Investments (Rollforward of expected credit-losses, AFS) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Beginning Balance	$ 122	$ 193	$ 156	$ 169
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	23	34	95	172
Debt Securities, Available-for-sale, Allowance for Credit Loss, Writeoff	(1)	(1)	(6)	(5)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Recovery	(69)	(68)	(170)	(178)
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Ending Balance	$ 75	$ 158	$ 75	$ 158

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

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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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