Equity Securities and Indexed Debt Securities (ZENS) - Schedule of Gain (Loss) On Equity Securities (CenterPoint Energy) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Debt and Equity Securities, FV-NI [Line Items]
Total gains on equity securities, net	$ 45	$ 79
AT&T Common
Debt and Equity Securities, FV-NI [Line Items]
Total gains on equity securities, net	42	56
Charter Common
Debt and Equity Securities, FV-NI [Line Items]
Total gains on equity securities, net	6	23
WBD Common
Debt and Equity Securities, FV-NI [Line Items]
Total gains on equity securities, net	$ (3)	$ 0