Investments - Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities	$ (35)	$ 12	$ (37)	$ 17
Net of tax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	(10)	10	(5)	20
Impairment allowance on securities	(18)	0	(24)	(6)
Realized gains (losses) on securities	(28)	10	(29)	14
Change in unrealized	(266)	58	(356)	159
Total pretax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	(13)	13	(7)	25
Impairment allowance on securities	(22)	(1)	(30)	(8)
Realized gains (losses) on securities	(35)	12	(37)	17
Change in unrealized	(337)	74	(451)	201
Fixed maturities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	(7)	0	(19)	(7)
Impairment allowance on fixed maturity securities	(4)	(1)	(12)	(8)
Realized gains (losses) on securities	(11)	(1)	(31)	(15)
Change in unrealized	(337)	74	(451)	201
Equity securities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	(6)	13	12	32
Realized gains (losses) on securities	(6)	13	12	32
Change in unrealized	0	0	0	0
Mortgage loans and other investments
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	0	0	0	0
Impairment allowance on mortgage loans and other investments	(18)	0	(18)	0
Realized gains (losses) on securities	(18)	0	(18)	0
Change in unrealized	0	0	0	0
Total tax effects
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	3	(3)	2	(5)
Impairment allowance on securities	4	1	6	2
Realized gains (losses) on securities	7	(2)	8	(3)
Change in unrealized	$ 71	$ (16)	$ 95	$ (42)

Change in unrealized appreciation depreciation.

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Increase (decrease) during the period in the allowance for credit losses on investments

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Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments.

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- Definition

Amount of realized gain (loss) on investment in debt and equity securities.

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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).

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount of increase (decrease) in allowance for credit loss on financing receivable.

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Amount of realized gain (loss) on investment in marketable security.

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