Related Party Transactions (Houston Electric and CERC) - Schedule of Affiliated-Related Net Interest Income (Expense) (Details) - Other Nonoperating Income (Expense) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Houston Electric
Related Party Transaction [Line Items]
Interest income (expense), net	$ (1)	$ 1	$ (1)	$ 9
CERC
Related Party Transaction [Line Items]
Interest income (expense), net	$ 0	$ 1	$ 10	$ 2

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details