Equity Securities and Indexed Debt Securities (ZENS) (CenterPoint Energy) - Schedule of Reference Shares (Details) - ZENS debt - shares	Dec. 31, 2021	Dec. 31, 2020
AT&T Common
Debt and Equity Securities, FV-NI [Line Items]
Number of shares referenced in exchangeable subordinated note	0.7185	0.7185
Charter Common
Debt and Equity Securities, FV-NI [Line Items]
Number of shares referenced in exchangeable subordinated note	0.061382	0.061382

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