabilities, Lessee [Abstract]
Operating ROU assets	6	1		6
Finance ROU assets	621	179		621
Total leased assets	627	180		627
Current operating lease liability	1	1		1
Non-current operating lease liability	5	0		5
Total leased liabilities	$ 6	$ 1		$ 6
Weighted-average remaining lease term (in years) - operating leases	4 years 9 months 18 days	4 years 1 month 6 days		4 years 9 months 18 days
Weighted-average discount rate - operating leases (as a percent)	4.01%	2.86%		4.01%
Weighted-average remaining lease term (in years) - finance leases	6 years 6 months	7 years 6 months		6 years 6 months
Weighted-average discount rate - finance leases (as a percent)	3.60%	2.21%		3.60%
Operating Lease Liabilities, Payments Due [Abstract]
2023	$ 1			$ 1
2024	2			2
2025	2			2
2026	1			1
2027	1			1
2028 and beyond	0			0
Total lease payments	7			7
Less: Interest	1			1
Present value of lease liabilities	6	$ 1		6
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2023	1			1
2024	1			1
2025	1			1
2026	0			0
2027	0			0
2028 and beyond	0			0
Total lease payments to be received	3			3
Other Information Related to Leases [Abstract]
Operating cash flows from operating leases included in the measurement of lease liabilities	1
Financing cash flows from finance leases included in the measurement of lease liabilities	485	179	$ 0
CERC Corp
Lease Disclosure [Line Items]
Operating lease income	3	3
Lease, Cost [Abstract]
Operating lease cost	2	4
Short-term lease cost	1	0
Total lease cost	3	4
Operating Leases, Lease Income [Abstract]
Operating lease income	3	3
Variable lease income	0	0
Total lease income	3	3
Assets and Liabilities, Lessee [Abstract]
Operating ROU assets	5	12		5
Finance ROU assets	0	0		0
Total leased assets	5	12		5
Current operating lease liability	2	2		2
Non-current operating lease liability	4	11		4
Total leased liabilities	$ 6	$ 13		$ 6
Weighted-average remaining lease term (in years) - operating leases	3 years 10 months 24 days	6 years 6 months		3 years 10 months 24 days
Weighted-average discount rate - operating leases (as a percent)	3.58%	3.20%		3.58%
Weighted-average discount rate - finance leases (as a percent)	0.00%	0.00%		0.00%
Operating Lease Liabilities, Payments Due [Abstract]
2023	$ 2			$ 2
2024	1			1
2025	1			1
2026	2			2
2027	0			0
2028 and beyond	0			0
Total lease payments	6			6
Less: Interest	0			0
Present value of lease liabilities	6	$ 13		6
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2023	4			4
2024	4			4
2025	4			4
2026	4			4
2027	4			4
2028 and beyond	156			156
Total lease payments to be received	176			$ 176
Other Information Related to Leases [Abstract]
Operating cash flows from operating leases included in the measurement of lease liabilities	2
Financing cash flows from finance leases included in the measurement of lease liabilities	$ 0