Investments - Schedule of Gross Realized Gains (Losses) on Sales of Fixed Income Securities (Details) - Fixed income securities - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Debt Securities, Available-for-Sale [Line Items]
Gross realized gains	$ 61	$ 116	$ 185	$ 187
Gross realized losses	$ (178)	$ (367)	$ (301)	$ (565)

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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