Investment Information - Aging of available for sale securities in an unrealized loss position (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	$ 21,742	$ 10,128
Estimated Fair Value - 12 Months or More	2,441	2,765
Estimated Fair Value	24,183	12,893
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	(242)	(121)
Gross Unrealized Losses - 12 Months or More	(173)	(169)
Gross Unrealized Losses	(415)	(290)
Fixed maturities
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	20,636	9,514
Estimated Fair Value - 12 Months or More	2,441	2,765
Estimated Fair Value	23,077	12,279
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	(241)	(120)
Gross Unrealized Losses - 12 Months or More	(173)	(169)
Gross Unrealized Losses	(414)	(289)
Corporate bonds
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	8,333	2,972
Estimated Fair Value - 12 Months or More	1,205	1,364
Estimated Fair Value	9,538	4,336
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	(116)	(64)
Gross Unrealized Losses - 12 Months or More	(82)	(78)
Gross Unrealized Losses	(198)	(142)
U.S. government and government agencies
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	6,483	3,092
Estimated Fair Value - 12 Months or More	128	274
Estimated Fair Value	6,611	3,366
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	(57)	(15)
Gross Unrealized Losses - 12 Months or More	(7)	(6)
Gross Unrealized Losses	(64)	(21)
Non-U.S. government securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	1,976	2,087
Estimated Fair Value - 12 Months or More	489	432
Estimated Fair Value	2,465	2,519
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	(32)	(35)
Gross Unrealized Losses - 12 Months or More	(45)	(46)
Gross Unrealized Losses	(77)	(81)
Asset backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	1,839	806
Estimated Fair Value - 12 Months or More	316	332
Estimated Fair Value	2,155	1,138
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	(15)	(2)
Gross Unrealized Losses - 12 Months or More	(11)	(13)
Gross Unrealized Losses	(26)	(15)
Residential mortgage backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	1,414	312
Estimated Fair Value - 12 Months or More	144	178
Estimated Fair Value	1,558	490
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	(19)	(3)
Gross Unrealized Losses - 12 Months or More	(19)	(18)
Gross Unrealized Losses	(38)	(21)
Commercial mortgage backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	591	239
Estimated Fair Value - 12 Months or More	40	48
Estimated Fair Value	631	287
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	(2)	(1)
Gross Unrealized Losses - 12 Months or More	(5)	(4)
Gross Unrealized Losses	(7)	(5)
Municipal bonds
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	0	6
Estimated Fair Value - 12 Months or More	119	137
Estimated Fair Value	119	143
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	0	0
Gross Unrealized Losses - 12 Months or More	(4)	(4)
Gross Unrealized Losses	(4)	(4)
Short-term investments
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract]
Estimated Fair Value - Less than 12 Months	1,106	614
Estimated Fair Value - 12 Months or More	0	0
Estimated Fair Value	1,106	614
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Gross Unrealized Losses - Less than 12 Months	(1)	(1)
Gross Unrealized Losses - 12 Months or More	0	0
Gross Unrealized Losses	$ (1)	$ (1)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

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