Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Estimated Uncollectible Reinsurance - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Credit Loss [Abstract]
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, beginning of period	$ 8,059	$ 8,132	$ 8,000	$ 8,143
Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, end of period	8,298	8,075	8,298	8,075
Reinsurance recoverables, allowance for uncollectible reinsurance [Roll Forward]
Reinsurance recoverables, allowance for uncollectible reinsurance, beginning balance	127	117	119	118
Current period change for estimated uncollectible reinsurance	14	3	22	2
Write-offs of uncollectible reinsurance recoverables	0	0	0	0
Reinsurance recoverables, allowance for uncollectible reinsurance, ending balance	$ 141	$ 120	$ 141	$ 120

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- Definition

Amount of the write-down or write-off of a receivable from a reinsurer.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of expense (reversal of expense) for expected credit loss on reinsurance recoverable.

+ References

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- Definition

Amount of allowance for credit loss on reinsurance recoverable.

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- Definition

Amount, after valuation allowance, recoverable under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, policy benefits and policy reserves. Excludes premiums paid under reinsurance contracts.

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