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Accounting Policies and Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 37	$ 24
Restricted cash included in Prepaid expenses and other current assets	8	6
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	$ 45	$ 30	$ 129	$ 109
Restricted Cash and Cash Equivalent, Statement of Financial Position [Extensible Enumeration]	Prepaid expenses and other current assets	Prepaid expenses and other current assets
VIEs
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 31	$ 21
Houston Electric
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	17	14
Restricted cash included in Prepaid expenses and other current assets	2	0
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	19	14	110	89
Houston Electric \| VIEs
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	15	14
CERC
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	2
Restricted cash included in Prepaid expenses and other current assets	0	0
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	$ 0	$ 2	$ 1	$ 1