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Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Supplemental Cash Flow Information [Abstract]
Interest, net of capitalized interest	$ 134	$ 159
Income tax refunds, net	(15)	(4)
Accounts payable related to capital expenditures	307	166
ROU assets obtained in exchange for lease liabilities (1)	0	1
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	125		$ 230
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	147	167	254	$ 167
Prepaid Expenses and Other Current Assets
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Restricted cash included in Prepaid expenses and other current assets	22		24
Houston Electric
Supplemental Cash Flow Information [Abstract]
Interest, net of capitalized interest	63	70
Income tax refunds, net	0	0
Accounts payable related to capital expenditures	232	140
ROU assets obtained in exchange for lease liabilities (1)	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	104		214
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	122	159	233	154
Houston Electric \| Bond Companies
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	104		92
Houston Electric \| Prepaid Expenses and Other Current Assets
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Restricted cash included in Prepaid expenses and other current assets	18		19
CERC Corp
Supplemental Cash Flow Information [Abstract]
Interest, net of capitalized interest	24	21
Income tax refunds, net	0	0
Accounts payable related to capital expenditures	79	56
ROU assets obtained in exchange for lease liabilities (1)	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	4		8
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	4	$ 1	8	$ 1
CERC Corp \| Prepaid Expenses and Other Current Assets
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Restricted cash included in Prepaid expenses and other current assets	$ 0		$ 0