Investments (Rollforward of expected credit-losses, AFS) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Beginning Balance	$ 63	$ 115	$ 70	$ 156
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	30	41	51	72
Debt Securities, Available-for-sale, Allowance for Credit Loss, Writeoff	(1)	0	(1)	(5)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Recovery	(21)	(34)	(49)	(101)
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Ending Balance	$ 71	$ 122	$ 71	$ 122

Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Amount of increase (decrease) in allowance for credit loss of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
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Amount of increase in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), from recovery.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of writeoff of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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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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